Granzyme B induction signalling pathway in acute myeloid leukemia cell lines stimulated by Tumor Necrosis Factor alpha and Fas Ligand

Acute myeloid leukemia (AML) cell lines treated by genotoxic agents or by Tumor Necrosis Factor alpha (TNFα) acquire potent cytotoxicity towards myeloid cells through activation of granzyme B (GrB)/perforin (PFN) system. Here we first extend this observation to another death receptor activator, Fas Ligand (FasL). Moreover, we analyzed GrB induction signalling pathway in TNFα- and FasL-stimulated AML cells. The effects of TNFα and FasL on GrB expression were specifically mediated by p38MAPK (Mitogen-activated-protein-kinase) activation. Otherwise, TNFα and FasL stimulation led to radical oxygen species (ROS) generation and ASK1 (Apoptosis-signal-regulating-kinase-1) activation. Endogenous activation of ASK1 by either H2O2 or thioredoxin (Trx) reductase inhibition had the same effects as TNFα and FasL on GrB up regulation. Altogether, our results suggest that TNFα- and FasL-stimulated AML cell lytic induction is regulated by a signalling pathway involving sequentially, ROS generation, Trx oxidation, ASK1 activation, p38MAPK stimulation and GrB induction at mRNA and protein levels.