| Background:Diffuse large B-cell lymphoma(DLBCL)is the most aggressive non-Hodgkin lymphoma in the world.The current standard chemotherapy regimen for DLBCL is usually a type of immunochemotherapy regimen represented by R-CHOP.Although R-CHOP can cure about 60%-70%of patients,there are still 30%-40%patients with poor response to the standard therapy.Among them,Double-hit lymphoma(DHL)is a more aggressive lymphoma in DLBCL,which carries the gene combination of MYC and BCL-2 rearrangement.DHL is characterized by high tumor proliferation,and has a very good prognosis in standard R-CHOP treatment.Therefore new targeted therapies are needed to improve the prognosis of patients.It has been found that epigenetic alterations contribute to the growth of lymphoma and the generation of chemoresistance phenotypes;The histone deacetylase HDAC inhibitor chidamide has shown good results in the treatment of refractory and relapsed DLBCL;BCL-2inhibitors have a good anti-tumor effect in DHL lymphoma;The changes in epigenetics and the expression of BCL-2 anti-apoptotic protein may jointly promote the aggressiveness of DHL.The effect and mechanism of combining HADC inhibitors and BCL-2 inhibitors is unknown,which may synergically promote the apoptosis of DHL.Objective:To explore the effects of the combination of BCL-2 inhibitor(venetoclax)and epigenetic HDAC inhibitor(chidamide)on the growth of DLBCL and its mechanism.Methods:1.Using biological information technology to analyze the correlation between the anti-apoptotic gene BCL-2 and the epigenetic modifying enzyme gene HDAC in DLBCL patients.2.Human DLBCL cell lines SUDHL-4(MYC~-/BCL-2~+)and DB(MYC~+/BCL-2~+) were cultured in vitro;The two cell lines were treated with single-drug and combined-drug treatments respectively for 24,48,72h,and a control group was set up;The CCK-8 method detected cell viability;Flow cytometry detected the apoptosis rate and cell cycle of the cells;RNA-seq technology detected MYC,BCL-2 and HDACs m RNA levels;Western blotting technology detected the expression of c-myc,bcl-2,p53,ac-histone-H3 and ac-Histone-H4.3.Established a mouse model of human DLBCL xenotransplantation and treat it with drugs for 3 weeks.Observed and recorded the effects of no-drug group, single-drug group and combined drug group on tumor growth;Taken tumor tissue for immunohistochemical staining and observed separately the expression of BCL-2,ac-Histone-H3 and CD20 in each group.Results:1.By comparing the samples from 47 DLBCL patients and 337 normal B lymphocytes,the expressions of HDAC1,HDAC4,HDAC5,HDAC7,HDAC9,HDAC10 and BCL-2 in DLBCL tissues are different,and HDAC1 HDAC7,HDAC9 and HDAC10 have a strong correlation with BCL-2.2.Venetoclax and chidamide had an effect on the viability of SUDHL-4 cells and DB cells,respectively,showing an obvious time-dose dependence.After 24 hours of combined treatment,the inhibition of the proliferation of the two cell lines was stronger than that of the single-drug group(P<0.05).3.Compared with the control group,both single-drug groups can induce apoptosis of two cell lines,while the combination of two drugs can increase more apoptosis(p<0.05)and induce cell cycle arrest in G0/G1 phase in two cell lines.4.Chidamide can down-regulate the m RNA level of MYC and co-regulate several important biological processes with ABT-199.5.The combination group can reduce the expression of c-myc,p53 and bcl-2 protein in two cell lines,and increase the expression of acetylated histone-H3 and bim.6.The volume and weight of tumors in the combined medication group were lower than those in the control group or single-drug group(P<0.05).The combination therapy could further decrease the expression of Bcl-2 and increase the expression of Ac-histone-H3 and CD20 in subcutaneous tumor tissues.Conclusions:1.Venetoclax and chidamide have inhibitory effects on the growth of DLBCL cell lines;2.Chidamide synergistically enhances the anti-tumor effect of the venetoclax on MYC+/BCL-2+DHL by regulating epigenetic changes,silencing the expression of the proto-oncogene MYC,reducing anti-apoptotic proteins Bcl-2 and increased expression of the pro-apoptotic protein bim;... |
