Expression failure of the Notch signaling system is associated with the pathogenesis of testicular germ cell tumor

Objectives: The expression of Notch 1 and its ligand Jagged 2, critical factors in cell type specification, in testicular germ cell tumors was examined in order to evaluate its possible relationship with their pathogenesis. Methods: Northern blot analysis and immunohistochemical staining for Notch 1 and Jagged 2 were done in 139 samples of testicular germ cell tumors. Results: Notch 1 and Jagged 2 transcripts were expressed in noncancerous testicular tissues and Notch 1 and Jagged 2 proteins were positive in the spermatids. However, the expressions of transcript and protein were negative for both Jagged 2 and Notch 1 in seminomas, they were negative for Jagged 2 but were positive for Notch 1 in embryonal carcinomas and choriocarcinomas, and they were positive for Jagged 2 and Notch 1 in teratomas. Conclusions: Our results offer, for the first time, the possibility that the activity of the Notch signaling system, one of the cell proliferation and differentiation pathways, correlates with the different histological subtypes of germ cell tumor, which may be responsible for characteristics of cancer cells such as responses to chemotherapy and/or irradiation. Copyright (C) 2004 S. Karger AG, Basel.