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Find video protocols related to scientific articles indexed in Pubmed.
Combined MEK and PI3K inhibition in a mouse model of pancreatic cancer.
Clin. Cancer Res.
PUBLISHED: 10-29-2014
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Purpose: Improved therapeutic approaches are needed for the treatment of pancreatic ductal adenocarcinoma (PDAC). As dual MEK and PI3K inhibition is presently being employed in clinical trials for PDAC patients, we sought to test the efficacy of combined targeting of these pathways in PDAC using both in vitro drug screens and genetically engineered mouse models (GEMMs). Experimental Design: We performed high-throughput screening of >500 human cancer cell lines (including 46 PDAC lines), for sensitivity to 50 clinically-relevant compounds, including MEK and PI3K inhibitors. We tested the top hit in the screen, the MEK1/2 inhibitor, AZD-6244, for efficacy alone or in combination with the PI3K inhibitors, BKM-120 or GDC-0941, in a KRASG12D-driven GEMM that recapitulates the histopathogenesis of human PDAC. Results: In vitro screens revealed that PDAC cell lines are relatively resistant to single-agent therapies. The response profile to the MEK1/2 inhibitor, AZD-6244, was an outlier, showing the highest selective efficacy in PDAC. While MEK inhibition alone was mainly cytostatic, apoptosis was induced when combined with PI3K inhibitors (BKM-120 or GDC-0941). When tested in a PDAC GEMM and compared to the single agents or vehicle controls, the combination delayed tumor formation in the setting of prevention and extended survival when used to treat advanced tumors, although no durable responses were observed. Conclusions: Our studies point to important contributions of MEK and PI3K signaling to PDAC pathogenesis and suggest that dual targeting of these pathways may provide benefit in some PDAC patients.
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Aberrant Expression of Regulatory Cytokine IL-35 and Pattern Recognition Receptor NOD2 in Patients with Allergic Asthma.
Inflammation
PUBLISHED: 10-19-2014
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We investigated the plasma concentration of the novel regulatory cytokine IL-35 and intracytosolic pattern recognition receptors nucleotide-binding oligomerization domain (NOD)-like receptors in granulocytes and explored their potential implication in disease severity monitoring of allergic asthma. The expression of circulating IL-35 and other pro-inflammatory mediators in asthmatic patients or control subjects were evaluated using enzyme-linked immunosorbent assay (ELISA). The intracellular expressions of NOD1 and NOD2 in CCR3+ granulocytes were assessed using flow cytometry. Plasma concentrations of IL-35, IL-17A, basophil activation marker basogranulin, and eosinophilic airway inflammation biomarker periostin were significantly elevated in allergic asthmatic patients compared to non-atopic control subjects (all probability (p) <0.05). Both granulocyte markers exhibited significant and positive correlation with plasma IL-35 concentration in asthmatic patients (all p?
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Granulin-Epithelin Precursor Renders Hepatocellular Carcinoma Cells Resistant to Natural Killer Cytotoxicity.
Cancer Immunol Res
PUBLISHED: 10-14-2014
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Immunoevasion is an emerging hallmark of cancer. Impairment of natural killer (NK) cytotoxicity is a mechanism to evade host immunosurveillance. Granulin-epithelin precursor (GEP) is a hepatic oncofetal protein regulating growth, invasion, and chemoresistance in hepatocellular carcinoma (HCC). We examined the role of GEP in conferring HCC cells the ability to evade NK cytotoxicity. In HCC cell lines, GEP overexpression reduced, whereas GEP suppression enhanced sensitivity to NK cytotoxicity. GEP downregulated surface expression of MHC class I chain-related molecule A (MICA), ligand for NK stimulatory receptor NK group 2 member D (NKG2D), and upregulated human leukocyte antigen-E (HLA-E), ligand for NK inhibitory receptor CD94/NKG2A. Functionally, GEP augmented production of soluble MICA, which suppressed NK activation. Matrix metalloproteinase (MMP)2 and MMP9 activity was involved partly in the GEP-regulated MICA shedding from HCC cells. In primary HCCs (n = 80), elevated GEP (P < 0.001), MICA (P < 0.001), and HLA-E (P = 0.089) expression was observed when compared with those in nontumor (n = 80) and normal livers (n = 10). Serum GEP (P = 0.010) and MICA (P < 0.001) levels were higher in patients with HCC (n = 80) than in healthy individuals (n = 30). High serum GEP and/or MICA levels were associated with poor recurrence-free survival (log-rank test, P = 0.042). Importantly, GEP blockade by mAbs sensitized HCC cells to NK cytotoxicity through MICA. In summary, GEP rendered HCC cells resistant to NK cytotoxicity by modulating MICA expression, which could be reversed by GEP blockade using antibody. Serum GEP and MICA levels are prognostic factors and can be used to stratify patients for targeted therapy. Cancer Immunol Res; 2(12); 1-11. ©2014 AACR.
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MUC1-C confers EMT and KRAS independence in mutant KRAS lung cancer cells.
Oncotarget
PUBLISHED: 09-24-2014
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Non-small cell lung cancers (NSCLCs) that harbor an oncogenic KRAS mutation are often associated with resistance to targeted therapies. The MUC1-C transmembrane protein is aberrantly overexpressed in NSCLCs and confers a poor outcome; however, the functional role for MUC1-C in mutant KRAS NSCLC cells has remained unclear. The present studies demonstrate that silencing MUC1-C in A549/KRAS(G12S) and H460/KRAS(Q61H) NSCLC cells is associated with downregulation of AKT signaling and inhibition of growth. Overexpression of a MUC1-C(CQC?AQA) mutant, which inhibits MUC1-C homodimerization and function, suppressed both AKT and MEK activation. Moreover, treatment with GO-203, an inhibitor of MUC1-C homodimerization, blocked AKT and MEK signaling and decreased cell survival. The results further demonstrate that targeting MUC1-C suppresses expression of the ZEB1 transcriptional repressor by an AKT-mediated mechanism, and in turn induces miR-200c. In concert with these effects on the ZEB1/miR-200c regulatory loop, targeting MUC1-C was associated with reversal of the epithelial-mesenchymal transition (EMT) and inhibition of self-renewal capacity. Loss of MUC1-C function also attenuated KRAS independence and inhibited growth of KRAS mutant NSCLC cells as tumors in mice. These findings support a model in which targeting MUC1-C inhibits mutant KRAS signaling in NSCLC cells and thereby reverses the EMT phenotype and decreases self-renewal.
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Targeting the Oncogenic MUC1-C Protein Inhibits Mutant EGFR-Mediated Signaling and Survival in Non-Small Cell Lung Cancer Cells.
Clin. Cancer Res.
PUBLISHED: 09-04-2014
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Non-small cell lung cancers (NSCLC) that express EGF receptor with activating mutations frequently develop resistance to EGFR kinase inhibitors. The mucin 1 (MUC1) heterodimeric protein is aberrantly overexpressed in NSCLC cells and confers a poor prognosis; however, the functional involvement of MUC1 in mutant EGFR signaling is not known.
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Upregulation of IGF1R by Mutant RAS in Leukemia and Potentiation of RAS Signaling Inhibitors by Small-Molecule Inhibition of IGF1R.
Clin. Cancer Res.
PUBLISHED: 09-03-2014
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Activating mutations in the RAS oncogene occur frequently in human leukemias. Direct targeting of RAS has proven to be challenging, although targeting of downstream RAS mediators, such as MEK, is currently being tested clinically. Given the complexity of RAS signaling, it is likely that combinations of targeted agents will be more effective than single agents.
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Catalytically impaired fluorescent Class C ?-lactamase enables rapid and sensitive cephalosporin detection by stabilizing fluorescence signals: Implications for biosensor design.
Biotechnol J
PUBLISHED: 09-02-2014
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Biosensors have found applications in many sectors including the food industry, where cephalosporin detection has played an important role in reducing the incidence of cephalosporin contamination, ensuring food safety, and reducing the spread of antibiotic resistance. Taking advantage of the specific interaction between ?-lactamase and its cephalosporin substrates/inhibitors, we previously constructed a biosensor based on a fluorescein-labeled class C ?-lactamase mutant, V211Cf, for specific and reagentless detection of cephalosporins and class C ?-lactamase inhibitors (Anal. Chem. 2011, 83, 1996-2004). Upon the addition of substrate/ inhibitor (i.e. the biosensor's analyte), the analyte induced a change in the local environment of the fluorescein molecule that was covalently tethered to a site close to the enzyme's active site (the 211 position), triggering a fluorescence enhancement of V211Cf. To improve the performance of V211Cf for better cephalosporin detection of the biosensor, we have developed Y150S/V211Cf, a derivative of V211Cf constructed by introducing the Y150S mutation to suppress the hydrolytic activity of V211Cf thereby improving the stability of the fluorescence signal. From our results, Y150S/V211Cf not only demonstrated improved fluorescence signal sustainability over V211Cf, but also showed a rapid response towards cephalothin (a first generation cephalosporin). These features make it feasible to of use Y150S/V211Cf for the rapid and specific detection of cephalosporins, and illustrate the possibilities for rational biosensor design of catalytically impaired fluorescent enzymes for rapid and sensitive analyte detection purposes.
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Rationale for co-targeting IGF-1R and ALK in ALK fusion-positive lung cancer.
Nat. Med.
