title: MicroRNA-1301-Mediated RanGAP1 Downregulation Induces BCR-ABL Nuclear Entrapment to Enhance Imatinib Efficacy in Chronic Myeloid Leukemia Cells.
abstract: Chronic myeloid leukemia (CML) is a myeloproliferative disease. Imatinib (IM), the first line treatment for CML, is excessively expensive and induces various side effects in CML patients. Therefore, it is essential to investigate a new strategy for improving CML therapy. Our immunoblot data revealed that RanGTPase activating protein 1 (RanGAP1) protein levels increased by approximately 30-fold in K562 cells compared with those in normal cells. RanGAP1 is one of the important components of RanGTPase system, which regulates the export of nuclear protein. However, whether RanGAP1 level variation influences BCR-ABL nuclear export is still unknown. In this report, using shRNA to downregulate RanGAP1 expression level augmented K562 cell apoptosis by approximately 40% after treatment with 250 nM IM. Immunofluorescence assay also indicated that three-fold of nuclear BCR-ABL was detected. These data suggest that BCR-ABL nuclear entrapment induced by RanGAP1 downregulation can be used to improve IM efficacy. Moreover, our qRT-PCR data indicated a trend of inverse correlation between the RanGAP1 and microRNA (miR)-1301 levels in CML patients. MiR-1301, targeting the RanGAP1 3' untranslated region, decreased by approximately 100-fold in K562 cells compared with that in normal cells. RanGAP1 downregulation by miR-1301 transfection impairs BCR-ABL nuclear export to increase approximately 60% of cell death after treatment of 250 nM IM. This result was almost the same as treatment with 1000 nM IM alone. Furthermore, immunofluorescence assay demonstrated that Tyr-99 of nuclear P73 was phosphorylated accompanied with nuclear entrapment of BCR-ABL after transfection with RanGAP1 shRNA or miR-1301 in IM-treated K562 cells. Altogether, we demonstrated that RanGAP1 downregulation can mediate BCR-ABL nuclear entrapment to activate P73-dependent apoptosis pathway which is a novel strategy for improving current IM treatment for CML.
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Department of Biochemistry and Molecular Cell Biology, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Tsung-Yao
authors.initials: TY
authors.lastname: Lin
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Department of Biochemistry and Molecular Cell Biology, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Ku-Chung
authors.initials: KC
authors.lastname: Chen
authors.affiliation: Division of Hematology Oncology, Department of Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Hsing-Jin Eugene
authors.initials: HJ
authors.lastname: Liu
authors.affiliation: Department of Neurosurgery, Taipei City Hospital Ren-Ai Branch, Taipei, Taiwan.
authors.forename: Ann-Jeng
authors.initials: AJ
authors.lastname: Liu
authors.affiliation: Institute of Chemical Engineering, National Taipei University of Technology, Taipei, Taiwan.
authors.forename: Kun-Li
authors.initials: KL
authors.lastname: Wang
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Department of Biochemistry and Molecular Cell Biology, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chwen-Ming
authors.initials: CM
authors.lastname: Shih
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D016044:Fusion Proteins, bcr-abl / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D000068877:Imatinib Mesylate / Q000494:pharmacology*; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D035683:MicroRNAs / Q000235:genetics*; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D020690:GTPase-Activating Proteins; C572423:MIRN1301 microRNA, human; D035683:MicroRNAs; C092317:RANGAP1 protein, human; D034741:RNA, Small Interfering; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl