Agonistic monoclonal antibody against DR5 induces ROS aggregation, sustained JNK activation and Endo G release in Jurkat leukemia T lymphocytes (33.22)

Abstract

Abstract We previously reported that AD5-10, a novel agonistic mAb to DR5, possessed a strong cytotoxic activity in various tumor cells. In this study, we further demonstrated the ROS generation, sustained activation of JNK, loss of mitochondrial membrane potential, and release of Endo G in Jurkat leukemia T lymphocytes upon AD5-10 stimulation. The dominant negative JNK, but not p38, enhanced NF-κB activation, suppressed caspase-8 recruitment in DISC, reduced the dysfunction of mitochondria, therefore, inhibited the cell death in these cells. The data may throw light on the therapeutic strategy for T lymphocyte leukemia and solid tumors. We further investigated the sensitivity of lung cancer cells to AD5-10. A549 and SCLC showed a moderate sensitivity and H460 resistant to the mAb, which was not related to DR5 expression, but c-FLIPL expression and cleavage. Inhibition of c-FLIPL by siRNA significantly enhanced AD5-10-induced cell death. The sensitizing effect was associated with decreased expression of Bid and Bcl-XL, change of mitochondrial membrane potential, release of cytochrome c, and caspase activation. Immunohistochemistry assay revealed that c-FLIPL was expressed in 87.9% of the lung carcinoma tissues from the patients, but little in the normal controls, suggesting that inhibition of c-FLIPL might be a potential strategy for lung cancer therapy.