FADD Knockout Cell Lysate

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) exhibits antitumor activity in various types of tumor cell and tumor-bearing animals. However, acquired TRAIL resistance is a common issue that restricts its clinical application. Previous studies have revealed that -catenin is associated with TRAIL resistance in melanoma and colorectal tumors. In the present study, an acquired-resistance non-small-cell lung cancer (NSCLC) cell line (H460-TR) was established from parental TRAIL-sensitive H460 cells using a gradient ascent model (8-256 ng/ml TRAIL). Cellular FADD-like interleukin-1 converting enzyme inhibitory protein and Mcl-1 were upregulated and the cell surface distribution of death receptor (DR)4 and DR5 was downregulated in H460-TR cells compared with the parental H460 cells. The results of reverse transcription-quantitative polymerase chain reaction and western blot analysis indicated that H460 cells expressed increased levels of -catenin and were more sensitive to TRAIL compared with H460-TR cells. -catenin-knockdown in H460 cells decreased their sensitivity to TRAIL, while upregulation of -catenin expression in H460-TR cells increased their sensitivity to TRAIL, increased the cell surface distribution of DRs and activated caspase-3/8. Taken together, the results of the present study suggest that -catenin impairs acquired TRAIL resistance in NSCLC cells by promoting the redistribution of DR4 and DR5 to the cytomembrane, and inducing TRAIL-mediated cell apoptosis via caspase-3/8 activation.

Aim of presented study was to investigate whether EGCG could sensitize TRAIL resistant NPC cells to TRAIL-mediated apoptosis. Three human NPC cell-lines CNE-1, CNE-2, C666-1 and a non-transformed nasopharyngeal epithelium cell-line NP-69 were treated with EGCG or/and TRAIL. The apoptosis and TRAIL receptors were determined by flow cytometric analysis. The protein expression was determined by western blotting. Mitochondrial transmembrane potential was dertemined by DiOC(6) (3). C666-1 cell-line was the only one that resistant to TRAIL and selected to be treated with EGCG. ECGC could sensitize C666-1 to TRAIL. Combinatorial treatments led to decrease expression of Bd-XL, Bcl-2, FADD and FLIP and enhance activation of capase-3,-8,-9. The DiOC6 (3) negative cell rate was increased and p65 of NF-kappa B, XIAP and survivin expression was reduced by the combination treatment. In summary, EGCG sensitizes NPC cells to TRAIL-mediated apoptosis via modulation of extrinsic and intrinsic apoptotic pathways and inhibition of NF-kappa B activation.