Targeting methyltransferase PRMT5 eliminates leukemia stem cells in chronic myelogenous leukemia
Yanli Jin, Jingfeng Zhou, Fang Xu, Bei Jin, Lijing Cui, Yun Wang, Xin Du, Juan Li, Peng Li, Ruibao Ren, Jingxuan Pan
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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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.