Diffuse Large B-cell Lymphoma Cell Proliferation Research Articles

Ouabain-mediated downregulation of ALKBH5 and IGF2BP2 inhibits the malignant progression of DLBCL.

m6A modification is a crucial epigenetic regulatory mechanism in diffuse large B-cell lymphoma (DLBCL). Low-dose cardiotonic drugs have been shown to induce apoptosis in DLBCL cells through epigenetic modulation. However, the involvement of the cardiotonic drug ouabain in the malignant progression of DLBCL remains unclear. Our study revealed that ouabain indeed contributes to the malignant progression of DLBCL through m6A modification. Through qPCR analysis, we observed a negative correlation between ouabain concentration and the expression levels of the demethylase ALKBH5 and the m6A-binding protein IGF2BP2 in DLBCL cells. Furthermore, high expression levels of ALKBH5 and IGF2BP2 were identified in both the GEO database and DLBCL patient tissue samples. Notably, elevated ALKBH5 and IGF2BP2 promoted cell proliferation both in vitro and in vivo. Inhibition of their expression rendered DLBCL cells more sensitive to ouabain treatment, resulting in significant suppression of cell proliferation, G1/S phase cell cycle arrest, and increased apoptosis. In summary, our results clarify that the demethylase ALKBH5 and the m6A-binding protein IGF2BP2 are involved in the malignant progression of DLBCL, and that the cardiotonic drug ouabain can inhibit the proliferation of DLBCL cells by inhibiting the expression of ALKBH5 and IGF2BP2, which provides new insights into the targeted treatment of DLBCL.

Low NDRG2, regulated by the MYC/MIZ-1 complex and methylation, predicts poor outcomes in DLBCL patients.

Diffuse large B-cell lymphoma (DLBCL) represents the most common tumor in non-Hodgkin's lymphoma. N-Myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor highly expressed in healthy tissues but downregulated in many cancers. Although cell proliferation-related metabolism rewiring has been well characterized, less is known about the mechanism of metabolic changes with DLBCL. Herein, we investigated the expressions of NDRG2, MYC and Myc-interacting zinc finger protein 1 (MIZ-1) in seven human lymphoma (mostly DLBCLs) cell lines. NDRG2 expression was inversely correlated with the expressions of MYC and MIZ-1. Further, we explored the regulatory mechanism and biological functions underlying the lymphomagenesis involving NDRG2, MYC and MIZ-1. MYC and MIZ-1 promoted DLBCL cell proliferation, while NDRG2 induced apoptosis in LY8 cells. Moreover, NDRG2 methylation was reversed by the 5-Aza-2'-deoxycytidine (5-Aza-CDR) treatment, triggering the downregulation of MYC and inhibiting DLBCL cell survival. MYC interacts with NDRG2 to regulate energy metabolism associated with mTOR. Remarkably, supporting the biological significance, the converse correlation between NDRG2 and MYC was observed in human DLBCL tumor tissues (R = -0.557). Bioinformatics analysis further validated the association among NDRG2, MYC, MIZ-1, mTOR, and related metabolism genes. Additionally, NDRG2 (P = 0.001) and MYC (P < 0.001) were identified as promising prognostic biomarkers in DLBCL patients through survival analysis. Together, our data demonstrate that the MYC/MIZ-1 complex interplays with NDRG2 to influence the proliferation and apoptosis of DLBCL cells and show the characterizations of NDRG2, MYC and MIZ-1 for metabolism features and prediction prognosis in DLBCL.

β-Sitosterol Inhibits Tumor Growth and Amplifies Rituximab Sensitivity through Acid Sphingomyelinase/Ceramide Signaling in Diffuse Large B-Cell Lymphoma.

