Elevated mitochondrial protein import in acute myeloid leukemia increases reliance on mitochondrial protease LONP1
Matthew Tcheng, Veronique Voisin, Geethu Emily Thomas, Anastasija A. Piric, Marcela Gronda, Rose Hurren, Dakai Ling, Yongran Yan, Lan Xin Zhang, Yue Feng, Ali Chegini, Nathan Duong, Ross S. Mancini, Stefan Quinn W. Currie, Zaynab Mamai, Brady Stock, Shahbaz Khan, Yulia Jitkova, Chaitra Sarathy, Edward Ayoub, Po Yee Mak, Andrea Arruda, Thomas Kislinger, Mark A. Reed, Bing Z. Carter, Michael Andreeff, Steven M. Kornblau, Mark D. Minden, Siavash Vahidi, Aaron D. Schimmer
Matthew Tcheng, Veronique Voisin, Geethu Emily Thomas, Anastasija A. Piric, Marcela Gronda, Rose Hurren, Dakai Ling, Yongran Yan, Lan Xin Zhang, Yue Feng, Ali Chegini, Nathan Duong, Ross S. Mancini, Stefan Quinn W. Currie, Zaynab Mamai, Brady Stock, Shahbaz Khan, Yulia Jitkova, Chaitra Sarathy, Edward Ayoub, Po Yee Mak, Andrea Arruda, Thomas Kislinger, Mark A. Reed, Bing Z. Carter, Michael Andreeff, Steven M. Kornblau, Mark D. Minden, Siavash Vahidi, Aaron D. Schimmer
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Research Article Cell biology Metabolism Oncology

Elevated mitochondrial protein import in acute myeloid leukemia increases reliance on mitochondrial protease LONP1

Abstract

Most mitochondrial proteins are nucleus-encoded, translated in the cytosol, and imported into the mitochondria. Through gene expression analysis and functional assays, we demonstrated that mitochondrial protein import was increased in acute myeloid leukemia (AML) cells compared with normal hematopoietic cells. Increased mitochondrial protein import was positively correlated with an increase in the mitochondrial unfolded protein response (UPRmt), a stress-activated pathway of mitochondrial proteases and chaperones that maintains protein solubility and prevents the formation of toxic aggregates. The UPRmt protease LONP1 (Lon peptidase 1) was upregulated in AML and positively correlated with increased mitochondrial protein import and UPRmt. Genetic or chemical inhibition of the LONP1 ATPase domain induced mitochondrial protein aggregation and selectively killed AML cells with high LONP1 expression, while sparing AML cells with low LONP1 expression and normal hematopoietic cells in vitro and in vivo. Thus, we uncovered a critical role of the UPRmt protease LONP1 in buffering stress from mitochondrial protein import in AML.

Authors

Matthew Tcheng, Veronique Voisin, Geethu Emily Thomas, Anastasija A. Piric, Marcela Gronda, Rose Hurren, Dakai Ling, Yongran Yan, Lan Xin Zhang, Yue Feng, Ali Chegini, Nathan Duong, Ross S. Mancini, Stefan Quinn W. Currie, Zaynab Mamai, Brady Stock, Shahbaz Khan, Yulia Jitkova, Chaitra Sarathy, Edward Ayoub, Po Yee Mak, Andrea Arruda, Thomas Kislinger, Mark A. Reed, Bing Z. Carter, Michael Andreeff, Steven M. Kornblau, Mark D. Minden, Siavash Vahidi, Aaron D. Schimmer

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Figure 3

Chemical inhibition of the LONP1 AAA+ domain preferentially targets AML cells with high LONP1 expression.

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Chemical inhibition of the LONP1 AAA+ domain preferentially targets AML ...
(A and B) Mean ± SD (A) ATPase activity and (B) proteolytic activity of recombinant LONP1 in the presence of omaveloxolone or bardoxolone methyl. (C) Primary AML samples were treated with 250 nM omaveloxolone (n = 16) or bardoxolone methyl (n = 30) for 72 hours. Cell growth and viability was measured by CellTiter-Fluor and LONP1 protein expression relative to OCI-AML2 cells by immunoblotting. (omaveloxolone: r2 = 0.66, bardoxolone methyl: r2 = 0.65). (D) Normal mononuclear hematopoietic cells (n = 3) were treated with omaveloxolone or bardoxolone methyl. After 72 hours, cell growth and viability were measured by CellTiter-Fluor. (E) Primary AML samples (n = 3) or normal mononuclear hematopoietic cells (n = 3) were treated with 200 nM omaveloxolone or bardoxolone methyl and plated for clonogenic growth assays. AML130433 cells (omaveloxolone: ***P = 0.0004; bardoxolone methyl: ***P = 0.0002); AML161868 cells (omaveloxolone, bardoxolone methyl: ****P < 0.0001); AML90784 cells (omaveloxolone: ***P = 0.0003; bardoxolone methyl: *P = 0.0239). NS, P > 0.05; 1-way ANOVA with Dunnett’s multiple-comparison test. (F) Primary AML cells were injected into the right femurs of NSG mice (n = 5–8 per group). After 6 weeks, mice were treated i.p. with omaveloxolone (7.5 mg/kg) or vehicle daily for 6 days. On day 7, engraftment of primary AML cells in the left femur was assessed with flow cytometry and anti–human CD45 and CD33 antibodies. ***P = 0.0009, by unpaired, 2-tailed Student’s t test. (G) Cord blood cells were injected into the right femurs of NS-GF mice (n = 8–10 per group). After 4 weeks, mice were treated with omaveloxolone (7.5 mg/kg) or vehicle for 8 weeks. Engraftment of cord blood cells in the left femur was assessed with flow cytometry and anti–human CD45 and CD33 antibodies. NS, P = 0.3091, by unpaired, 2-tailed Student’s t test. Data are presented as mean ± SD.