EXPRESSION OF LUTEINIZING-HORMONE-RELEASING HORMONE AND ITS MESSENGER-RNA IN HUMAN ENDOMETRIAL CANCER CELL-LINES

Recent results have shown that specific binding sites for luteinizing hormone-releasing hormone (LHRH) are present in biopsy samples of huma n endometrial cancer and in the human endometrial cancer cell lines Is hikawa and HEC-1A. The proliferation of these cell lines was retarded by LHRH analogs. The present study was undertaken to determine wether these endometrial tumor cells also produce LHRH or an LHRH-like peptid e which could serve as natural ligand for the LHRH binding sites. Usin g a specific antibody, LHRH-immunoreactivity was detected in extracts of Ishikawa (426 +/- 84 fmol/10(6) cells) and HEC-1A (368 +/- 41. fmol /10(6) cells) cells. LHRH-like bioactivity of these samples was assess ed in a rat pituitary cell culture system. The release of luteinizing hormone induced by endometrial cancer cell extracts corresponded to th at obtained with comparable amounts of authentic LHRH. The expression of the mRNA for LHRH could be demonstrated by reverse transcriptase - polymerase chain reaction using specific primers according to the publ ished sequence and by subsequent Southern blot analysis. The presence of immuno- and bioactive LHRH-like factors and the demonstration of ex pression of the mRNA for LHRH in two human endometrial cancer cell lin es supports the concept of an autocrine regulatory system based on LHR H in endometrial cancer.