In addition, most of the drugs significantly inhibited cisplatin induced FANCD2 foci formation in 24 hours co treatment experiments. These results demonstrate selleck chem that most FA pathway inhibitors inhibit HR processes in addition to FANCD2 foci formation, indicating that the identified chemicals target multiple steps of the DNA damage response pathway and Inhibitors,Modulators,Libraries are not specific for FA pathway Inhibitors,Modulators,Libraries inhibition. The lack of inhibition of FANCD2 monoubiquitination suggests that the FA pathway inhibi tors may inhibit processes involved in the recruitment of proteins at sites of damage, rather than damage signaling upstream of FANCD2 monoubiquitination. Identification of the compounds that synergize with cisplatin in ovarian cancer cells Since the integrity of the FA pathway is critical for cellular resistance to ICL inducing agents such as cisplatin, FA pathway inhibitors may sensitize tumor cells to cisplatin in an FA pathway dependent manner.

To test this hypothesis, we performed isobologram analyses on the ovarian cancer cell line 2008, which is deficient in the FA pathway due to hypermethylation of the FANCF promoter, and on its isogenic, complemented FA pathway proficient coun Inhibitors,Modulators,Libraries terpart 2008 FANCF cell line. First, single agent survival curves were generated, and the dose producing a 50% reduction of cell survival was determined. As previously reported, 2008 cells were significantly more sensitive to cisplatin than 2008 FANCF cells. 2008 and 2008 FANCF cells were equally sensitive Inhibitors,Modulators,Libraries to all FA pathway inhibitors, except for puromycin and geldanamycin.

Higher tolerance of 2008 FANCF cells to puromycin was likely due to the use of puromycin Inhibitors,Modulators,Libraries selec tion to generate the complemented cell line, and therefore, puromycin was omitted from further analysis. The reason for the differential sensitivity of 2008 and 2008 FANCF cells toward geldanamycin remains unknown. Next, isobolograms at the LD50 level were generated following the method previously described. Survival assays were performed using the combination of 10 cisplatin concentrations with 6 concentrations of each inhibitor manufacture FA pathway inhibitor. LD50/LD500 unit values of each FA pathway inhibitor were plotted against corresponding LD50/LD500 unit values of cisplatin. The distribution of points along the line connecting values of 1 corresponds to an additive effect of the two drugs while scattering below or above represents synergism and antagonism, respectively. In addition, combination index values were calculated according to Chou and Tallays method . CI 0. 90 indicates synergism. Analyses performed at 50% killing revealed that 11 FA pathway inhibitors exhibited synergism with cisplatin in 2008 and/or 2008 FANCF cells.