Production of inhibin A and inhibin B in human ovarian sex cord stromal tumors.

Our purpose was to examine the cellular localization of inhibin subunits and messenger ribonucleic acid expressions for the inhibin subunits and the serum levels of inhibin A and inhibin B in human ovarian sex cord stromal tumors. We examined the immunohistochemical localization of the inhibin subunits and the expression of the corresponding messenger ribonucleic acids by Northern blot analysis in a granulosa cell tumor and a Sertoli-Leydig cell tumor. We also measured serum concentrations of dimeric inhibin A and inhibin B by two-site enzyme-linked immunosorbent assay. Immunostaining specific for the inhibin alpha, betaA, and betaB subunits was observed in the granulosa cell tumor. In the Sertoli-Leydig cell tumor we observed immunostaining specific for the alpha subunit in Leydig tumor cells and that specific for the betaA subunit in Sertoli tumor cells and that specific for the betaB subunit in both tumor cells. Northern blot analysis revealed the presence of messenger ribonucleic acids for the alpha, betaA, and betaB subunits in the granulosa cell tumor and the Sertoli-Leydig cell tumor. The serum levels of dimeric inhibin A and inhibin B in patients were elevated preoperatively and decreased progressively after surgery. Our results suggest that inhibin A and inhibin B are produced by the human sex cord stromal tumors and that inhibins might be the useful markers of the tumors.