Inhibition of estrogen receptor-positive human breast carcinoma cell growth by retinoic acid

Objective: To evaluate whether the growth inhibition by retinoic acid and RAR alpha mRNA expression levels were affected by the change of ER expression.

Methods: The ER-negative breast cancer cell line MDA-MB-231 was transfected with the ER gene by stable transfection.

Results: In ER-transfected cells not only was the RAR alpha mRNA expression increased, but their growth was inhibited by retinoic acid as well. Estrogen could greatly stimulate the RAR alpha gene expression not only in established ER-positive cell lines but also in ER-transfected MDA-MB-231 cells.

Conclusions: Our data strongly suggest that ER-mediated enhancement of RAR alpha levels play an important role in RA inhibition of human breast cancer cell growth.