ENDOTHELIAL CELL-SPECIFIC EXPRESSION OF TUMOR-NECROSIS-FACTOR-ALPHA FROM THE KDR OR E-SELECTIN PROMOTERS FOLLOWING RETROVIRAL DELIVERY

The tumor vasculature offers a target for anti-cancer gene therapy whi ch has the advantages both of good accessibility to systemically deliv ered therapy and comparative homogeneity across solid tumor types, We aimed to develop retroviruses carrying endothelial-specific promoters for the delivery of genes to proliferating endothelial cells in vitro and to tumor endothelial cells in vivo, This paper reports the generat ion of such retroviral vectors and the level of expression of murine t umor necrosis factor-alpha (mTNF-alpha) cDNA following infection into endothelial cells and stromal fibroblasts, Retroviral vectors carrying mTNF-alpha have been generated whose expression is controlled either by the retroviral long terminal repeat or by 5' proximal promoter sequ ences from the endothelial-specific kinase insert domain receptor (KDR )/VEGE receptor and E-Selectin promoters within the context of a self- inactivating (SIN) vector backbone, Both KDR and E-Selectin have been shown to be upregulated on tumor endothelium, A putative polyadenylati on sequence AAATAAA within the E-Selectin promoter was mutated to perm it faithful transmission of retroviral vectors carrying this promoter, We demonstrate a 10- to 11-fold increase in mTNF-alpha expression fro m promoter elements within sEND endothelioma cells as compared to NIH- 3T3 fibroblasts, Suggestions for further improvements in vector design are discussed.