PUBLISHED: 08-31-2014
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Crizotinib, a selective tyrosine kinase inhibitor (TKI), shows marked activity in patients whose lung cancers harbor fusions in the gene encoding anaplastic lymphoma receptor tyrosine kinase (ALK), but its efficacy is limited by variable primary responses and acquired resistance. In work arising from the clinical observation of a patient with ALK fusion-positive lung cancer who had an exceptional response to an insulin-like growth factor 1 receptor (IGF-1R)-specific antibody, we define a therapeutic synergism between ALK and IGF-1R inhibitors. Similar to IGF-1R, ALK fusion proteins bind to the adaptor insulin receptor substrate 1 (IRS-1), and IRS-1 knockdown enhances the antitumor effects of ALK inhibitors. In models of ALK TKI resistance, the IGF-1R pathway is activated, and combined ALK and IGF-1R inhibition improves therapeutic efficacy. Consistent with this finding, the levels of IGF-1R and IRS-1 are increased in biopsy samples from patients progressing on crizotinib monotherapy. Collectively these data support a role for the IGF-1R-IRS-1 pathway in both ALK TKI-sensitive and ALK TKI-resistant states and provide a biological rationale for further clinical development of dual ALK and IGF-1R inhibitors.
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?-Catenin Contributes to Lung Tumor Development Induced by EGFR Mutations.
Cancer Res.
PUBLISHED: 08-27-2014
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The discovery of somatic mutations in EGFR and development of EGFR tyrosine kinase inhibitors (TKI) have revolutionized treatment for lung cancer. However, resistance to TKIs emerges in almost all patients and currently no effective treatment is available. Here, we show that ?-catenin is essential for development of EGFR-mutated lung cancers. ?-Catenin was upregulated and activated in EGFR-mutated cells. Mutant EGFR preferentially bound to and tyrosine phosphorylated ?-catenin, leading to an increase in ?-catenin-mediated transactivation, particularly in cells harboring the gefitinib/erlotinib-resistant gatekeeper EGFR-T790M mutation. Pharmacologic inhibition of ?-catenin suppressed EGFR-L858R-T790M mutated lung tumor growth, and genetic deletion of the ?-catenin gene dramatically reduced lung tumor formation in EGFR-L858R-T790M transgenic mice. These data suggest that ?-catenin plays an essential role in lung tumorigenesis and that targeting the ?-catenin pathway may provide novel strategies to prevent lung cancer development or overcome resistance to EGFR TKIs. Cancer Res; 74(20); 5891-902. ©2014 AACR.
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Non-small-cell lung cancers: a heterogeneous set of diseases.
Nat. Rev. Cancer
PUBLISHED: 07-25-2014
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Non-small-cell lung cancers (NSCLCs), the most common lung cancers, are known to have diverse pathological features. During the past decade, in-depth analyses of lung cancer genomes and signalling pathways have further defined NSCLCs as a group of distinct diseases with genetic and cellular heterogeneity. Consequently, an impressive list of potential therapeutic targets was unveiled, drastically altering the clinical evaluation and treatment of patients. Many targeted therapies have been developed with compelling clinical proofs of concept; however, treatment responses are typically short-lived. Further studies of the tumour microenvironment have uncovered new possible avenues to control this deadly disease, including immunotherapy.
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Kinase domain activation of FGFR2 yields high-grade lung adenocarcinoma sensitive to a Pan-FGFR inhibitor in a mouse model of NSCLC.
Cancer Res.
PUBLISHED: 07-17-2014
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Somatic mutations in FGFR2 are present in 4% to 5% of patients diagnosed with non-small cell lung cancer (NSCLC). Amplification and mutations in FGFR genes have been identified in patients with NSCLCs, and clinical trials are testing the efficacy of anti-FGFR therapies. FGFR2 and other FGFR kinase family gene alterations have been found in both lung squamous cell carcinoma and lung adenocarcinoma, although mouse models of FGFR-driven lung cancers have not been reported. Here, we generated a genetically engineered mouse model (GEMM) of NSCLC driven by a kinase domain mutation in FGFR2. Combined with p53 ablation, primary grade 3/4 adenocarcinoma was induced in the lung epithelial compartment exhibiting locally invasive and pleiotropic tendencies largely made up of multinucleated cells. Tumors were acutely sensitive to pan-FGFR inhibition. This is the first FGFR2-driven lung cancer GEMM, which can be applied across different cancer indications in a preclinical setting.
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Neurotrophin receptor TrkB promotes lung adenocarcinoma metastasis.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 06-30-2014
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Lung cancer is notorious for its ability to metastasize, but the pathways regulating lung cancer metastasis are largely unknown. An in vitro system designed to discover factors critical for lung cancer cell migration identified brain-derived neurotrophic factor, which stimulates cell migration through activation of tropomyosin-related kinase B (TrkB; also called NTRK2). Knockdown of TrkB in human lung cancer cell lines significantly decreased their migratory and metastatic ability in vitro and in vivo. In an autochthonous lung adenocarcinoma model driven by activated oncogenic Kras and p53 loss, TrkB deficiency significantly reduced metastasis. Hypoxia-inducible factor-1 directly regulated TrkB expression, and, in turn, TrkB activated Akt signaling in metastatic lung cancer cells. Finally, TrkB expression was correlated with metastasis in patient samples, and TrkB was detected more often in tumors that did not have Kras or epidermal growth factor receptor mutations. These studies demonstrate that TrkB is an important therapeutic target in metastatic lung adenocarcinoma.
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Antimicrobial activity of a quinuclidine-based FtsZ inhibitor and its synergistic potential with ?-lactam antibiotics.
J. Antibiot.
PUBLISHED: 06-10-2014
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Filamenting temperature-sensitive mutant Z (FtsZ) is an essential cell division protein that cooperates in the formation of the cytokinetic Z-ring in most bacteria and has thus been recognized as a promising antimicrobial drug target. We have recently used a structure-based virtual screening approach to identify pyrimidine-linked quinuclidines as a novel class of FtsZ inhibitors. In this study, we further investigated the antibacterial properties of one of the most potent compounds (quinuclidine 1) and its synergistic activity with ?-lactam antibiotics. Susceptibility results showed that quinuclidine 1 was active against multiple antibiotic-resistant bacterial strains including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium with minimal inhibitory concentrations of 24??g?ml(-1). When quinuclidine 1 was combined with ?-lactam antibiotics, synergistic antimicrobial activities against antibiotic-resistant strains of S. aureus were found. Further in vitro studies suggest that prevention of FtsZ protofilament formation by quinuclidine 1 impairs the formation of Z-ring, and thus inhibits bacterial division. These findings open a new approach for development of quinuclidine-based FtsZ inhibitors into potent antimicrobial agents.The Journal of Antibiotics advance online publication, 8 October 2014; doi:10.1038/ja.2014.140.
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The indispensable value of clinical trials in the modernization of traditional Chinese medicine: 12 years' experience at CUHK and future perspectives.
Am. J. Chin. Med.
PUBLISHED: 05-30-2014
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The last decade has seen a wealth of information reporting the beneficial effects of Chinese herbal medicines. While a lot more studies were done using in vitro and in vivo research platforms, much fewer investigations were conducted according to evidence-based requirements in clinical settings. The Institute of Chinese Medicine at the Chinese University of Hong Kong (CUHK) has had the opportunity to collaborate with clinicians over the years to initiate and conduct dozens of clinical trials investigating and verifying the therapeutic values of Chinese herbs in selected disease conditions. Of the many disorders, we chose to focus on those that are known for their difficulties achieving perfect results with conventional treatment methods. Examples include non-healing ulcers, allergic conditions, degenerative diseases and cancer. Protective effects of the herbs in such chronic diseases as coronary artery disease and osteoporosis were also part of our focus. Even in healthy individuals and those recovering from chemotherapy, Chinese herbs could help with the immune system and were studied in our clinical trials as well. This paper aims to highlight the important findings from these clinical studies while at the same time, stressing the indispensable value of clinical trials in modernizing the use of Chinese herbs in present-day medicine.
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Mutant IDH inhibits HNF-4? to block hepatocyte differentiation and promote biliary cancer.
Nature
PUBLISHED: 05-02-2014
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Mutations in isocitrate dehydrogenase 1 (IDH1) and IDH2 are among the most common genetic alterations in intrahepatic cholangiocarcinoma (IHCC), a deadly liver cancer. Mutant IDH proteins in IHCC and other malignancies acquire an abnormal enzymatic activity allowing them to convert ?-ketoglutarate (?KG) to 2-hydroxyglutarate (2HG), which inhibits the activity of multiple ?KG-dependent dioxygenases, and results in alterations in cell differentiation, survival, and extracellular matrix maturation. However, the molecular pathways by which IDH mutations lead to tumour formation remain unclear. Here we show that mutant IDH blocks liver progenitor cells from undergoing hepatocyte differentiation through the production of 2HG and suppression of HNF-4?, a master regulator of hepatocyte identity and quiescence. Correspondingly, genetically engineered mouse models expressing mutant IDH in the adult liver show an aberrant response to hepatic injury, characterized by HNF-4? silencing, impaired hepatocyte differentiation, and markedly elevated levels of cell proliferation. Moreover, IDH and Kras mutations, genetic alterations that co-exist in a subset of human IHCCs, cooperate to drive the expansion of liver progenitor cells, development of premalignant biliary lesions, and progression to metastatic IHCC. These studies provide a functional link between IDH mutations, hepatic cell fate, and IHCC pathogenesis, and present a novel genetically engineered mouse model of IDH-driven malignancy.
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Epiphyseal osteosarcoma revisited: four illustrative cases with unusual histopathology and literature review.
