Reated with carboplatin, a DNA alkylating agent (Figure 2C). The response amongst K-Ras independent cells

Reated with carboplatin, a DNA alkylating agent (Figure 2C). The response amongst K-Ras independent cells to DNA damaging agents was variable, while general they have been nearly 4 occasions more responsive to etoposide and twice as responsive to SN-38 as K-Ras dependent cells (Figures 2A and 2B). When cells had been treated with the microtubule disruption agent, paclitaxel, some cell lines in both the K-Ras dependent and independent sub-groups responded, with no considerable difference in response amongst groups (Figure 2D). Many tumor cells inactivate DNA damage induced apoptotic pathways, suggesting a achievable mechanism for the resistance of K-Ras dependent cells to apoptosis. TP53, which encodes the tumor suppressor protein p53, is mutated in about 50 of NSCLC, and mutation of TP53 predicts resistance to chemotherapeutic drugs in lung as well as other forms of cancer (29). Ra Inhibitors Related Products Analysis of TP53 Flufenoxuron In Vitro mutations through the COSMIC (http://cancer.sanger.ac.uk/ cosmic) and UMD TP53 mutation databases (http://p53.fr) indicates that 4/7 K-Ras independent cell lines have mutant TP53 (H157, H1792, H1155 and CaLu-6), even though all ten K-Ras dependent cell lines have TP53 mutations (30). Particular TP53 mutations are summarized in Table S1. As not all TP53 mutations are inactivating, we verified the functional status of p53 by analyzing p53 stability, Ser15 phosphorylation, and expression in the p53 target gene, p21. Within a handful of cell lines with mutant TP53 (see H2009 and H727, Figure 2E), remedy with etoposide elevated p53 protein stability and/or Ser15 phosphorylation, as well as p21 expression, indicating a partially functional p53 protein. Notably, H2009 and H727 cells are among the least PKC dependent from the K-Ras dependent NSCLC cells (see Figure 1C). From the K-Ras independent cell lines, these with WT TP53 (A549, H460 and SW-1573) are among probably the most sensitive to etoposide, even so some K-Ras independent cells with mutant TP53, particularly H157 cells, still showed sensitivity. Therefore, whilst mutations in TP53 correlate with resistance to apoptosis and with a pro-tumorigenic function for PKC in K-Ras dependent cells, in the K-Ras independent sub-group, wild sort TP53 alone does not predict sensitivity to apoptosis. Our information suggests that the pro-apoptotic function of PKC, specially in the context of topoisomerase inhibitors, is lost or suppressed in K-Ras dependent NSCLC cells, relative to K-Ras independent cells. To explore this straight, we analyzed etoposide-induced apoptosis in cells depleted of PKC. Depletion of PKC with either 193 or 203 resulted inAuthor Manuscript Author Manuscript Author Manuscript Author ManuscriptOncogene. Author manuscript; accessible in PMC 2017 October 03.Ohm et al.Pagesuppression of apoptosis in K-Ras independent A549 and H460 cells compared to cells expressing scr (Figure 3A). In contrast, depletion of PKC had small impact on etoposideinduced apoptosis, or synergized with etoposide to further improve DNA fragmentation in K-Ras dependent H2009 and HCC-44 cells (Figure 3C). We next explored the hypothesis that PKC is differentially linked to survival or apoptotic pathways in K-Ras dependent and independent NSCLC cells. We found no constant variations in basal ERK or Akt activation involving these NSCLC subsets (data not shown). Having said that, our prior research suggested that ERK activation is differentially regulated by PKC depletion in K-Ras dependent versus independent NSCLC cells (9). In our present study we explored this additional utilizing our pan.