title: Glucosylceramide synthase inhibitor PDMP sensitizes chronic myeloid leukemia T315I mutant to Bcr-Abl inhibitor and cooperatively induces glycogen synthase kinase-3-regulated apoptosis.
abstract: Inactivation of glycogen synthase kinase (GSK)-3 has been implicated in cancer progression. Previously, we showed an abundance of inactive GSK-3 in the human chronic myeloid leukemia (CML) cell line. CML is a hematopoietic malignancy caused by an oncogenic Bcr-Abl tyrosine kinase. In Bcr-Abl signaling, the role of GSK-3 is not well defined. Here, we report that enforced expression of constitutively active GSK-3 reduced proliferation and increased Bcr-Abl inhibition-induced apoptosis by nearly 1-fold. Bcr-Abl inhibition activated GSK-3 and GSK-3-dependent apoptosis. Inactivation of GSK-3 by Bcr-Abl activity is, therefore, confirmed. To reactivate GSK-3, we used glucosylceramide synthase (GCS) inhibitor PDMP to accumulate endogenous ceramide, a tumor-suppressor sphingolipid and a potent GSK-3 activator. We found that either PDMP or silence of GCS increased Bcr-Abl inhibition-induced GSK-3 activation and apoptosis. Furthermore, PDMP sensitized the most clinical problematic drug-resistant CML T315I mutant to Bcr-Abl inhibitor GNF-2-, imatinib-, or nilotinib-induced apoptosis by >5-fold. Combining PDMP and GNF-2 eliminated transplanted-CML-T315I-mutants in vivo and dose dependently sensitized primary cells from CML T315I patients to GNF-2-induced proliferation inhibition and apoptosis. The synergistic efficacy was Bcr-Abl restricted and correlated to increased intracellular ceramide levels and acted through GSK-3-mediated apoptosis. This study suggests a feasible novel anti-CML strategy by accumulating endogenous ceramide to reactivate GSK-3 and abrogate drug resistance.
authors.affiliation: Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Wei-Ching
authors.initials: WC
authors.lastname: Huang
authors.forename: Cheng-Chieh
authors.initials: CC
authors.lastname: Tsai
authors.forename: Chia-Ling
authors.initials: CL
authors.lastname: Chen
authors.forename: Tsai-Yun
authors.initials: TY
authors.lastname: Chen
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Chen
authors.forename: Yee-Shin
authors.initials: YS
authors.lastname: Lin
authors.forename: Pei-Jung
authors.initials: PJ
authors.lastname: Lu
authors.forename: Chun-Mao
authors.initials: CM
authors.lastname: Lin
authors.forename: Shwu-Huey
authors.initials: SH
authors.lastname: Wang
authors.forename: Chiung-Wen
authors.initials: CW
authors.lastname: Tsao
authors.forename: Chi-Yun
authors.initials: CY
authors.lastname: Wang
authors.forename: Yi-Lin
authors.initials: YL
authors.lastname: Cheng
authors.forename: Chia-Yuan
authors.initials: CY
authors.lastname: Hsieh
authors.forename: Po-Chun
authors.initials: PC
authors.lastname: Tseng
authors.forename: Chiou-Feng
authors.initials: CF
authors.lastname: Lin
mesh_terms: D017485:1-Deoxynojirimycin / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D045744:Cell Line, Tumor; D002518:Ceramides / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D016313:Genes, abl / Q000187:drug effects / Q000502:physiology; D005964:Glucosyltransferases / Q000037:antagonists & inhibitors*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy*; D008558:Melphalan; D051379:Mice; D016513:Mice, SCID; D009025:Morpholines / Q000494:pharmacology*; D009154:Mutation; D009374:Neoplasms, Experimental; D011743:Pyrimidines; D014183:Transplantation, Heterologous
chemical_list: D002518:Ceramides; D004791:Enzyme Inhibitors; C508526:GNF-2 compound; D007074:Immunoglobulin G; D009025:Morpholines; D011743:Pyrimidines; C051713:antineoplastic agent K 18; D017485:1-Deoxynojirimycin; C033110:RV 538; C059896:miglustat; D005964:Glucosyltransferases; C023246:ceramide glucosyltransferase; D038362:Glycogen Synthase Kinase 3; D008558:Melphalan