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Find video protocols related to scientific articles indexed in Pubmed.
SIRT1 activation by a c-MYC oncogenic network promotes the maintenance and drug resistance of human FLT3-ITD acute Myeloid Leukemia stem cells.
Cell Stem Cell
PUBLISHED: 02-04-2014
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The FLT3-ITD mutation is frequently observed in acute myeloid leukemia (AML) and is associated with poor prognosis. In such patients, FLT3 tyrosine kinase inhibitors (TKIs) are only partially effective and do not eliminate the leukemia stem cells (LSCs) that are assumed to be the source of treatment failure. Here, we show that the NAD-dependent SIRT1 deacetylase is selectively overexpressed in primary human FLT3-ITD AML LSCs. This SIRT1 overexpression is related to enhanced expression of the USP22 deubiquitinase induced by c-MYC, leading to reduced SIRT1 ubiquitination and enhanced stability. Inhibition of SIRT1 expression or activity reduced the growth of FLT3-ITD AML LSCs and significantly enhanced TKI-mediated killing of the cells. Therefore, these results identify a c-MYC-related network that enhances SIRT1 protein expression in human FLT3-ITD AML LSCs and contributes to their maintenance. Inhibition of this oncogenic network could be an attractive approach for targeting FLT3-ITD AML LSCs to improve treatment outcomes.
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T cells expressing CD123-specific chimeric antigen receptors exhibit specific cytolytic effector functions and antitumor effects against human acute myeloid leukemia.
Blood
PUBLISHED: 09-12-2013
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Induction treatments for acute myeloid leukemia (AML) have remained largely unchanged for nearly 50 years, and AML remains a disease of poor prognosis. Allogeneic hematopoietic cell transplantation can achieve cures in select patients and highlights the susceptibility of AML to donor-derived immunotherapy. The interleukin-3 receptor ? chain (CD123) has been identified as a potential immunotherapeutic target because it is overexpressed in AML compared with normal hematopoietic stem cells. Therefore, we developed 2 chimeric antigen receptors (CARs) containing a CD123-specific single-chain variable fragment, in combination with a CD28 costimulatory domain and CD3-? signaling domain, targeting different epitopes on CD123. CD123-CAR-redirected T cells mediated potent effector activity against CD123+ cell lines as well as primary AML patient samples. CD123 CAR T cells did not eliminate granulocyte/macrophage and erythroid colony formation in vitro. Additionally, T cells obtained from patients with active AML can be modified to express CD123 CARs and are able to lyse autologous AML blasts in vitro. Finally, CD123 CAR T cells exhibited antileukemic activity in vivo against a xenogeneic model of disseminated AML. These results suggest that CD123 CAR T cells are a promising immunotherapy for the treatment of high-risk AML.
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The Src and c-Kit kinase inhibitor dasatinib enhances p53-mediated targeting of human acute myeloid leukemia stem cells by chemotherapeutic agents.
Blood
PUBLISHED: 07-29-2013
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The SRC family kinases (SFKs) and the receptor tyrosine kinase c-Kit are activated in human acute myeloid leukemia (AML) cells. We show here that the SFKs LYN, HCK, or FGR are overexpressed and activated in AML progenitor cells. Treatment with the SFK and c-KIT inhibitor dasatinib selectively inhibits human AML stem/progenitor cell growth in vitro. Importantly, dasatinib markedly increases the elimination of AML stem cells capable of engrafting immunodeficient mice by chemotherapeutic agents. In vivo dasatinib treatment enhances chemotherapy-induced targeting of primary murine AML stem cells capable of regenerating leukemia in secondary recipients. Our studies suggest that enhanced targeting of AML cells by the combination of dasatinib with daunorubicin may be related to inhibition of AKT-mediated human mouse double minute 2 homolog phosphorylation, resulting in enhanced p53 activity in AML cells. Combined treatment using dasatinib and chemotherapy provides a novel approach to increasing p53 activity and enhancing targeting of AML stem cells.
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Microenvironmental protection of CML stem and progenitor cells from tyrosine kinase inhibitors through N-cadherin and Wnt-?-catenin signaling.
Blood
PUBLISHED: 01-08-2013
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Tyrosine kinase inhibitors (TKIs) are highly effective in treatment of chronic myeloid leukemia (CML) but do not eliminate leukemia stem cells (LSCs), which remain a potential source of relapse. TKI treatment effectively inhibits BCR-ABL kinase activity in CML LSCs, suggesting that additional kinase-independent mechanisms contribute to LSC preservation. We investigated whether signals from the bone marrow (BM) microenvironment protect CML LSCs from TKI treatment. Coculture with human BM mesenchymal stromal cells (MSCs) significantly inhibited apoptosis and preserved CML stem/progenitor cells following TKI exposure, maintaining colony-forming ability and engraftment potential in immunodeficient mice. We found that the N-cadherin receptor plays an important role in MSC-mediated protection of CML progenitors from TKI. N-cadherin-mediated adhesion to MSCs was associated with increased cytoplasmic N-cadherin-?-catenin complex formation as well as enhanced ?-catenin nuclear translocation and transcriptional activity. Increased exogenous Wnt-mediated ?-catenin signaling played an important role in MSC-mediated protection of CML progenitors from TKI treatment. Our results reveal a close interplay between N-cadherin and the Wnt-?-catenin pathway in protecting CML LSCs during TKI treatment. Importantly, these results reveal novel mechanisms of resistance of CML LSCs to TKI treatment and suggest new targets for treatment designed to eradicate residual LSCs in CML patients.
