The T47D cell line is an ideal experimental model to elucidate the progesterone-specific effects of a luminal A subtype of breast cancer.

Cell lines are often used as in vitro tools to mimic certain types of in vivo system; several cell lines, including MCF-7 and T47D, have been widely used in breast cancer studies without investigating the cell lines' characteristics. In this study, we compared the genome-wide binding profiles of ERα, PR, and P300, and the gene expression changes between MCF-7 and T47D cell lines that represent the luminal A subtype of breast cancer. Surprisingly, several thousand genes were differentially expressed under estrogenic condition. In addition, ERα, PR, and P300 binding to regulatory elements showed distinct genomic landscapes between MCF-7 and T47D cell lines in the same hormonal states. In particular, the T47D cell line was markedly susceptible to progesterone, whereas the MCF-7 cell line did not respond to progesterone in the presence of estrogen. Consistently, changes in the expression level of the PR-target gene, STAT5A, were only observed in the T47D cell line, not the MCF-7 cell line, when treated with progesterone. Overall, the results highlight the importance of selecting appropriate cell lines for breast cancer studies and suggest that T47D cell lines can be an ideal experimental model to elucidate the progesterone-specific effects of a luminal A subtype of breast cancer.