The results were the average of duplicate measurements and expressed as percentage inhibition. Cardiac toxicology study hERG binding assay Astemizole competitive binding assays are per formed to determine the ability of compounds to dis place the known radioligand astemizole from the hERG potassium channels, following standard protocol with minor modifications. In brief, assays were per formed in 200 ul of binding buffer containing 1. 5 nM of astemizole, 3 ug well of hERG membrane protein, and TAI 1 at 27 C for 60 min. Nonspecific binding was determined in the presence of 10 uM astemizole. IC50 assay for TAI 1 contained 8 concentration points with 10 fold serial dilution in triplicate. Binding was terminated by rapid filtration onto polyethyleneimine presoaked, buffer washed UniFilter 96, and GF C using a vacuum manifold.

Captured radiolabel signal was detected using TopCount NXT. The data were analyzed with nonlinear curve fitting soft ware and IC50 value was calculated. All results are derived from two independent selleck inhibitor experiments. Drug drug synergy experiments Interaction between Hec1 inhibitor TAI 1 and anticancer drugs were evaluated using standard assays. Twenty four hours after seeding, cells were treated with TAI 1, the other testing drug, or in combination. For combination testing, TAI 1 or the other testing drugs were added to plate in tripli cate wells in ratios of GI50, and cells are incubated in drug treated medium for 96 h and cell viability determined by MTS. Synergy was determined by calculating combination index value with the formula where CA,X and CB,X are concentrations of drug A and drug B used in combination to achieve x% drug effect.

ICx,A and ICx,B are concentrations selleck chemicals for single agents to achieve the same effect. All data represent results of triplicate experiments. Gene silencing by siRNA transfection Cells were seeded onto 96 well plates and transfected with siPort NeoFx transfection method according to manufacturers instructions. Cells were cultured for 24 h and treated with compound. SiRNA from two different sources were used to confirm results. At least two independent experiments are used to determine representative results. Control siRNA, RB siRNA, and P53 siRNA were employed. The sequences of these control siRNAs are detailed in the manufacturer websites. Quantitative real time RT PCR Total RNA was isolated with Quick RNA miniPrep. Reverse transcription and quantitative real time PCR was performed on ABI Prism 7500 using the One Step SYBR ExTaq qRT PCR kit according to manufacturers instructions. The fol lowing primers were used, for GAPDH.