Prognostic significance of AMPK activation and therapeutic effects of metformin in hepatocellular carcinoma.
OBJECTIVE
The AMP-activated protein kinase (AMPK) serves as an energy sensor in eukaryotic cells and occupies a central role in linking metabolism and cancer development. However, the phosphorylation status of AMPK and its therapeutic value in human hepatocellular carcinoma (HCC) remain unclear.


METHODS
The phosphorylation status of AMPK (Thr172) was determined by immunoblotting and immunostaining in specimens from 273 patients with HCC (including 253 patients with hepatitis B virus -related HCC). Kaplan-Meier survival analysis was used to determine the correlation with prognosis. The effects of therapeutic metformin/AMPK activation were assessed in cultured human HCC cell lines and primary HCC cells in vitro and in xenograft tumors model in vivo. To define the mechanisms of anticancer effects of metformin, we examined its influence on AMPK activation and NF-κB pathway.


RESULTS
AMPK is dysfunctional in patients with HCC, and low p-AMPK staining is correlated with aggressive clinicopathologic features and poor prognosis. Activation of AMPK by metformin not only inhibited HCC cells growth in vitro and in vivo, but also augmented cisplatin-induced growth inhibition in HCC cells. Knockdown of AMPKα expression can greatly decrease the inhibitory effect of metformin, indicating that AMPK activation is required for the anticancer action of metformin. Mechanistically, metformin/AMPK activation inhibited NF-κB signaling through upregulation of IκBα. Activation of NF-κB signaling by ectopic expression of P65 or overexpression of an undegradable mutant form of IκBα attenuated the anticancer effects of metformin.


CONCLUSIONS
These results present novel insight into a critical role of AMPK in HCC progression. Anticancer effects of therapeutic metformin/AMPK activation unravel metformin's potential in treatment of HCC.
Authors' Affiliations: International Cooperation Laboratory on Signal Transduction, Eastern Hepatobiliary Surgery Institute; Department of Endocrinology, Changhai Hospital, Second Military Medical University; National Center for Liver Cancer Research; Liver Transplant Centers and Hepatic Surgery; and State Key Laboratory of Oncogenes and related Genes, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China.
Longyi
L
Zheng
Wen
W
Yang
Fuquan
F
Wu
Chao
C
Wang
Lexing
L
Yu
Liang
L
Tang
Bijun
B
Qiu
Yuqiong
Y
Li
Linna
L
Guo
Mengchao
M
Wu
Gensheng
G
Feng
Dajin
D
Zou
Hongyang
H
Wang
D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D002453:Cell Cycle / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008113:Liver Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D008297:Male; D008687:Metformin / Q000008:administration & dosage / Q000494:pharmacology*; D051379:Mice; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism; D009367:Neoplasm Staging; D010766:Phosphorylation / Q000187:drug effects; D011379:Prognosis; D012307:Risk Factors; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D047368:Tumor Burden / Q000187:drug effects
D000970:Antineoplastic Agents; D015850:Interleukin-6; D016328:NF-kappa B; D050796:STAT3 Transcription Factor; D008687:Metformin; D055372:AMP-Activated Protein Kinases