Adenovirus-mediated wild-type p53 gene transfer induces apoptosis and inhibits proliferation of human uveal melanoma cells

Purpose. To test the effect of a replication-deficient adenovirus (Ad) vector carrying wild-type p53 cDNA (AdCMV.p53) on the growth of 3 human uveal melanoma cell lines: SP-6.5, MKT-BR and OMM-1. Methods. Endogenous p53 mutations were assessed by PCR-SSCP on exons 5 to 9 of the p53 gene. Cells were infected eather with AdCMV.p53, with the control virus AdCMV.Null. (100 pfu/cell) or were uninfected. Expression of p53 was detected by Western Blot up to 7 days after infection. Proliferation was assessed by cell counting. The occurrence of apoptosis was evaluated by Tdt Biotin dUTP Nick-end Labeling (TUNEL) test and DNA gel electrophoresis. Results. Endogenous p53 mutations were detected only in exons 5 and 8 on OMM-1 cells. AdCMV.p53 infection enhanced p53 expression vs both infected and uninfected controls at 1, 3, 5 and 7 days after the beginning of experiments. Both infected and uninfected controls exhibited similar proliferation rates and at 3 days AdCMV.p53-infected cells were 27.3+-2.7%, 54.4+-6.5% and 16.3+-1.6% of controls for SP-6.5, MKT-BR and OMM-1 cell lines respectively (p<0.05 for all cell lines AdCMV.p53 vs AdCMV.Null infected cells). All AdCMV.p53 infected cell lines exhibited evidence of apoptosis by TUNEL test and DNA laddering. Conclusions. AdCMV.p53 results in human uveal melanoma cell apoptopsis and growth inhibition in vitro regardless of whether cells express wild-type or mutated endogenous p53.