Activity of Adenoviral E1A CR2 Deletion Mutants in Ovarian Cancer

• Main Author: Lockley, Michelle
• Published: Queen Mary, University of London 2008
• Subjects: 616.994
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504564

d1922-947 is a type 5 adenovirus deleted in a portion of its genome, EIA CR2, which releases E2F by binding retinoblastoma protein (PRb). Transactivation of E2Fresponsive genes stimulates S phase entry and viral DNA is preferentially replicated. Since over 90% of human cancers have pRb pathway abnormalities, d1922-947 replicates selectively in malignant cells. Co-immunoprecipitation in IGROVI human ovarian cancer cells and cytotoxicity in hTERT and SV 40 immortalised ovarian epithelial cells confirmed the proposed mechanism of d1922-947 activity. In IGROVI cells, d1922~947 induced S phase and viral protein expression more rapidly, and replicated more efficiently, than Ad5 WT. Cytotoxicity of d1922-947 exceeded Ad5 WT and the EIB 55K deleted adenovirus, . d11520. In female nude mice bearing intraperitoneal (IP) IGROVI xenografts, d1922- 947 increased survival above control (p<0.001), particularly when delivered in icodextrin. Hepatotoxicity, which was less severe than Ad5 WT, was seen in some nude mice treated with d1922-947 and in immunocompetent .C57B1I6 mice bearing CMT64 murine non.,.small cell lung cancer cells IP. Transformed murine ovarian epithelial cells (IDS) did not' suppoli production of late adenovirai proteins, despite efficient DNA replication, transcription and nuclear export of late viral RNAs. This could explain the .inability of IP viruses to improve survival in C57B1I6 mice bearing ID8 cells IP . . Ovarian cancer disseminates diffusely across peritoneal surfaces, so quantifying ill VIVO eIhcacy IS pro51emauc. In IllICe oeanng ll' xenograIts 01 FIreny Iucnerase expressing IGROVI cells (IGROVI-Luc), light output increased over time, whereas IP d1922-947 held bioluminescence at baseline for over two months. A Renilla relliformis luciferase expressing EIA CR2 deleted adenovirus, dlCR2 Ren, was created, which had comparable ,anti-tumour efficacy to dI922-.947. Light emission by dlCR2 Ren correlated with EIA expression and, after a single IP injection in murine models of ovarian cancer, light emission and therefore viral' persistence was demonstrated for 2 weeks.