Improved gene transfer efficiency to primary and established human pancreatic carcinoma target cells via epidermal growth factor receptor and integrin-targeted adenoviral vectors

In this study we analyzed two ways of retargeting of Advectors to human pan creatic carcinoma with the aim of enhancing the gene transfer efficiency. F irst, we analyzed the expression of the epidermal growth factor receptor (E GFR) on primary, as well as established pancreatic carcinoma cells by flow cytometry which revealed high expression levels of EGFR on the surface of t hese cells. We showed that EGFR-retargeted entry pathway using a bispecific fusion protein formed by a recombinant soluble form of truncated Coxsackie and Adenovirus Receptor (sCAR) genetically fused with human EGF (sCAR-EGF) redirects them to the EGFR leading to an enhanced gene transfer efficiency to pancreatic carcinoma cells. Since flow cytometry revealed absence of CA R expression, but the presence of at least one of both alphav integrins on the pancreatic carcinoma cells, a second way of targeting was investigated using a genetically modified Ad vector which has an RGD (Arg-Gly-Asp)-conta ining peptide inserted into the HI-loop of the fiber knob. This RGD targete d Ad (AdlucRGD) revealed efficient CAR-independent infection by allowing bi nding to cellular integrins resulting in a dramatic enhancement of gene tra nsfer. These findings have direct relevance for Ad-vector based gene therap y strategies for pancreatic carcinoma.