Abstract LB-371: Evaluating the protein SUMOylation pathway as a potential cancer therapeutic target using inducible RNA interference

Abstract

Abstract Protein SUMOylation is a conserved ubiquitin-like protein posttranslational modification pathway catalyzed by the SUMO enzymatic cascade. Previous studies have indicated SUMO pathway genes are highly expressed in cancer and are required for development and cell viability. We applied lentivirus based shRNA methods to efficiently knockdown SUMO pathway components in human cancer cells. shRNAs for SAE2 and UBC9 lead to reduced SUMO pathway activity as measured by cell based reporter assays. Knockdown of SUMO enzymes suppresses proliferation of human cancer cells including U2OS, HCT116 and HeLa cells. Multiple shRNAs for each gene showed a similar growth arrest phenotype suggesting that the results are not RNAi off target effects. Furthermore, SUMO pathway inhibition by RNAi sensitize U2OS cells to the DNA damage agent Camptothecin, indicating a chemo-sensitizing effect of SUMO pathway inhibition. To improve the reproducibility of our experiments and avoid an observed negative selection for the constitutively expressed shRNAs, we established a doxycycline inducible conditional shRNA (tet-on) system to achieve acute and reversible SUMO enzyme knockdown. Acute SAE2 knockdown in U2OS and HCT116 cells reduces S phase and slows cell growth in vitro. Our data demonstrate SUMO pathway is a potential therapeutic target to treat cancer and this study demonstrates that inducible shRNA systems are valuable for early stage drug discovery. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-371. doi:10.1158/1538-7445.AM2011-LB-371