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 gigantism-overgrowth Simpson-Golabi-Behm el syndrome. Its involvement in growth control is consistent with recent re ports that it can bind to growth factors, possibly including insulin-like g rowth 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 h epatoblastoma tissue samples and GPC3 levels were measured in these extract s by Northern blotting, reverse transcription polymerase chain reaction, an d immunoblotting. Results: In contrast to published results with carcinomas, high levels of G PC3 expression were found in Wilms tumor and hepatoblastoma. Low or undetec table 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 rath er than a growth-suppressive effect.