APMIS
PUBLISHED: 04-22-2014
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Osteosarcomas arising in the epiphysis are extremely rare and easily missed in the diagnostic consideration of epiphyseal tumors. It is the purpose of this study to delineate the clinical pathological characteristics of 'epiphyseal osteosarcoma' under the definition of 'a solitary long bone osteosarcoma radiographically considered an epiphyseal tumor for which the main radiologic differential diagnosis would encompass giant cell tumor, chondroblastoma and clear cell chondrosarcoma'. Four such cases with unusual histopathology were retrieved among 110 cases of osteosarcoma. Their clinical, radiological and pathological features, together with all 10 reported cases, were analyzed. The radiographic diagnoses of our four cases include two giant cell tumors, one chondroblastoma and one clear cell chondrosarcoma but turn out to be fibroblastic, giant cell rich, telangiectatic and epithelioid variant of epiphyseal osteosarcoma. Including our patients, the 14 reported epiphyseal osteosarcomas comprise 8 males and 6 females, the age at presentation ranges from 11 to 39 years, two-third in the second decade, 71.4% affect the femur. Due to their epiphyseal locations, many carry benign radiological diagnoses notably giant cell tumor and chondroblastoma. Epiphyseal osteosarcomas may not only masquerade as benign radiological bony lesions but also assume many histological patterns; orthopedic surgeons, radiologists and pathologists should be aware of such possibility. Their behavior and prognosis are dictated by the histologic types, grading and staging rather than location.
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Evaluating TBK1 as a therapeutic target in cancers with activated IRF3.
Mol. Cancer Res.
PUBLISHED: 04-21-2014
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TBK1 (TANK-binding kinase 1) is a noncanonical I?B protein kinase that phosphorylates and activates downstream targets such as IRF3 and c-Rel and, mediates NF-?B activation in cancer. Previous reports demonstrated synthetic lethality of TBK1 with mutant KRAS in non-small cell lung cancer (NSCLC); thus, TBK1 could be a novel target for treatment of KRAS-mutant NSCLC. Here, the effect of TBK1 on proliferation in a panel of cancer cells by both genetic and pharmacologic approaches was evaluated. In KRAS-mutant cancer cells, reduction of TBK1 activity by knockdown or treatment with TBK1 inhibitors did not correlate with reduced proliferation in a two-dimensional viability assay. Verification of target engagement via reduced phosphorylation of S386 of IRF3 (pIRF3(S386)) was difficult to assess in NSCLC cells due to low protein expression. However, several cell lines were identified with high pIRF3(S386) levels after screening a large panel of cell lines, many of which also harbor KRAS mutations. Specifically, a large subset of KRAS-mutant pancreatic cancer cell lines was uncovered with high constitutive pIRF3(S386) levels, which correlated with high levels of phosphorylated S172 of TBK1 (pTBK1(S172)). Finally, TBK1 inhibitors dose-dependently inhibited pIRF3(S386) in these cell lines, but this did not correlate with inhibition of cell growth. Taken together, these data demonstrate that the regulation of pathways important for cell proliferation in some NSCLC, pancreatic, and colorectal cell lines is not solely dependent on TBK1 activity.
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Hairpin DNA probes based on target-induced in situ generation of luminescent silver nanoclusters.
Chem. Commun. (Camb.)
PUBLISHED: 04-02-2014
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Novel hairpin DNA probes are designed and constructed based on target-induced in situ generation of luminescent silver nanoclusters. This design allows specific and versatile detection of diverse targets with easy operation and low cost.
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Failure to induce apoptosis via BCL-2 family proteins underlies lack of efficacy of combined MEK and PI3K inhibitors for KRAS-mutant lung cancers.
Cancer Res.
PUBLISHED: 03-27-2014
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Although several groups have demonstrated that concomitant use of MEK and phosphoinositide 3-kinase (PI3K) inhibitors (MEKi/PI3Ki) can induce dramatic tumor regressions in mouse models of KRAS-mutant non-small cell lung cancer (NSCLC), ongoing clinical trials investigating this strategy have been underwhelming to date. While efficacy may be hampered by a narrow therapeutic index, the contribution of biologic heterogeneity in the response of KRAS-mutant NSCLCs to MEKi/PI3Ki has been largely unexplored. In this study, we find that most human KRAS-mutant NSCLC cell lines fail to undergo marked apoptosis in response to MEKi/PI3Ki, which is key for tumor responsiveness in vivo. This heterogeneity of apoptotic response occurs despite relatively uniform induction of growth arrest. Using a targeted short hairpin RNA screen of BCL-2 family members, we identify BIM, PUMA, and BCL-XL as key regulators of the apoptotic response induced by MEKi/PI3Ki, with decreased expression of BIM and PUMA relative to BCL-XL in cell lines with intrinsic resistance. In addition, by modeling adaptive resistance to MEKi/PI3Ki both in vitro and in vivo, we find that, upon the development of resistance, tumors have a diminished apoptotic response due to downregulation of BIM and PUMA. These results suggest that the inability to induce apoptosis may limit the effectiveness of MEKi/PI3Ki for KRAS-mutant NSCLCs by contributing to intrinsic and adaptive resistance to this therapy.
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D-2-hydroxyglutarate produced by mutant IDH2 causes cardiomyopathy and neurodegeneration in mice.
Genes Dev.
PUBLISHED: 03-05-2014
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Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2) have been discovered in several cancer types and cause the neurometabolic syndrome D2-hydroxyglutaric aciduria (D2HGA). The mutant enzymes exhibit neomorphic activity resulting in production of D2-hydroxyglutaric acid (D-2HG). To study the pathophysiological consequences of the accumulation of D-2HG, we generated transgenic mice with conditionally activated IDH2(R140Q) and IDH2(R172K) alleles. Global induction of mutant IDH2 expression in adults resulted in dilated cardiomyopathy, white matter abnormalities throughout the central nervous system (CNS), and muscular dystrophy. Embryonic activation of mutant IDH2 resulted in more pronounced phenotypes, including runting, hydrocephalus, and shortened life span, recapitulating the abnormalities observed in D2HGA patients. The diseased hearts exhibited mitochondrial damage and glycogen accumulation with a concordant up-regulation of genes involved in glycogen biosynthesis. Notably, mild cardiac hypertrophy was also observed in nude mice implanted with IDH2(R140Q)-expressing xenografts, suggesting that 2HG may potentially act in a paracrine fashion. Finally, we show that silencing of IDH2(R140Q) in mice with an inducible transgene restores heart function by lowering 2HG levels. Together, these findings indicate that inhibitors of mutant IDH2 may be beneficial in the treatment of D2HGA and suggest that 2HG produced by IDH mutant tumors has the potential to provoke a paraneoplastic condition.
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Structure-based Design, Synthesis, and Biological Evaluation of Isatin Derivatives as Potential Glycosyltransferase Inhibitors.
Chem Biol Drug Des
PUBLISHED: 03-04-2014
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Peptidoglycan glycosyltransferase (PGT) has been shown to be an important pharmacological target for the inhibition of bacterial cell wall biosynthesis. Structure-based virtual screening of about 3 000 000 commercially available compounds against the crystal structure of the glycosyltransferase (GT) domain of the Staphylococcus aureus penicillin-binding protein 2 (S. aureus PBP2) resulted in identification of an isatin derivative, 2-(3-(2-carbamimidoylhydrazono)-2-oxoindolin-1-yl)-N-(m-tolyl)acetamide (4) as a novel potential GT inhibitor. A series of 4 derivatives were synthesized. Several compounds showed more active antimicrobial activity than the initial hit compound 4, in particular 2-(3-(2-carbamimidoylhydrazono)-2-oxoindolin-1-yl)-N-(3-nitrophenyl)acetamide (4l), against Gram-positive Bacillus subtilis and S. aureus with MIC values of 24 and 48 ?g/mL, respectively. Saturation transfer difference (STD) NMR study revealed that there is a binding contact between 4l and the GT domain of S. aureus PBP2. Competitive STD-NMR further proved that 4l and moenomycin A bind to GT domain in a competitive manner. Molecular docking study suggests a potential binding pocket of 4l in the GT domain of S. aureus PBP2. Taken together, compound 4l would provide a new scaffold for further development of potent GT inhibitors.
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Calcium-dependent FAK/CREB/TNNC1 signalling mediates the effect of stromal MFAP5 on ovarian cancer metastatic potential.
Nat Commun
PUBLISHED: 03-03-2014
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Ovarian cancer is the most lethal gynaecologic malignancy in the United States, and advanced serous ovarian adenocarcinoma is responsible for most ovarian cancer deaths. However, the stroma-derived molecular determinants that modulate patient survival are yet to be characterized. Here we identify a stromal gene signature for advanced high-grade serous ovarian cancer using microdissected stromal ovarian tumour samples and find that stromal microfibrillar-associated protein 5 (MFAP5) is a prognostic marker for poor survival. Further functional studies reveal that FAK/CREB/TNNC1 signalling pathways mediate the effect of MFAP5 on ovarian cancer cell motility and invasion potential. Targeting stromal MFAP5 using MFAP5-specific siRNA encapsulated in chitosan nanoparticles significantly decreases ovarian tumour growth and metastasis in vivo, suggesting that it may be a new modality of ovarian cancer treatment.
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SOX2 and p63 colocalize at genetic loci in squamous cell carcinomas.
J. Clin. Invest.
PUBLISHED: 03-03-2014
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The transcription factor SOX2 is an essential regulator of pluripotent stem cells and promotes development and maintenance of squamous epithelia. We previously reported that SOX2 is an oncogene and subject to highly recurrent genomic amplification in squamous cell carcinomas (SCCs). Here, we have further characterized the function of SOX2 in SCC. Using ChIP-seq analysis, we compared SOX2-regulated gene profiles in multiple SCC cell lines to ES cell profiles and determined that SOX2 binds to distinct genomic loci in SCCs. In SCCs, SOX2 preferentially interacts with the transcription factor p63, as opposed to the transcription factor OCT4, which is the preferred SOX2 binding partner in ES cells. SOX2 and p63 exhibited overlapping genomic occupancy at a large number of loci in SCCs; however, coordinate binding of SOX2 and p63 was absent in ES cells. We further demonstrated that SOX2 and p63 jointly regulate gene expression, including the oncogene ETV4, which was essential for SOX2-amplified SCC cell survival. Together, these findings demonstrate that the action of SOX2 in SCC differs substantially from its role in pluripotency. The identification of the SCC-associated interaction between SOX2 and p63 will enable deeper characterization the downstream targets of this interaction in SCC and normal squamous epithelial physiology.
