Activation of AMP-activated Protein Kinase by Temozolomide Contributes to Apoptosis in Glioblastoma Cells via p53 Activation and mTORC1 Inhibition

• Published in: The Journal of biological chemistry 2010-12, Vol.285 (52), p.40461-40471
• Main Authors: Zhang, Wen-bin, Wang, Zhuo, Shu, Fei, Jin, Yong-hua, Liu, Hong-yi, Wang, Qiu-juan, Yang, Yong
• Format: Article
• Language: English
• Subjects: AMP Kinase; AMP-Activated Protein Kinases - metabolism; Anticancer Drug; Antineoplastic Agents, Alkylating - pharmacology; Apoptosis - drug effects; bcl-2-Associated X Protein - biosynthesis; Cancer Therapy; Cell Biology; Cell Death; Cell Line, Tumor; Dacarbazine - analogs & derivatives; Dacarbazine - pharmacology; DNA Methylation; DNA Modification Methylases - antagonists & inhibitors; DNA Modification Methylases - metabolism; Enzyme Activation - drug effects; Enzyme Inhibitors - pharmacology; Gene Expression Regulation, Neoplastic - drug effects; Glioblastoma - drug therapy; Glioblastoma - metabolism; Glioblastoma - pathology; Guanine - analogs & derivatives; Guanine - metabolism; Guanine - pharmacology; Humans; Mechanistic Target of Rapamycin Complex 1; Methylnitronitrosoguanidine - pharmacology; Multiprotein Complexes; Proteins - metabolism; Proto-Oncogene Proteins c-bcl-2 - biosynthesis; Reactive Oxygen Species - metabolism; Signal Transduction - drug effects; Temozolomide; TOR Serine-Threonine Kinases; Tumor Suppressor Protein p53 - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.164046

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 O6-methylguanine production is involved in AMPK activation. O6-benzylguanine, an O6-methylguanine-DNA methyltransferase inhibitor, enhances TMZ-induced O6-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.