Objective: To investigate RASSF1A expression in tissue of primary gastric cancer (GC) at mRNA and protein levels and analyze the relationship between DNA methylation status and RASSF1A expression in GC.
Methods: RASSF1A mRNA expression was determined with RT-PCR in 54 specimens of cancer tissue and adjacent normal tissue. RASSF1A promoter methylation was detected with methylation-specific PCR. The expression of RASSF1A protein level was determined with Western blot in tissue of GC in 20 patients.
Results: RASSF1A mRNA and protein expressions in GC were reduced significantly than those in corresponding normal tissue (A value: 0.2589 +/- 0.2407 vs 0.5448 +/- 0.2971, P < 0.0001; 0.1874 +/- 0.0737 vs 0.6654 +/- 0.2201, P < 0.0001, respectively). Methylation frequency of RASSF1A in primary GC was higher than that in corresponding normal tissue (66.7% vs 14.8%, P < 0.0001). Furthermore, RASSF1A mRNA expression in methylation group of GC was much reduced than that in unmethylation group of GC (0.1384 +/- 0.1142 vs 0.5018 +/- 0.2463, P < 0.0001).
Conclusion: Expression of RASSF1A is reduced in the tissue of GC at mRNA and protein levels. Low expression of RASSF1A is associated with hypermethylation of the promoter of RASSF1A gene.