title: Silencing Nrf2 impairs glioma cell proliferation via AMPK-activated mTOR inhibition.
abstract: Gliomas are the leading cause of death among adults with primary brain malignancies. Treatment for malignant gliomas remains limited, and targeted therapies have been incompletely explored. Nuclear factor erythroid 2-related factor 2 (Nrf2), a key transcription regulator for antioxidant and detoxification enzymes, is abundantly expressed in cancer cells. In this study, the role and mechanism of Nrf2 in cancer cell proliferation was investigated in multiple glioma cell lines. We first evaluated the expression patterns of Nrf2 in four glioma cell lines and found all four cell lines expressed Nrf2, but the highest level was observed in U251 cells. We further evaluated the biological functions of Nrf2 in U251 glioma cell proliferation by specific inhibition of Nrf2 using short hairpin RNA (shRNA). We found that Nrf2 depletion inhibited glioma cell proliferation. Nrf2 depletion also decreased colony formation in U251 cells stably expressing Nrf2 shRNA compared to scrambled control shRNA. Moreover, suppression of Nrf2 expression could lead to ATP depletion (with concomitant rise in AMP/ATP ratio) and consequently to AMPK-activated mTOR inhibition. Finally, activation of adenosine monophosphate-activated protein kinase (AMPK) by treated with phenformin, an AMPK agonist, can mimic the inhibitory effect of Nrf2 knockdown in U251 cells. In conclusion, our findings will shed light to the role and mechanism of Nrf2 in regulating glioma proliferation via ATP-depletion-induced AMPK activation and consequent mTOR inhibition, a novel insight into our understanding the role and mechanism of Nrf2 in glioma pathoetiology. To our knowledge, this is also the first report to provide a rationale for the implication of cross-linking between Nrf2 and mTOR signaling.
authors.affiliation: Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, 305 East Zhongshan Road, Nanjing 210002, Jiangsu Province, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Jia
authors.affiliation: Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, 305 East Zhongshan Road, Nanjing 210002, Jiangsu Province, China. Electronic address: njhdwang@hotmail.com.
authors.forename: Handong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, 305 East Zhongshan Road, Nanjing 210002, Jiangsu Province, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Neurosurgery, Jinling Hospital, School of Medicine, Southern Medical University (Guangzhou), 305 East Zhongshan Road, Nanjing 210002, Jiangsu Province, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Ding
authors.affiliation: Department of Neurosurgery, Nanjing Jingdu Hospital, No. 34, Biao 34, Yanggongjing Road, Nanjing 210002, Jiangsu Province, China.
authors.forename: Heming
authors.initials: H
authors.lastname: Wu
authors.affiliation: Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, 305 East Zhongshan Road, Nanjing 210002, Jiangsu Province, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Pan
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004789:Enzyme Activation; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D005910:Glioma / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases
keywords: AMPK/mTOR; ATP; Glioma; Nrf2; Proliferation