Abstract #3791: Adenoviral vector expressing short hairpin RNA targeting Wnt2B has a strong antitumor activity against Wnt2b-overexpressing tumors

Abstract

Introduction: The Wnt family encodes the multi-functional signaling glycoproteins regulating a wide variety of normal and pathological processes including tumorigenesis. Wnt2B is a member of Wnts, which is considered to be involved in the canonical Wnt signal pathway. Recent our clinical studies revealed the Wnt2B overexpression to affect the tumor progression through the induction of tumor-associated Wnt-targets in non-small cell lung cancers. Therefore, we performed experimental studies using a Wnt2B-suppressing adenoviral vector in order to establish the gene therapy against Wnt2B-overexpressing tumors. Method: Three human tumor cells with an overexpression of Wnt2B, including lung carcinoma A549 cells, pancreatic carcinoma PANC1 cells, and head and neck carcinoma Hela cells, were used. First, the transfection of chemically-synthesized siRNAs was investigated to select the specific sequence targeting Wnt2B. After the shRNA template targeting Wnt2B was synthesized, it was then cloned into a pBAsi-hU6 plasmid vector. Finally, an E1-deleted replication-deficient recombinant adenoviral vector expressing shRNA targeting Wnt2B under the control of the human U6 promoter (Ad-shWnt2B) was constructed. Results: The infection of Ad-shWnt2B effectively downregulated the Wnt2B expression in all the Wnt2B-overexpressing tumor cells. Regarding the in vitro experiment, MTT assays demonstrated the infection of Ad-shWnt2B to significantly inhibit the growth of all three Wnt2b-overexpressing tumor cells (p<0.001, respectively). A flow cytometric analysis revealed the infection with Ad-shWnt2B into Wnt2B-overexpressing tumor cells to increase the percentage of apoptotic cells. Regarding in vivo experiments, a human tumor xenograft model in nude mice was prepared by the implantation of Wnt2B-overexpressing tumors derived from A549 cells. The antitumor effects were compared between the Ad-shWnt2B treatment, the PBS treatment, and the control group. Ad-shWnt2B or PBS was administered by intratumoral injection every 4 days. Consequently, the Ad-shWnt2B treatment was found to have the strongest antitumor effect against the Wnt2B-overexpressing tumor xenografts (p<0.001). Conclusions: The cancer gene therapy using the adenoviral vector expressing shRNA against Wnt2B has a strong antitumor effect against Wnt2B-overexpressing tumors. We will perform further experimental studies on the cancer gene therapy using additional vectors suppressing other Wnts.

Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 3791.