Rituximab (RTX) resistance is a notable challenge in treating diffuse large B-cell lymphoma (DLBCL). β-Sitosterol (β-ST) is a plant sterol that has been found in a broad variety of fruits, spices, and medicinal plants. The antineoplastic properties of β-ST are established in various solid malignancies; however, its effect on DLBCL is uncharted. This study investigates the role of β-ST in DLBCL as well as the underlying mechanisms. Our findings indicated that β-ST impeded DLBCL cell proliferation in a concentration- and time-dependent manner. β-ST appeared to alter sphingolipid metabolism, facilitate acid sphingomyelinase (ASM) translocation to the plasma membrane, augment ceramide platforms through increased ceramide synthesis, and consequently induce apoptosis in DLBCL cells. Furthermore, we found that RTX initiated both apoptotic and survival pathways in vitro, with the former contingent on the transient activation of the ASM, and β-ST could amplify the anti-DLBCL efficacy of RTX by modulating ASM/Ceramide (Cer) signaling. Collectively, our findings elucidate the mechanistic role of β-ST in DLBCL and underscore its potential in amplifying the antineoplastic efficacy of RTX via ASM activation, proposing a potential avenue to improve the efficacy of RTX therapy.

PGM5-AS1 Promotes Progression of Diffuse Large B-Cell Lymphoma and Immune Escape by Regulating miR-503-5p.

Diffuse large B-cell lymphoma (DLBCL) is a prevalent malignant condition with a dismal prognosis. LncRNA PGM5 antisense RNA 1 (PGM5-AS1) appears to be intricately involved in the progression of DLBCL, yet the modulatory mechanism remains unclear. The purpose of this study was to explore the expression of lncRNA PGM5-AS1 in DLBCL and its effect on the disease progression of DLBCL, as well as to explore its mechanisms. A total of 35 patients were included in the study. The expression levels of PGM5-AS1 and miR-503-5p in DLBCL tumor tissues and cell lines were detected by RT-qPCR. Cell proliferation was assessed using CCK8. Apoptosis rate was determined by flow cytometry. Cell invasion was examined by transwell assays. The specific interaction between PGM5-AS1 and miR-503-5p was verified through dual luciferase reporter gene assays. The immune related factors were detected by ELASA kits. The CD8+ T cells cytotoxicity was evaluated by LDH cytotoxicity kit. In DLBCL tumor tissues and cells, upregulated PGM5-AS1 expression, downregulated miR-503-5p expression, and elevated PD-L1 expression were observed. PGM5-AS1 functioned as a regulator in controlling DLBCL cell proliferation, apoptosis, and invasion by downregulating miR-503-5p expression. When CD8+ T cells were co-cultured with cells transfected with si-PGM5-AS1, the secretion of immunoregulatory factors increased, and the cytotoxicity of CD8+ T cells increased. These effects were mitigated by miR-503-5p inhibitors. PGM5-AS1 accelerated DLBCL development and facilitated tumor immune escape through the miR-503-5p. Our discoveries offered an insight into lncRNA PGM5-AS1 serving as a prospective therapeutic target for DLBCL.

FAT1 inhibits the proliferation of DLBCL cells via increasing the m6A modification of YAP1 mRNA

Emerging evidence shows that FAT atypical cadherin 1 (FAT1) mutations occur in lymphoma and are associated with poorer overall survival. Considering that diffuse large B cell lymphoma (DLBCL) is the category of lymphoma with the highest incidence rate, this study aims to explore the role of FAT1 in DLBCL. The findings demonstrate that FAT1 inhibits the proliferation of DLBCL cell lines by downregulating the expression of YAP1 rather than by altering its cellular localization. Mechanistic analysis via meRIP-qPCR/luciferase reporter assays showed that FAT1 increases the m6A modification of YAP1 mRNA 3′UTR and the subsequent binding of heterogeneous nuclear ribonucleoprotein D (HNRNPD) to the m6A modified YAP1 mRNA, thus decreasing the stability of YAP1 mRNA. Furthermore, FAT1 increases YAP1 mRNA 3′UTR m6A modification by decreasing the activity of the TGFβ-Smad2/3 pathway and the subsequent expression of ALKBH5, which is regulated at the transcriptional level by Smad2/3. Collectively, these results reveal that FAT1 inhibits the proliferation of DLBCL cells by increasing the m6A modification of the YAP1 mRNA 3’UTR via the TGFβ-Smad2/3-ALKBH5 pathway. The findings of this study therefore indicate that FAT1 exerts anti-tumor effects in DLBCL and may represent a novel target in the treatment of this form of lymphoma.

