title: Amiloride modulates alternative splicing in leukemic cells and resensitizes Bcr-AblT315I mutant cells to imatinib.
abstract: The antihypertensive drug amiloride is being considered as a tactic to improve cancer therapy including that for chronic myelogenous leukemia. In this study, we show that amiloride modulates the alternative splicing of various cancer genes, including Bcl-x, HIPK3, and BCR/ABL, and that this effect is not mainly related to pH alteration, which is a known effect of the drug. Splice modulation involved various splicing factors, with the phosphorylation state of serine-arginine-rich (SR) proteins also altered during the splicing process. Pretreatment with okadaic acid to inhibit protein phosphatase PP1 reversed partially the phosphorylation levels of SR proteins and also the amiloride-modulated yields of Bcl-xs and HIPK3 U(-) isoforms. Genome-wide detection of alternative splicing further revealed that many other apoptotic genes were regulated by amiloride, including APAF-1, CRK, and SURVIVIN. Various proteins of the Bcl-2 family and MAPK kinases were found to be involved in amiloride-induced apoptosis. Moreover, the effect of amiloride on mRNA levels of Bcl-x was demonstrated to translate to the protein levels. Cotreatment of K562 and BaF3/Bcr-AblT315I cells with amiloride and imatinib induced more loss of cell viability than either agent alone. Our findings suggest that amiloride may offer a potential treatment option for chronic myelogenous leukemia either alone or in combination with imatinib.
authors.affiliation: Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Department of Laboratory Medicine, Kaohsiung Medical University Hospital,Center for Excellence in Environmental Medicine, Kaohsiung, Taiwan.
authors.forename: Wen-Hsin
authors.initials: WH
authors.lastname: Chang
authors.forename: Ta-Chih
authors.initials: TC
authors.lastname: Liu
authors.forename: Wen-Kuang
authors.initials: WK
authors.lastname: Yang
authors.forename: Chien-Chih
authors.initials: CC
authors.lastname: Lee
authors.forename: Yi-Hsiung
authors.initials: YH
authors.lastname: Lin
authors.forename: Tsai-Yun
authors.initials: TY
authors.lastname: Chen
authors.forename: Jan-Gowth
authors.initials: JG
authors.lastname: Chang
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects; D000584:Amiloride / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001549:Benzamides; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D004357:Drug Synergism; D005091:Exons; D016044:Fusion Proteins, bcr-abl / Q000235:genetics*; D018922:HL-60 Cells; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D000068877:Imatinib Mesylate; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000235:genetics*; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D010879:Piperazines / Q000494:pharmacology*; D054645:Protein Phosphatase 1 / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D000068103:Serine-Arginine Splicing Factors; D051020:bcl-X Protein / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D010879:Piperazines; D011743:Pyrimidines; D016601:RNA-Binding Proteins; D051020:bcl-X Protein; D000068103:Serine-Arginine Splicing Factors; D000584:Amiloride; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl; C109102:HIPK3 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D054645:Protein Phosphatase 1