HESRG: a novel biomarker for intracranial germinoma and embryonal carcinoma.

The novel stem cell-related gene, HESRG, was first identified by our group, and its expression pattern in human tumors remains unknown. In this study, we used RT-PCR to systematically investigate the expression of HESRG in various types of intracranial tumors and found that HESRG was expressed only in germinoma and embryonal carcinoma, but hardly at all in other types of brain tumors. Real-time PCR results further confirmed this expression pattern. Subsequently, we tested 134 intracranial non-germ cell tumors and 64 intracranial germ cell tumors by immunohistochemistry. Our results showed that HESRG was expressed strongly and diffusively in the nuclei of tumor cells in intracranial germinoma and embryonal carcinoma as well as in human embryonic stem cells. No positive staining signal was observed in any other type of intracranial tumors. In germinomas, 25 of 31 showed intensive (3+) expression, four cases showed moderate (2+) immunostaining and the remaining 2 cases showed weak (1+) immunostaining. In embryonal carcinoma, 6 of 9 showed intensive (3+) immunostaining and 3 of 9 showed moderate (2+) immunostaining. These results suggest that HESRG is a novel, sensitive and specific biomarker for intracranial germinoma and embryonal carcinoma.