Tetrahydrobenzimidazole TMQ0153 triggers apoptosis, autophagy and necroptosis crosstalk in chronic myeloid leukemia (Part 3 Figure 5-9, Supple 1-12))

Abstract Chronic myeloid leukemia (CML) results from a t(9;22) (q34; q11) translocation, also called Philadelphia chromosome (Ph). This reciprocal translocation causes a constitutively-activated tyrosine kinase BCR-ABL fusion gene. By comparing imatinib-sensitive and -resistant CML cell models, we investigated the molecular mechanisms by which tetrahydrobenzimidazole derivative TMQ0153 triggered caspase-dependent apoptosis at low concentrations accompanied by loss of mitochondrial membrane potential (MMP) and increase of cytosolic free Ca2+ levels. Interestingly, at higher concentrations, TMQ0153 induced necroptotic cell death with accumulation of ROS, both preventable by N-acetyl-L-cysteine (NAC) pretreatment. At necroptosis-inducing concentrations, we observed increased ROS and decreased ATP and GSH levels, concomitant with protective autophagy induction. Inhibitors such as bafilomycin A1 (baf-A1) and siRNA against beclin 1 abrogated autophagy, sensitized CML cells against TMQ0153 and enhanced necroptotic cell death. Importantly, TMQ153-induced necrosis led to cell surface exposure of calreticulin (CRT) and ERp57 as well as the release of extracellular ATP and high mobility group box (HMGB1) demonstrating the immunological cell death markers by TMQ0153. We validated the anti-cancer potential of TMQ0153 by in vivo inhibition of K562 microtumor formation in zebrafish. Taken together, our findings provide evidence that cellular stress and redox modulation by TMQ0153 concentration-dependently leads to different cell death modalities including controlled necrosis in CML cell models