Our results show that in RKO this particular cancer cell trait is modulated by and dependent sellckchem on B RafV600E and that targeting mutant BRAF is sufficient to restore sensitivity to caspase dependent apoptosis after serum withdrawal via p53 independent PUMA induction. Complementing and extending previous studies, we thus provide evidence from an endogenous and quantitative genetic model of BRAF mutant colorectal cancer cells, thereby ruling out the occurrence of artifacts caused by unspecific cellular response or incomplete knockdown in RNAi setups and, likewise, avoiding inter species bias potentially experienced in mouse models of colorectal cancer. Pharmacogenetic characterization Hyperactivated Raf Mek Erk signaling has been sug gested to mediate resistance towards drug induced cell death.

However, data from prostate cancer cells transfected with mutant BRAF showed that there might be tumor entity dependent differences. Our Inhibitors,Modulators,Libraries model system of corresponding tumor cells is ideally suited to determine the B RafV600E specific effects of a com prehensive panel of widely used chemotherapeutic agents including crosslinking agents, a taxane, a topoisomerase II inhibitor, and the nucleic acid metabolism in hibitor 5 fluorouracil. We found that the BRAF mutational status did not have a detectable impact on chemosensitivity towards any of these agents. These findings Inhibitors,Modulators,Libraries suggest that B RafV600E does not significantly contribute to resistance towards conventional chemotherapeutics in colorectal cancer cells and are in accordance with previous studies suggesting Inhibitors,Modulators,Libraries the Raf Mek Erk cascade to play a minor role in chemoresistance.

Taken together with the observed differential sensitivity of BRAF mutant cells towards Inhibitors,Modulators,Libraries starvation induced apoptosis, these results further dissect the distinct apoptosis pathways in our model, i. e. serum starvation versus chemotherapeutic agents. wild type clones express the epidermal growth factor re ceptor at comparable levels. To test whether loss of mutant BRAF might reconstitute respon siveness to the inhibition of EGFR, cells were treated with the monoclonal antibody cetuximab. However, no difference in proliferation was observed between BRAF wild type and mutant cells, while cetuximab sufficiently inhibited growth of the control cell line Lim1215. All cells revealed a similar slight decrease in the prolifer ation index down to 0.

6 at Inhibitors,Modulators,Libraries very high concentrations of cetuximab. This modest effect might be due to unspecific toxicity or to dilution, rather than to a spe cific anti proliferative effect of cetuximab, since at 0. 8 g L the antibody solution accounts for 16% of the culture medium. These findings are in line with previous studies showing that resistance against EGFR targeted treatment frequently occurs in selleck compound BRAF mutant tumors. Next, we investigated the impact of the BRAF V600E mutation on several established B Raf inhibitors.