Abstract: Breast cancer is a highly heterogeneous disease. Its accurate molecular subtyping helps us to improve the precision of breast cancer prognosis and the corresponding therapeutic decision making. By comparing the transcriptional and translational expression of foxa1 among breast cancer cell lines, the previous hypothesis that FOXA1 is a critical factor discriminating breast cancer subtypes was validated. In addition, by silencing foxa1 and observing the subsequent proliferation and apoptosis, the roles of FOXA1 played in breast cancer occurrence, development and prognosis were explored. Analyzing the expression of foxa1 in 10 cell lines covering four subtypes by Western Blot and real-time quantitative PCR, the expression of foxa1 in Luminal A and Luminal B breast cancers was significantly higher than that in Her2 positive and Triple negative subtypes. By analyzing the expression of other genes that promote cell growth, the result showed that FOXA1 was a key regulatory factor between GATA3 and ER, which inhibited cell proliferation.

Key words: breast cancer, FOXA1, molecular subtypes, transcription factor