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 2

LONP1 is essential for a subgroup of AML cell lines and patient samples.

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LONP1 is essential for a subgroup of AML cell lines and patient samples....
(A) Mean ± SD growth and viability of OCI-AML2, OCI-M2, or Cas9-expressing OCI-AML2 cells by trypan blue staining after transduction with shRNA or sgRNA targeting LONP1 or control sequences. After 7 days (shRNA) or 14 days (gRNA), expression levels of LONP1 and β-actin were measured by immunoblotting. Representative data from 3 biological replicates are shown. (B) Primary AML samples (n = 9) were transduced with an shRNA targeting LONP1. After 7 days, cell viability was assessed by CellTiter-Fluor and LONP1 expression by immunoblotting. Basal protein expression before transduction relative to OCI-AML2 cells was calculated by densitometry. r2 = 0.71. (C) Normal hematopoietic samples (n = 3) were transduced with an shRNA targeting LONP1 or control sequences. After 7 days, the mean ± SD cell growth, and viability was measured by CellTiter-Fluor. P > 0.05, by unpaired, 2-tailed Student’s t test. (D) Equal numbers of primary AML cells transduced with an shRNA targeting LONP1 or control sequences in GFP-containing vectors were injected into right femurs of NSG mice (n = 8 per group). After 12 weeks, mice were sacrificed, and engraftment of CD45+CD33+ cells was measured in left femurs. Transduction efficiencies were 18.5% and 16.7% for shControl and shLONP1 3′-UTR groups, respectively. ***P = 0.0002, by unpaired, 2-tailed Student’s t test. (E) Equal numbers of primary AML cells from D were injected into the right femurs of NSG mice (n = 8 per group). After 12 weeks, left femur engraftment was measured. ****P < 0.0001, by unpaired, 2-tailed Student’s t test. (F) Equal numbers of cord blood cells transduced with shRNA targeting LONP1 or control sequences in GFP-containing vectors were injected into right femurs of NS-GF mice (n = 9 per group). After 12 weeks, left femur engraftment was measured. Transduction efficiencies were 38.5% and 37.6% for shControl and shLONP1 3′-UTR groups, respectively. P = 0.0988, by unpaired, 2-tailed Student’s t test. Data are presented as mean ± SD.