establishment-human-multiple-myeloma-xenograft-model-chicken-to-study

Establishment of a Human Multiple Myeloma Xenograft Model in the Chicken to Study Tumor Growth, Invasion and Angiogenesis

Multiple myeloma (MM), a malignant plasma cell disease, remains incurable and novel drugs are required to improve the prognosis of patients. Due to the ...

Innsbruck Medical University

Oncotyrol GmbH

A critical event in tumor growth and progression is the upregulation of angiogenesis. Thus, targeting angiogenesis has become an attractive treatment modality in cancer medicine. Our study analyzed various solid tumor types for the expression of Dkk-3, a cystein-rich, N-glycosylated secreted member of the Dickkopf protein family that has been proposed as a tumor suppressor gene. Tissue microarrays of gliomas (n = 30), high-grade non-Hodgkin's lymphomas (NHL, n = 80), colorectal cancer (n = 35) and melanoma (n = 30) were immunohistochemically analyzed for Dkk-3 and CD31 expression. Moreover, the effects of Dkk-3 were studied in vitro in primary endothelial colony-forming cells (ECFC) and in vivo in a mouse melanoma model. In comparison to normal tissue, the number of blood vessels expressing Dkk-3 was increased in glioma, high-grade NHL, melanoma and colorectal carcinoma. Confocal laser scanning microscopy revealed that Dkk-3 vesicles localized also in Weibel Palade bodies. In vitro cell proliferation and migration of ECFC was not significantly affected by adenoviral overexpression or siRNA-mediated downregulation of Dkk-3. Interestingly, tube formation in matrigel decreased after downregulation of Dkk-3 and increased after adenoviral overexpression. Stable overexpression of murine Dkk-3 in B16F10 cells significantly increased microvessel density in the C57/BL6 melanoma model. Thus, we postulate a novel function of Dkk-3 in endothelial cells as a differentiation factor involved in remodeling the tumor vasculature.

The Dickkopf-homolog 3 is expressed in tumor endothelial cells and supports capillary formation.

In this study, the alternative splicing product of vasohibin 1 (VASH1B) was analyzed in direct comparison to the major isoform (VASH1A) for antiangiogenic effects on endothelial colony forming cells (ECFCs) from peripheral blood and on human umbilical vein endothelial cells (HUVECs).

Alternative splicing of vasohibin-1 generates an inhibitor of endothelial cell proliferation, migration, and capillary tube formation.

Circulating endothelial cells (CEC) and endothelial precursor cells (CEP) have been suggested as markers for angiogenesis in cancer. However, CEC/CEP represent a tiny and heterogeneous cell population, rendering a standardized monitoring in peripheral blood difficult. Thus, we investigated whether a PCR-based detection method of CEC/CEP might overcome the limitations of rare-event flow cytometry.

Quantification of circulating endothelial and progenitor cells: comparison of quantitative PCR and four-channel flow cytometry.

The murine homologue of human vasohibin (mVASH1), a putative antiangiogenic protein, was investigated for its effects on in vitro and in vivo angiogenesis.

Vasohibin inhibits angiogenic sprouting in vitro and supports vascular maturation processes in vivo.

Antiangiogenic effects of the proteasome inhibitor bortezomib were analyzed on tumor xenografts in vivo. Bortezomib strongly inhibited angiogenesis and vascularization in the chicken chorioallantoic membrane. Bortezomib's inhibitory effects on chorioallantoic membrane vascularization were abrogated in the presence of distinct tumor xenografts, thanks to a soluble factor secreted by tumor cells. Through size-exclusion and ion-exchange chromatography as well as mass spectroscopy, we identified GRP-78, a chaperone protein of the unfolded protein response, as being responsible for bortezomib resistance. Indeed, a variety of bortezomib-resistant solid tumor cell lines (PC-3, HRT-18), but not myeloma cell lines (U266, OPM-2), were able to secrete high amounts of GRP-78. Recombinant GRP-78 conferred bortezomib resistance to endothelial cells and OPM-2 myeloma cells. Knockdown of GRP78 gene expression in tumor cells and immunodepletion of GRP-78 protein from tumor cell supernatants restored bortezomib sensitivity. GRP-78 did not bind or complex bortezomib but induced prosurvival signals by phosphorylation of extracellular signal-related kinase and inhibited p53-mediated expression of proapoptotic Bok and Noxa proteins in endothelial cells. From our data, we conclude that distinct solid tumor cells are able to secrete GRP-78 into the tumor microenvironment, thus demonstrating a hitherto unknown mechanism of resistance to bortezomib.

