Reproduction Abstracts

Introduction: Testicular germ cell cancer (TGCC) has been increasing in incidence over recent decades. We have previously shown that the precursor lesion for TGCC, carcinoma in situ (CIS) cells, have different phenotypes which determine proliferation rate. CIS which express only OCT4, a well-established marker for CIS, proliferate more that those expressing OCT4 and MAGE-A4 (differentiated germ cells marker). Gankyrin is an oncogene that interacts with MAGE-A4 and supresses the degradation of OCT4. We hypothesize that Gankyrin would maintain OCT4 expression, whilst MAGE-A4 would reduce the oncogenic potential in CIS cells.

Materials and methods: We performed qPCR and immunofluorescence for Gankyrin expression using TGCC tissue obtained from patients undergoing orchidectomy. We assessed the expression in areas of normal spermatogenesis (NT), CIS adjacent to the tumour (AT) and tumour (TT). We also used siRNA to inhibit Gankyrin and study the effects of its down regulation on germ cell development.

Results and discussion: Gankyrin expression was localised to Sertoli cells cytoplasm in tubules with active spermatogenesis and in CIS containing tubules adjacent to the tumour, whilst no expression was observed in the tumour tissue. Overall relative mRNA amount of Gankyrin was 27% higher in TT (1.03×10¹⁷) compared to AT (7.51×10¹⁶) and AT was 29% higher compared to NT (4.52×10¹⁶), although this did not reach significance. The immunohistochemistry has shown that MAGEA4, OCT4, and Gankyrin can be found together in an individual tubule however no relationship between Gankyrin expression and the phenotype of CIS could be observed. siRNA studies are ongoing and will also be presented.