Chidamide represses MYC expression and might improve survival for patients with double expressor lymphoma

Abstract

Double expressor lymphoma (DEL), characterized by high expressions of both MYC and BCL-2, displays poor prognosis after current therapies. The HDAC inhibitor chidamide has been approved for treatment of T cell lymphoma, but its efficacy on B cell lymphoma is unclear. Here, by combining inhibition screening and transcriptomic analyses, we found that the sensitivity of B lymphoma cells to chidamide was positively correlated with the expression levels of MYC. Chidamide treatment reduced MYC protein levels and repressed MYC pathway in B lymphoma cells with high MYC expressions. Ectopic expression of MYC in chidamide-insensitive B lymphoma cells increased their response to chidamide. Thus, we proposed that adding chidamide into R-CHOP (CR-CHOP) might be effective for DEL, and retrospectively analyzed 185 DEL patients treated in West China Hospital. 80% of patients showed response to CR-CHOP treatment. In the median follow-up of 42 months, CR-CHOP significantly improve the survival for DEL patients with R-IPI ≤2. Totally 35 patients underwent autologous stem cell transplantation (ASCT) in remission and demonstrated a trend for better survival. Combining CR-CHOP with ASCT resulted in the most superior PFS and OS above all. For response patients, CR-CHOP reduced relapse with better PFS than R-CHOP-like regimens with or without ASCT. Taken together, our data indicated that chidamide repressed the MYC pathway in B lymphoma and is potentially efficacious to treat DEL.

Keywords: Chidamide; HDAC inhibitor; MYC; double expressor lymphoma; epigenetics.

Figure 1

MYC pathway in B cell lymphoma cells was inhibited after chidamide treatment. A. The curve-fitting analysis of cell viability. The dotted line represents half inhibition concentration (IC50) of chidamide. B. Heatmap shows the significantly differentially expressed genes in the JeKo-1 treated chidamide or vehicle (p.adj=0.05). C. Expression levels of MYC in JeKo-1 and Granta-519 cells treated with vehicle and chidamide by transcriptome analysis. TPM: transcript per million. D. The Venn diagram shows the overlap of down-regulated genes in chidamide-treated JeKo-1 cells with the MYC target genes (HALLMARK MYC TARGET V1, P=7.7e-19). E. Gene set enrichment analysis (GSEA) shows that the HALLMARK MYC TARGET V2 was enriched in the vehicle-treated JeKo-1 cells. F. Binding sites of down-regulated genes in the chidamide-treated JeKo-1 cells were regulated by c-MYC.

Figure 2

MYC expression level was positively correlated with the sensitivity of B-cell lymphoma cells to chidamide. (A) The correlation between chidamide sensitivity and MYC expression levels analyzed by qRT-PCR in different B-cell lymphoma cell lines (R=0.8393, P=0.0047). (B, C) Western blotting of MYC in chidamide-sensitive (B) and chidamide-insensitive (C) B-cell lymphoma cell lines treated with vehicle or 2 μM chidamide. (D) Quantitation of MYC proteins in chidamide-sensitive and chidamide-insensitive cell lines treated with vehicle or 2 μM chidamide. (E, F) Western blotting of CDK4 in chidamide-sensitive (E) and chidamide-insensitive (F) B-cell lymphoma cell lines. (G) Inhibition rate of MYC overexpressed Karpas-299 cells after chidamide treatment. (H, I) Tumor growth ratio curve after chidamide administration in vivo (H) and exfoliated tumor mass on day 15 (I). (J, K) The MYC protein (J) and mRNA (K) level change in lymphoma cells from a DEL patient treated with 4 µM chidamide. *P<0.05, **P<0.01, ***P<0.001 (two-tailed Student’s t-test).

Figure 3

CR-CHOP improved survival of DEL patients with R-IPI ≤2 without transplantation. Progression-free survival (A, C, E) and overall survival (B, D, F) for all DEL patients (A, B), patients with R-IPI ≤2 (C, D) and patient with R-IPI >2 (E, F), without transplantation. R-IPI: revised international prognostic index; R-CHOP: rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone; CR-CHOP: chidamide plus R-CHOP.

Figure 4

CR-CHOP reduced relapse for DEL patients with/without ASCT after remission. Progression-free survival (A) and overall survival (B) for DEL patient after remission. ASCT: Autologous stem cell transplantation.