Aberrant methylation of RASSF1A is associated with poor survival in Tunisian breast cancer patients

Epigenetic gene silencing is one of the major causes of inactivation of tumor-suppressor genes in many human cancers. The aim of the present study was to determine the methylation status of the promoter region CpG islands of four cancer-related genes RASSF1A, RAR beta 2, CDH1, and p16 (INK4a) in 78 breast cancer specimens and to evaluate whether the methylation status is associated with estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2/neu) together with the major clinico-pathological parameters. We showed that the methylation frequencies ranged from 19.6% (p16 (INK4a) ) to 87% (RASSF1A) in primary breast tumors of Tunisian patients. Aberrant methylation of RAR beta 2 was observed in 66.6% of cases and associated with age at diagnosis (P = 0.043), while CDH1 was methylated in 47.4% of tumors and was correlated with tumor size (P = 0.013). RASSF1A presented the highest percentage of methylation (87%) and was strongly associated with poor survival (P = 0.014), with age (P = 0.048), and tumor stage (P = 0.033). Loss of ER and PR was strongly associated with GIII tumors (P = 0.000 and 0.037 respectively) while HER2/neu was associated with lymph node involvement (P = 0.026) and 5-year survival rate (P = 0.028). Our preliminary findings suggested that aberrant methylation of RASSF1A and RAR beta 2 occurs frequently in Tunisian breast cancer patients compared with others. Furthermore, RASSF1A hypermethylation could be used as a potential marker of poor prognosis.