SRY-related high-mobility-group box 6 suppresses cell proliferation and is downregulated in breast cancer

Breast cancer is one of the most common cancers endangering women's health. SRY-related high-mobility-group box 6 (SOX6) is associated with many cancers, though its role has not been reported in breast cancer. Here, we aimed to explore the expression and function of SOX6 in breast cancer. On the basis of the analysis of SOX6 in The Cancer Genome Atlas, Cancer Cell Line Encyclopedia and Genotype-Tissue Expression databases, we revealed that SOX6 was downregulated in breast cancer, and we verified the results at the cellular level by means of western blotting and quantitative real-time PCR. When SOX6 was overexpressed, the proliferation of breast cancer cells was inhibited, and apoptosis was promoted. Moreover, the methylation level of the SOX6 promoter in breast cancer was significantly higher than that in normal tissues. 5'-Aza-2'-deoxycytidine reversed the high level of methylation that was caused by decreased expression of SOX6. This evidence suggests that SOX6 is a tumor suppressor gene associated with breast cancer. This study could provide a new target for breast cancer treatment.