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Persistence of leukemia stem cells in chronic myelogenous leukemia patients in prolonged remission with imatinib treatment.
Blood
PUBLISHED: 09-19-2011
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Imatinib mesylate treatment markedly reduces the burden of leukemia cells in chronic myelogenous leukemia (CML) patients. However, patients remain at risk for relapse on discontinuing treatment. We have previously shown that residual BCR-ABL(+) progenitors can be detected in CML patients within the first 2 years of imatinib treatment. However, reduced rates of relapse and continued decline of BCR-ABL levels with prolonged treatment, together with the ability of selected patients to maintain remission after discontinuing treatment, led us to investigate whether prolonged imatinib exposure resulted in reduction or elimination of BCR-ABL(+) stem cells. We evaluated BCR-ABL expression in CD34(+)CD38(+) (38(+)) committed progenitors and CD34(+)CD38(-) (38(-)) stem/primitive progenitor cells in samples from CML patients on imatinib treatment for at least 4 years with cytogenetic and molecular response. High levels of BCR-ABL expression were maintained over time in the 38(-) stem cell fraction. The absolute frequency of BCR-ABL(+) cells as determined by limiting dilution analysis was consistently higher in 38(-) compared with 38(+) cells. Transplantation into NOD/SCID-IL2R?-chain knockout mice demonstrated that BCR-ABL(+) cells had long-term in vivo repopulating capacity. These results directly demonstrate that BCR-ABL(+) stem cells persist in CML patients despite prolonged treatment with imatinib, and support ongoing efforts to target this population.
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Altered hematopoietic cell gene expression precedes development of therapy-related myelodysplasia/acute myeloid leukemia and identifies patients at risk.
Cancer Cell
PUBLISHED: 07-02-2011
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Therapy-related myelodysplasia or acute myeloid leukemia (t-MDS/AML) is a major complication of cancer treatment. We compared gene expression in CD34+ cells from patients who developed t-MDS/AML after autologous hematopoietic cell transplantation (aHCT) for lymphoma with controls who did not develop t-MDS/AML. We observed altered gene expression related to mitochondrial function, metabolism, and hematopoietic regulation in pre-aHCT samples from patients who subsequently developed t-MDS/AML. Progression to overt t-MDS/AML was associated with additional alterations in cell-cycle regulatory genes. An optimal 38-gene PBSC classifier accurately distinguished patients who did or did not develop t-MDS/AML in an independent group of patients. We conclude that genetic programs associated with t-MDS/AML are perturbed long before disease onset, and accurately identify patients at risk for this complication.
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A critical role for SHP2 in STAT5 activation and growth factor-mediated proliferation, survival, and differentiation of human CD34+ cells.
Blood
PUBLISHED: 06-13-2011
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SHP2, a cytoplasmic protein-tyrosine phosphatase encoded by the PTPN11 gene, plays a critical role in developmental hematopoiesis in the mouse, and gain-of-function mutations of SHP2 are associated with hematopoietic malignancies. However, the role of SHP2 in adult hematopoiesis has not been addressed in previous studies. In addition, the role of SHP2 in human hematopoiesis has not been described. These questions are of considerable importance given the interest in development of SHP2 inhibitors for cancer treatment. We used shRNA-mediated inhibition of SHP2 expression to investigate the function of SHP2 in growth factor (GF) signaling in normal human CD34(+) cells. SHP2 knockdown resulted in markedly reduced proliferation and survival of cells cultured with GF, and reduced colony-forming cell growth. Cells expressing gain-of-function SHP2 mutations demonstrated increased dependency on SHP2 expression for survival compared with cells expressing wild-type SHP2. SHP2 knockdown was associated with significantly reduced myeloid and erythroid differentiation with retention of CD34(+) progenitors with enhanced proliferative capacity. Inhibition of SHP2 expression initially enhanced and later inhibited STAT5 phosphorylation and reduced expression of the antiapoptotic genes MCL1 and BCLXL. These results indicate an important role for SHP2 in STAT5 activation and GF-mediated proliferation, survival, and differentiation of human progenitor cells.
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Activation of p53 by SIRT1 inhibition enhances elimination of CML leukemia stem cells in combination with imatinib.
Cancer Cell
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BCR-ABL tyrosine kinase inhibitors (TKI) fail to eliminate quiescent leukemia stem cells (LSC) in chronic myelogenous leukemia (CML). Thus, strategies targeting LSC are required to achieve cure. We show that the NAD(+)-dependent deacetylase SIRT1 is overexpressed in human CML LSC. Pharmacological inhibition of SIRT1 or SIRT1 knockdown increased apoptosis in LSC of chronic phase and blast crisis CML and reduced their growth in vitro and in vivo. SIRT1 effects were enhanced in combination with the BCR-ABL TKI imatinib. SIRT1 inhibition increased p53 acetylation and transcriptional activity in CML progenitors, and the inhibitory effects of SIRT1 targeting on CML cells depended on p53 expression and acetylation. Activation of p53 via SIRT1 inhibition represents a potential approach to target CML LSC.
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What is Visualize?

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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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

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.