Detection of aromatase and estrogen receptors (ERalpha, ERbeta1, ERbeta2) in human Leydig cell tumor

A Leydig cell tumor is a rare neoplasm, deriving from the interstitial cells, whose pathogenesis has not been still defined. Leydig cells of normal adult testis are known as physiological targets for estrogens. However, some studies on transgenic rodents suggest a role of estrogens in the development of Leydig cell hyperplasia and Leydig cell tumor. Therefore, with the aim to evaluate a possible link between estrogens and testicular tumorigenesis, this study investigated the expression of aromatase and estrogen receptors (ERα, ERβ1, ERβ2) in testes from two patients with Leydig cell tumor. A strong immunoreactivity for aromatase, ERβ1, and ERβ2, together with a detectable ERα immunostaining, was revealed in tumoral tissues. These findings were confirmed by western blot analysis of tumor extracts detecting a 55 kDa P450arom, a 67 kDa ERα band, a 59 kDa ERβ1, band, and a 53 kDa ERβ2 band. The pattern of ER expression in neoplastic cells appears different from that of control Leydig cells exhibiting only ERβ1, and ERβ2 isoforms. The authors hypothesize how the high estrogen production could play a role in the neoplastic transformation of Leydig cells, while the exclusive presence of ERα in tumoral cells could amplify estradiol-17β signaling contributing to the tumor cell growth and progression.