GRP-78 secreted by tumor cells blocks the antiangiogenic activity of bortezomib.

Dickkopf-3 (Dkk3) has been proposed as tumour suppressor gene and a marker for tumour blood vessels. We analysed the expression and function of Dkk3 in platelets and megakaryocytes from healthy controls and patients with BCR-ABL1-negative myeloproliferative neoplasms (MPN). Dkk3 protein and gene expression in platelets was compared with endothelial and other blood cell populations by ELISA, real-time PCR, and immunofluorescence. Moreover, megakaryocytes were isolated from bone marrow aspirates by CD61 microbeads. Immunohistochemical studies of Dkk3 expression were performed in essential thrombocythemia (ET), polycythemia vera (PV), primary myelofibrosis (PMF) and control reactive bone marrow cases (each n=10). Compared to all other blood cell populations platelets showed the highest concentration of Dkk3 protein (150 ± 19 ng/mg total protein). A strong DKK3 gene and protein expression was also observed in isolated megakaryocytes. Dkk3 co-localised with VEGF in α-granules of platelets and was released similar to VEGF upon stimulation. Addition of recombinant Dkk3 had no influence on blood coagulation (aPTT, INR) and platelet aggregation. Significantly more Dkk3+ megakaryocytes/mm2 could be found in bone marrow biopsies from patients with MPN (ET 40 ± 10, PV 31 ± 4, PMF 22 ± 3) than in controls (15 ± 3). The mean proportion of Dkk3+ megakaryocytes was increased in MPN as well (ET 83% ± 15%; PV 84% ± 12%; PMF 77% ± 8%) compared to controls (53% ± 11%). Dkk3+ megakaryocytes correlated with microvessel density in PV and PMF. We conclude that Dkk3 might be involved in the pathogenesis of MPN.

Increased Dkk3 protein expression in platelets and megakaryocytes of patients with myeloproliferative neoplasms.

Despite recent advances in therapy, multiple myeloma, the second most common hematologic tumor in the Western world, is still incurable. Identification of substances that display a wide range of tumor-killing activities and target cancer-specific pathways constitute a basis for the development of novel therapies. In this study, we investigate the cytotoxic effect of the natural substance cnicin in multiple myeloma. Cnicin treatment reveals potent antiproliferative effects and induces cell death in cell lines and primary myeloma cells even in the presence of survival cytokines and the tumor microenvironment. Other cell lines of hematopoietic origin also succumb to cell death whereas stromal cells and endothelial cells are unaffected. We show that activation of caspases, accumulation of reactive oxygen species and downregulation of nuclear factor kappa-light-chain-enhancer of activated B cell contribute to the cytotoxic effects of cnicin. Microarray analysis reveals downregulation of Pim-2, a serine/threonine kinase. We provide evidence that Pim-2 constitutes a new survival kinase for myeloma cells in vitro and is highly expressed in malignant but not in normal plasma cells in vivo. Combining cnicin with current standard or experimental therapeutics leads to enhanced cell death. Thus, our data indicate that cnicin induces myeloma cell death via several pathways and reveals Pim-2 as a novel target. These findings provide a rational for further evaluation of cnicin as a new anti-tumor drug and underline the potential of sesquiterpene lactones in tumor therapy.

Antimyeloma activity of the sesquiterpene lactone cnicin: impact on Pim-2 kinase as a novel therapeutic target.

