Somatic mutations of the von Hippel-Lindau tumor suppressor gene and loss of heterozygosity on chromosome 3p in human glial tumors.

Molecular genetic analysis of von Hippel-Lindau tumor suppressor gene (VHL gene) was performed on 38 tissues of human glial tumors (ependymoma, 1; astrocytoma, 6; oligodendroglioma, 1; oligoastrocytoma, 2; anaplastic oligoastrocytoma, 3; anaplastic astrocytoma, 14; glioblastoma multiforme, 11). Somatic DNAs extracted from frozen tumor specimens were examined by single-strand conformational polymorphism analysis and direct sequencing. In addition, loss of heterozygosity (LOH) on chromosome 3p in 15 glial tumor cases, lymphocyte DNAs of which were available, was examined by use of 10 microsatellite probes and two polymorphism markers for the VHL gene. Two cases of low-grade gliomas showed somatic sense mutations in exon 3 of the VHL gene, and 6 of 15 cases (40.0%) showed LOH of chromosome 3p. The VHL gene-mutated cases also showed LOH. The retention of heterozygosity and high pathological grade of glial tumors were correlated significantly. In addition, Kaplan-Meier survival analysis for patients with glial tumors showed that patients with LOH had a significantly longer survival time than those without LOH. These results suggest that somatic mutations on 3p, including the VHL gene, may be involved in tumorigenesis of some low-grade glial tumors.