Predictive value of expression and promoter hypermethylation of XAF1 in hepatitis B virus-associated hepatocellular carcinoma treated with transplantation.
BACKGROUND
Transcriptional regulation of the putative tumor suppressor gene X-linked inhibitor of apoptosis protein-associated factor 1 (XAF1) by promoter methylation has been related to tumor progression in gastric and bladder cancer. The aim of this study was to investigate the methylation status and expression level of XAF1 in human hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) treated with liver transplantation (LT), and to evaluate potential predictive value for tumor recurrence.


METHODS
The expression level and methylation status of XAF1 in three liver cancer cell lines (SMMC-7721, HepG2, and Hep3B) and 65 cases of HBV-associated HCC following LT were analyzed by RT-PCR (RT, reverse-transcriptase), immunohistochemistry, and methylation-specific polymerase chain reaction (PCR).


RESULTS
XAF1 transcripts were not observed or present at low levels in liver cancer cell lines and were restored by treatment with demethylating agent 5-aza-2'-deoxycytidine (5-Aza-dC). In vivo, methylation status was associated with protein level of XAF1 (P < 0.001) and serum level of alpha-fetoprotein (AFP) (P = 0.009). The expression pattern of XAF1 was associated with portal vein tumor thrombi (PVTT), preoperative AFP level, tumor size, and recurrence. Multivariate analysis revealed that expression level of XAF1 was an independent factor for predicting recurrence-free survival [hazard ratio 0.237, 95% confidence interval (CI) 0.095-0.592, P = 0.002]. However, no significant association was found between methylation status and the risk of tumor recurrence.


CONCLUSIONS
Promoter hypermethylation is a critical, but not the sole, mechanism for gene silencing of XAF1 in HCC. Protein level of XAF1 may serve as a potential biomarker for tumor recurrence after LT.
Zhang
Feng
F
Department of Hepatobiliary and Pancreatic Surgery, Key Lab of Combined Multi-organ Transplantation, Ministry of Public Health, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
Wu
Li-Ming
LM
Zhou
Lin
L
Chen
Qi-Xing
QX
Xie
Hai-Yang
HY
Feng
Xiao-Wen
XW
Zheng
Shu-Sen
SS
D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000368:Aged; D051017:Apoptosis Regulatory Proteins; D001374:Azacitidine / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000150:complications / Q000235:genetics* / Q000601:surgery; D019175:DNA Methylation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006509:Hepatitis B / Q000150:complications / Q000235:genetics* / Q000821:virology; D006515:Hepatitis B virus / Q000235:genetics; D006801:Humans; D007124:Immunoenzyme Techniques; D047908:Intracellular Signaling Peptides and Proteins; D008113:Liver Neoplasms / Q000150:complications / Q000235:genetics* / Q000601:surgery; D016031:Liver Transplantation; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D009364:Neoplasm Recurrence, Local / Q000235:genetics / Q000601:surgery; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015996:Survival Rate; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; C417551:XAF1 protein, human; D001374:Azacitidine