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Alterations of LKB1 and KRAS and risk of brain metastasis: Comprehensive characterization by mutation analysis, copy number, and gene expression in non-small-cell lung carcinoma.
Lung Cancer
PUBLISHED: 03-02-2014
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Brain metastases are one of the most malignant complications of lung cancer and constitute a significant cause of cancer related morbidity and mortality worldwide. Recent years of investigation suggested a role of LKB1 in NSCLC development and progression, in synergy with KRAS alteration. In this study, we systematically analyzed how LKB1 and KRAS alteration, measured by mutation, gene expression (GE) and copy number (CN), are associated with brain metastasis in NSCLC.
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Rescue of Hippo coactivator YAP1 triggers DNA damage-induced apoptosis in hematological cancers.
Nat. Med.
PUBLISHED: 02-25-2014
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Oncogene-induced DNA damage elicits genomic instability in epithelial cancer cells, but apoptosis is blocked through inactivation of the tumor suppressor p53. In hematological cancers, the relevance of ongoing DNA damage and the mechanisms by which apoptosis is suppressed are largely unknown. We found pervasive DNA damage in hematologic malignancies, including multiple myeloma, lymphoma and leukemia, which leads to activation of a p53-independent, proapoptotic network centered on nuclear relocalization of ABL1 kinase. Although nuclear ABL1 triggers cell death through its interaction with the Hippo pathway coactivator YAP1 in normal cells, we show that low YAP1 levels prevent nuclear ABL1-induced apoptosis in these hematologic malignancies. YAP1 is under the control of a serine-threonine kinase, STK4. Notably, genetic inactivation of STK4 restores YAP1 levels, triggering cell death in vitro and in vivo. Our data therefore identify a new synthetic-lethal strategy to selectively target cancer cells presenting with endogenous DNA damage and low YAP1 levels.
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Neuropsychiatric disturbance after aneurysmal subarachnoid hemorrhage.
J Clin Neurosci
PUBLISHED: 02-23-2014
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Although aneurysmal subarachnoid hemorrhage (aSAH) accounts for only 3-5% of all strokes, a high degree of morbidity has been reported in this relatively young subset of patients. Neuropsychiatric disturbance has often been neglected in these reports. We aimed to investigate the pattern and pathological factors of chronic neuropsychiatric disturbance in aSAH patients. This cross-sectional observational four-center study was carried out in Hong Kong. Neuropsychiatric outcome (Neuropsychiatric Inventory Chinese Version [CNPI]) assessments were conducted cross-sectionally 1-4 years after ictus. Pathological factors considered were early brain injury as assessed by admission World Federation of Neurosurgical Societies grade, aneurysm treatment (clipping versus coiling), delayed cerebral infarction, and chronic hydrocephalus. One hundred and three aSAH patients' spouses or caregivers completed the CNPI. Forty-two (41%) patients were reported to have one or more domain(s) of neuropsychiatric disturbance. Common neuropsychiatric disturbance domains included agitation/aggression, depression, apathy/indifference, irritability/lability, and appetite/eating disturbance. Chronic neuropsychiatric disturbance was associated with presence of chronic hydrocephalus. A subscore consisting of the five commonly affected domains seems to be a suitable tool for aSAH patients and should be further validated and replicated in future studies.
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Targeting an IKBKE cytokine network impairs triple-negative breast cancer growth.
J. Clin. Invest.
PUBLISHED: 02-19-2014
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Triple-negative breast cancers (TNBCs) are a heterogeneous set of cancers that are defined by the absence of hormone receptor expression and estrogen-related receptor ? (ERBB2) amplification. Here, we found that inducible I?B kinase-related (IKK-related) kinase IKBKE expression and JAK/STAT pathway activation compose a cytokine signaling network in the immune-activated subset of TNBC. We found that treatment of cultured IKBKE-driven breast cancer cells with CYT387, a potent inhibitor of TBK1/IKBKE and JAK signaling, impairs proliferation, while inhibition of JAK alone does not. CYT387 treatment inhibited activation of both NF-?B and STAT and disrupted expression of the protumorigenic cytokines CCL5 and IL-6 in these IKBKE-driven breast cancer cells. Moreover, in 3D culture models, the addition of CCL5 and IL-6 to the media not only promoted tumor spheroid dispersal but also stimulated proliferation and migration of endothelial cells. Interruption of cytokine signaling by CYT387 in vivo impaired the growth of an IKBKE-driven TNBC cell line and patient-derived xenografts (PDXs). A combination of CYT387 therapy with a MEK inhibitor was particularly effective, abrogating tumor growth and angiogenesis in an aggressive PDX model of TNBC. Together, these findings reveal that IKBKE-associated cytokine signaling promotes tumorigenicity of immune-driven TNBC and identify a potential therapeutic strategy using clinically available compounds.
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A randomized placebo controlled trial of an innovative herbal formula in the prevention of atherosclerosis in postmenopausal women with borderline hypercholesterolemia.
Complement Ther Med
PUBLISHED: 02-10-2014
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Danshen (Salvia miltiorrhiza) and Gegen (Radix puerariae) (D&G) are two herbs frequently used for the treatment of angina and other cardiac symptoms in Chinese materia medica. Recent studies have demonstrated their cardio-protective and anti-atherosclerosis effects. Earlier we have conducted two clinical trials in 2004 and 2007 which demonstrated such effects in extremely high risk patients.
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Tumor-propagating cells and Yap/Taz activity contribute to lung tumor progression and metastasis.
EMBO J.
PUBLISHED: 02-04-2014
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Metastasis is the leading cause of morbidity for lung cancer patients. Here we demonstrate that murine tumor propagating cells (TPCs) with the markers Sca1 and CD24 are enriched for metastatic potential in orthotopic transplantation assays. CD24 knockdown decreased the metastatic potential of lung cancer cell lines resembling TPCs. In lung cancer patient data sets, metastatic spread and patient survival could be stratified with a murine lung TPC gene signature. The TPC signature was enriched for genes in the Hippo signaling pathway. Knockdown of the Hippo mediators Yap1 or Taz decreased in vitro cellular migration and transplantation of metastatic disease. Furthermore, constitutively active Yap was sufficient to drive lung tumor progression in vivo. These results demonstrate functional roles for two different pathways, CD24-dependent and Yap/Taz-dependent pathways, in lung tumor propagation and metastasis. This study demonstrates the utility of TPCs for identifying molecules contributing to metastatic lung cancer, potentially enabling the therapeutic targeting of this devastating disease.
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Primary osseous inflammatory malignant fibrous histiocytoma masquerading as chronic osteomyelitis.
Orthopedics
PUBLISHED: 02-03-2014
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Inflammatory malignant fibrous histiocytoma, in addition to a mass lesion, may present with fever and other constitutional symptoms, mimicking an infectious process. This article presents an extremely rare and unique case of primary osseous inflammatory malignant fibrous histiocytoma, highlighting retrospectively the subtle clinical, radiologic, and pathologic features that can suggest this diagnosis. A 63-year-old woman with a history of nephrectomy for right kidney tuberculosis 20 years ago presented with slowly increasing left hip pain for 6 months. The relatively benign-appearing radiograph and biopsy report of chronic inflammation resulted in curettage and nailing of the lesion. The pathologic diagnosis was chronic osteomyelitis, but culture findings for bacteria and tuberculosis were negative. The patient remained well until 4 months later, when left thigh pain returned with fever and leukocytosis (white blood cell count as high as 20.7×10(9)/L, 80% neutrophils). No source of infection was localized. The patient showed no response to broad-spectrum antibiotics and antituberculous drugs. Radiographs showed substantial enlargement of the femoral lesion and extraosseous extension; biopsy results and review of previous histopathologic findings led to a diagnosis of inflammatory malignant fibrous histiocytoma. The fever gradually resolved and the white blood cell count returned to normal within a few days after segmental resection of the proximal femur tumor and its soft tissue extension. However, deep venous thrombosis developed, resulting in left foot ischemia and toe gangrene, necessitating left below-the-knee amputation. Disseminated metastasis occurred 3 months after tumor resection. The patient declined further aggressive treatment and died 13 months after initial presentation.
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Loss of Lkb1 and Pten leads to lung squamous cell carcinoma with elevated PD-L1 expression.
Cancer Cell
PUBLISHED: 01-29-2014
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Lung squamous cell carcinoma (SCC) is a deadly disease for which current treatments are inadequate. We demonstrate that biallelic inactivation of Lkb1 and Pten in the mouse lung leads to SCC that recapitulates the histology, gene expression, and microenvironment found in human disease. Lkb1;Pten null (LP) tumors expressed the squamous markers KRT5, p63 and SOX2, and transcriptionally resembled the basal subtype of human SCC. In contrast to mouse adenocarcinomas, the LP tumors contained immune populations enriched for tumor-associated neutrophils. SCA1(+)NGFR(+) fractions were enriched for tumor-propagating cells (TPCs) that could serially transplant the disease in orthotopic assays. TPCs in the LP model and NGFR(+) cells in human SCCs highly expressed Pd-ligand-1 (PD-L1), suggesting a mechanism of immune escape for TPCs.
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Rapamycin prevents the development and progression of mutant epidermal growth factor receptor lung tumors with the acquired resistance mutation T790M.
