title: Aclacinomycin A sensitizes K562 chronic myeloid leukemia cells to imatinib through p38MAPK-mediated erythroid differentiation.
abstract: Expression of oncogenic Bcr-Abl inhibits cell differentiation of hematopoietic stem/progenitor cells in chronic myeloid leukemia (CML). Differentiation therapy is considered to be a new strategy for treating this type of leukemia. Aclacinomycin A (ACM) is an antitumor antibiotic. Previous studies have shown that ACM induced erythroid differentiation of CML cells. In this study, we investigate the effect of ACM on the sensitivity of human CML cell line K562 to Bcr-Abl specific inhibitor imatinib (STI571, Gleevec). We first determined the optimal concentration of ACM for erythroid differentiation but not growth inhibition and apoptosis in K562 cells. Then, pretreatment with this optimal concentration of ACM followed by a minimally toxic concentration of imatinib strongly induced growth inhibition and apoptosis compared to that with simultaneous co-treatment, indicating that ACM-induced erythroid differentiation sensitizes K562 cells to imatinib. Sequential treatment with ACM and imatinib induced Bcr-Abl down-regulation, cytochrome c release into the cytosol, and caspase-3 activation, as well as decreased Mcl-1 and Bcl-xL expressions, but did not affect Fas ligand/Fas death receptor and procaspase-8 expressions. ACM/imatinib sequential treatment-induced apoptosis was suppressed by a caspase-9 inhibitor and a caspase-3 inhibitor, indicating that the caspase cascade is involved in this apoptosis. Furthermore, we demonstrated that ACM induced erythroid differentiation through the p38 mitogen-activated protein kinase (MAPK) pathway. The inhibition of erythroid differentiation by p38MAPK inhibitor SB202190, p38MAPK dominant negative mutant or p38MAPK shRNA knockdown, reduced the ACM/imatinib sequential treatment-mediated growth inhibition and apoptosis. These results suggest that differentiated K562 cells induced by ACM-mediated p38MAPK pathway become more sensitive to imatinib and result in down-regulations of Bcr-Abl and anti-apoptotic proteins, growth inhibition and apoptosis. These results provided a potential management by which ACM might have a crucial impact on increasing sensitivity of CML cells to imatinib in the differentiation therapeutic approaches.
authors.affiliation: Department of Microbiology and Immunology, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yueh-Lun
authors.initials: YL
authors.lastname: Lee
authors.forename: Chih-Wei
authors.initials: CW
authors.lastname: Chen
authors.forename: Fu-Hwa
authors.initials: FH
authors.lastname: Liu
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Huang
authors.forename: Huei-Mei
authors.initials: HM
authors.lastname: Huang
mesh_terms: D015250:Aclarubicin / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides / Q000494:pharmacology* / Q000627:therapeutic use; D053148:Caspase 3 / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D004354:Drug Screening Assays, Antitumor; D004789:Enzyme Activation / Q000187:drug effects; D041905:Erythroid Cells / Q000187:drug effects / Q000201:enzymology / Q000473:pathology*; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006801:Humans; D000068877:Imatinib Mesylate; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D010879:Piperazines / Q000494:pharmacology* / Q000627:therapeutic use; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology* / Q000627:therapeutic use; D051020:bcl-X Protein / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D001549:Benzamides; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D010879:Piperazines; D019253:Proto-Oncogene Proteins c-bcl-2; D011743:Pyrimidines; D051020:bcl-X Protein; D019014:fas Receptor; D015250:Aclarubicin; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl; D048051:p38 Mitogen-Activated Protein Kinases; D053148:Caspase 3