Phosphodiesterase type 5 (PDE5) inhibitors have been demonstrated to improve lower urinary tract symptoms secondary to benign prostatic hyperplasia (BPH). Because BPH is primarily driven by fibroblast-to-myofibroblast trans-differentiation, this study aimed to evaluate the potential of the PDE5 inhibitor vardenafil to inhibit and reverse trans-differentiation of primary human prostatic stromal cells (PrSC). Vardenafil, sodium nitroprusside, lentiviral-delivered short hairpin RNA-mediated PDE5 knockdown, sodium orthovanadate, and inhibitors of MAPK kinase, protein kinase G, Ras homolog family member (Rho) A, RhoA/Rho kinase, phosphatidylinositol 3 kinase and protein kinase B (AKT) were applied to PrSC treated with basic fibroblast growth factor (fibroblasts) or TGFβ1 (myofibroblasts) in vitro, in chicken chorioallantoic membrane xenografts in vivo, and to prostatic organoids ex vivo. Fibroblast-to-myofibroblast trans-differentiation was monitored by smooth muscle cell actin and IGF binding protein 3 mRNA and protein levels. Vardenafil significantly attenuated TGFβ1-induced PrSC trans-differentiation in vitro and in chorioallantoic membrane xenografts. Enhancement of nitric oxide/cyclic guanosine monophosphate signaling by vardenafil, sodium nitroprusside, or PDE5 knockdown reduced smooth muscle cell actin and IGF binding protein 3 mRNA and protein levels and restored fibroblast-like morphology in trans-differentiated myofibroblast. This reversal of trans-differentiation was not affected by MAPK kinase, protein kinase G, RhoA, or RhoA/Rho kinase inhibition, but vardenafil attenuated phospho-AKT levels in myofibroblasts. Consistently, phosphatidylinositol 3 kinase or AKT inhibition induced reversal of trans-differentiation, whereas the tyrosine phosphatase inhibitor sodium orthovanadate abrogated the effect of vardenafil. Treatment of prostatic organoids with vardenafil ex vivo reduced expression of myofibroblast markers, indicating reverse remodeling of stroma towards a desired higher fibroblast/myofibroblast ratio. Thus, enhancement of the nitric oxide/cyclic guanosine monophosphate signaling pathway by vardenafil attenuates and reverts fibroblast-to-myofibroblast trans-differentiation, hypothesizing that BPH patients might benefit from long-term therapy with PDE5 inhibitors.

Phosphodiesterase type 5 inhibition reverts prostate fibroblast-to-myofibroblast trans-differentiation.

Insufficient angiogenesis and arteriogenesis in cardiac tissue after myocardial infarction (MI) is a significant factor hampering the functional recovery of the heart. To overcome this problem we screened for compounds capable of stimulating angiogenesis, and herein investigate the most active molecule, 5-Methoxyleoligin (5ML), in detail.

5-Methoxyleoligin, a lignan from Edelweiss, stimulates CYP26B1-dependent angiogenesis in vitro and induces arteriogenesis in infarcted rat hearts in vivo.

