Fig. 5.
Downregulation of c-FLIPL expression sensitizes human glioma cells to anti-DR5 mAb. (A) Western blot showing reduced expression of c-FLIPL protein upon treatment with siRNA against c-FLIPL (siFLIPL) in U87MG and LNZ308 cells. Cells were transfected with either nontargeting siRNA (siCtl) or siFLIPL and were harvested for the preparation of total lysates after being cultured for 48 hours. Twenty micrograms of total lysate was size fractionated in a 10% SDS–polyacrylamide gel, transferred to a PVDF membrane and reacted with a monoclonal antibody against human c-FLIPL. The β-Actin blot demonstrates the loading of lysate in each lane. No Tx, no treatment. (B and C) Enhanced anti-DR5 mAb-induced cytotoxicity by the suppression of c-FLIPL expression. U87MG (B) or LNZ308 (C) cells were transfected with either siCtl or siFLIPL, followed by treatment with or without E11 at a sublethal concentration (0.01 µg/mL) for 24 hours and then were subjected to the MTT assay. Similar results were obtained when treated with KMTR2. ***P < .001, **P < .01 (Student's t-test).