PTHrP and PTH/PTHrP receptor expressions in human endometrium

We investigated menstrual cycle-dependent changes in the expression of PTHr P and PTH/PTHrP receptor in the human endometrium by immunohistochemistry, and competitive reverse transcription and polymerase chain reaction (RT-PCR ). Human endometrial tissues were obtained from patients who underwent gyne cological surgery due to cervical cancer (carcinoma in situ) or ovarian can cer. The mean age of the 20 patients was 36.5 (range 31-44) years. For anal ysis of mRNA expression, specimens from proliferative (mid, n=5; late, n=5) and secretory (early, n=4; mid, n=4) phases were used. Immunohistochemical expression of PTHrP and PTH/PTHrP receptor was observed in the cytoplasm o f both epithelial and stromal cells. Stronger staining of PTHrP was found i n glandular epithelial cells than in stromal cells. The staining during the proliferative phase was stronger than that in the secretory phase and the difference was particularly remarkable when comparing samples from the same patient. PTH/PTHrP receptor was also present in both epithelial and stroma l cells of the endometrium. However, no difference was observed in receptor expression between the proliferative and secretory phases. Competitive RT- PCR revealed that the expression of PTHrP mRNA was higher during the prolif erative phase than in the secretory phase, although no difference was obser ved in PTH/PTHrP receptor mRNA expression. The data suggest that endometria l proliferation may be mediated by a local PTHrP autocrine and/or paracrine mechanism.