Three or more siRNAs against 26 of the 79 genes that enhanced TRAIL read more induced activation of caspase 3 7 also enhanced TRAIL cytotoxicity by greater than 2 standard deviations from the mean Inhibitors,Modulators,Libraries viability seen in siNeg transfected cells plus TRAIL. As indicated by the red rectangles in Figure 4A, 14 of these 26 genes map to the direct interaction network. The silencing of BCL2L1 and two genes directly linked to it, ATP5A1 and HIPK2, by multiple siRNAs Inhibitors,Modulators,Libraries increased TRAIL induced caspase 3 7 ac tivation and cytotoxicity. In addition, the RNAi induced LOF of several genes linked to SRC enhanced TRAIL induced cytotoxicity including PDPK1, CNKSR1, PIP5K1C, FGFR4, BCR, RIOK3, and MKNK1.

All three of the siRNAs corresponding to SRC that activated caspase 3 7 in the presence of TRAIL en hanced cytotoxicity, but only by using a relaxed criterion of greater than 1 standard deviation from the mean viabil ity seen in siNeg transfected cells plus TRAIL. Multiple Inhibitors,Modulators,Libraries siRNAs corresponding to PDPK1 and several genes linked to PDPK1 also increased TRAIL induced caspase 3 7 activation and cytotoxicity. These included PRKC1, the known apop tosis inhibitor BIRC2, PLK3, PKN1, and ACTN4. Silencing by two of four siRNAs of many of the remaining genes mapping to the direct interaction network induced a decrease in cell viability greater than 2 standard deviations from that seen in siNeg transfected cells Inhibitors,Modulators,Libraries plus TRAIL, with at least one further siRNA inducing a decrease in viability at least 1 standard deviation from that seen in siNeg transfected cells plus TRAIL. This included silencing of IKBKB, BLK, ERBB2, FGFR2, NAGK, and ZC3HC1.

The results for the activation of caspase 8 were more variable. Only one gene BCL2L1 showed an increase in caspase 8 levels more than 1 standard devi ation from that seen in siNeg transfected cells for three or more siRNAs. In several other cases, two of four siRNAs corresponding to a specific gene medi ated an increase in caspase 8 levels more Inhibitors,Modulators,Libraries than 1 stand ard deviation from that seen in siNeg, including CNKSR1, BCR, and PIP5KIC, which all linked to SRC, ATP5A1 that links to BCL2L1, and PRKC1, which is linked to PDPK1. Two genes for which three siRNAs activated caspase 3 7 and ?8 but did not map to the network based on direct interactions, BCL2L2 and APEX1. Interestingly, all four siRNAs corresponding to BCL2L2 enhanced TRAIL induced caspase 3 7 activation, and three of these siRNAs also enhanced TRAIL induced caspase 8 activation, but no effect on cell viability was observed. Three siRNAs corre sponding to the APEX nuclease 1 gene, APEX1, enhanced TRAIL activated caspase 3 7 and caspase 8 and decreased cell viability, selleck chemicals llc but the individual siRNAs that generated these phenotypic changes were inconsistent.