EXPRESSION OF THE RETINOIC ACID RECEPTORS(RARs)AND RETINOID X RECEPTOR(RXRs)GENES IN BREAST CANCER

A number of studies have been shown that retiniodscan inhibit malignant cell growth including certain breastcarcinoma cells. its inhibitory effort is observed only inER-positive but not in ER-negative breast cancer cells.We examined retinoic acid receptors (RARs) andretinoids X receptors(RXRs) levels in 6 breast carcinomacell lines and 18 breast cancer biopsy specimens. Wefound that RAR-α mRNA level was significantly higher inER Positive cell lines and samples. RAR-γ mRNA wasexpressed at relatively high levels in majority of tumorsamples independent of the ER-status while RAR-βmRNA was expressed at low levels. We also found highRXR-α mRNA levels in all of the tumor samplesexamined while RXR-γ mRNA could not be detected.Our study suggests a possibility that retinoids inhibittumor cell growth through RAR-α and RAR-α levels mayserve as a potential marker to determine responsivenessof patients to retinoids therapy.

Expression of the retinoic acid receptors (RARs) and retinoid X receptor (RXRs) genes in breast cancer

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.