Arsenic disulfide promoted the demethylation of PTPL1 in diffuse large B cell lymphoma cells.

Promoter hypermethylation of the tumor suppressor gene is one of the well-studied causes of cancer development. The drugs that reverse the process by driving demethylation could be a candidate for anticancer therapy. This study was designed to investigate the effects of arsenic disulfide on PTPL1 methylation in diffuse large B cell lymphoma (DLBCL). We knocked down the expression of PTPL1 in two DLBCL cell lines (i.e., DB and SU-DHL-4 cells) using siRNA. Then the DLBCL proliferation was determined in the presence of PTPL1 knockdown. The methylation of PTPL1 in DLBCL cells was analyzed by methylation specific PCR (MSPCR). The effect of arsenic disulfide on the PTPL1 methylation was determined in DLBCL cell lines in the presence of different concentrations of arsenic disulfide (5 µM, 10 µM and 20 µM), respectively. To investigate the potential mechanism on the arsenic disulfide-mediated methylation, the mRNA expression of DNMT1, DNMT3B and MBD2 was determined. PTPL1 functioned as a tumor suppressor gene in DLBCL cells, which was featured by the fact that PTPL1 knockdown promoted the proliferation of DLBCL cells. PTPL1 was found hypermethylated in DLBCL cells. Arsenic disulfide promoted the PTPL1 demethylation in a dose-dependent manner, which was related to the inhibition of DNMTs and the increase of MBD2. Experimental evidence shows that PTPL1 functions as a tumor suppressor gene in DLBCL progression. PTPL1 hyper-methylation could be reversed by arsenic disulfide in a dose-dependent manner.

Recombinant hirudin suppresses angiogenesis of diffuselarge B-cell lymphoma through regulation of the PAR-1-VEGF.

Hirudin is one of the specific inhibitors of thrombin, which has been confirmed to have strong bioactivities, including inhibiting tumors. However, the function and mechanism of hirudin and protease-activated receptor 1 (PAR-1) in diffuse large B-cell lymphoma (DLBCL) have not been clear. Detecting the expression PAR-1 in DLBCL tissues and cells by RT-qPCR and IHC. Transfected sh-NC, sh-PAR-1, or pcDNA3.1-PAR-1 in DLBCL cells or processed DLBCL cells through added thrombin, Vorapaxar, Recombinant hirudin (RH), or Na2S2O4 and co-culture with EA.hy926. And built DLBCL mice observed tumor growth. Detecting the expression of related genes by RT-qPCR, Western blot, IHC, and immunofluorescence, measured the cellular hypoxia with Hypoxyprobe-1 Kit, and estimated the cell inflammatory factors, proliferation, migration, invasion, and apoptosis by ELISA, CCK-8, flow cytometry, wound-healing and Transwell. Co-immunoprecipitation and pull-down measurement were used to verify the relationship. PAR-1 was highly expressed in DLBCL tissues and cells, especially in SUDHL2. Na2S2O4 induced SUDHL2 hypoxia, and PAR-1 did not influence thrombin-activated hypoxia. PAR-1 could promote SUDHL2 proliferation, migration, and invasion, and it was unrelated to cellular hypoxia. PAR-1 promoted proliferation, migration, and angiogenesis of EA.hy926 or SUDHL2 through up-regulation vascular endothelial growth factor (VEGF). RH inhibited tumor growth, cell proliferation, and migration, promoted apoptosis of DLBCL, and inhibited angiogenesis by down-regulating PAR-1-VEGF. RH inhibits proliferation, migration, and angiogenesis of DLBCL cells by down-regulating PAR-1-VEGF.

