Abstract 1976: Systematic Identification of Protein-Protein Interactions by Proximity Ligation Assay

Abstract Signal transduction pathways at cellular level require massive protein-protein interactions (PPIs) in response to different environmental cues. Diverse experimental techniques for detecting PPIs have been developed; however, the large amount of data accumulated from various sources has posed a grand challenge in data reliability for PPI. To evaluate the role of PPIs within signaling pathways, we have systematic profiled PPI residing in 28 KEGG pathways, for example mTOR, MAPK, Wnt, VEGF, and Hedgehog, and 3 cancer-related pathways stored in KEGG (http://www.genome.jp/kegg/). Of ∼60000 human PPI collected, 2786 PPI can be detected within targeted 14 pathways. To validate these PPIs, we used a newly developed Proximity Ligation Assay, which detects endogenous PPI through a pair of antibodies that bind to proteins in close proximity. Each PPI can be made visible through DNA amplification and quantified by counting fluorescent dots in the cell. Of 1,204 PPIs examined, 557 PPIs can be confirmed in HeLa cells. Specifically, 383 out of 557 validated PPIs residing within pathways in cancer and mTOR, Wnt and MAPK pathways are considered novel “links” based on annotations of KEGG. Moreover, 79 validated PPIs are cross-talk events among 35 signaling transduction and cancer related pathways. Surprisingly, only 16 PPIs (out of 557 confirmed PPIs) are highly correlated in 7 sets of cancer cells from NCI60 microarray dataset. In this large scale PPI profiling, 41 apoptosis related PPIs were further tested in 3 cancer cell lines to explore the possibility for drug screening. These systematic analyses of endogenous PPI pairs within and between pathways may set the foundation to disrupt the signaling pathways by targeting PPIs in cancer 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 1976. doi:10.1158/1538-7445.AM2011-1976