Summary The growth inhibitory effects of all-trans and 13-cis retinoic acid (RA) and of the synthetic retinoids TTNPB, TTNPB-ethylester and TTNN were studied on seven human epithelial ovarian cancer cell lines and one ovarian teratocarcinoma cell line. Six of seven ovarian adenocarcinoma cell lines were inhibited in their growth by RA and by synthetic retinoids in a dose dependent manner. No response to these substances was observed for the ovarian teratocarcinoma cell line. The knowledge that RA and retinoids exert their action on the cells via nuclear receptors led us to examine the expression of RAR-a, -,B and -mRNA by these cell lines by polymerase chain reaction following reverse transcription. All cell lines expressed RAR-x and -mRNA and six of the eight cell lines were found to express additionally RAR-P mRNA, among them the ovarian teratocarcinoma cell line. Our data indicate that there was no direct association between the presence of RAR subtype transcripts and the response to retinoids in ovarian cancer cell lines.Retinoic acid (RA) is a morphogenic compound involved in vertebrate development (Eichele, 1989) and it plays a major role in epithelial cell growth and cellular differentiation (Sporn et al., 1984). RA induces differentiation of mouse embryonal carcinoma cells in vitro and influences the development of the regenerating amphibian limb (for review see de Luca, 1991).It has also been shown that retinoids cause growth inhibition in many hyperproliferating cell lines, a feature that makes the compounds of fundamental interest as antitumour agents. Retinoids prevent the development of cancer of the skin and are effective as agents in the treatment of human premalignant and malignant cutaneous disorders (Lippman & Meyskens, 1989). In addition, retinoids are successfully used in the therapy of the acute promyelocytic leukaemia (Meng-er et al., 1988).Several intracellular proteins interacting with RA have been identified, such as the cellular retinoic acid binding protein (CRABP) and the nuclear retinoic acid receptors (RARs). Three RAR subtypes RAR-a, -P and -y have been identified so far (Petkovich et al., 1987;Giguere et al., 1987;Benbrook et al., 1988;Brand et al., 1988;Krust et al., 1989 NIH:OVCAR-3 and the ovarian teratocarcinoma cell line CRL 1572 (PA-1) were received from the American Tissue Type Culture Collection (ATCC, Rockville, MD, USA). All cell lines were cultivated in a-MEM (Gibco, Scotland) supplemented with 10% heat-inactivated foetal calf serum (Gibco, Scotland) and were maintained in an humidified 5% CO2 atmosphere at 37°C. Cultures were refed after 4 days and passaged weekly 1:5 -1:10.All cells were used within 30 passages from the original stock.Tests for mycoplasma contamination were negative (DAPI, Boehringer Mannheim, Germany).
RetinoidsAll-trans RA, 1 3-cis RA, (E)-4- [2-(5,6,7,8-tetrahydro-5,5,8,8,-tetramethyl-2-naphthalenyl)-1-propenyl] benzoic acid -(5,6,7,8-tetrahydro-5,5,8,8,-tetramethyl-2-