Analysis of adenovirus trans-complementationmediated gene expression controlled by melanoma-specific TETP promoter in vitro | Fontecedro et al. Virology Journal 2010 7 175 http content 7 1 175 VIROLOGY JOURNAL RESEARCH Open Access Analysis of adenovirus trans-complementation-mediated gene expression controlled by melanoma-specific TETP promoter in vitro 1 3 1 Alessandra Curioni Fontecedro Verena Lutschg 1 Ossia Eichhoff Reinhard Dummer Urs F Greber Silvio Hemmi1 Abstract Background Human adenoviruses Ads have substantial potential for clinical applications in cancer patients. Conditionally replicating adenoviruses CRAds include oncolytic adenoviruses in which expression of the immediate early viral transactivator protein E1A is controlled by a cancer cell-selective promoter. To enhance efficacy CRAds are further armed to contain therapeutic genes. Due to size constraints of the capsid geometry the capacity for packaging transgenes into Ads is however limited. To overcome this limitation the employment of E1A-deleted replicationdeficient viruses carrying therapeutic genes in combination with replication-competent CRAd vectors expressing E1A in trans has been proposed. Most trans-complementing studies involved transgene expressions from strong ubiquitous promoters and thereby relied entirely on the cancer cell specificity of the CRAd vector. Results Here we tested the trans-complementation of a CRAd and a replication-deficient transgene vector containing the same cancer cell-selective promoter. Hereto we generated two new vectors expressing IL-2 and CD40L from a bicistronic expression cassette under the control of the melanoma melanocyte-specific tyrosinase enhancer tyrosinase promoter TETP which we previously described for the melanoma-specific CRAd vector AdAEP-TETP. These vectors gave rise to tightly controlled melanoma-specific transgene expression levels which were only 5 to 40-fold lower than those from vectors controlled by the nonselective CMV promoter. Reporter analyses using Ad-CMV-eGFP in combination with AdAEP-TETP revealed a high level of .