Genome analyses of endothelial cells identified genes specifically expressed by tumor endothelial cells, called tumor endothelial markers (TEMs). Currently there are no data available concerning the role of TEMs in non-small cell lung cancer (NSCLC). Therefore, the aim of this study was to investigate the role of TEMs in NSCLC in vitro and in vivo. First we evaluated the expression of various TEMs (Robo4, Clec14 and ECSCR) by qRT-PCR and Western blot analyses in three NSCLC cell lines (A549, Calu1, Colo699) and compared them to human umbilical vein endothelial cells (HUVECs), endothelial colony forming cells (ECFCs) and human bronchial epithelial cells (HBEpCs). Next the expression of TEMs was measured in resected tumor tissue of NSCLC patients (n = 63) by qRT-PCR and compared to adjacent non-cancerous lung tissue (n = 52). Further, immunohistochemical analysis of Robo4 expression in tumor tissue (n = 33) and adjacent non-cancerous tissue (n = 27) was performed. We found that NSCLC cell lines and HBEpC did not express TEMs on the mRNA level compared to HUVECs (p = 0.001). In the contrary, a significant up-regulation of Robo4 and Clec14 was found in tumor samples (Robo4 p = 0.03, Clec14 p = 0.002). Both facts clearly indicate that these proteins are allocated to the tumor stromal department. Correlation with clinical data showed that increased TEM expression correlated with prolonged overall survival of operated NSCLC patients (Robo4 high 120.5 vs. Robo4 low 47.6 months, Clec14 high 108.1 vs. Clec14 low 54.5 months and ECSCR high 120.5 vs. ECSCR low 42.2 months). In summary, we found that TEMs are overexpressed in NSCLC stromal tissue and that an increased TEM expression correlated with an increased overall survival in early stage NSCLC.

Favorable prognosis of operable non-small cell lung cancer (NSCLC) patients harboring an increased expression of tumor endothelial markers (TEMs).

Deregulation of cytokine and growth factor signaling due to an altered expression of endogenous regulators is well recognized in prostate cancer (PCa) and other cancers. Suppressor of cytokine signaling 2 (SOCS2) is a key regulator of the GH, IGF, and prolactin signaling pathways that have been implicated in carcinogenesis. In this study, we evaluated the expression patterns and functional significance of SOCS2 in PCa. Protein expression analysis employing tissue microarrays from two independent patient cohorts revealed a significantly enhanced expression in tumor tissue compared with benign tissue as well as association with Gleason score and disease progression. In vitro and in vivo assays uncovered the involvement of SOCS2 in the regulation of cell growth and apoptosis. Functionally, SOCS2 knockdown inhibited PCa cell proliferation and xenograft growth in a CAM assay. Decreased cell growth after SOCS2 downregulation was associated with cell-cycle arrest and apoptosis. In addition, we proved that SOCS2 expression is significantly elevated upon androgenic stimulation in androgen receptor (AR)-positive cell lines, providing a possible mechanistic explanation for high SOCS2 levels in PCa tissue. Consequently, SOCS2 expression correlated with AR expression in the malignant tissue of patients. On the whole, our study linked increased SOCS2 expression in PCa with a pro-proliferative role in vitro and in vivo.

SOCS2 correlates with malignancy and exerts growth-promoting effects in prostate cancer.

We scrutinized the effect of insulin receptor (INSR) in addition to IGF1R in PCa using in vitro and in vivo models. In-vitro overexpression of IGF1R and INSRA, but not INSRB increased cell proliferation, colony formation, migration, invasion and resistance to apoptosis in prostate cancer cells (DU145, LNCaP, PC3). Opposite effects were induced by downregulation of IGF1R and total INSR, but not INSRB. In contrast to tumor cells, non-cancerous epithelial cells of the prostate (EP156T, RWPE-1) were inhibited on overexpression and stimulated by knockdown of receptors. In-vivo analyses using the chicken allantoic membrane assay confirmed the tumorigenic effects of IGF1R and INSR. Apart of promoting tumor growth, IGF1R and INSR overexpression also enhanced angiogenesis indicated by higher vessel density and increased number of desmin-immunoreactive pericytes. Our study underscores the oncogenic impact of IGF1R including significant effects on tumor growth, cell migration, sensitivity to apoptotic/chemotherapeutic agents and angiogenesis, and characterizes the INSR, in particular the isoform INSRA, as additional cancer-promoting receptor in prostate cancer. Both, the insulin-like growth factor receptor 1 and the insulin receptor exert oncogenic functions, thus proposing that both receptors need to be considered in therapeutic settings.

Oncogenic functions of IGF1R and INSR in prostate cancer include enhanced tumor growth, cell migration and angiogenesis.

