Aberrant methylation of RASSF2A in human pancreatic ductal adenocarcinoma and its relation to clinicopathologic features.

OBJECTIVES: Tumor suppressor gene Ras-association domain family 2A (RASSF2A) is inactivated by promoter hypermethylation in many cancers. The study was performed to evaluate the methylation status of RASSF2A in pancreatic ductal adenocarcinoma and cell lines and its relation to clinicopathologic features.

METHODS: The RASSF2 expression in 8 pancreatic carcinoma cell lines and 1 normal pancreatic tissue was detected. The methylation status of RASSF2A in 8 pancreatic carcinoma cell lines, 41 cases of pancreatic ductal adenocarcinoma, and corresponding normal pancreatic tissue was also examined by methylation-specific PCR. BxPC-3 and AsPC-1 cell lines were treated with 5-aza-2'-deoxycytidine (5-aza-dC), and RASSF2 expression was determined by quantitative real-time reverse transcriptase-polymerase chain reaction.

RESULTS: The expression of RASSF2 was down-regulated in all cell lines. Hypermethylation of RASSF2A was detected in all cell lines and 9 of 41 pancreatic ductal adenocarcinomas. Whereas none of hypermethylation of RASSF2A was found in the normal pancreatic tissue. The expression of RASSF2 could be restored by 5-aza-dC in cell lines.

CONCLUSIONS: Promoter hypermethylation of RASSF2A is observed in pancreatic ductal adenocarcinoma, while not in normal pancreatic tissue. RASSF2A is inactivated in pancreatic ductal adenocarcinoma by CpG island promoter hypermethylation and may play a role in pancreatic carcinogenesis.