Adenovirus-Mediated ING4 Expression Suppresses Pancreatic Carcinoma Cell Growth via Induction of Cell-Cycle Alteration, Apoptosis, and Inhibition of Tumor Angiogenesis

Recent studies have demonstrated that ING4, as a novel member of the ING (inhibitor of growth) family, has a potential effect on tumor inhibition via multiple pathways. However, adenovirus-mediated ING4 expression in the application of gene therapy for pancreatic carcinoma has not been reported. To explore its therapeutic effect on human pancreatic carcinoma, we constructed a recombinant adenoviral vector, Ad-ING4, expressing the green fluorescent protein (GFP) marker gene and the tumor-suppressor gene, humanized ING4 derived from murine ING4 with two amino-acid modifications at residues 66 (Arg to Lys) and 156 (Ala to Thr) by site-directed mutagenesis. We demonstrated that Ad-ING4-mediated transfection of PANC-1 human pancreatic carcinoma cells inhibited cell growth, altered the cell cycle with S-phase reduction and G2/M phase arrest, induced apoptosis, and downregulated interleukin (IL)-6 and IL-8 expression of transfected tumor cells. In athymic mice bearing the PANC-1 human pancreatic tumors, intratumoral injections of Ad-ING4 suppressed the tumor growth, downregulated CD34 expression, and reduced the tumor microvessel formation. Therefore, this study will provide a framework for future clinical application of Ad-ING4 in human pancreatic carcinoma gene therapy.