Abstract A43: Inhibition studies of Siah2, a ubiquitin ligase, involved in hypoxia induced cancer

Abstract

Abstract Ubiquitin ligase siah2 has been shown to regulate the hypoxia response by regulating prolyl hydroxylase3 (PHD3) involved in a hypoxia inducible factor 1α (Hif-1α) dependent pathway which up regulates the genes like vascular endothelial growth factor (VEGF), resulting in tumor cell survival. Thus it has been suggested that siah2 may act as a target for developing inhibitors. In this study we have proved the interaction of siah2 and PHD3 using co-immunoprecipitation and GST pull down assay. Interaction studies indicate that C-terminal substrate binding domain (SBD) of Siah2 is involved in the binding to PHD3 irrespective of the N-terminal ring domain. The structure-based high throughput virtual screening (HTVS) method was used to identify potential small molecule inhibitors and we have identified five drug-like lead molecules specific for the Siah2 using 14400 drug-like subsets obtained from the Maybridge database, which might inhibit the interaction between Siah2 and PHD3. The lead molecules from screening were then tested in silico for their pharmacokinetic properties and percent human oral absorption using QikProp. Further, pharmacokinetic analysis based on Lipinski's rule of five which is based on ADMET (absorption, distribution, metabolism, excretion and toxicity) properties suggested potential utility of these compounds as drug leads. Docking studies were carried out to analyze the binding conformations of the identified lead molecules towards the Siah2 which reveals that Ser39 residue of SBD may be the key amino acid residue interacting with these ligands necessary for the induction of Siah2 activity. These results set the stage for the development of a workflow for selection of domain specific drug development. Five potential drug-like molecules specific to the SBD domain were eventually selected on the basis of binding characteristics, docking energy and ADMET properties. Further in-vivo and in-vitro experimental studies to investigate the inhibitory potential of these lead drug-like small molecules on this ligase and its binding are under progress. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A43.