Activation of Breast Cancer Cell Proliferation by ROR-Alpha Through Aromatase Promoter

The document reports on a study that investigated the role of retinoic acid receptor-related orphan receptor (ROR) alpha in the proliferation of estrogen receptor-positive breast cancer cells. The study involved transfecting an ROR-alpha expression vector into MCF7 cells, a clonal cell line derived from breast cancer, and measuring the effects on aromatase gene expression, endogenous aromatase activity, and cell proliferation. The results showed that ROR-alpha transfection significantly increased aromatase mRNA levels and endogenous aromatase activity in a dose-dependent manner. Additionally, in the presence of androstenedione, which is converted to estrone by aromatase, cell proliferation was stimulated by ROR-alpha. Without androstenedione, proliferation was not stimulated. The conclusion drawn from these findings is that ROR-alpha partly regulates the expression of aromatase and its activity, which may lead to the proliferation of ER-positive breast cancer cells, suggesting that ROR-alpha could be a critical factor for the prognosis of breast cancer.