EXPRESSION AND LOCALIZATION OF INHIBIN ACTIVIN AND ACTIVIN RECEPTORS IN GH3 CELLS, A RAT PITUITARY ADENOCARCINOMA CELL-LINE

Inhibins and activins are members of the transforming growth factor be ta (TGF beta) superfamily. Since TGF beta has been shown to be a poten t proliferation-inhibiting agent for the pituitary adenocarcinoma cell line, GH3, we determined whether this cell line (a) transcribes mRNAs coding for inhibin/activin subunits (alpha and beta A) and activin re ceptors I, II, and IIB; and (b) produces inhibin and/or activin protei ns. Messenger RNAs for the alpha- and beta A-subunits of inhibin and a ctivin receptors I, II, and IIB in GH3 cells were detected and localiz ed using the reverse transcription-polymerase chain reaction (RT-PCR) analysis and in situ hybridization, respectively. The identity of the RT-PCR products was confirmed by DNA sequencing of PCR products. Immun ocytochemically, inhibin and activin were localized in these cells. Ou r findings indicate that messenger RNAs encoding inhibin alpha- and be ta A-subunits and activin receptors I, Il, and IIB were expressed, and inhibin/activin proteins were produced, by GH3 cells, imply that thes e gonadal growth factors may have paracrine/autocrine functions in rat pituitary adenocarcinoma. Further, these observation suggest that the se growth factors may be involved in regulating the growth and differe ntiational of rat pituitary adenocarcinoma cells.