Aberrant promoter methylation may be responsible for the control of CD146 (MCAM) gene expression during breast cancer progression.

The CD146 (also known as MCAM, MUC-18, Mel-CAM) was initially reported in 1987, as a protein crucial for the invasiveness of malignant melanoma. Recently, it has been confirmed that CD146 has been involved in progression and poor overall survival of many cancers including breast cancer. Importantly, in independent studies, CD146 was reported to be a trigger of epithelial to mesenchymal transition in breast cancer cells. The goal of our current study was to verify the potential involvement of epigenetic mechanism behind the regulation of CD146 expression in breast cancer cells, as it has been previously reported in prostate cancer. First, we analysed the response of breast cancer cell lines, differing in the initial CD146 mRNA and protein content, to epigenetic modifier, 5-aza-2-deoxycytidine, and subsequently the methylation status of CD146 gene promoter was investigated, using direct bisulfite sequencing. We observed that treatment with demethylating agent led to induction of CD146 expression in all analysed breast cancer cell lines, both at mRNA and protein level, what was accompanied by increased expression of selected mesenchymal markers. Importantly, CD146 gene promoter analysis showed aberrant CpG island methylation in 2 out of 3 studied breast cancer cells lines, indicating epigenetic regulation of CD146 gene expression. In conclusion, our study revealed, for the first time, that aberrant methylation maybe involved in expression control of CD146, a very potent EMT inducer in breast cancer cells. Altogether, the data obtained may provide the basis for novel therapies as well as diagnostic approaches enabling sensitive and very accurate detection of breast cancer cells.