title: The Inhibition of microRNA-128 on IGF-1-Activating mTOR Signaling Involves in Temozolomide-Induced Glioma Cell Apoptotic Death.
abstract: Temozolomide (TMZ), an alkylating agent of the imidazotetrazine series, is a first-line chemotherapeutic drug used in the clinical therapy of glioblastoma multiforme, the most common and high-grade primary glioma in adults. Micro (mi)RNAs, which are small noncoding RNAs, post-transcriptionally regulate gene expressions and are involved in gliomagenesis. However, no studies have reported relationships between TMZ and miRNA gene regulation. We investigated TMZ-mediated miRNA profiles and its molecular mechanisms underlying the induction of glioma cell death. By performing miRNA microarray and bioinformatics analyses, we observed that expression of 248 miRNAs was altered, including five significantly upregulated and 17 significantly downregulated miRNAs, in TMZ-treated U87MG cells. miR-128 expression levels were lower in different glioma cells and strongly associated with poor survival. TMZ treatment significantly upregulated miR-128 expression. TMZ significantly enhanced miR-128-1 promoter activity and transcriptionally regulated miR-128 levels through c-Jun N-terminal kinase 2/c-Jun pathways. The overexpression and knockdown of miR-128 expression significantly affected TMZ-mediated cell viability and apoptosis-related protein expression. Furthermore, the overexpression of miR-128 alone enhanced apoptotic death of glioma cells through caspase-3/9 activation, poly(ADP ribose) polymerase degradation, reactive oxygen species generation, mitochondrial membrane potential loss, and non-protective autophagy formation. Finally, we identified that key members in mammalian target of rapamycin (mTOR) signaling including mTOR, rapamycin-insensitive companion of mTOR, insulin-like growth factor 1, and PIK3R1, but not PDK1, were direct target genes of miR-128. TMZ inhibited mTOR signaling through miR-128 regulation. These results indicate that miR-128-inhibited mTOR signaling is involved in TMZ-mediated cytotoxicity. Our findings may provide a better understanding of cytotoxic mechanisms of TMZ involved in glioblastoma development.
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Peng-Hsu
authors.initials: PH
authors.lastname: Chen
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chia-Hsiung
authors.initials: CH
authors.lastname: Cheng
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chwen-Ming
authors.initials: CM
authors.lastname: Shih
authors.affiliation: Department of Clinical Pharmacy, School of Pharmacy, Taipei Medical University, Taipei, Taiwan.
authors.forename: Kuo-Hao
authors.initials: KH
authors.lastname: Ho
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Lin
authors.affiliation: Department of Pathology and Laboratory Medicine, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan.
authors.forename: Chin-Cheng
authors.initials: CC
authors.lastname: Lee
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: Department of Neurosurgery, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.|Graduate Institute of Injury Prevention and Control, Taipei Medical University, Taipei, Taiwan.
authors.forename: Cheng-Kuei
authors.initials: CK
authors.lastname: Chang
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Ku-Chung
authors.identifier: http://orcid.org/0000-0002-4696-3924
authors.initials: KC
authors.lastname: Chen
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001932:Brain Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005910:Glioma / Q000188:drug therapy / Q000235:genetics / Q000473:pathology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D035683:MicroRNAs / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015996:Survival Rate; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D000077204:Temozolomide; D014407:Tumor Cells, Cultured
chemical_list: D018906:Antineoplastic Agents, Alkylating; C545189:MIRN128 microRNA, human; D035683:MicroRNAs; D017382:Reactive Oxygen Species; D007334:Insulin-Like Growth Factor I; D003606:Dacarbazine; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D000077204:Temozolomide