Human chorionic gonadotropin is expressed virtually in all intracranial germ cell tumors

Abstract

Human chorionic gonadotropin (hCG) production has been utilized as a diagnostic marker for germinoma with syncytiotrophoblastic giant cells (STGC) and choriocarcinoma. Elevated hCG in germinoma is considered to predict less favorable prognosis, and an intensive treatment strategy may accordingly be applied. However, there is some evidence that any germinoma may produce hCG to varying extent. We investigated mRNA expression of the hCG β subunit (hCGβ) using real time quantitative polymerase chain reaction in 94 germ cell tumors (GCTs). Most (93.3%) GCTs showed higher expression levels compared with that of normal brain tissue (1.09×10(0)-1.40×10(5) fold). The expression was the highest in GCTs which harbor choriocarcinoma or STGC components. The expression level of hCGβ in germinoma was highly variable (1.09×10(0)-5.88×10(4) fold) in linear but not bimodal distribution. hCG concentrations in serum and CSF correlated with gene expression, especially when GCTs with single histological component were analyzed separately. The expression was not significantly associated with recurrence in pure germinoma. These results suggest that the serum/CSF hCG levels may need to be interpreted with caution as most GCTs appear to have the capacity of producing hCG irrespective of their histology. The clinical significance of ubiquitous hCG expression in GCTs needs further investigation.