RESUMO
Cell proliferation is controlled by classical hormones and peptide growth factors. Uncontrolled, neoplastic growth is characterized by abrogation of the cell's requirement for extracellular regulators. Steroid hormones and serum growth factors have been shown to alter the cell's transcriptional program. fos and jun are immediate early genes induced by serum growth factors. Fos and Jun proteins interact with other proteins and with DNA, thus modulating the activity of both the glucocorticoid receptor and of genes directly related to DNA synthesis and cell division. To better understand the molecular basis for growth control and the anti-inflammatory and antitumor effects of glucocorticoid hormones, we here describe: a) cloning of cDNA sequences regulated by glucocorticoids in a rat glioma cell line that reversibly reacts to hormone treatment by changing from a transformed, malignant phenotype to normal; b) expression of the c-fos proto-oncogene in the eukaryotic baculovirus expression system.