Lysosomal disruption preferentially targets acute myeloid leukemia cells and progenitors
Mahadeo A. Sukhai, … , Guri Giaever, Aaron D. Schimmer
Mahadeo A. Sukhai, … , Guri Giaever, Aaron D. Schimmer
Published December 3, 2012
Citation Information: J Clin Invest. 2013;123(1):315-328. https://doi.org/10.1172/JCI64180.
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Research Article Oncology

Lysosomal disruption preferentially targets acute myeloid leukemia cells and progenitors

Abstract

Despite efforts to understand and treat acute myeloid leukemia (AML), there remains a need for more comprehensive therapies to prevent AML-associated relapses. To identify new therapeutic strategies for AML, we screened a library of on- and off-patent drugs and identified the antimalarial agent mefloquine as a compound that selectively kills AML cells and AML stem cells in a panel of leukemia cell lines and in mice. Using a yeast genome-wide functional screen for mefloquine sensitizers, we identified genes associated with the yeast vacuole, the homolog of the mammalian lysosome. Consistent with this, we determined that mefloquine disrupts lysosomes, directly permeabilizes the lysosome membrane, and releases cathepsins into the cytosol. Knockdown of the lysosomal membrane proteins LAMP1 and LAMP2 resulted in decreased cell viability, as did treatment of AML cells with known lysosome disrupters. Highlighting a potential therapeutic rationale for this strategy, leukemic cells had significantly larger lysosomes compared with normal cells, and leukemia-initiating cells overexpressed lysosomal biogenesis genes. These results demonstrate that lysosomal disruption preferentially targets AML cells and AML progenitor cells, providing a rationale for testing lysosomal disruption as a novel therapeutic strategy for AML.

Authors

Mahadeo A. Sukhai, Swayam Prabha, Rose Hurren, Angela C. Rutledge, Anna Y. Lee, Shrivani Sriskanthadevan, Hong Sun, Xiaoming Wang, Marko Skrtic, Ayesh Seneviratne, Maria Cusimano, Bozhena Jhas, Marcela Gronda, Neil MacLean, Eunice E. Cho, Paul A. Spagnuolo, Sumaiya Sharmeen, Marinella Gebbia, Malene Urbanus, Kolja Eppert, Dilan Dissanayake, Alexia Jonet, Alexandra Dassonville-Klimpt, Xiaoming Li, Alessandro Datti, Pamela S. Ohashi, Jeff Wrana, Ian Rogers, Pascal Sonnet, William Y. Ellis, Seth J. Corey, Connie Eaves, Mark D. Minden, Jean C.Y. Wang, John E. Dick, Corey Nislow, Guri Giaever, Aaron D. Schimmer

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Figure 4

Mefloquine disrupts lysosomes in leukemia cells.

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Mefloquine disrupts lysosomes in leukemia cells. (A) Left panel: TEM ana...
(A) Left panel: TEM analysis of lysosomes in TEX cells treated for 24 hours with mefloquine (10 μM). Data represent mean percent intact lysosomes ± SD relative to control-treated cells. Middle and right panels: Quantification of LysoTracker and acridine orange uptake in TEX cells treated for 24 hours with mefloquine (10 μM). Results (mean ± SD of 3 replicates in a representative experiment) represent the percent lysosomal integrity relative to control cells. (B) Lysosome integrity, measured by LysoTracker and acridine orange uptake, after treatment with mefloquine (10 μM) for 24 hours in cells from insensitive (sample 1, EC50 >12 μM) or sensitive AML samples (samples 2–6, EC50 5–8 μM) and normal human hematopoietic cells (n = 3). Results (mean ± SD of 3 replicates in a representative experiment) represent the percent lysosomal integrity relative to control cells. *P < 0.05. (C) Cathepsin B release after mefloquine (10 μM) treatment shown by immunofluorescence microscopy. Representative fields (×80 objective magnification) are shown. Arrow indicates an aggregate of cathepsin B activity. Scale bars: 5 μm. (D) TEX cells were treated with 8 μM mefloquine alone or in combination with bafilomycin A1 (900 nM) for 24 hours, and cell viability was determined by Annexin V/PI. Results (mean ± SD of 3 replicates in a representative experiment) represent viability compared with controls.