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AMPK promotes p53 acetylation via phosphorylation and inactivation of SIRT1 in liver cancer cells.

ABSTRACT: AMP-activated protein kinase (AMPK), a biologic sensor for cellular energy status, has been shown to act upstream and downstream of known tumor suppressors. However, whether AMPK itself plays a tumor suppressor role in cancer remains unclear. Here, we found that the ?2 catalytic subunit isoform of AMPK is significantly downregulated in hepatocellular carcinoma (HCC). Clinicopathologic analysis revealed that underexpression of AMPK-?2 was statistically associated with an undifferentiated cellular phenotype and poor patient prognosis. Loss of AMPK-?2 in HCC cells rendered them more tumorigenic than control cells both in vitro and in vivo. Mechanistically, ectopic expression of AMPK enhanced the acetylation and stability of p53 in HCC cells. The p53 deacetylase, SIRT1, was phosphorylated and inactivated by AMPK at Thr344, promoting p53 acetylation and apoptosis of HCC cells. Taken together, our findings suggest that underexpression of AMPK is frequently observed in HCC, and that inactivation of AMPK promotes hepatocarcinogenesis by destabilizing p53 in a SIRT1-dependent manner.

SUBMITTER: Lee CW

PROVIDER: S-EPMC3433393 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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AMPK promotes p53 acetylation via phosphorylation and inactivation of SIRT1 in liver cancer cells.

Lee Chi-Wai CW Wong Leo Lap-Yan LL Tse Edith Yuk-Ting EY Liu Heong-Fai HF Leong Veronica Yee-Law VY Lee Joyce Man-Fong JM Hardie D Grahame DG Ng Irene Oi-Lin IO Ching Yick-Pang YP

Cancer research 20120622 17

AMP-activated protein kinase (AMPK), a biologic sensor for cellular energy status, has been shown to act upstream and downstream of known tumor suppressors. However, whether AMPK itself plays a tumor suppressor role in cancer remains unclear. Here, we found that the α2 catalytic subunit isoform of AMPK is significantly downregulated in hepatocellular carcinoma (HCC). Clinicopathologic analysis revealed that underexpression of AMPK-α2 was statistically associated with an undifferentiated cellular ...[more]

PMID: 22728651

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Project description:BackgroundUbiquitin-conjugating enzyme E2T (UBE2T) acts as an oncogene in various types of cancer. However, the mechanisms behind its oncogenic role remain unclear in lung cancer. This study aims to explore the function and clinical relevance of UBE2T in lung cancer.MethodsLentiviral vectors were used to mediate UBE2T depletion or overexpress UBE2T in lung cancer cells. CCK8 analysis and western blotting were performed to investigate the effects of UBE2T on proliferation, autophagy, and relevant signaling pathways. To exploit the clinical significance of UBE2T, we performed immunohistochemistry staining with an anti-UBE2T antibody on 131 NSCLC samples. Moreover, we downloaded the human lung adenocarcinoma (LUAD) dataset from The Cancer Atlas Project (TCGA). Lasso Cox regression model was adopted to establish a prognostic model with UBE2T-correlated autophagy genes.ResultsWe found that UBE2T stimulated proliferation and autophagy, and silencing this gene abolished autophagy in lung cancer cells. As suggested by Gene set enrichment analysis, we observed that UBE2T downregulated p53 levels in A549 cells and vice versa. Blockade of p53 counteracted the inhibitory effects of UBE2T depletion on autophagy. Meanwhile, the AMPK/mTOR signaling pathway was activated during UBE2T-mediated autophagy, suggesting that UBE2T promotes autophagy via the p53/AMPK/mTOR pathway. Interestingly, UBE2T overexpression increased cisplatin-trigged autophagy and led to cisplatin resistance of A549 cells, whereas inhibiting autophagy reversed drug resistance. However, no association was observed between UEB2T and overall survival in a population of 131 resectable NSCLC patients. Therefore, we developed and validated a multiple gene signature by considering UBE2T and its relevance in autophagy in lung cancer. The risk score derived from the prognostic signature significantly stratified LUAD patients into low- and high-risk groups with different overall survival. The risk score might independently predict prognosis. Interestingly, nomogram and decision curve analysis demonstrated that the signature's prognostic accuracy culminated while combined with clinical features. Finally, the risk score showed great potential in predicting clinical chemosensitivity.ConclusionsWe found that UBE2T upregulates autophagy in NSCLC cells by activating the p53/AMPK/mTOR signaling pathway. The clinical predicting ability of UBE2T in LUAD can be improved by considering the autophagy-regulatory role of UBE2T.

Dataset Information

AMPK promotes p53 acetylation via phosphorylation and inactivation of SIRT1 in liver cancer cells.

Publications

AMPK promotes p53 acetylation via phosphorylation and inactivation of SIRT1 in liver cancer cells.

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