Development of Human Silent Information Regulator 1 Modulators for Treatment of Cancer and Metabolic Disorders

Abstract

Silent Information Regulators or sirtuins are class III NAD+-dependent proteins which newlinepossess either histone deacetylase or mono-ribosyltransferase activity found in organisms newlineranging from bacteria to humans. These are important for many cellular metabolisms including newlinegene silencing, regulation of p53, cell cycle regulation, life span extension, cancer, diabetes, newlineobesity, etc. Among all seven human sirtuins, SIRT1 is well studied, having more than a dozen newlinesubstrates, known to have protective role against oxidative stress and DNA damage and plays a newlinepredominant role in metabolism. newlineIn the present study, a diverse set of series of molecules viz. Acridinedione (ACD), newlineBenzthiazolyl-2-thiosemicarbazone (B2TS) as SIRT1 inhibitors and Spiro-piperidine-4-one (SP), newlinePyrido[2,3-d]pyrimidine (PP), 1-(isonicotinamido)azetidine-2,4-dicarboxamides (AZD) as newlineSIRT1 activators were identified by virtual screening of in house database against catalytic core newlineand allosteric site of SIRT1. Further to develop a significant SAR, various derivatives of ACD, newlineB2TS, SP, PP, and AZD were designed, synthesized and characterized. Upon fluorescence based newlinecell-free deacetylation SIRT1 assay, compound 4d (ACD series), BH1 and BH13 (B2TS series) newlineshowed significant inhibition with an IC50 of 10.13±0.08 and#956;M, 46.27±0.7 and#956;M and 15.3±0.8 and#956;M newlinerespectively and H3 (SP series), B9 (PP series) and 6A11 (AZD series) showed significant 2-3 newlinefold increase in deacetylase activity of SIRT1 at 10 and#956;M, 5 and#956;M and 5 and#956;M concentrations newlinerespectively. newlineMTT assay of SIRT1 inhibitors (ACD and B2TS series) on various cancer (K562, MDAMB231, newlineLNCaP and PC3) cell lines yielded that compound 4d (ACD series) induced apoptosis newlinevi newlinein MDA-MB 231 cells with an IC50 of 0.25 and#956;M and compound BH1 and BH13 induced newlineapoptosis in LNCaP cells with an IC50 of 4.09±0.02 and#956;M and 5.07±1.25 and#956;M respectively. Further newlinemechanistic studies of active compounds revealed down regulation of SIRT1 and upregulation of newlinecaspase 3 and acetylated p53K382 protein levels.