Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HMGB1 is associated with human cancers and is an activator of autophagy which mediates chemotherapy resistance. We here show that the mRNA levels of HMGB1 are high in leukemia cells and it is involved in the progression of childhood chronic myeloid leukemia (CML). HMGB1 decreases the sensitivity of human myeloid leukemia cells K562 to anti-cancer drug induced death through up-regulating the autophagy pathway, which is confirmed by the observation with an increase in fusion of autophagosomes and autophagolysosomes. When overexpressing HMGB1, both mRNA levels of Beclin-1, VSP34 and UVRAG which are key genes involved in mammalian autophagy and protein levels of p-Bcl-2 and LC3-II are increased. Luciferase assays document that over-expression of HMGB1 increases the transcriptional activity of JNK and ERK, which may be silenced by siRNA. The results suggest that HMGB1 regulates JNK and ERK required for autophagy, which provides a potential drug target for therapeutic interventions in childhood CML.
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PMID:HMGB1 regulates autophagy through increasing transcriptional activities of JNK and ERK in human myeloid leukemia cells. 2194 54

An attractive strategy among adenovirus-based oncolytic systems is to design adenoviral vectors to express pro-apoptotic genes, in which this gene-virotherapy approach significantly enhances tumor cell death by activating apoptotic pathways. However, the existence of cancer cells with apoptotic defects is one of the major obstacles in gene-virotherapy. Here, we investigated whether a strategy that combines the oncolytic effects of an adenoviral vector with simultaneous expression of Beclin-1, an autophagy gene, offers a therapeutic advantage for leukemia. A Beclin-1 cDNA was cloned in an oncolytic adenovirus with chimeric Ad5/11 fiber (SG511-BECN). SG511-BECN treatment induced significant autophagic cell death, and resulted in enhanced cell killing in a variety of leukemic cell lines and primary leukemic blasts. SG511-BECN effects were seen in chronic myeloid leukemia and acute myeloid leukemia with resistance to imatinib or chemotherapy, but exhibited much less cytotoxicity on normal cells. The SG511-BECN-induced autophagic cell death could be partially reversed by RNA interference knockdown of UVRAG, ATG5, and ATG7. We also showed that SG511-BECN strongly inhibited the growth of leukemic progenitors in vitro. In murine leukemia models, SG511-BECN prolonged the survival and decreased the xenograft tumor size by inducing autophagic cell death. Our results suggest that infection of leukemia cells with an oncolytic adenovirus overexpressing Beclin-1 can induce significant autophagic cell death and provide a new strategy for the elimination of leukemic cells via a unique mechanism of action distinct from apoptosis.
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PMID:Potent antitumor activity of oncolytic adenovirus expressing Beclin-1 via induction of autophagic cell death in leukemia. 2376 61

Background: The development of drug resistance and the persistence of leukemia stem cells are major obstacles for the use of tyrosine kinase inhibitors (TKIs) in the treatment of chronic myeloid leukemia (CML). The induction of autophagic death in tumor cells represents a new route for leukemia treatment. Our previous study showed that infection of CML cells with oncolytic viruses carrying the autophagy gene Beclin1 downregulated BCR/ABL protein expression and significantly increased the killing effect of the oncolytic viruses on CML cells via autophagy activation. However, the specific molecular mechanisms underlying the regulation of BCR/ABL and Beclin1-dependent CML cell killing remain unclear. Methods: A physical interaction between BCR/ABL and Beclin1 was characterized via GST-pulldown, co-IP and dual-luciferase reporter assays. Cell proliferation was examined via CCK-8 and clone formation assays. The expression levels of the related proteins were measured via Western blotting. Autophagosomes were observed under transmission electron microscopy. Lentiviral vectors carrying Atg7/UVRAG shRNA or the Beclin1 gene were used to modulate the expression levels of the indicated genes. Immunofluorescence were performed to examine colocalization of BCR/ABL and p62/SQSTM1. CD34+CD38- cells were isolated from bone marrow samples from CML patients via fluorescence-activated cell sorting. Results: In this study, we observed that Beclin1 directly interacts with BCR/ABL. Beclin1 inhibited the activity of the BCR/ABL promoter to downregulate the level of BCR/ABL protein and to promote the downstream colocalization of p62/SQSTM1 and BCR/ABL to autolysosomes for degradation via activation of the autophagy signaling pathway. In CML cell lines, primary cells and CD34+CD38- leukemia stem cells, Beclin1 overexpression significantly inhibited cell growth and proliferation and induced autophagy. Conclusion: Taken together, our results suggest that autophagy induction via Beclin1 overexpression might offer new approaches for treating TKI-resistant CML and for promoting the clearance of leukemia stem cells, both of which have important clinical implications.
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PMID:The molecular mechanisms underlying BCR/ABL degradation in chronic myeloid leukemia cells promoted by Beclin1-mediated autophagy. 3123 74

Autophagy is a genetically regulated process of adaptation to metabolic stress and was recently shown to be involved in the treatment response of chronic myeloid leukemia (CML). However, in vivo data are limited and the molecular mechanism of autophagy regulators in the process of leukemogenesis is not completely understood. Here we show that Beclin-1 knockdown, but not Atg5 deletion in a murine CML model leads to a reduced leukemic burden and results in a significantly prolonged median survival of targeted mice. Further analyses of murine cell lines and primary patient material indicate that active BCR-ABL directly interacts with BECLIN-1 and phosphorylates its tyrosine residues 233 and 352, resulting in autophagy suppression. By using phosphorylation-deficient and phosphorylation-mimic mutants, we identify BCR-ABL induced BECLIN-1 phosphorylation as a crucial mechanism for BECLIN-1 complex formation: interaction analyses exhibit diminished binding of the positive autophagy regulators UVRAG, VPS15, ATG14 and VPS34 and enhanced binding of the negative regulator Rubicon to BCR-ABL-phosphorylated BECLIN-1. Taken together, our findings show interaction of BCR-ABL and BECLIN-1 thereby highlighting the importance of BECLIN-1-mediated autophagy in BCR-ABL+ cells.
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PMID:Phosphorylation of BECLIN-1 by BCR-ABL suppresses autophagy in chronic myeloid leukemia. 3139 21