Research Of RASSF2A Expression And Aberrant Methylation In Breast Cancer

Objective In many cancers, tumor-suppressing gene RASSF2 A was deactivated because of promoter methylation. The objective of present study was to explore RASSF2 A expression and aberrant methylation in breast cancer.Methods(1) RASSF2 A m RNA expression level in two breast cancer cell lines MCF-7 and MDA-MB-231, and one normal breast cell line HBL-100 was detected using real-time PCR. The two breast cancer cell lines was treated with increasing concentrations 5-Aza-2’-deoxycytidine(5-Aza-Cd R) for 5 days and then expression level of RASSF2 A m RNA was detected; Methylation specific PCR(MSP) was used to detect RASSF2 A methylation status of the three cell lines.(2) 42 paired breast tissues(tumor and tumor-adjacent tissues) were collected, and m RNA expression level and methylation status of these tissues were detected using real-time PCR and MSP to analysis the relationship between RASSF2 A methylation and main clinicopathologic features. Results RASSF2 A m RNA expression level in human breast cancer cell lines MCF-7(P=0.000) and MDA-MB-231(P=0.000) was lower than that of in normal breast cell line, especially in MCF-7 cells; the results of MSP revealed exhaustive methylation of RASSF2 A promoter in two breast cancer cell lines, but methylation was not detected in normal breast cells; after treatment with 5-Aza-Cd R for 3 days, RASSF2 A m RNA expression level increased and showed a dose- and time-dependent manner, especially for MCF-7 cells, indicating abnormal expression of RASSF2 A gene was due to methylation modification in MCF-7 and MDA-MB-231 cells. The analysis result of42 paired breast tissues indicated that m RNA expression level of tumor tissues was lower than that of tumor-adjacent tissues(P=0.016). RASSF2 A promoter was methylated in 17(17/42) low RASSF2 A m RNA expression tumor tissues, but not in paired tumor-adjacent tissues(P=0.000). Methylation status of RASSF2 A promoter was not associated with age, tumor size, tumor stage, TNM Classification, status of ER, PR and Her2, and axillary node metastasis in breast cancer(P>0.05). Conclusion Decreased RASSF2 A m RNA expression level in breast cancer lines and breast cancer tissues were associated with methylation status of RASSF2 A promoter; further analysis of clinical tissues indicated methylation of RASSF2 A promoter in tumor tissues but not in tumor-adjacent tissues. The methylation of RASSF2 A promoter may inhibit transcription of the gene, thus losing tumor-suppressing function and promoting breast cancer occurrence and development.