Abstract 248: Functional characterization of MED29 gene in pancreatic cancer

Abstract

Abstract Pancreatic cancer is a highly aggressive malignancy characterized by rapid progression and an extremely poor prognosis. More knowledge is needed to better understand the mechanisms of the disease pathogenesis. Identification of new disease genes can improve our understanding about the biology of pancreatic cancer and might provide us tools for improving both diagnostics and treatment. Previously, we performed a detailed characterization of the 19q13 locus, one the recurrently amplified regions in pancreatic cancer, and identified a set of putative amplification target genes that showed consistent overexpression in amplified cell lines versus non-amplified cell lines. Subsequent high-throughput RNAi screen targeting genes within the amplified region revealed a number of genes whose downregulation led to decreased cell viability in the amplified but not in the non-amplified cells. Of these, the mediator complex subunit 29 (MED29) was consistently overexpressed in all amplified cell lines and had the most dramatic effect on cell viability. By flow cytometry analysis, we showed that MED29 silencing resulted in G0/G1 cell cycle arrest and increased apoptosis in the amplified PANC-1 cells. MED29 is a subunit of a large multiprotein complex that is involved in transcriptional regulation and may function both as a transcriptional repressor and enhancer. To further define the function of MED29 we constructed a lentiviral vector for MED29 gene delivery. Mouse embryonic fibroblasts (NIH/3T3) and two pancreatic cancer cell lines with low basal MED29 expression (MIAPaCa2 and Hs700T) were transduced with a lentivirus vector containing MED29. Stable MED29 expression was confirmed in all three cell lines by quantitative RT-PCR and western blot analysis. MED29 expression led to statistically significant changes in proliferation and/or survival in both the NIH/3T3 cells and the pancreatic cancer cells. Finally, MED29 overexpressing human pancreatic cancer cell lines were subcutaneously inoculated into immunocompromized mice to follow tumor growth in vivo. Significant growth difference was observed between MED29 expressing cancer cells compared to control cells when injected into mice. To conclude, our results implicate MED29 as an important regulator of growth and survival in pancreatic cancer both in vivo and in vitro. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 248.