INCREASED EXPRESSION OF LUTEINIZING-HORMONE HUMAN CHORIONIC-GONADOTROPIN RECEPTOR GENE IN HUMAN ENDOMETRIAL CARCINOMAS

Normal human endometrium expresses LH/hCG receptor gene. In the presen t study, we investigated whether human endometrial carcinomas also exp ress this receptor gene. Reverse transcription-nested polymerase chain reaction amplified LH/hCG receptor sequences from human endometrial c arcinoma just as it did those from normal human endometrium and human ovary as a positive control tissue. Northern blotting demonstrated tha t endometrial carcinomas contain a greater abundance of multiple LH/hC G receptor transcripts, which increased with increasing tumor grade. W estern immunoblotting revealed that all grades of endometrial carcinom as contain multiple immunoreactive receptor proteins in greater abunda nce than normal endometrium. In situ hybridization and immunocytochemi stry demonstrated not only the presence, but also higher LH/hCG recept or messenger ribonucleic acid and receptor protein levels in glands of endometrial carcinoma compared to glands in normal endometrium. Ligan d blotting demonstrated that the 35-kilodalton protein receptor could bind [I-125]hCG and that this binding was inhibited by excess unlabele d hCG. The binding was higher in endometrial carcinoma than in normal endometrium. Atrophic and endocervical glands from endometrial carcino ma samples contained very few or no receptors. In summary, our results demonstrate that human endometrial carcinomas not only contain but al so appear to overexpress LH/hCG receptors compared to normal endometri um. This novel finding introduces previously unsuspected possibilities concerning the role of LH and its receptors in human endometrial carc inomas.