Prolactin stimulates transcription of growth-related genes in Nb2 T lymphoma cells.

The pituitary peptide hormone prolactin exerts a profound effect on various physiological processes involving both cellular proliferation and differentiation. The rat Nb2 T lymphoma cell line has been used as a model system for studying prolactin regulation of cell proliferation. Several genes associated with cell growth (c-myc, ornithine decarboxylase (ODC), heat shock protein 70 (hsp 70)-homologue, and beta-actin) are induced rapidly within 4 h after prolactin addition. Nuclear run-on transcription assays indicate that prolactin induction of these growth-related genes occurs primarily at the transcriptional level. According to the different kinetics of transcriptional response to prolactin, these growth-related genes can be divided into immediate-early (actin, c-myc), early (ODC) and mid-G1 (hsp 70-homologue) genes. Thus, prolactin may regulate Nb2 T cell-proliferative responses by modulating the transcriptional induction of various growth-related genes. These studies also represent a first report of a transcriptional cascade set off in rapid response to prolactin in cultured T cells.