The lysosomotropic drug LeuLeu-OMe induces lysosome disruption and autophagy-independent cell death in Trypanosoma brucei

• Published in: Microbial cell Vol. 2; no. 8; pp. 288 - 298
• Main Authors: Koh, Hazel X, Aye, Htay M, Tan, Kevin S W, He, Cynthia Y
• Format: Journal Article
• Language: English
• Published: Austria Shared Science Publishers OG 30.07.2015
• Subjects: autophagy; LeuLeu-OMe; lysosome; lysosomotropic; Microbiology; Molecular Biology; necrosis; Trypanosoma brucei; lysosomotropic; LeuLeu-OMe; autophagy; Trypanosoma brucei; necrosis; lysosome
• ISSN: 2311-2638; 2311-2638
• DOI: 10.15698/mic2015.08.217

is a blood-borne, protozoan parasite that causes African sleeping sickness in humans and nagana in animals. The current chemotherapy relies on only a handful of drugs that display undesirable toxicity, poor efficacy and drug-resistance. In this study, we explored the use of lysosomotropic drugs to induce bloodstream form cell death via lysosome destabilization. We measured drug concentrations that inhibit cell proliferation by 50% (IC50) for several compounds, chosen based on their lysosomotropic effects previously reported in . The lysosomal effects and cell death induced by L-leucyl-L-leucyl methyl ester (LeuLeu-OMe) were further analyzed by flow cytometry and immunofluorescence analyses of different lysosomal markers. The effect of autophagy in LeuLeu-OMe-induced lysosome destabilization and cytotoxicity was also investigated in control and autophagy-deficient cells. LeuLeu-OMe was selected for detailed analyses due to its strong inhibitory profile against with minimal toxicity to human cell lines . Time-dependent immunofluorescence studies confirmed an effect of LeuLeu-OMe on the lysosome. LeuLeu-OMe-induced cytotoxicity was also found to be dependent on the acidic pH of the lysosome. Although an increase in autophagosomes was observed upon LeuLeu-OMe treatment, autophagy was not required for the cell death induced by LeuLeu-OMe. Necrosis appeared to be the main cause of cell death upon LeuLeu-OMe treatment. LeuLeu-OMe is a lysosomotropic agent capable of destabilizing lysosomes and causing necrotic cell death in bloodstream form of .