Promoter hypermethylation of the RB1 gene in glioblastomas.

摘要: Loss of expression the retinoblastoma gene (RB1) has been shown to occur in up 25% glioblastomas (WHO Grade IV). To elucidate underlying mechanism, we assessed RB1 promoter hypermethylation using methylation-specific polymerase chain reaction and by immunohistochemistry 35 primary (de novo) 21 secondary that had progressed from low-grade diffuse astrocytoma II) or anaplastic III). Promoter was significantly more frequent (9 21, 43%) than (5 35, 14%; p = 0.0258). There a clear correlation between loss hypermethylation. In majority with expression, there (11 13, 85%), whereas 93% tumors normal status (p < 0.0001). three glioblastomas, areas without were microdissected; detected only lacking expression. patients multiple biopsies, methylation not detectable less malignant precursor lesions, ie, astrocytoma. These results indicate is late event during progression major mechanism glioblastomas.