Restoration of growth arrest by p16INK4, p21WAF1, pRB, and p53 is dependent on the integrity of the endogenous cell-cycle control pathways in human glioblastoma cell lines

The aim of this study was to demonstrate that the induction of growth arrest in human glioblastoma multiforme (GEM) cell lines by retrovirus-mediated transduction of growth control genes was dependent upon the integrity of specific endogenous control pathways. We assessed the status of the endogenous p16(INK4A), p21(CIP1), pRb, or p53 genes in eight GEM lines. As expected, we found varied combinations of gene defects. The outcome of transducing five of these cell lines with p16(INK4A), p21(CIP1), pRb, or p53 genes was not entirely predictable, The growth-inhibitory effects mediated by the transfer of the gene encoding pie was dependent on the presence of the pRb protein, but was independent of p53 status. p21, a broadly active CDK inhibitor and a strong inducer of growth arrest, was not a universal growth suppressor in the group of glioblastoma cell lines analyzed. The suppression of GEM cell proliferation by viruses encoding pRb or p53 was generally predictable and appeared to be independent of the status of either pie or p21. Suppression of cell growth was assessed by a colony formation assay, by observance of alterations in morphology, and by cell viability staining for trypan blue exclusion. Our findings suggest that to accomplish the suppression of GEM cell proliferation by the transduction of these cell-cycle control genes, the status of endogenous cell-cycle control genes must be taken into account. (C) 1998 Academic Press.