ADENOVIRUS-MEDIATED P16 CDKN2 GENE-TRANSFER INDUCES GROWTH ARREST ANDMODIFIES THE TRANSFORMED PHENOTYPE OF GLIOMA-CELLS/

The p16 (MTS1/CDKN2) gene localized at the 9p21 chromosomal region enc odes for a cell cycle inhibitor protein and is altered in many human c ancers. The frequency of p16 alterations in gliomas exceeds 50%. To re store the missing wild-type p16 gene efficiently in glioma cells an ad enovirus vector carrying the full length coding sequence of the wild-t ype p16 cDNA, Ad5RSV-p16, was constructed. Three human glioma cell lin es, U-251 MG, U-87 MG and D54 MG, that did not express endogenous p16/ CDKN2 gene and were easily infected with adenovirus vectors were selec ted for these experiments. Introduction of the Ad5RSV-p16 in these mal ignant glioma cell lines directed the biosynthesis of functional p16 p rotein in the majority of the exposed cells, significantly inhibited c ell growth, influenced cell morphology and modified the transformed ph enotype of cells including the ability to form colonies in soft agar. Flow cytometric studies revealed that the majority of the Ad5RSV-p16 i nfected glioma cells were arrested in the G0-G1 phases of the cell cyc le. These results suggest that p16/CDKN2 inactivation is a significant factor in the genesis and progression of gliomas and that the restora tion of the wild-type p16 protein could have clinical and therapeutic utility.