Glypican-3 expression in Wilms tumor and hepatoblastoma.

Background: Glypican-3 (GPC3) is a heparan sulfate proteoglycan. When it is disrupted, it causes the X-linked gigantismovergrowth Simpson-Golabi-Behmel syndrome. Its involvement in growth control is consistent with recent reports that it can bind to growth factors, possibly including insulin-like growth factor 2. Further, it has been hypothesized that it may function as a tumor suppressor gene in breast and ovarian carcinomas and mesotheliomas. Patients and Methods: RNA and protein were extracted from Wilms tumor and hepatoblastoma tissue samples and GPC3 levels were measured in these extracts by Northern blotting, reverse transcription polymerase chain reaction, and immunoblotting. Results: In contrast to published results with carcinomas, high levels of GPC3 expression were found in Wilms tumor and hepatoblastoma. Low or undetectable expressions of this gene were found in normal tissue surrounding the tumor. Conclusions: Increased expression of GPC3 in Wilms tumor and hepatoblastoma suggests a growth-promoting or neutral activity for this gene product rather than a growth-suppressive effect.