DEVELOPMENT AND CHARACTERIZATION OF RECOMBINANT ADENOVIRUSES ENCODINGHUMAN P53 FOR GENE-THERAPY OF CANCER

We have constructed recombinant human adenoviruses that express wild-t ype human p53 under the control of either the Ad 2 major late promoter (MLP) or the human cytomegalovirus (CMV) immediate early gene promote r. Each construct replaces the Ad 5 E1a and E1b coding sequences neces sary for viral replication with the p53 cDNA and MLP or CMV promoter. These p53/Ad recombinants are able to express p53 protein in a dose-de pendent manner in infected human cancer cells. Tumor suppressor activi ty of the expressed p53 protein was assayed by several methods. [H-3]T hymidine incorporation assays showed that the recombinant adenoviruses were capable of inhibiting DNA synthesis in a p53-specific, dose-depe ndent fashion. Ex vivo treatment of Saos-2 tumor cells, followed by in jection of the treated cells into nude mice, led to complete tumor sup pression using the MLP/p53 recombinant. Following a single injection o f CMV/p53 recombinant adenovirus into the peritumoral space surroundin g an in vivo established tumor derived from a human small cell lung ca rcinoma cell line (NIH-H69), we were able to detect p53 mRNA in the tu mors at 2 and 7 days post-injection. Continued treatment of establishe d H69 tumors with MLP/p53 recombinant led to reduced tumor growth and increased survival time compared to control treated animals. These res ults indicate that recombinant adenoviruses expressing wild-type p53 m ay be useful vectors for gene therapy of human cancer.