Abstract 188: Stromal expression of suicide gene FCU1 affects proliferation of tumor cells and depletes stromal cells in co-culture models of pancreatic cancer

Abstract

Abstract Background: Genetic targeting of tumor-surrounding tissue is a promising direction of the development of new methods of anticancer therapy, especially for solid tumor types with a pronounced stromal component. Specific expression of suicide genes, such as HSVtk or CD, in the tumor microenvironment potentially can inhibit the growth of tumor cells within stroma and restrict their metastasizing potential. We studied the cytotoxic effect of expressing the therapeutic gene FCU1 on pancreatic ductal adenocarcinoma stromal cells, as well as on co-cultured tumor cells, in different culturing systems and in the presence of various low-molecular inhibitors of signal pathways. Methods: For experiments, we used primary cultures of pancreatic ductal adenocarcinoma stromal cells at early passages. The stromal cells were transfected with a lentivirus vector carrying the chimeric suicide gene FCU1 (the fusion of yeast FCY1 and FUR1 genes). In the experiments with co-culturing, we used tumor cells of Panc1 and AsPC-1 lines labeled with a reporter gene. We studied the effect of low-molecular inhibitors of IGF signal pathway (picropodophyllin and PQ4011) and inhibitors of Shh signal pathway (cyclopamine and GANT61). Results: The transfection of pancreatic ductal adenocarcinoma stromal cells with the lentivirus carrying FCU1 induced proliferation arrest and stromal cell death in the presence of 5-FC prodrug. The cytotoxic effect was stronger for tumor stromal cells as compared with stromal cells of the normal pancreas. It should be noted that 5-FC-containing conditioned medium from tumor stromal cells transfected with FCU1-containing construct, but not with the empty vector, also had a cytotoxic effect on tumor cells. In the co-culturing system, transfection of tumor stromal cells with the lentivirus vector with FCU1 in the presence of 5-FC induced a pronounced cytotoxic effect on the co-cultured pancreas tumor cells. Addition of low-molecular inhibitors of IGF signal pathway to the co-cultured cells enhanced the cytotoxic effect of the suicide gene expression. On the contrary, addition of cyclopamine (an inhibitor of Shh signal pathway) to the co-culturing system reduced the cytotoxic effect of the stromal suicide gene FCU1 expression on tumor cells. Conclusions: Expression of the suicide gene FCU1 in the tumor microenvironment can induce considerable depletion of the tumor stroma of pancreatic ductal adenocarcinoma that is supposed to essentially enhance the antitumor effect of standard chemotherapy. The use of low-molecular inhibitors of the signal pathways activated in tumors does not always increase the antitumor efficiency of gene therapeutic constructs with suicide genes. The work is supported by grant of Russian Foundation for Basic Research 13-04-40171-H. Citation Format: Marina Kopantseva, Eugenia Usova, Maria Kostina, Olga Melekhina, Vyacheslav Egorov, Eugene P. Kopantzev, Eugene D. Sverdlov. Stromal expression of suicide gene FCU1 affects proliferation of tumor cells and depletes stromal cells in co-culture models of pancreatic cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 188. doi:10.1158/1538-7445.AM2014-188