Differential Akt Signalling in Non-seminomatous Testicular Germ Cell Tumors

To investigate the protein kinase B (Akt) signalling proteins phosphatase and tensin homolog (PTEN), phosphorylated-Akt (p-Akt) and cyclin-dependent kinase inhibitor 1B (p27(Kip1)) in non-seminomatous germ cell tumors (NST) with a view to future investigative approaches. The expressions of PTEN, p-Akt and p27(Kip1) were immunohistochemically assessed in 17 teratomas, 27 embryonal cell carcinomas, 6 yolk sac tumors and 24 benign testicular parenchymas. The cytoplasmic and corresponding nuclear expressions were compared and correlated to tumor entity. PTEN was dramatically reduced in all the NST subgroups. Concentrated nuclear p27(Kip1) and loss of the cytoplasmic form was found in teratomas and embryonal cell carcinomas. Neither altered expression nor negative Akt regulation was found. The yolk sac tumors showed late cytoplasmic shift of PTEN and p27(Kip1). Both, the absence of overexpression of p-Akt and of negative correlations to PTEN and p27(Kip1) suggest that signalling of these parameters in NST might include additional mechanisms such as crosstalk to other pathways rather than classical Akt activation.