Involvement of C-jun NH2-terminal kinase and apoptosis induced factor in apoptosis induced by deglycosylated bleomycin in laryngeal carcinoma cells

Abstract

In our previous studies, we demonstrated that the deglycosylation of bleomycin-A2 (BLM-A2) does not affect the capacity of this drug to induce cell death by apoptosis in a caspase-independent manner in laryngeal cancer cells (HEp-2), but suppresses the ability of BLM-A2 to induce ROS formation. We have now investigated the consequence of BLM-A2 deglycosylation in terms of the involvement of apoptotic pathways in HEp-2 cells. Apoptosis induced by bleomycin-A2 and deglyco-BLM-A2 is associated with the release of cytochrome c and AIF. Only Bax was oligomerized with BLM-A2-induced HEp-2 cell death. BLM-A2 and deglyco-BLM-A2-induced apoptosis depended on JNK activation but was independent of death receptors expression. In contrast, both of these drugs would sensitize HEp-2 cells to death receptor ligand-induced cell death. These observations indicate that the deglycosylation of BLM does not impair the ability of the drug to trigger cell death through activation of the intrinsic pathway by the release of AIF responsible for mitochondrial permeability and chromatin condensation independent of caspases activation.