Ezh2 loss propagates hypermethylation at T cell differentiation–regulating genes to promote leukemic transformation
Changshan Wang, … , Atsushi Iwama, Goro Sashida
Changshan Wang, … , Atsushi Iwama, Goro Sashida
Published August 6, 2018
Citation Information: J Clin Invest. 2018;128(9):3872-3886. https://doi.org/10.1172/JCI94645.
View: Text | PDF
Research Article Hematology Oncology

Ezh2 loss propagates hypermethylation at T cell differentiation–regulating genes to promote leukemic transformation

Abstract

Early T cell precursor acute lymphoblastic leukemia (ETP-ALL) is a new pathological entity with poor outcomes in T cell ALL (T-ALL) that is characterized by a high incidence of loss-of-function mutations in polycomb repressive complex 2 (PRC2) genes. We generated a mouse model of ETP-ALL by deleting Ezh2, one of the PRC2 genes, in p53-null hematopoietic cells. The loss of Ezh2 in p53-null hematopoietic cells impeded the differentiation of ETPs and eventually induced ETP-ALL–like disease in mice, indicating that PRC2 functions as a bona fide tumor suppressor in ETPs. A large portion of PRC2 target genes acquired DNA hypermethylation of their promoters following reductions in H3K27me3 levels upon the loss of Ezh2, which included pivotal T cell differentiation–regulating genes. The reactivation of a set of regulators by a DNA-demethylating agent, but not the transduction of single regulator genes, effectively induced the differentiation of ETP-ALL cells. Thus, PRC2 protects key T cell developmental regulators from DNA hypermethylation in order to keep them primed for activation upon subsequent differentiation phases, while its insufficiency predisposes ETPs to leukemic transformation. These results revealed a previously unrecognized epigenetic switch in response to PRC2 dysfunction and provide the basis for specific rational epigenetic therapy for ETP-ALL with PRC2 insufficiency.

Authors

Changshan Wang, Motohiko Oshima, Daisuke Sato, Hirotaka Matsui, Sho Kubota, Kazumasa Aoyama, Yaeko Nakajima-Takagi, Shuhei Koide, Jun Matsubayashi, Makiko Mochizuki-Kashio, Takako Nakano-Yokomizo, Jie Bai, Toshitaka Nagao, Akinori Kanai, Atsushi Iwama, Goro Sashida

×

Figure 3

The loss of Ezh2 impeded T cell differentiation at the CD4–CD8– stage.

Options: View larger image (or click on image) Download as PowerPoint
The loss of Ezh2 impeded T cell differentiation at the CD4–CD8– stage. (...
(A) Experimental schematic of the procedure to examine the T cell differentiation potential of purified CD45.2+CD44+CD25–Lin– DN1 cells. DN1 cells were cultured with TSt-4/DLL1 stromal cells in the presence of SCF, IL-7, and Flt3L (10 ng/ml) for 7 to 14 days. (B) Total cell counts of WT (black line), Ezh2Δ/Δ (black broken line), p53Δ/Δ (blue line), and Ezh2Δ/Δp53Δ/Δ (broken blue line) cells during culture (n = 3–6). Data are shown as mean ± SEM. **P < 0.01; ***P < 0.001, Student’s t test. (C) Proportions of CD4+CD8+ cells in CD45.2+ cells on day 7 of WT, Ezh2Δ/Δ, p53Δ/Δ, and Ezh2Δ/Δp53Δ/Δ DN1 cell culture (n = 3–6). Data are shown as mean ± SEM. (D) Representative flow cytometric profiles of CD4 and CD8 expression in WT, Ezh2Δ/Δ, p53Δ/Δ, and Ezh2Δ/Δp53Δ/Δ CD45.2+ cells on day 7 of the culture. (E) Proportions of DN1, DN2, DN3, and DN4 cells in CD45.2+CD4–CD8– DN cells on day 7 of the culture (n = 3–6). Data are shown as mean ± SEM. (F) Representative flow cytometric profiles of CD44 and CD25 expression in CD45.2+CD4–CD8– cells on day 7 of the culture. Data are representative of 2 independent experiments.