Methylation Pattern Of BCSG1 Gene And Its Relationship With Gene Expression In Breast Tumor

BCSG1 (breast cancer specific gene 1) was first identified in 1997. A series of studies suggested that BCSG1 gene may play an important role in breast carcinogenesis. Demethylation of BCSG1 has been correlated with its abnormally high expression in breast cancer. To determine the role of DNA methylation of BCSG1 gene in the development of breast cancer in Chinese women, we examined the methylation status of exon 1 of the BCSG1 gene in breast tissues using MSP and sequencing analysis, and corresponding mRNA expression levels using real-time PCR. We found: (1) the BCSG1 gene was universally unmethylated in all breast tissues regardless of the tissue state, although 50-60% of the samples displayed methylated products as well; (2) DNA methylation correlated to expression of the BCSG1 gene in tumor tissues, but not in non-neoplastic adjacent and benign tissues; (3) the mean expression level of tumors was nearly 5-fold lower than expression of normal tissues, but there was no expression difference between benign tissues and normal tissues. Our data revealed a unique expression pattern and methylation status of the BCSG1 gene in breast tissues in Chinese patients and suggested both methylation status and mechanisms underlying BCSG1 regulation might be closely related to racial background. Further investigation within populations with varied genetic background is required before applying BCSG1 expression or methylation status as a breast cancer marker.