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 3

PRMT5 knockdown by lentiviral shRNA reduces growth, survival, and colony formation in human CML CD34+ cells.

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PRMT5 knockdown by lentiviral shRNA reduces growth, survival, and colon...
Human CML CD34+ (A, C, E, and G) versus NBM CD34+ (n = 3 each) (B, D, F, and H) cells were transduced with control shRNA (Scramble), shPRMT5 #1, or shPRMT5 #2 for 48 hours, then treated with IM (2.5 μM) for 24 hours. (A and B) Western blot analysis of PRMT5 and BCR-ABL. (C and D) Cell viability was determined by MTS assay (Promega). (E and F) Apoptosis was detected by flow cytometry after dually staining CML and NBM CD34+ cells with annexin V–FITC and anti-CD38–PE. (G and H) The same number of Scramble, shPRMT5 #1, or shPRMT5 #2 in CML and NBM CD34+ cells (5,000 cells/well) were seeded in methylcellulose medium (H4434). Colonies were counted at 14 days. (I and J) Forty-eight hours after 2 rounds of transduction with control shRNA (Scramble), shPRMT5 #1, or shPRMT5 #2 lentivirus, the human CML CD34+ cells (n = 3) were exposed to PJ-68 at 25 μM for another 24 hours, and cell numbers (I) and CFC formation (J) were determined. *P < 0.05, **P < 0.01, ***P < 0.0001, 1-way ANOVA, post-hoc intergroup comparisons, Tukey’s test.