Bright blue fluorescent signals showed the damaged nuclear DNA due to apoptosis. More bright blue fluorescent spots were observed in FLCN-deficient cells. Scale bar = 10 μm. D. Cells were treated with 50, 80, and 100 nM paclitaxel for 24 hours, cleaved caspase-3 and FLCN protein were detected by western blot. Elevated cleaved caspase-3 expression was detected in FLCN-deficient cells. RG7112 molecular weight Paclitaxel induced autophagy in FLCN-deficient renal cancer cells To determine whether paclitaxel

induces autophagy as well in FLCN-deficient renal cancer cells, we measured the expression of microtubule-associated protein 1 light chain 3 (LC3) in paclitaxel-treated cells by Western blot. LC3 is an important autophagy marker recruited to the autophagosome

membrane. LC3 has two isoforms, LC3-I and LC3-II. During autophagy, LC3-I is conjugated to autophagic membrane-associated phosphatidylethanolamine and converted to LC3-II. Increased LC3-II level, especially increased LC3-II/LC3-I ratio, may indicate the occurrence of autophagy [19, 20]. To exclude the possibility that the increased LC3-II levels were resulted from the accumulation of LC3-II due to downstream inhibition other than paclitaxel induction, we treated the cells with paclitaxel in presence or absence of lysosomal inhibitor bafilomycin A1. As shown in Figure 2, although increased LC3-II levels were detected in all of the bafilomycin A1-treated cells due to inhibition of lysosomal degradation of LC3-II, LC3-II selleckchem levels were even higher in the paclitaxel-treated FLCN-deficient cells compared to that in the FLCN-expressing cells regardless of balfilomycin Aspartate A1 (Figure 2A). The paclitaxel-mediated LC3 expression levels were also measured at various drug concentrations and different time points with or without bafilomycin A1 treatment (Figure 2B, C). The paclitaxel treatment led to increase of LC3-II level in a dose-dependent manner and seemed to peak at 24 hours in FLCN-deficient cells. To further confirm

that paclitaxel could induce autophagy in FLCN-deficient cells, we examined the p62 expression by Western blot. The reduced p62 level usually indicates activation of autophagy in cells [19, 21]. In the absence of lysosomal inhibitor bafilomycin A1, we observed that expression of p62 protein was decreased in paclitaxel-treated FLCN-deficient cells, suggesting that autophagy was activated and the p62 protein was degraded via autophagy (Figure 2D). The p62 level was obviously elevated in FLCN-deficient cells treated with bafilomycin A1 and paclitaxel, indicating autophagy was blocked by bafilomycin A1 and p62 was accumulated in these cells (Figure 2D) These results demonstrated that paclitaxel could induce autophagy in FLCN-deficient cells. Figure 2 Paclitaxel induced autophagy in UOK257 and ACHN-5968 cells. A. UOK257/UOK257-2 and ACHN-sc/ACHN 5968 cells were treated with 100 nM paclitaxel for 24 hours.