Clinicopathological significance of RASSF1A reduced expression and hypermethylation in hepatocellular carcinoma

Protein downregulation and hypermethylation of Ras association domain family 1A (RASSF1A) has been recognized as an important early event in different classes of carcinogenesis, but clinicopathological significance of RASSF1A protein expression and methylation in hepatocellular carcinoma (HCC) remains largely unknown. The aim of the study was to investigate the expression of RASSF1A protein and methylation in HCC and their clinical significance.

Immunohistochemistry was employed to detect the expression of RASSF1A proteins in liver tissue microarrays. Aberrant promoter hypermethylation of RASSF1A was investigated in DNA from HCC, matching noncancerous tissues and serum of 35 HCC patients by methylation-specific PCR.

RASSF1A protein expression in HCC was significantly lower than that in noncancerous (p = 0.015) and paracancerous tissues (p = 0.017). In addition, reduced RASSF1A protein expression is related to TNM stage, metastasis, α-fetoprotein, portal vein embolus, capsular infiltration, and multiple tumor nodes. Furthermore, RASSF1A promoter methylation in HCC was significantly higher than that in noncancerous liver tissues (p < 0.05). Meanwhile, RASSF1A promoter hypermethylation was detected in 14 in the serum DNA from HCC patients, whereas no hypermethylation was detected in the normal controls. Hypermethylation of RASSF1A in HCC serum and tissues was negatively correlated with the expression of RASSF1A protein expression (p < 0.05).

The loss or abnormal protein downregulation and the promoter hypermethylation of RASSF1A could play important roles in the tumorigenesis development and metastases of HCC. The detection of the promoter hypermethylation of RASSF1A in serum DNA could be a valuable biomarker for early-stage diagnosis in populations at high risk of HCC.