E1B-deleted adenovirus replicates in p53-deficient lung cancer cells due to the absence of apoptosis.

E1B55K adenovirus codes the protein that inactivates the p53 protein of host cells and facilitates its own cell proliferation. We prepared E1B55K-deleted adenovirus and investigated its cytopathic effects in primary lung cancer cells to evaluate the possibility of its application in gene therapy. A p53 wild-type small cell lung cancer cell line (SBC3) and three p53 mutant cell lines (SBC5, small cell lung cancer; PC3, adenocarcinoma; and EBC1, squamous cell carcinoma) were infected with AxE1AdB, in which the E1B55K gene was deleted, to assess the cytotoxicity and induction of apoptosis. Moreover, the mRNA expression in virus-infected cells was studied with cDNA array analysis to investigate the response of cancer cells to the virus infection. As a result, AxE1AdB had no detectable cytopathic effect on SBC3 cells, and SBC3 cells continued to replicate. In contrast, AxE1AdB killed SBC5, PC3, and EBC1 cells with great efficiency. In SBC3, apoptosis of the host cells was observed in the early infection stage; in the p53-mutant cell lines, apoptosis of the cells was restricted. An analysis of gene expression in the host cells indicated a significant increase of Bax mRNA in SBC3 and its deficiency in SBC5. Overall, our results suggest that AxE1AdB replicated selectively in the p53-mutant lung cancer cells and showed strong cytotoxicity against them. In the p53-intact cells, p53 induced apoptosis through Bax expression and prevented virus replication and escalation of the infection.