Cell Rep
PUBLISHED: 01-27-2014
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Lung cancer in never-smokers is an important disease often characterized by mutations in epidermal growth factor receptor (EGFR), yet risk reduction measures and effective chemopreventive strategies have not been established. We identify mammalian target of rapamycin (mTOR) as potentially valuable target for EGFR mutant lung cancer. mTOR is activated in human lung cancers with EGFR mutations, and this increases with acquisition of T790M mutation. In a mouse model of EGFR mutant lung cancer, mTOR activation is an early event. As a single agent, the mTOR inhibitor rapamycin prevents tumor development, prolongs overall survival, and improves outcomes after treatment with an irreversible EGFR tyrosine kinase inhibitor (TKI). These studies support clinical testing of mTOR inhibitors in order to prevent the development and progression of EGFR mutant lung cancers.
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Inhibition of KRAS-driven tumorigenicity by interruption of an autocrine cytokine circuit.
Cancer Discov
PUBLISHED: 01-20-2014
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Although the roles of mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K) signaling in KRAS-driven tumorigenesis are well established, KRAS activates additional pathways required for tumor maintenance, the inhibition of which are likely to be necessary for effective KRAS-directed therapy. Here, we show that the I?B kinase (IKK)-related kinases Tank-binding kinase-1 (TBK1) and IKK? promote KRAS-driven tumorigenesis by regulating autocrine CCL5 and interleukin (IL)-6 and identify CYT387 as a potent JAK/TBK1/IKK? inhibitor. CYT387 treatment ablates RAS-associated cytokine signaling and impairs Kras-driven murine lung cancer growth. Combined CYT387 treatment and MAPK pathway inhibition induces regression of aggressive murine lung adenocarcinomas driven by Kras mutation and p53 loss. These observations reveal that TBK1/IKK? promote tumor survival by activating CCL5 and IL-6 and identify concurrent inhibition of TBK1/IKK?, Janus-activated kinase (JAK), and MEK signaling as an effective approach to inhibit the actions of oncogenic KRAS.
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Significant enhancement in photocatalytic reduction of water to hydrogen by Au/Cu2 ZnSnS4 nanostructure.
Adv. Mater. Weinheim
PUBLISHED: 01-16-2014
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Enhanced photocatalytic activities by Au core Novel Au/Cu2 ZnSnS4 core/shell nanoparticles (NPs) are synthesized for the first time via wet chemistry approach. The insertion of Au core into CZTS NPs dramatically enhances light absorption due to surface plasmon resonance effect, especially in the Vis-NIR region. Au/CZTS core/shell NPs show much higher photocatalytic activities for hydrogen evolution compared with other CZTS nanostructures.
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Transdifferentiation of lung adenocarcinoma in mice with Lkb1 deficiency to squamous cell carcinoma.
Nat Commun
PUBLISHED: 01-15-2014
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Lineage transition in adenocarcinoma (ADC) and squamous cell carcinoma (SCC) of non-small cell lung cancer, as implicated by clinical observation of mixed ADC and SCC pathologies in adenosquamous cell carcinoma, remains a fundamental yet unsolved question. Here we provide in vivo evidence showing the transdifferentiation of lung cancer from ADC to SCC in mice: Lkb1-deficient lung ADC progressively transdifferentiates into SCC, via a pathologically mixed mAd-SCC intermediate. We find that reduction of lysyl oxidase (Lox) in Lkb1-deficient lung ADC decreases collagen disposition and triggers extracellular matrix remodelling and upregulates p63 expression, a SCC lineage survival oncogene. Pharmacological Lox inhibition promotes the transdifferentiation, whereas ectopic Lox expression significantly inhibits this process. Notably, ADC and SCC show differential responses to Lox inhibition. Collectively, our findings demonstrate the de novo transdifferentiation of lung ADC to SCC in mice and provide mechanistic insight that may have important implications for lung cancer treatment.
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Integrative genomic analysis reveals a high frequency of LKB1 genetic alteration in Chinese lung adenocarcinomas.
J Thorac Oncol
PUBLISHED: 01-15-2014
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Liver kinase B1 (LKB1) genetic alteration in lung cancer involves not only point mutations and small deletion of several base pairs but also exonic loss. However, most of recent studies in LKB1 gene status only focus on point mutations and small deletion, and thus may underestimate the actual frequency of LKB1 genetic alteration in lung cancer. Thus, an integrative analysis of LKB1 genetic alteration is timely and important for providing a better estimate for the incidence of genetic alterations in this important tumor suppressor gene. One hundred and seven lung adenocarcinomas with more than 70% tumor have been analyzed for mutation of LKB1 as well as LKB1 large deletions detection by using multiplex ligation-dependent probe amplification analysis. These samples were also analyzed for EGFR, KRAS, HER2, BRAF, ALK, ROS1, and RET status in stepwise method. Among 107 lung adenocarcinomas analyzed, 29 (27.1%) harbored LKB1 genetic alteration. Twenty-three (21.5%) harbored LKB1 large exonic deletions and eight (7.48%) had LKB1 points mutations, two samples harbored both LKB1 large exonic deletions and point mutations. Eighty-seven samples (81.31%) harbored known driver mutations and 20 samples (18.69%) had no identifiable driver mutations. A high rate of LKB1 genetic alteration in Chinese lung adenocarcinomas is revealed by the integrative analysis of point mutation and exonic deletion. Moreover, LKB1 genetic alterations are concurrent with EGFR, KRAS, HER2, and CD74-ROS fusions.
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Preexisting oncogenic events impact trastuzumab sensitivity in ERBB2-amplified gastroesophageal adenocarcinoma.
J. Clin. Invest.
PUBLISHED: 01-14-2014
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Patients with gastric and esophageal (GE) adenocarcinoma tumors in which the oncogene ERBB2 has been amplified are routinely treated with a combination of cytotoxic chemotherapy and the ERBB2-directed antibody trastuzumab; however, the addition of trastuzumab, even when tested in a selected biomarker-positive patient population, provides only modest survival gains. To investigate the potential reasons for the modest impact of ERBB2-directed therapies, we explored the hypothesis that secondary molecular features of ERBB2-amplified GE adenocarcinomas attenuate the impact of ERBB2 blockade. We analyzed genomic profiles of ERBB2-amplified GE adenocarcinomas and determined that the majority of ERBB2-amplified tumors harbor secondary oncogenic alterations that have the potential to be therapeutically targeted. These secondary events spanned genes involved in cell-cycle regulation as well as phosphatidylinositol-3 kinase and receptor tyrosine kinase signaling. Using ERBB2-amplified cell lines, we demonstrated that secondary oncogenic events could confer resistance to ERBB2-directed therapies. Moreover, this resistance could be overcome by targeting the secondary oncogene in conjunction with ERBB2-directed therapy. EGFR is commonly coamplified with ERBB2, and in the setting of ERBB2 amplification, higher EGFR expression appears to mark tumors with greater sensitivity to dual EGFR/ERBB2 kinase inhibitors. These data suggest that combination inhibitor strategies, guided by secondary events in ERBB2-amplified GE adenocarcinomas, should be evaluated in clinical trials.
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Effect of tumor necrosis factor family member LIGHT (TNFSF14) on the activation of basophils and eosinophils interacting with bronchial epithelial cells.
Mediators Inflamm.
PUBLISHED: 01-09-2014
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Allergic asthma can cause airway structural remodeling, involving the accumulation of extracellular matrix and thickening of smooth muscle. Tumor necrosis factor (TNF) family ligand LIGHT (TNFSF14) is a cytokine that binds herpesvirus entry mediator (HVEM)/TNFRSF14 and lymphotoxin ? receptor (LT?R). LIGHT induces asthmatic cytokine IL-13 and fibrogenic cytokine transforming growth factor-? release from allergic asthma-related eosinophils expressing HVEM and alveolar macrophages expressing LT?R, respectively, thereby playing crucial roles in asthmatic airway remodeling. In this study, we investigated the effects of LIGHT on the coculture of human basophils/eosinophils and bronchial epithelial BEAS-2B cells. The expression of adhesion molecules, cytokines/chemokines, and matrix metalloproteinases (MMP) was measured by flow cytometry, multiplex, assay or ELISA. Results showed that LIGHT could significantly promote intercellular adhesion, cell surface expression of intercellular adhesion molecule-1, release of airway remodeling-related IL-6, CXCL8, and MMP-9 from BEAS-2B cells upon interaction with basophils/eosinophils, probably via the intercellular interaction, cell surface receptors HVEM and LT?R on BEAS-2B cells, and extracellular signal-regulated kinase, p38 mitogen activated protein kinase, and NF-?B signaling pathways. The above results, therefore, enhance our understanding of the immunopathological roles of LIGHT in allergic asthma and shed light on the potential therapeutic targets for airway remodeling.
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Rational design of berberine-based FtsZ inhibitors with broad-spectrum antibacterial activity.
PLoS ONE
PUBLISHED: 01-01-2014
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Inhibition of the functional activity of Filamenting temperature-sensitive mutant Z (FtsZ) protein, an essential and highly conserved bacterial cytokinesis protein, is a promising approach for the development of a new class of antibacterial agents. Berberine, a benzylisoquinoline alkaloid widely used in traditional Chinese and native American medicines for its antimicrobial properties, has been recently reported to inhibit FtsZ. Using a combination of in silico structure-based design and in vitro biological assays, 9-phenoxyalkyl berberine derivatives were identified as potent FtsZ inhibitors. Compared to the parent compound berberine, the derivatives showed a significant enhancement of antibacterial activity against clinically relevant bacteria, and an improved potency against the GTPase activity and polymerization of FtsZ. The most potent compound 2 strongly inhibited the proliferation of Gram-positive bacteria, including methicillin-resistant S. aureus and vancomycin-resistant E. faecium, with MIC values between 2 and 4 µg/mL, and was active against the Gram-negative E. coli and K. pneumoniae, with MIC values of 32 and 64 µg/mL respectively. The compound perturbed the formation of cytokinetic Z-ring in E. coli. Also, the compound interfered with in vitro polymerization of S. aureus FtsZ. Taken together, the chemical modification of berberine with 9-phenoxyalkyl substituent groups greatly improved the antibacterial activity via targeting FtsZ.