Occurrence of an inherent or acquired resistance to the chemotherapeutic drug docetaxel is a major burden for patients suffering from different kinds of malignancies, including castration resistant prostate cancer (PCa). In the present study we address the question whether PIAS1 targeting can be used to establish a basis for improved PCa treatment. The expression status and functional relevance of PIAS1 was evaluated in primary tumors, in metastatic lesions, in tissue of patients after docetaxel chemotherapy, and in docetaxel resistant cells. Patient data were complemented by functional studies on PIAS1 knockdown in vitro as well as in chicken chorioallantoic membrane and mouse xenograft in vivo models. PIAS1 was found to be overexpressed in local and metastatic PCa and its expression was further elevated in tumors after docetaxel treatment as well as in docetaxel resistant cells. Furthermore, PIAS1 knockdown experiments revealed an increased expression of tumor suppressor p21 and declined expression of anti-apoptotic protein Mcl1, which caused diminished cell proliferation and tumor growth in vitro and in vivo. In summary, the presented data indicate that PIAS1 is crucial for parental and docetaxel resistant PCa cell survival and is therefore a promising new target for treatment of primary, metastatic, and chemotherapy resistant PCa.

PIAS1 is a crucial factor for prostate cancer cell survival and a valid target in docetaxel resistant cells.

The prognosis of patients with multiple myeloma (MM) is still dismal despite recent improvements achieved by introducing new therapeutic agents. However, there remains an urgent need for progress in myeloma drug development. We here show that novel marine-derived compounds can exert potent anti-myeloma activity.

Article	Year
The Dickkopf-homolog 3 is expressed in tumor endothelial cells and supports capillary formation. International journal of cancer. Journal international du cancer\| PubMed ID: 18033687	2008
Alternative splicing of vasohibin-1 generates an inhibitor of endothelial cell proliferation, migration, and capillary tube formation. Arteriosclerosis, thrombosis, and vascular biology\| PubMed ID: 18187668	2008
Quantification of circulating endothelial and progenitor cells: comparison of quantitative PCR and four-channel flow cytometry. BMC research notes\| PubMed ID: 18755033	2008
Vasohibin inhibits angiogenic sprouting in vitro and supports vascular maturation processes in vivo. BMC cancer\| PubMed ID: 19682397	2009
GRP-78 secreted by tumor cells blocks the antiangiogenic activity of bortezomib. Blood\| PubMed ID: 19713465	2009
Increased Dkk3 protein expression in platelets and megakaryocytes of patients with myeloproliferative neoplasms. Thrombosis and haemostasis\| PubMed ID: 20978717	2011
Antimyeloma activity of the sesquiterpene lactone cnicin: impact on Pim-2 kinase as a novel therapeutic target. Journal of molecular medicine (Berlin, Germany)\| PubMed ID: 22205266	2012
Phosphodiesterase type 5 inhibition reverts prostate fibroblast-to-myofibroblast trans-differentiation. Endocrinology\| PubMed ID: 22948216	2012
5-Methoxyleoligin, a lignan from Edelweiss, stimulates CYP26B1-dependent angiogenesis in vitro and induces arteriogenesis in infarcted rat hearts in vivo. PloS one\| PubMed ID: 23554885	2013
Favorable prognosis of operable non-small cell lung cancer (NSCLC) patients harboring an increased expression of tumor endothelial markers (TEMs). Lung cancer (Amsterdam, Netherlands)\| PubMed ID: 23664449	2013
SOCS2 correlates with malignancy and exerts growth-promoting effects in prostate cancer. Endocrine-related cancer\| PubMed ID: 24280133	2014
Oncogenic functions of IGF1R and INSR in prostate cancer include enhanced tumor growth, cell migration and angiogenesis. Oncotarget\| PubMed ID: 24809298	2014
PIAS1 is a crucial factor for prostate cancer cell survival and a valid target in docetaxel resistant cells. Oncotarget\| PubMed ID: 25474038	2014
Marine compounds inhibit growth of multiple myeloma in vitro and in vivo. Oncotarget\| PubMed ID: 25860931	2015

Johann Kern

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