New oncolytic adenoviruses with hypoxia- and estrogen receptor-regulated replication

• Published in: Human gene therapy Vol. 13; no. 14; p. 1737
• Main Authors: Hernandez-Alcoceba, Ruben, Pihalja, Michael, Qian, Dalong, Clarke, Michael F
• Format: Journal Article
• Language: English
• Published: United States 20.09.2002
• Subjects: Adenocarcinoma - pathology; Adenocarcinoma - therapy; Adenovirus E1A Proteins - genetics; Adenovirus E1A Proteins - physiology; Adenovirus E4 Proteins - genetics; Adenovirus E4 Proteins - physiology; Adenoviruses, Human - genetics; Adenoviruses, Human - physiology; Animals; Breast Neoplasms - pathology; Breast Neoplasms - therapy; Cell Hypoxia - genetics; Cytopathogenic Effect, Viral - drug effects; DNA-Binding Proteins; Estradiol - pharmacology; Estrogens - physiology; Female; Fibroblasts - drug effects; Fibroblasts - virology; Gene Expression Regulation, Viral - drug effects; Genes, Synthetic; Genetic Therapy; Genetic Vectors - drug effects; Genetic Vectors - genetics; Genetic Vectors - physiology; Genetic Vectors - toxicity; HeLa Cells - drug effects; HeLa Cells - virology; Humans; Lung Neoplasms - pathology; Mice; Mice, Nude; Neoplasms, Hormone-Dependent - pathology; Neoplasms, Hormone-Dependent - therapy; Promoter Regions, Genetic - drug effects; Receptors, Estrogen - drug effects; Receptors, Estrogen - genetics; Tamoxifen - analogs & derivatives; Tamoxifen - pharmacology; Telomerase - genetics; Transcription, Genetic; Transfection; Tumor Cells, Cultured - drug effects; Tumor Cells, Cultured - virology; Virus Replication - drug effects; Xenograft Model Antitumor Assays
• ISSN: 1043-0342
• DOI: 10.1089/104303402760293574

Oncolytic adenoviruses with restricted replication can be produced if the expression of crucial transcription units of the virus is controlled by tissue- or tumor-specific promoters. Here we describe a method for the rapid incorporation of exogenous promoters into the E1A and E4 regions of the human adenovirus type 5 genome. Using this system, we have generated AdEHT2 and AdEHE2F, two conditionally replicative adenoviruses for the treatment of breast cancer. The expression of the E1A gene in both viruses is controlled by a minimal dual-specificity promoter that responds to estrogens and hypoxia. The tight regulation of E1A expression correlated with the ability of these viruses to replicate and kill human cancer cells that express estrogen receptors, or are maintained under hypoxic conditions. The telomerase reverse transcriptase (TERT) promoter and the E2F-1 promoter are preferentially activated in cancer cells. They were introduced into the E4 region of AdEHT2 and AdEHE2F, respectively. The telomerase core promoter failed to block the replication of the virus in telomerase-negative cells. In contrast, AdEHE2F was attenuated in nontransformed quiescent cells growing under normoxic conditions, suggesting that an intact pRB pathway with low levels of E2F transcription factors acts as a negative modulator for the virus. These data indicate that the simultaneous regulation of E1A and E4 viral transcription units by the appropriate combination of promoters can increase the tumor selectivity of oncolytic adenoviruses.