Expression of retinoic acid receptor-beta 2 mRNA in normal cervical epithelium and cervical squamous cell carcinoma

Abstract

Retinoids have antiproliferative effects on epithelial cells and have been used as chemopreventive and chemotherapeutic agents for several human cancers. Retinoid/interferon combinations have demonstrated activity in advanced stage cervical cancer. The objective of this study was to quantify and localize the expression of RAR-beta 2, a retinoid inducible receptor, in normal cervix and cervical squamous cell carcinoma by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ RT-PCR. Specimens where obtained from 11 patients enrolled in a clinical trial to test all-trans retinoic acid (tRA) in combination with interferon-alpha 2a (IFN-alpha 2a) in the treatment of metastatic or recurrent cervical carcinoma. Expression of RAR-beta 2 in cervical carcinoma and normal cervix was measured by quantitative RT-PCR. DNA competitors were used to estimate the relative expression level of RAR-beta 2. Expression of RAR-beta 2 was examined in normal cervix by in situ RT-PCR. Expression of RAR-beta 2 in cervical carcinoma ranged from 0.33 to 1.40 with a mean of 0.89+/-0.13 vs. 1.0+/-0.13 for normal cervix (NS) with RAR-beta 2 reduced to less than or equal to 65% in five cases. Irt situ RT-PCR identified RAR-beta 2 most prominently in basal and para-basal epithelial cell layers of normal exocervix; stromal expression was markedly decreased. This is the first report to localize expression of RAR-beta 2 mRNA in normal cervical epithelium and quantify expression in normal cervix and cervical squamous cell carcinoma. Because retinoid receptors are the proximate mediators of retinoid action on gene expression, alteration of their expression or function could result in cancer development.