Abstract 4431: NFATc1 silencing increases sensitivity of pancreatic cancer cells to phosphosulindac

Pancreatic cancer is the fourth leading cause of cancer-related deaths in the U.S. Current chemotherapeutic agents have limited efficacy and play a minor role in its treatment. We previously determined that the novel agent phosphosulindac (P-S) significantly prevents colon cancer and have now extended our studies into pancreatic cancer. Microarray data demonstrated a 5-fold increase in the gene expression of Nuclear Factor of Activated T-cells (NFAT) in MIA PaCa-2 cells after 2 h of treatment with P-S. NFATc1 and NFATc2 isoforms have been shown to be up-regulated in pancreatic cancer. To determine the role NFATc1 played in response to treatment with our compound, we developed a NFATc1 shRNA model in BxPC-3 and GFP positive MIA PaCa-2 cells, and a NFATc1 overexpression model in GFP labeled MIA PaCa-2 cells. Knockdown of NFATc1 expression by shRNA was confirmed by western blot and qRT-PCR. A 2-fold decrease in IC50 of P-S was observed in NFATc1 shRNA cells. In contrast, overexpression of NFATc1 increased the IC50 of P-S by 1.2-fold. The ability of our compound to reduce cell viability more potently in NFATc1 shRNA cells prompted us to assess the effect of the protein on tumor growth in a MIA PaCa-2 xenograft. 5-6 week old female BALB/c nude mice were subcutaneously injected with NFATc1 wt, knock-down, and overexpression GFP labeled MIA PaCa-2 cells. Animals were treated for 5 weeks, euthanized and tumor volume assessed. We observed a 50% reduction in tumor volume in NFATc1 wt, 63% reduction in NFATC1 knock-down, and a 26% reduction in NFATc1 overexpression xenograft. NFATc1 localization is indicative of its activity, with nuclear localization being the active form. We assessed OCT-embedded sections of our xenograft tissue to determine the localization of NFATc1 in GFP labeled tumor cells. Confocal microscopy data showed that in comparison to control, P-S treated tissue demonstrated decreased nuclear localization of the protein, indicating that P-S may suppress the activation of NFATc1. We observed a similar trend in NFATc1 knock-down and overexpression tissue, though our compound demonstrated a greater effect on tumor reduction in NFATc1 knock-down mice. We conclude that P-S is a potentially important agent for the treatment of pancreatic cancer and that our compound may play a role in NFATc1 localization and activation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4431. doi:1538-7445.AM2012-4431