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CDK4/6 Inhibition Induces Epithelial Cell Cycle Arrest and Ameliorates Acute Kidney Injury.
Am. J. Physiol. Renal Physiol.
PUBLISHED: 12-11-2013
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Acute kidney injury (AKI) is common and urgently requires new preventative therapies. Expression of a cyclin-dependent kinase (CDK) inhibitor transgene protects against acute kidney injury, suggesting that manipulating the tubular epithelial cell cycle may be a viable therapeutic strategy. Broad spectrum small molecule CDK inhibitors are protective in some kidney injury models, but these have toxicities and epithelial proliferation is eventually required for renal repair. Here, we tested the effect of a novel and specific inhibitor of cyclin-dependent kinase 4 (CDK4) and CDK6, PD 0332991, which is already in human trials, on epithelial survival in vitro and kidney injury in vivo. We report that CDK4/6 inhibition induced G0/G1 cycle arrest in cultured human renal proximal tubule cells (hRPTC) at baseline and after injury. CDK4/6 inhibition protected hRPTC from DNA damage and caspase 3/7 activation following exposure to the nephrotoxins cisplatin, etoposide, and antimycin A. In vivo, mice treated with PD 0332991 prior to IRI exhibited dramatically reduced epithelial progression through S-phase 24 hours after IRI. Despite reduced epithelial proliferation, PD 0332991 ameliorated kidney injury as reflected by improved serum creatinine and blood urea nitrogen levels 24 hours after injury. Inflammatory markers and macrophage infiltration were also significantly decreased in injured kidneys. Importantly, cell cycle inhibition was transient, and the epithelial proliferative response completely recovered by day three after IRI, allowing repair to occur. These results indicate that induction of transient proximal tubule cell cycle arrest with specific CDK4/6 inhibitors, or "pharmacological quiescence," represents a novel strategy to prevent AKI.
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Acquired resistance to dasatinib in lung cancer cell lines conferred by DDR2 gatekeeper mutation and NF1 loss.
Mol. Cancer Ther.
PUBLISHED: 12-02-2013
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The treatment of non-small cell lung cancer has evolved dramatically over the past decade with the adoption of widespread use of effective targeted therapies in patients with distinct molecular alterations. In lung squamous cell carcinoma (lung SqCC) recent studies have suggested that DDR2 mutations are a biomarker for therapeutic response to dasatinib and clinical trials are underway testing this hypothesis. While targeted therapeutics are typically quite effective as initial therapy for patients with lung cancer, nearly all patients develop resistance with long-term exposure to targeted drugs. Here, we use DDR2-dependent lung cancer cell lines to model acquired resistance to dasatinib therapy. We perform targeted exome sequencing to identify two distinct mechanisms of acquired resistance: acquisition of the T654I gatekeeper mutation in DDR2 and loss of NF1. We show that NF1 loss activates a bypass pathway which confers ERK dependency downstream of RAS activation. These results indicate that acquired resistance to dasatinib can occur via both second-site mutations in DDR2 and by activation of bypass pathways. These data may help to anticipate mechanisms of resistance which may be identified in upcoming clinical trials of anti-DDR2 therapy in lung cancer and suggest strategies to overcome resistance.
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The Myeloma Drug Lenalidomide Promotes the Cereblon-Dependent Destruction of Ikaros Proteins.
Science
PUBLISHED: 11-29-2013
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Thalidomide-like drugs such as lenalidomide are clinically important treatments for multiple myeloma and show promise for other B cell malignancies. The biochemical mechanism(s) underlying their antitumor activity are unknown. Thalidomide was recently shown to bind to, and inhibit, the cereblon ubiquitin ligase. Cereblon loss in zebrafish causes fin defects reminiscent of the limb defects seen in children exposed to thalidomide in utero. Here, we show that lenalidomide-bound cereblon acquires the ability to target for proteasomal degradation two specific B cell transcription factors, Ikaros family zinc finger proteins- 1 and -3 (IKZF1 and IKZF3). Analysis of myeloma cell lines revealed that loss of IKZF1 and IKZF3 is both necessary and sufficient for lenalidomides therapeutic effect, suggesting that the antitumor and teratogenic activities of thalidomide-like drugs are dissociable.
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Activation of the PD-1 Pathway Contributes to Immune Escape in EGFR-Driven Lung Tumors.
Cancer Discov
PUBLISHED: 09-27-2013
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The success in lung cancer therapy with programmed death (PD)-1 blockade suggests that immune escape mechanisms contribute to lung tumor pathogenesis. We identified a correlation between EGF receptor (EGFR) pathway activation and a signature of immunosuppression manifested by upregulation of PD-1, PD-L1, CTL antigen-4 (CTLA-4), and multiple tumor-promoting inflammatory cytokines. We observed decreased CTLs and increased markers of T-cell exhaustion in mouse models of EGFR-driven lung cancer. PD-1 antibody blockade improved the survival of mice with EGFR-driven adenocarcinomas by enhancing effector T-cell function and lowering the levels of tumor-promoting cytokines. Expression of mutant EGFR in bronchial epithelial cells induced PD-L1, and PD-L1 expression was reduced by EGFR inhibitors in non-small cell lung cancer cell lines with activated EGFR. These data suggest that oncogenic EGFR signaling remodels the tumor microenvironment to trigger immune escape and mechanistically link treatment response to PD-1 inhibition.
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Cetuximab response of lung cancer-derived EGF receptor mutants is associated with asymmetric dimerization.
Cancer Res.
PUBLISHED: 09-24-2013
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Kinase domain mutations of the EGF receptor (EGFR) are common oncogenic events in lung adenocarcinoma. Here, we explore the dependency upon asymmetric dimerization of the kinase domain for activation of lung cancer-derived EGFR mutants. We show that whereas wild-type EGFR and the L858R mutant require dimerization for activation and oncogenic transformation, the exon 19 deletion, exon 20 insertion, and L858R/T790M EGFR mutants do not require dimerization. In addition, treatment with the monoclonal antibody, cetuximab, shrinks mouse lung tumors induced by the dimerization-dependent L858R mutant, but exerts only a modest effect on tumors driven by dimerization-independent EGFR mutants. These data imply that different EGFR mutants show differential requirements for dimerization and that disruption of dimerization may be among the antitumor mechanisms of cetuximab.
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Efficacy of BET bromodomain inhibition in Kras-mutant non-small cell lung cancer.
Clin. Cancer Res.
PUBLISHED: 09-17-2013
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Amplification of MYC is one of the most common genetic alterations in lung cancer, contributing to a myriad of phenotypes associated with growth, invasion, and drug resistance. Murine genetics has established both the centrality of somatic alterations of Kras in lung cancer, as well as the dependency of mutant Kras tumors on MYC function. Unfortunately, drug-like small-molecule inhibitors of KRAS and MYC have yet to be realized. The recent discovery, in hematologic malignancies, that bromodomain and extra-terminal (BET) bromodomain inhibition impairs MYC expression and MYC transcriptional function established the rationale of targeting KRAS-driven non-small cell lung cancer (NSCLC) with BET inhibition.
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New cast for a new era: preclinical cancer drug development revisited.
J. Clin. Invest.
PUBLISHED: 09-03-2013
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Molecularly targeted agents promise to revolutionize therapeutics by reducing morbidity and mortality in patients with cancer. However, despite an urgent need for more effective anticancer compounds, current preclinical drug evaluations largely fail to satisfy the demand. New preclinical strategies, including the improvement of sophisticated mouse models and co-clinical study designs, are being used to augment the predictive value of animal-based translational cancer research. Here, we review the development of successful preclinical antineoplastic agents, their associated limitations, and alternative methods to predict clinical outcomes.
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Förster resonance energy transfer-based biosensing platform with ultrasmall silver nanoclusters as energy acceptors.
Anal. Chem.
PUBLISHED: 08-29-2013
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We studied the energy transfer (ET) property of ultrasmall Ag nanoclusters (Ag NCs) and exploited its biosensing application for the first time. A hybridized DNA duplex model was designed to study the energy transfer process from fluorescent energy donors to Ag NCs. By changing the DNA duplex model and the number of hybridized pairs, the separation distance between the energy donor and Ag NCs was adjusted to investigate the distance dependence and possible mechanisms involved in the ET process, which was assigned to Förster resonance energy transfer (FRET). Using Ag NCs with different photophysical properties as energy acceptors, FRET-based biosensing platforms with two different energy donors were constructed utilizing either the off-on or ratiometric fluorescence signaling. This study will provide the basis for understanding energy transfer properties of Ag NCs and bring to light the universal application of these properties in bio/chemo sensing.
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Outcomes of traumatic brain injury in Hong Kong: validation with the TRISS, CRASH, and IMPACT models.
J Clin Neurosci
PUBLISHED: 08-28-2013
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We aimed to test prognostic models (the Trauma Injury Severity Score, International Mission for Prognosis and Analysis of Clinical Trials in Traumatic Brain Injury, and Corticosteroid Randomisation After Significant Head Injury models) for 14-day mortality, 6-month mortality, and 6-month unfavorable outcome in a cohort of trauma patients with traumatic brain injury (TBI) in Hong Kong. We analyzed 661 patients with significant TBI treated in a regional trauma centre in Hong Kong over a 3-year period. The discriminatory power of the models was assessed as the area under the receiver operating characteristic curve. One-sample t-tests were used to compare actual outcomes in the cohort against predicted outcomes. All three prognostic models were shown to have good discriminatory power and no significant systemic over-estimation or under-estimation. In conclusion, all three predictive models are applicable to eligible TBI patients in Hong Kong. These predictive models can be utilized to audit TBI management outcomes for trauma service development in the future.
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Integrative radiogenomic profiling of squamous cell lung cancer.
