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392COMUNICAZIONI LIBEREAromatase expression in human testicularseminomaF. Romeo * , V. Rago ** , G. Capocasale * , S. Andò *** , A. Carpino***Pathologic Anatomy Unit, Annunziata Hospital, Cosenza; **Cell Biology and Pharmaco-Biology Departments; *** Facultyof Pharmacy, University of CalabriaIntroductionCytocrome P450arom is a terminal enzyme catalysing theconversion of androgens into estrogens. Its expression hasbeen reported in different human tissues, including testes. Inaddition, aromatase has been investigated in human neoplastictissues for the estrogen ability to regulate the cell growth.In fact, P450arom overexpression has been detected in somebreast, endometrial and ovarian malignancies. Conversely,the enzyme expression in testicular tumors is scarcelyknown. This study has been addressed to immunolocalizearomatase in human testicular seminoma.Materials and methodsThe tumour-bearing testes were obtained, after informed consent,from 7 patients (aged from 30 to 50) with classic seminoma,undergoing to therapeutic orchidectomy. Paraffin-embeddedtestes were processed for immunohistochemistry usinga rabbit polyclonal antibody generated against humanplacental cytochrome P450arom. Then, biotinylated goatanti-rabbitIgG was applied followed by avidin-biotin-peroxidasecomplex. The peroxidase reaction was developed withdiaminobenzidine. Furthermore, hematoxylin-eosin stainingwas used for morphological analysis.ResultsP450arom immunoreactivity in the cells was detected as cytoplasmicstaining. All the samples showed similar immunostainingpatterns: i) In tumoral region, the cords of neoplasticcells showed a strong immunoreactivity, while thesurrounding abundant lymphocytes and connective cellswere immunonegative ii) In the region near the tumor margin,Leydig cells were strongly immunoreactive and an intensestaining was also observed in the big neoplastic cells ofthe modified tubules, identified as intratubular seminoma iii)In the region far from the tumor, Leydig cells were immunopositiveand no staining was observed in the tubuleswith seminiferous epithelium showing all the spermatogeneticstages. Conversely, those tubules with spermatogenetic arrest,showed a clear immunostaining in the basal cells.ConclusionsThe present study has demonstrated, for the first time, aromataseexpression in neoplastic cells of human seminoma. Infact, still now, aromatase presence in human testis tumors hasbeen reported only in stromal cells of non-seminoma tumorsand in sex cord tumor of young patients with the Peutz-Jeghers syndrome. Furthermore, testicular parenchyma, adjacentto the tumor, showed a differential aromatase expressionaccording to the tubular dysmorphy. This suggests a possiblerelationship between tumor progression and intratubular localizationof the enzyme. In fact, estrogens deriving from the“in situ” aromatization could act as autocrin mytogen factorspromoting neoplastic process.Bibliografia1Cairns P et al. Cancer Res 1994;54:1422-1424.2Gonzalgo ML et al. Cancer Res 1998;58:1245-1252.