CHARACTERIZATION OF THE FUNCTIONAL PROGESTERONE-RECEPTOR IN AN ENDOMETRIAL ADENOCARCINOMA CELL-LINE (ISHIKAWA) - PROGESTERONE-INDUCED EXPRESSION OF THE ALPHA-1 INTEGRIN

Endometrial progesterone receptors (PR) are regulated by both estrogen (E(2)) and progesterone (P) and mediate the expression of specific en dometrial proteins. Ishikawa cells are a well-differentiated human end ometrial adenocarcinoma cell line, with both estrogen receptors (ER) a nd PR, regulated in a manner similar to that of normal endometrium. Im munohistochemical and biochemical analyses demonstrate that the concen tration of PR is increased by E(2) priming and decreased by subsequent treatment with P. Scatchard plot analysis showed a K-d of 1 nM. On th e basis of biochemical analysis, PR concentrations reached approximate ly 1400 fmol/mg cytosol protein in cells after treatment with E(2) (10 (-8) M) for 4 days. Immunoprecipitation and Western blot studies revea led the presence of both the 116 kDa and 81 kDa proteins with multiple isoforms of the high molecular weight (MW) protein. Northern blot ana lysis demonstrated transcriptional control of PR by steroid treatment. These studies demonstrate the coordinate regulation of all PR mRNA sp ecies. The functionality of Ishikawa PR was demonstrated by the expres sion of alpha 1 beta 1 integrin in response to E(2) plus P, at the lev el of transcription and translation. This effect was blocked by the ad dition of the anti-progestin, RU-486. These studies reconfirm that the Ishikawa cell line is an excellent model for the study of hormonally regulated events in the human endometrial epithelium. Copyright (C) 19 96 Elsevier Science Ltd.