Growth inhibitory effect of p21 and p53 containing adenoviruses on transitional cell carcinoma cell lines in vitro and in vivo
Altered p53 expression has been demonstrated in the majority of advanced transitional cell carcinoma (TCC) of the bladder tumors. The objective of this investigation was to examine the effect of the introduction of a p53 or p21((WAF1/CIP1)) adenovirus on the proliferation and apoptosis of various human TCC cell lines in vitro and in vivo. Proliferation was measured by 3H-thymidine incorporation. Apoptosis was measured by DNA fragmentation and bax expression. We also examined the effect of ex vivo introduction of the p21((WAF1/CIP1)) or the p53 gene on growth of the T24 TCC cells and UMUC-3 TCC cells introduced subcutaneously into athymic nude mice. We found that although the effect of the p21-adenovirus on the proliferation of various TCC lines varied with each individual cell line, there was a substantial growth inhibition observed (greater than 80% growth inhibition) in seven of the eight TCC cell lines at the highest viral dosage. In contrast, after 24 h, the highest dosage of the p53-adenovirus produced only a heterogeneous decrease in proliferation compared to the highest dose of the p21((WAF1/CIP1))-adenovirus (40-90%). In ex vivo experiments, no tumors were found in nude mice injected subcutaneously with either TCC cell line exposed in vitro to the AdSCMV-p21((WAF1/CIP1)) or AdSCMV-p53 viruses before three weeks. There was a threefold decrease in tumor square area at week 5 in the Ad5CMV-p21((WAF1/CIP1)) or Ad5CMV-p53 TCC cells injected mice (p<0.001, p<0.009) compared to either mock or Ad5CMVLacZ TCC bladder tumor cells. These data suggest that significant portion of the effect of altered p53 on TCC phenotype may be mediated through the p21((WAF1/CIP1)) pathway. Thus, the restoration of p21((WAF1/CIP1)) function in this tumor system may be a beneficial therapeutic strategy.
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