Our research examines the role of the EGF/erbB gene family of receptors and ligands in the growth of ovarian carcinoma. The expression of several of these ligands and receptors was examined in ovarian carcinoma cell lines and the several histologic stages of human ovarian carcinogenesis. Using differential RT-PCR techniques, OVCAR-8 and OVCA 429 ovarian carcinoma cell lines (even when grown in serum-free medium) concurrently and simultaneously expressed high levels of mRNA for Transforming Growth Factor-Alpha (TGF-a), Epidermal Growth Factor Receptor ( EGFR), and erbB-2 receptor, which is consistent with an autocrine involvement of these three gene products in in vitro ovarian carcinoma cell growth (Gordon, et al, Cancer Letters89, 63-71, 1995). Moreover, using an inducible erb-B2 antisense expression vector in one of these ovarian carcinoma lines, we observed reduced erbB-2 protein expression by Western Blot analysis and an inhibition of anchorage-independent growth (Pegues, J.C. and Stromberg, K., Cancer Letters 117, 73-79, 1997). This further links erbB-2 expression to the malignant phenotype. Ovarian carcinoma tissues have also been examined. In an immunohistochemical study, the apparent preferential association of Amphiregulin immunoreactivity in ovarian carcinomas of low malignant potential and TGF-a in advanced carcinomas (Stromberg et al, Int. J. Gyncol. Path 13, 342-347,1995) was noted, and now is being confirmed using quantitative RT-PCR assay (TAQman assay, Heid, et al, Genome Reseach 6:984, 1996) in 20 mRNA samples from each of these two types of ovarian tumors. Although c-erbB2 receptor message has been consistently overexpressed in ovarian cell lines and tumors, suggesting a essential biological role for this receptor, Amphiregulin mRNA expression has not been examined. When coupled with EGF-R, erbB-3 and erbB-4, and the additional ligands HGR and HB-EGF, the long-term objective is to profile comparative mRNA expression of 5 ligands and 4 receptors of the EGF family in ovarian carcinoma cells and tissues. In collaboration with M.X. Sliwkowski at Genentech, Inc., the antitumor effects of an erbB-4-IgG fusion protein on well-established intraperitoneal tumors of Ovca 429 and NIH:OVCAR-8 cells in athymic mice was minimal. A second similar tumorigenesis experiment will target this Heregulin-binding therapy to only newly IP-injected tumor cells.