Cancer Res.
PUBLISHED: 08-26-2013
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Radiotherapy is one of the mainstays of anticancer treatment, but the relationship between the radiosensitivity of cancer cells and their genomic characteristics is still not well defined. Here, we report the development of a high-throughput platform for measuring radiation survival in vitro and its validation in comparison with conventional clonogenic radiation survival analysis. We combined results from this high-throughput assay with genomic parameters in cell lines from squamous cell lung carcinoma, which is standardly treated by radiotherapy, to identify parameters that predict radiation sensitivity. We showed that activation of NFE2L2, a frequent event in lung squamous cancers, confers radiation resistance. An expression-based, in silico screen nominated inhibitors of phosphoinositide 3-kinase (PI3K) as NFE2L2 antagonists. We showed that the selective PI3K inhibitor, NVP-BKM120, both decreased NRF2 protein levels and sensitized NFE2L2 or KEAP1-mutant cells to radiation. We then combined results from this high-throughput assay with single-sample gene set enrichment analysis of gene expression data. The resulting analysis identified pathways implicated in cell survival, genotoxic stress, detoxification, and innate and adaptive immunity as key correlates of radiation sensitivity. The integrative and high-throughput methods shown here for large-scale profiling of radiation survival and genomic features of solid-tumor-derived cell lines should facilitate tumor radiogenomics and the discovery of genotype-selective radiation sensitizers and protective agents.
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Quality of Life after Brain Injury (QOLIBRI) Overall Scale for patients after aneurysmal subarachnoid hemorrhage.
J Clin Neurosci
PUBLISHED: 08-14-2013
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The Quality of Life after Brain Injury Overall Scale (QOLIBRI-OS) is a recently developed instrument that provides a brief summary measure of health-related quality of life (HRQoL) in domains typically affected by brain injury. This study examined the application of the six item QOLIBRI-OS in patients after aneurysmal subarachnoid hemorrhage (aSAH). Hong Kong Chinese aSAH patients were evaluated prospectively within the chronic phase of 1year after aSAH in this multi-center observational study. Cronbachs ? was 0.88, and correlations were satisfactory for all six items. QOLIBRI-OS demonstrated good criterion validity with other 1year outcome assessments. In conclusion, QOLIBRI-OS can be used as a brief index for disease-specific HRQoL assessment after aSAH. Further validation in another population of aSAH patients is recommended.
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Development of a short form of Stroke-Specific Quality of Life Scale for patients after aneurysmal subarachnoid hemorrhage.
J. Neurol. Sci.
PUBLISHED: 08-12-2013
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The identification of aneurysmal subarachnoid hemorrhage (aSAH) patients with a decrease in health-related quality of life (HRQOL) is challenging. Stroke-Specific Quality of Life (SS-QOL) Scale is one of the commonest disease-specific quality of life measures initially developed and validated for ischemic stroke patients. A disadvantage is subject burden and a short form is more practical to use in clinical and research setting.
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Identification of a new class of FtsZ inhibitors by structure-based design and in vitro screening.
J Chem Inf Model
PUBLISHED: 07-25-2013
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The Filamenting temperature-sensitive mutant Z (FtsZ), an essential GTPase in bacterial cell division, is highly conserved among Gram-positive and Gram-negative bacteria and thus considered an attractive target to treat antibiotic-resistant bacterial infections. In this study, a new class of FtsZ inhibitors bearing the pyrimidine-quinuclidine scaffold was identified from structure-based virtual screening of natural product libraries. Iterative rounds of in silico studies and biological evaluation established the preliminary structure-activity relationships of the new compounds. Potent FtsZ inhibitors with low micromolar IC?? and antibacterial activity against S. aureus and E. coli were found. These findings support the use of virtual screening and structure-based design for the rational development of new antibacterial agents with innovative mechanisms of action.
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Incidence and mortality of spontaneous subarachnoid haemorrhage in Hong Kong from 2002 to 2010: a Hong Kong Hospital Authority Clinical Management System database analysis.
World Neurosurg
PUBLISHED: 07-22-2013
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Ninety-five percent of the Hong Kong population is Chinese and no previous epidemiological study has focused on spontaneous subarachnoid hemorrhage (SAH) in Hong Kong. These data would have significant public health implications and can guide future resource allocations and service development in Hong Kong.
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Label-free detection of endocrine disrupting chemicals by integrating a competitive binding assay with a piezoelectric ceramic resonator.
Biosens Bioelectron
PUBLISHED: 07-11-2013
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A piezoelectric biosensor for detection of endocrine disrupting chemicals (EDCs) was developed by incorporating chemical/biochemical recognition elements on the ceramic resonator surface for competitive binding assays. A facile electrodeposition was employed to modify the sensor surface with Au nanoparticles, which increased the surface area and enhanced the binding capacity of the immobilized probes. Thiol-labeled long chain hydrocarbon with bisphenol A (BPA) as head group was synthesized and self-assembled on the Au nanoparticle surface as the sensing probes, which showed a linear response upon the binding of estrogen receptor (ER-?) ranging from 1 to 30nM. Detection of estrone, 17?-estradiol and BPA was achieved by integrating a competitive binding assay with the piezoelectric sensor. In this detection scheme, different concentrations of EDCs were incubated with 30nM of ER-?, and the un-bounded ER-? in the solution was captured by the probes immobilized on the ceramic resonator, which resulted in the frequency changes for different EDCs. The biosensor assay exhibited a linear response to EDCs with a low detection limit of 2.4-2.9nM (S/N=3), and required only a small volume of sample (1.5µl) with the assay time of 2h. The performance of the biosensor assay was also evaluated for rapid and facile determination of EDCs of environmental relevant concentrations in drinking water and seawater, and the recovery rate was in the range between 94.7% and 109.8%.
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TGF-? modulates ovarian cancer invasion by upregulating CAF-derived versican in the tumor microenvironment.
Cancer Res.
PUBLISHED: 07-03-2013
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TGF-? has limited effects on ovarian cancer cells, but its contributions to ovarian tumor growth might be mediated through elements of the tumor microenvironment. In the present study, we tested the hypothesis that TGF modulates ovarian cancer progression by modulating the contribution of cancer-associated fibroblasts (CAF) that are present in the microenvironment. Transcriptome profiling of microdissected stromal and epithelial components of high-grade serous ovarian tumors and TGF-?-treated normal ovarian fibroblasts identified versican (VCAN) as a key upregulated target gene in CAFs. Functional evaluations in coculture experiments showed that TGF-? enhanced the aggressiveness of ovarian cancer cells by upregulating VCAN in CAFs. VCAN expression was regulated in CAFs through TGF-? receptor type II and SMAD signaling. Upregulated VCAN promoted the motility and invasion of ovarian cancer cells by activating the NF-?B signaling pathway and by upregulating expression of CD44, matrix metalloproteinase-9, and the hyaluronan-mediated motility receptor. Our work identified a TGF-?-inducible gene signature specific to CAFs in advanced high-grade serous ovarian tumors, and showed how TGF-? stimulates ovarian cancer cell motility and invasion by upregulating the CAF-specific gene VCAN. These findings suggest insights to develop or refine strategies for TGF-?-targeted therapy of ovarian cancer.
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Inhibitor-sensitive FGFR2 and FGFR3 mutations in lung squamous cell carcinoma.
Cancer Res.
PUBLISHED: 06-20-2013
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A comprehensive description of genomic alterations in lung squamous cell carcinoma (lung SCC) has recently been reported, enabling the identification of genomic events that contribute to the oncogenesis of this disease. In lung SCC, one of the most frequently altered receptor tyrosine kinase families is the fibroblast growth factor receptor (FGFR) family, with amplification or mutation observed in all four family members. Here, we describe the oncogenic nature of mutations observed in FGFR2 and FGFR3, each of which are observed in 3% of samples, for a mutation rate of 6% across both genes. Using cell culture and xenograft models, we show that several of these mutations drive cellular transformation. Transformation can be reversed by small-molecule FGFR inhibitors currently being developed for clinical use. We also show that mutations in the extracellular domains of FGFR2 lead to constitutive FGFR dimerization. In addition, we report a patient with an FGFR2-mutated oral SCC who responded to the multitargeted tyrosine kinase inhibitor pazopanib. These findings provide new insights into driving oncogenic events in a subset of lung squamous cancers, and recommend future clinical studies with FGFR inhibitors in patients with lung and head and neck SCC.
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Early MoCA-Assessed Cognitive Impairment After Aneurysmal Subarachnoid Hemorrhage and Relationship to 1-Year Functional Outcome.
Transl Stroke Res
PUBLISHED: 06-18-2013
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Recent clinical research into aneurysmal subarachnoid hemorrhage (aSAH) has confirmed the long-term effect of cognitive dysfunction on functional outcomes. We hypothesized that early cognitive impairment was a marker of permanent brain injury and hence predicted long-term functional outcome. Hong Kong Chinese patients with aneurysmal subarachnoid hemorrhage were evaluated prospectively by means of the Montreal Cognitive Assessment (MoCA) in the subacute phase (2-4 weeks after aSAH) and by neuropsychological evaluation of functional outcomes in the chronic phase (1 year after aSAH). This multi-center prospective observational study is registered at ClinicalTrials.gov of the US National Institutes of Health (NCT01038193). One hundred and eight patients completed both the subacute and chronic phase assessments. Cognitive dysfunction in the subacute phase independently correlated with functional outcomes at 1 year, after adjusting for age, admission clinical condition, treatment modality, motor score, and mobility in the subacute phase, but the positive predictive values remained low. MoCA-assessed cognitive impairment in the subacute phase cannot accurately predict functional outcomes at 1 year. Future study should focus on understanding the relative importance of different components of early cognitive impairment.
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Metabolic and functional genomic studies identify deoxythymidylate kinase as a target in LKB1-mutant lung cancer.
