Activation of Epidermal Growth Factor Receptor (pEGFR) and Expression of Argentophilic Nucleolus Organizer Regions (AgNOR) in Seminomas.

ABSTRACT

Activation of epidermal growth factor receptor (p-EGFR) is one of the triggers in the development of many malignant tumors, and the measurement of Argentophilic Nucleolus Organizer Regions (AgNOR) area is used as a marker of tumor proliferation. Alpha actin smooth muscle (αASM) of peritubular cells (PT) and Vimentin expression are modified during the expansion of the CIS /intratubular germ cell neoplasia (ITGCN) to solid seminoma. We evaluated the expression pEGFR, the AgNOR areas, the expression of αASM in PT and the Vimentin in neoplastic cells from CIS/ ITGCN to solid seminoma. 28 formalin-fixed paraffin-embedded archival tissue blocks of Seminomas from the Departments of Pathology of Clinical Hospital and Ramos Mejía Hospital (CABA, Argentina) were used in this study. pEGFR was expressed in CIS/ ITGCN with membranous pattern (8/9), switching to a cytoplasmic pattern in the solid seminoma (15/19). AgNOR areas of atypical gonocytes were increasing from CIS (3.5±0.3 µ2) to intratubular seminoma (3.8±0.4µ2) (p<.5), until solid seminoma (5.3±0.7 µ2) (p<.01). Increase of AgNOR areas is proportional to the expression of pEGFR. Conclusions: pEGFR was expressed in CIS/ ITGCN with membranous pattern, switching to a cytoplasmic pattern in the solid seminoma. The activation of this receptor could be the first step in the mitogenic signal transduction. AgNOR areas complement diagnosis of testicular CIS, but not differentiate between CIS and intratubular seminoma. The value of AgNOR areas is maximum in the invasive seminoma, and statistically different from intratubular seminoma. The intensity of αASM in PT decreased as the tumor progressed and Vimentin was negative in neoplastic cells.