Hypermethylation and Expression Silencing of PDCD4 Gene in Hepatocellular Carcinoma: A Consort Study

Programmed cell death 4 (PDCD4) is a novel tumor suppressor, which is involved in the initiation and progression of cancers. However, the role of PDCD4 in hepatocellular carcinoma (HCC) has not been reported. The aim of this study was to investigate the molecular mechanism and clinical significance of PDCD4 inactivation in HCC. The mRNA levels of PDCD4 in HCC tissues and adjacent nontumor tissues were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Bisulfite sequencing PCR was performed to determine the methylation status of PDCD4 promoter. Furthermore, the mRNA expression level and the methylated level of PDCD4 were analyzed with the clinical and pathological characteristics. qRT-PCR analysis showed that PDCD4 mRNA levels in tumor tissues were significantly decreased compared with that in adjacent nontumor tissues. The methylation rate of PDCD4 promoter was significantly higher in HCC tissues than that in adjacent nontumor tissues. PDCD4 mRNA levels and promoter methylation levels were both statistically correlated with metastasis and the degree of differentiation in HCC. In addition, the correlation between PDCD4 hypermethylation, mRNA levels, and overall survival (OS) was statistically significant. Our results indicated that PDCD4 may be a novel candidate of tumor suppressor gene in HCC, and that promoter hypermethylation is an important mechanism for its downregulation and is also a good predictor of OS for HCC.