PRDM Gene Products in Testicular Germ Cell Tumors

ST2. PRDM Gene Products in Testicular Germ Cell Tumors E. di Zazzo1, C. Porcile1, C. De Rosa2, A. Marino1, S. Bartollino1, C. Abbondanza2, B. Moncharmont1 1Università degli Studi del Molise, Campobasso, Italy; 2Seconda Università degli studi di Napoli, Naples, Italy Background: Testicular germ cell tumors (TGCT) originate from primordial germ cells blocked at different stages during maturation, reflecting different histological tumor subtypes. A common genetic alteration in TGCT is a deletion of chromosome 1 short arm, where the PRDM2 gene, a member of positive regulatory domain gene family, is located. Moreover recent studies demonstrated that members of PRDM gene family have an essential role in the early stages of testicular development. The aim of this study is to evaluate PRDM gene family members for a possible tumorsuppressor function in TGCT. Methods: PRDM gene expression was assessed by mRNA RT-PCR. Cells were treated with 100 nM 17β-Estradiol (E2), 100 nM DHT or 10 uM RA in serum free medium for 24h. RNA interference was performed using BLOCK-iT™ Pol II miR RNAi system. Proliferation assay was performed with propidium iodide staining and FACS analysis. Results: In GC1 mouse spermatogonial cells treatment with proliferation agents 5α-dihydrotestosterone (DHT) and E2 reduced PRDM2/RIZ1 expression levels whereas PRDM2 total forms showed no variation; the same treatment significantly increased PRDM4 and PRDM10 expression levels. Silencing PRDM2 gene expression by RNA interference increased PRDM10 expression levels and reduced the proliferation rate of spermatogonia. Conclusions: In spermatogonia as in MCF-7 cell line, E2 and DHT regulate PRDM2 gene expression suggesting that PRDM2 gene products could mediate the effect of these agents on cell cycle progression. PRDM4 and PRDM10 are also responsive to steroid hormones and PRDM10 probably cooperates with PRDM2, as demonstrated by the increase of its expression levels after PRDM2 gene silencing.