Synergistic action of glucocorticoid and insulin in expression of transfected rat beta-casein promoter/human growth hormone fusion gene in a mammary epithelial cell line

Abstract

Transcription from the P-casein gene promoter is induced by the synergistic action of glucocorticoid and prolactin hormones in the murine mammary epithelial cell line, HC11. We analyzed the synergistic action of lactogenic hormones for the expression of human growth hormone in HC11 cells which was transfected with rat P-casein promoter/human growth hormone fusion gene (pChGH). The hybrid gene, containing 5' flanking sequence of rat p-casein gene (？2300/+487) fused to the structural sequence of the human growth hormone (hGH) gene, was stably introduced into HC11 cells. Northern hybridization results showed that transcription of human growth hormone gene was induced by the synergistic action of prolactin, insulin, and glucocorticoid hormones in a manner analogous to that of p-casein chloramphenicol acetyltransferase chimeric gene. However, radioimmunoassay results showed that the synergistic effect of glucocorticoid and insulin hormones on the production of human growth hormone was prominent, while the effect of prolactin was not.