Figure 1: Relative growth of MDA-MB-435 cells and skin fibroblasts after treatment with apoptosis-related siRNAs. The growth was normalized against non-treated cells (taken as 100%).
In a second screen, a relatively small siRNA library targeting 169 genes involved in cell cycle regulations (Dharmacon siGENOME Cell Cycle Regulation siRNA library; 169 members) was used to assess the effect of siRNAs on the cytotoxicity of two common cancer drugs (paclitaxel and doxorubicin). As can be seen in Figure 2, the results indicated significant variations in the response to siRNA treatment alone: growth inhibition ranged from no effect to ~70% inhibition. For some siRNAs, adding the drug to the treatment did not yield any beneficial effect (e.g., siRNA #97), but the beneficial effects of paclitaxel, more so than the doxorubicin, was evident in some cases (e.g., siRNA #17).
Figure 2:Relative growth of MDA-MB-435 cells after treatment with cell cycle siRNAs with/without paxlitaxel (PXT) and doxorubicin (DOX). The growth was normalized against non-treated cells (taken as 100%).