Targeting methyltransferase PRMT5 eliminates leukemia stem cells in chronic myelogenous leukemia
Yanli Jin, … , Ruibao Ren, Jingxuan Pan
Yanli Jin, … , Ruibao Ren, Jingxuan Pan
Published September 19, 2016
Citation Information: J Clin Invest. 2016;126(10):3961-3980. https://doi.org/10.1172/JCI85239.
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Research Article Hematology

Targeting methyltransferase PRMT5 eliminates leukemia stem cells in chronic myelogenous leukemia

Abstract

Imatinib-insensitive leukemia stem cells (LSCs) are believed to be responsible for resistance to BCR-ABL tyrosine kinase inhibitors and relapse of chronic myelogenous leukemia (CML). Identifying therapeutic targets to eradicate CML LSCs may be a strategy to cure CML. In the present study, we discovered a positive feedback loop between BCR-ABL and protein arginine methyltransferase 5 (PRMT5) in CML cells. Overexpression of PRMT5 was observed in human CML LSCs. Silencing PRMT5 with shRNA or blocking PRMT5 methyltransferase activity with the small-molecule inhibitor PJ-68 reduced survival, serial replating capacity, and long-term culture-initiating cells (LTC-ICs) in LSCs from CML patients. Further, PRMT5 knockdown or PJ-68 treatment dramatically prolonged survival in a murine model of retroviral BCR-ABL–driven CML and impaired the in vivo self-renewal capacity of transplanted CML LSCs. PJ-68 also inhibited long-term engraftment of human CML CD34+ cells in immunodeficient mice. Moreover, inhibition of PRMT5 abrogated the Wnt/β-catenin pathway in CML CD34+ cells by depleting dishevelled homolog 3 (DVL3). This study suggests that epigenetic methylation modification on histone protein arginine residues is a regulatory mechanism to control self-renewal of LSCs and indicates that PRMT5 may represent a potential therapeutic target against LSCs.

Authors

Yanli Jin, Jingfeng Zhou, Fang Xu, Bei Jin, Lijing Cui, Yun Wang, Xin Du, Juan Li, Peng Li, Ruibao Ren, Jingxuan Pan

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Figure 4

PRMT5 knockdown inhibits LSC growth in the CML mouse model.

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PRMT5 knockdown inhibits LSC growth in the CML mouse model. (A) Schemat...
(A) Schematic strategy of evaluation of the in vivo effect of PRMT5 knockdown on LSCs in the CML mouse model. (B) The effect of PRMT5 knockdown in spleen nucleated cells from CML mice was confirmed by Western blot analysis. (C) A representative photograph of spleens from each group. (D) Kaplan-Meier survival curves (n = 8 per group). *P = 0.0142 (Control versus IM), **P = 0.0029 (Control versus shPRMT5), #P = 0.0259 (Control versus shPRMT5+IM), log-rank test. (E–H) Analysis of LSKs in BM cells of CML mice that received treatment with shPRMT5 ± IM. Control, n = 10; IM, n = 8; shPRMT5, n = 6; shPRMT5+IM, n = 6. (E) Schema for analysis of LSK cells, LT-HSCs, and ST-HSCs. Results for the GFP+ population in BM: LSK cells (F), LT-HSCs (G), and ST-HSCs (H). **P < 0.01, ***P < 0.0001, compared with control; #P < 0.05, ##P < 0.01, shPRMT5 compared with shPRMT5+IM, 1-way ANOVA, post hoc intergroup comparisons, Tukey’s test. (I) LSK (Lin–Sca-1+c-Kit+) cells sorted by flow cytometry from the BM and spleens of first-generation CML mice underwent 2 rounds of transduction with lentiviral Scramble shRNA (Control) or shPRMT5 for 48 hours, and were then transplanted via tail veins into the secondary recipient mice, and survival curve was analyzed. Control, n = 8; shPRMT5, n = 9; ***P = 0.0001, log-rank test.