title: Activation of AMP-activated protein kinase by temozolomide contributes to apoptosis in glioblastoma cells via p53 activation and mTORC1 inhibition.
abstract: Methylating drugs such as temozolomide (TMZ) are widely used in the treatment of brain tumors including malignant glioblastoma. The mechanism of TMZ-induced glioblastoma cell death and apoptosis, however, is not fully understood. Here, we tested the potential involvement of AMP-activated protein kinase (AMPK) in this process. We found that methylating agents TMZ and N-methyl-N'-nitro-N-nitrosoguanidine induce AMPK activation in primary cultured human glioblastoma and glioblastoma cell lines. TMZ-induced O(6)-methylguanine production is involved in AMPK activation. O(6)-benzylguanine, an O(6)-methylguanine-DNA methyltransferase inhibitor, enhances TMZ-induced O(6)-methylguanine production, leading to enhanced reactive oxygen species production, which serves as an upstream signal for AMPK activation. Activation of AMPK is involved in TMZ-induced glioblastoma cell death and apoptosis. AMPK inhibitor (Compound C) or AMPKα siRNA knockdown inhibits TMZ-induced glioblastoma cell death and apoptosis, whereas AMPK activator 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside enhances it. In further studies, we found that activation of AMPK is involved in TMZ-induced p53 activation and subsequent p21, Noxa, and Bax up-regulation. Activation of AMPK by TMZ also inhibits mTOR complex 1 (mTORC1) signaling and promotes anti-apoptosis protein Bcl-2 down-regulation, which together mediate TMZ-induced pro-cell apoptosis effects. Our study suggests that activation of AMPK by TMZ contributes to glioblastoma cell apoptosis, probably by promoting p53 activation and inhibiting mTORC1 signaling.
authors.affiliation: Department of Physiology, China Pharmaceutical University, Nanjing 210009, China.
authors.forename: Wen-bin
authors.initials: WB
authors.lastname: Zhang
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Wang
authors.forename: Fei
authors.initials: F
authors.lastname: Shu
authors.forename: Yong-hua
authors.initials: YH
authors.lastname: Jin
authors.forename: Hong-yi
authors.initials: HY
authors.lastname: Liu
authors.forename: Qiu-juan
authors.initials: QJ
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors / Q000378:metabolism; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005909:Glioblastoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D006147:Guanine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D000076222:Mechanistic Target of Rapamycin Complex 1; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D046912:Multiprotein Complexes; D011506:Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases; D000077204:Temozolomide; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis
chemical_list: D018906:Antineoplastic Agents, Alkylating; C494826:BAX protein, human; D004791:Enzyme Inhibitors; D046912:Multiprotein Complexes; C498702:PMAIP1 protein, human; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; C064976:O(6)-benzylguanine; D008769:Methylnitronitrosoguanidine; D006147:Guanine; D003606:Dacarbazine; C008449:O-(6)-methylguanine; D015254:DNA Modification Methylases; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; D000077204:Temozolomide