Expression of the retinoic acid receptors (RARs) and retinoid X receptor (RXRs) genes in breast cancer
Abstract
A number of studies have been shown that retinoids can inhibit malignant cell growth including certain breast carcinoma cells. Its inhibitory effort is observed only in ER-positive but not in ER-negative breast cancer cells.
We examined retinoic acid receptors (RARs) and retinoids X receptors (RXRs) levels in 6 breast carcinoma cell lines and 18 breast cancer biopsy specimens.
We found that RAR-α mRNA level was significantly higher in ER positive cell lines and samples.
RAR-γ mRNA was expressed at relatively high levels in majority of tumor samples independent of the ER-status while RAR-β mRNA was expressed at low levels.
We also found high RXR-α mRNA levels in all of the tumor samples examined while RXR-γ mRNA could not be detected.
Our study suggests a possibility that retinoids inhibit tumor cell growth through RAR-α and RAR-α levels may serve as a potential marker to determine responsiveness of patients to retinoids therapy.