Analysis of the p21 gene in gliomas

The p21 gene encodes a cyclin dependent kinase inhibitor protein (p21) whic h has a tumor suppressive activity in a variety of tumor cell lines. Since, the p21 gene is up-regulated by the p53 tumor suppressor gene, which is fr equently mutated in gliomas, acting therefore in the same control pathway, it constitutes a good candidate gene to be also inactivated in these tumors . To test this hypothesis, DNAs from 81 gliomas (48 glioblastomas, 11 anapl astic astrocytomas, 10 low-grade astrocytomas, 12 oligodendrogliomas and mi xed gliomas), were investigated for mutations in the p21 coding sequence by denaturant gradient gel electrophoresis followed by sequencing. All these tumors have been previously screened for p53 mutations. Three different DNA variants were identified on codon 31 (17 cases),27 (1 case) and 117 (1 cas e) and shown to be also present in matching constitutional DNA, suggesting they were polymorphisms. None of the tumors demonstrated a somatic mutation : No significant correlation between the presence of a p21 variant and the p53 mutation tumor status was observed. In conclusion, mutation in the p21 gene unlikely contributes to the development of gliomas.