The p16/Cdkn2a/Ink4a gene is frequently deleted in nitrosourea-induced ratglial tumors

The present study investigates nitrosourea-induced rat (Rattus norvegicus) glioma cell lines for the functional status of the p16/Cdkn2a/Ink4a gene, w hich encodes the p16 cdk4 inhibitor and the alternative reading frame prote in, p19ARF. We detected homozygous deletions of the p16/Cdkn2a/Ink4a gene l ocus in 4 of 5 glioma cell lines (C6, F98, RG2, and RGL.3), but not in the 9L gliosarcoma cell line or in a rat primary fibroblast cell line. RT-PCR d emonstrated expression of the p16 and p19ARF mRNAs only in 9L cells and in rat fibroblasts. Comparative genomic in situ hybridization showed that the copy number of rat chromosome RNO5 was not altered in any of the glioma cel l lines investigated, indicating that the deletions result from a discrete loss in the region of the p16/Cdkn2a/Ink4a locus. This is the first report of p16/Cdkn2a/Ink4a deletions present in nitrosourea-induced rat glioma cel l lines. Since this genetic alteration is also commonly observed in human m alignant glial tumors, our results validate the use of chemically induced r at glioma cell lines as an experimental model in the development of gene th erapy strategies. Copyright (C) 2000 S. Karger AG, Basel.