BIOLOGICAL ASSAY FOR ACTIVITY AND MOLECULAR MECHANISM OF RETINOIDS INCERVICAL TUMOR-CELLS

The composition and response of the retinoid signaling pathway in a hu man cell line (CC-1), representative of a low grade cervical carcinoma , were evaluated. Reverse-transcriptase polymerase chain reaction (RT- PCR) analysis demonstrated expression of cytoplasmic retinol binding p rotein, CRBPI, cytoplasmic retinoic acid binding protein, CRABPII, and nuclear retinoic acid receptors, RAR alpha, RAR gamma, RXR alpha, and RXR beta, but not CRABPI or RAR beta. This pattern is similar to that of the ectocervix. Activation of endogenous nuclear receptors was eva luated in a reporter subline of CC-1, called CC-B, containing a report er gene controlled by a retinoic acid responsive element (RARE) and th ymidine kinase promoter. Retinoid treatment of CC-B resulted in dose-d ependent increases in reporter gene expression. Retinoids inhibited gr owth at concentrations greater than 100 nM. 9-cis retinoic acid (1 nM) significantly stimulated growth. Immunohistochemical analysis of CC-B organotypic cultures demonstrated a high level of epidermal growth fa ctor receptor (EGF-R) expression that was decreased by retinoids. The degree of RARE transactivation induced by retinoids significantly corr elated with the degree of inhibition of growth (R = (-)0.96) and EGF-R expression (R = (-)0.92), The dose-dependent and retinoid-specific re sponses of CC-1 at the molecular and biological levels demonstrate the utility of this reporter cell line for evaluation of retinoid activit ies. (C) 1997 Academic Press.