Glucocorticoid-regulated gene in transformed to normal phenotypic reversion

Glucocorticoid hormones modulate the actions of peptide growth factors and constitute important therapeutic tools as anti-inflammatory and anti-tumor agents. The C6 rat glioma cell line responds to glucocorticoids with changes in morphology and growth block. The hyper-responsive STI cell variant displays a dramatic phenotypic reversion under the influence ofthese hormones. Thus, the transformed and tumorigenic cells reversibly change to a normal and non-tumorigenic phenotype. In addition, the cells also produce a C-type retrovirus. We used poly A + mRNA from ST1 cells that had been treated with hydrocortisone to generate a cDNA library that was then screened, by differential hybridization, for glucocorticoid-responsive cellular sequences