J. Stero~l I~oehem. Molec. BtoL 3/ol. 37, No. 2, pp. 223-230, 1990 0960-0760/90$3.00+ 0.00 Prihte¢in Great Britain. All rights reL.rved Copyright ~ 1990PergamonPress pk GLUCOCORTICOID EFFECTS AND RECEPTORS IN TWO RAT COLON CARCINOMA CELL LINES DIFFERING BY THEIR TUMORIGENICITY AHMED BERRADA, MARC G. EmNm,* PHILIPPE BLAN~m, COmNNE OIADt~2~mAU and PATRICK LuSTmqm~o~ Department of Medical Biochemistry, Nantes University Hospital, 1 rue G. Veil, F-44035 Nantes Cedex, France (Received I4 April I990) Sammary--Steroid hormones, regulators of cell differentiation and proliferation, are believed to play a role in carcinogenesis. Glucocerticoid hormones in particular modulate the expression of a number of proteins implicated in this process. We have investigated the effect of dexamethasone on two cell lines derived from a colon carcinoma, which differ by their tumorigenicity. Dexamethasone was found to inhibit growth of both the progressive (PROb) and the regressive clone (REGb). Upon hormonal treatment, glucc~rticoid hormones induced fibronectin secretion by the two clones, whereas PROb cells were found to secrete an additional M, ~ 43,000 protein. The cellular effect of gincocorticeid hormones being mediated through a specific soluble receptor, we have characterized this protein. The progressive cells (PROb) contained more specificglucocorticoid-binding rites (~ 170,000 sites per cell) than the regressive ones (REGb cells; ~100,000 rites per cell). In both clones, the receptor was associated with the M, ~ 90,000 heat shock protein to yield large complexes (Stokes radius Rs ~ 7.5 nm), which were dissociated to the same extent upon heat- and salt-treatment. The steroid- and DNA-binding unit of the receptor, characterized under denaturing conditions using an anti-receptor monoclonai antibody was found to be more degraded in the progressive cell line. INTRODUCTION Steroid hormones are known to affect the proliferation, the metabolism, and the differen- tiation of both normal and malignant ceils [1-3]. These effects of steroid hormones are mainly mediated by specific receptors, and it is now well established that the presence or absence of steroid receptors in malignant cells is of importance in the regulation of tumor growth. For instance, the presence or absence of estrogen and progesterone receptors is an accurate pre- dictor of responsiveness to endocrine therapy in patients with breast cancer[4, 5]. In colonic tumors, the presence of receptors for estro- gen [6-8], progesterone [6-8], androgen [9, 10], mineralocorticoid [II] and glucocorticoid hor- mones [6] has been clearly demonstrated. *To whom corrcel~ndenc~ should be addS. Abbreviations: Dezamethasone, 9,,-fluoro-16~-methyl- 1 lp, 17%2 l-trihydroxy-pregna- 1,4-diene-3,20-dione; FCS, fetal calf serum; hspg0, M, ~ 90,000 heat shock protein; MOPS, 3-(N-morpholino)pr~onic acid; SDS-PAGE, polyacrylamide gel eleetrophomsis per- formed in the presence of sodium dodecyl ~Ifate; SSC, standard saline citrate (0.15M HaCl, 0.015M sodium citrate, pH 7.4). Glucocorticoid hormones in particular have been shown to influence a wide variety of different cell properties. They generally have an antiproliferative effect [12-15], although growth- stimulatory responses have been seen in foreskin fibroblasts [16] and in a human leiomyosarcoma cell line [17]. They also appear to be involved in different steps of carcinogenesis and formation of metastasis, as they up-regulate the production of different proteins which are involved in these processes, such as fibronectin [18-20] and a number of proteases [21]. All these observations suggest that glucocorti- coid hormones may play an important role in the biology of cancer. The purpose of this study was to investigate the effect of glucocorticoid hor- mones on two rat colon carcinoma cell lines differing by their tumorigenicity: after s.c. injec- tion into syngeneic BDIX rats, the cell line REGb yields regressive tumors, while PROb cells give progressive tumors which spread into the lungs, the kidneys, and the lymph nodes [22-24]. We also performed a detailed character- ization of the glucocorticoid receptors present in these two cell lines. 223