Antibody-induced nonapoptotic cell death in human lymphoma and leukemia cells is mediated through a novel reactive oxygen species-dependent pathway.

Honeychurch, Jamie, Alduaij, Waleed, Azizyan, Mahsa, Cheadle, Eleanor J., Pelicano, Helene, Ivanov, Andrei, Huang, Peng, Cragg, Mark S. and Illidge, Tim M. (2012) Antibody-induced nonapoptotic cell death in human lymphoma and leukemia cells is mediated through a novel reactive oxygen species-dependent pathway. Blood, 119 (15), 3523-3533. (doi:10.1182/blood-2011-12-395541). (PMID:22354003)

Abstract

Monoclonal antibodies (mAbs) have revolutionized the treatment of B-cell malignancies. Although Fc-dependent mechanisms of mAb-mediated tumor clearance have been extensively studied, the ability of mAbs to directly evoke programmed cell death (PCD) in the target cell and the underlying mechanisms involved remain under-investigated. We recently demonstrated that certain mAbs (type II anti-CD20 and anti-HLA DR mAbs) potently evoked PCD through an actin-dependent, lysosome-mediated process. Here, we reveal that the induction of PCD by these mAbs, including the type II anti-CD20 mAb GA101 (obinutuzumab), directly correlates with their ability to produce reactive oxygen species (ROS) in human B-lymphoma cell lines and primary B-cell chronic lymphocytic leukemia cells. ROS scavengers abrogated mAb-induced PCD indicating that ROS are required for the execution of cell death. ROS were generated downstream of mAb-induced actin cytoskeletal reorganization and lysosome membrane permeabilization. ROS production was independent of mitochondria and unaffected by BCL-2 overexpression. Instead, ROS generation was mediated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. These findings provide further insights into a previously unrecognized role for NADPH oxidase-derived ROS in mediating nonapoptotic PCD evoked by mAbs in B-cell malignancies. This newly characterized cell death pathway may potentially be exploited to eliminate malignant cells, which are refractory to conventional chemotherapy and immunotherapy.

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Contributors

Author: Mark S. Cragg

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