Cancer Discov
PUBLISHED: 05-28-2013
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The LKB1/STK11 tumor suppressor encodes a serine/threonine kinase, which coordinates cell growth, polarity, motility, and metabolism. In non-small cell lung carcinoma, LKB1 is somatically inactivated in 25% to 30% of cases, often concurrently with activating KRAS mutations. Here, we used an integrative approach to define novel therapeutic targets in KRAS-driven LKB1-mutant lung cancers. High-throughput RNA interference screens in lung cancer cell lines from genetically engineered mouse models driven by activated KRAS with or without coincident Lkb1 deletion led to the identification of Dtymk, encoding deoxythymidylate kinase (DTYMK), which catalyzes dTTP biosynthesis, as synthetically lethal with Lkb1 deficiency in mouse and human lung cancer lines. Global metabolite profiling showed that Lkb1-null cells had a striking decrease in multiple nucleotide metabolites as compared with the Lkb1-wild-type cells. Thus, LKB1-mutant lung cancers have deficits in nucleotide metabolism that confer hypersensitivity to DTYMK inhibition, suggesting that DTYMK is a potential therapeutic target in this aggressive subset of tumors.
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A dinuclear ruthenium catalyst with a confined cavity: selectivity in the addition of aliphatic carboxylic acids to phenylacetylene.
Chem. Commun. (Camb.)
PUBLISHED: 05-15-2013
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A dinuclear ruthenium catalyst with a rigid anthracene spacer shows excellent regio- and stereo-selectivity in the atom-economic addition of aliphatic carboxylic acids to phenylacetylene, producing exclusively anti-Markovnikov enol-esters with high E/Z ratios of the isomers.
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A genetic screen identifies an LKB1-MARK signalling axis controlling the Hippo-YAP pathway.
Nat. Cell Biol.
PUBLISHED: 05-13-2013
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The Hippo-YAP pathway is an emerging signalling cascade involved in the regulation of stem cell activity and organ size. To identify components of this pathway, we performed an RNAi-based kinome screen in human cells. Our screen identified several kinases not previously associated with Hippo signalling that control multiple cellular processes. One of the hits, LKB1, is a common tumour suppressor whose mechanism of action is only partially understood. We demonstrate that LKB1 acts through its substrates of the microtubule affinity-regulating kinase family to regulate the localization of the polarity determinant Scribble and the activity of the core Hippo kinases. Our data also indicate that YAP is functionally important for the tumour suppressive effects of LKB1. Our results identify a signalling axis that links YAP activation with LKB1 mutations, and have implications for the treatment of LKB1-mutant human malignancies. In addition, our findings provide insight into upstream signals of the Hippo-YAP signalling cascade.
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Acquired substrate preference for GAB1 protein bestows transforming activity to ERBB2 kinase lung cancer mutants.
J. Biol. Chem.
PUBLISHED: 04-23-2013
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Activating mutations in the ?C-?4 loop of the ERBB2 kinase domain, such as ERBB2(YVMA) and ERBB2(G776VC), have been identified in human lung cancers and found to drive tumor formation. Here we observe that the docking protein GAB1 is hyper-phosphorylated in carcinomas from transgenic mice and in cell lines expressing these ERBB2 cancer mutants. Using dominant negative GAB1 mutants lacking canonical tyrosine residues for SHP2 and PI3K interactions or lentiviral shRNA that targets GAB1, we demonstrate that GAB1 phosphorylation is required for ERBB2 mutant-induced cell signaling, cell transformation, and tumorigenesis. An enzyme kinetic analysis comparing ERBB2(YVMA) to wild type using physiologically relevant peptide substrates reveals that ERBB2(YVMA) kinase adopts a striking preference for GAB1 phosphorylation sites as evidenced by ?150-fold increases in the specificity constants (kcat/Km) for several GAB1 peptides, and this change in substrate selectivity was predominantly attributed to the peptide binding affinities as reflected by the apparent Km values. Furthermore, we demonstrate that ERBB2(YVMA) phosphorylates GAB1 protein ?70-fold faster than wild type ERBB2 in vitro. Notably, the mutation does not significantly alter the Km for ATP or sensitivity to lapatinib, suggesting that, unlike EGFR lung cancer mutants, the ATP binding cleft of the kinase is not significantly changed. Taken together, our results indicate that the acquired substrate preference for GAB1 is critical for the ERBB2 mutant-induced oncogenesis.
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Cognitive domain deficits in patients with aneurysmal subarachnoid haemorrhage at 1 year.
J. Neurol. Neurosurg. Psychiatr.
PUBLISHED: 04-20-2013
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Cognitive domain deficits can occur after aneurysmal subarachnoid haemorrhage (aSAH) though few studies systemically evaluate its impact on 1-year outcomes.
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A multicenter phase II study of ganetespib monotherapy in patients with genotypically defined advanced non-small cell lung cancer.
Clin. Cancer Res.
PUBLISHED: 04-03-2013
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Ganetespib is a novel inhibitor of the heat shock protein 90 (Hsp90), a chaperone protein critical to tumor growth and proliferation. In this phase II study, we evaluated the activity and tolerability of ganetespib in previously treated patients with non-small cell lung cancer (NSCLC).
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NOD-like receptors mediated activation of eosinophils interacting with bronchial epithelial cells: a link between innate immunity and allergic asthma.
Cell. Mol. Immunol.
PUBLISHED: 03-25-2013
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Key intracytosolic pattern recognition receptors of innate immunity against bacterial infections are nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs). We elucidated the NOD1 and NOD2-mediated activation of human eosinophils, the principal effector cells for allergic inflammation, upon interacting with human bronchial epithelial BEAS-2B cells in allergic asthma. Eosinophils constitutively expressed NOD1,2 but exhibited nonsignificant responses to release chemokines upon the stimulation by NOD1 ligand ?-D-glutamyl-meso-diaminopimelic acid (iE-DAP) and NOD2 ligand muramyl dipeptide (MDP). However, iE-DAP and MDP could significantly upregulate cell surface expression of CD18 and intercellular adhesion molecule (ICAM)-1 on eosinophils and ICAM-1 on BEAS-2B cells, as well as induce chemokines CCL2 and CXCL8 release in the coculture system (all P<0.05). Both eosinophils and BEAS-2B cells were the main source for CXCL8 and CCL2 release in the coculture system upon iE-DAP or MDP stimulation. Direct interaction between eosinophils and BEAS-2B cells is responsible for CCL2 release, and soluble mediators are implicated in CXCL8 release. ERK and NF-?B play regulatory roles for the expression of adhesion molecules and chemokines in coculture. Treatment with NOD1,2 ligand could induce the subepithelial fibrosis and significantly enhance the serum concentration of total IgE, chemokine CCL5 for eosinophils and T helper type 2 (Th2) cells and asthma Th2 cytokine IL-13 in bronchoalveolar lavage fluid of ovalbumin-sensitized allergic asthmatic mice (all P<0.05). This study provides further evidence of bacterial infection-mediated activation of NOD1,2 in triggering allergic asthma via the activation of eosinophils interacting with bronchial epithelial cells at inflammatory airway.
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G-Quadruplex conformational change driven by pH variation with potential application as a nanoswitch.
Biochim. Biophys. Acta
PUBLISHED: 03-14-2013
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G-Quadruplex is a highly polymorphic structure, and its behavior in acidic condition has not been well studied.
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Poor survival with wild-type TP53 ovarian cancer?
Gynecol. Oncol.
PUBLISHED: 03-08-2013
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The objective of this study is to investigate whether wild-type TP53 status in high-grade serous ovarian carcinoma is associated with poorer survival.
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Role of human Toll-like receptors in naturally occurring influenza A infections.
Influenza Other Respir Viruses
PUBLISHED: 02-26-2013
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We investigated the roles of Toll-like receptors (TLRs) in naturally occurring influenza.
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Characterization of Torin2, an ATP-competitive inhibitor of mTOR, ATM, and ATR.
Cancer Res.
PUBLISHED: 02-22-2013
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mTOR is a highly conserved serine/threonine protein kinase that serves as a central regulator of cell growth, survival, and autophagy. Deregulation of the PI3K/Akt/mTOR signaling pathway occurs commonly in cancer and numerous inhibitors targeting the ATP-binding site of these kinases are currently undergoing clinical evaluation. Here, we report the characterization of Torin2, a second-generation ATP-competitive inhibitor that is potent and selective for mTOR with a superior pharmacokinetic profile to previous inhibitors. Torin2 inhibited mTORC1-dependent T389 phosphorylation on S6K (RPS6KB1) with an EC(50) of 250 pmol/L with approximately 800-fold selectivity for cellular mTOR versus phosphoinositide 3-kinase (PI3K). Torin2 also exhibited potent biochemical and cellular activity against phosphatidylinositol-3 kinase-like kinase (PIKK) family kinases including ATM (EC(50), 28 nmol/L), ATR (EC(50), 35 nmol/L), and DNA-PK (EC(50), 118 nmol/L; PRKDC), the inhibition of which sensitized cells to Irradiation. Similar to the earlier generation compound Torin1 and in contrast to other reported mTOR inhibitors, Torin2 inhibited mTOR kinase and mTORC1 signaling activities in a sustained manner suggestive of a slow dissociation from the kinase. Cancer cell treatment with Torin2 for 24 hours resulted in a prolonged block in negative feedback and consequent T308 phosphorylation on Akt. These effects were associated with strong growth inhibition in vitro. Single-agent treatment with Torin2 in vivo did not yield significant efficacy against KRAS-driven lung tumors, but the combination of Torin2 with mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitor AZD6244 yielded a significant growth inhibition. Taken together, our findings establish Torin2 as a strong candidate for clinical evaluation in a broad number of oncologic settings where mTOR signaling has a pathogenic role.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.