The histogenesis and interrelationship of the various types of germ cell tumors (GCTs) have been proposed. Dysgerminoma/seminoma (D/S) is a primitive GCT that has not acquired the potential for further differentiation, whereas other types of GCTs are in a dynamic process of differentiation towards a somatic or extraembryonal direction. A primordial germ cell giving rise to a GCT undergoes a developmentally regulated erasure and resetting of imprinted genes, but changes in the imprinting pattern in GCTs as the tumor differentiates have not been well defined. We aimed to investigate the changes of the SNRPNmethylation pattern between the germinomas and non-germinomatous GCTs, as compared with the somatic methylation pattern.
The SNRPNmethylation pattern was changed in 53/74 (71.6%) of GCTs as non-somatic patterns. There were significant differences in the methylation pattern between the germinomas and non-germinomatous GCTs, the GCTs being frequently hypo- methylated in Ds/Ss (73.3%), in contrast to the frequent hypermethylation seen in the YSTs and teratomas (47.7%, p<0.05).
CONCLUSIONS:
The methylation status of an imprinting gene may be involved in the mechanism causing cellular differentiation and tumorigenesis of GCTs.