Eukaryotic initiation factor 3a promotes the development of diffuse large B-cell lymphoma through regulating cell proliferation

BackgroundOne-third of diffuse large B-cell lymphoma (DLBCL) patients suffer relapse after standard treatment. Eukaryotic initiation factor 3a (eIF3a) is a key player in the initial stage of translation, which has been widely reported to be correlated with tumorigenesis and therapeutic response. This study aimed to explore the biological role of eIF3a, evaluate its prognostic and therapeutic potential in DLBCL.MethodsRNA-seq datasets from GEO database were utilized to detect the expression and prognostic role of eIF3a in DLBCL patients. Protein level of eIF3a was estimated by western blot and immunohistochemical. Next, DLBCL cells were transfected with lentiviral vector either eIF3a-knockdown or empty to assess the biological role of eIF3a. Then, samples were divided into 2 clusters based on eIF3a expression and differentially expressed genes (DEGs) were identified. Function enrichment and mutation analysis of DEGs were employed to detect potential biological roles. Moreover, we also applied pan-cancer and chemosensitivity analysis for deep exploration.ResultseIF3a expression was found to be higher in DLBCL than healthy controls, which was associated with worse prognosis. The expression of eIF3a protein was significantly increased in DLBCL cell lines compared with peripheral blood mononuclear cells (PBMCs) from healthy donors. eIF3a knockdown inhibited the proliferation of DLBCL cells and the expression of proliferation-related proteins and increase cell apoptosis rate. Besides, 114 DEGs were identified which had a close linkage to cell cycle and tumor immune. eIF3a and DEGs mutations were found to be correlated to chemosensitivity and vital signal pathways. Pan-cancer analysis demonstrated that high eIF3a expression was associated with worse prognosis in several tumors. Moreover, eIF3a expression was found to be related to chemosensitivity of several anti-tumor drugs in DLBCL, including Vincristine and Wee1 inhibitor.ConclusionsWe firstly revealed the high expression and prognostic role of eIF3a in DLBCL, and eIF3a might promote the development of DLBCL through regulating cell proliferation and apoptosis. eIF3a expression was related to immune profile and chemosensitivity in DLBCL. These results suggest that eIF3a could serve as a potential prognostic biomarker and therapeutic target in DLBCL.

A promising natural product in diffuse large B-cell lymphoma therapy by targeting PIM1.

Diffuse large B-cell lymphoma (DLBCL) is the most common and aggressive type of B-cell lymphoma. Unfortunately, about one-third of patients either relapse after the initial treatment or are refractory to first-line therapy, indicating a need for new treatment modalities. PIM serine/threonine kinases are proteins that are associated with genetic mutations, overexpression, or translocation events in B-cell lymphomas. We conducted an integrative analysis of whole-exome sequencing in 52 DLBCL patients, and no amplification, mutation, or translocation of the PIM1 gene was detected. Instead, analyses of TCGA and GTEx databases identified that PIM1 expression was increased in DLBCL samples compared to normal tissue, and high expression levels were associated with poor overall survival. Moreover, interference of PIM1 significantly suppressed DLBCL cell proliferation. In addition, we identified anwulignan, a natural small-molecule compound, as a PIM1 inhibitor. Anwulignan directly binds to PIM1 and exerts antitumor effects on DLBCL in vitro and in vivo by inducing apoptosis, cell cycle arrest, and autophagic cell death. Furthermore, we identified an effective synergistic combination between anwulignan and chidamide. Our findings suggested that PIM1 could be a therapeutic target and prognostic factor for DLBCL, and anwulignan holds promise for future development as a natural product for treatment.

Chidamide and orelabrutinib synergistically induce cell cycle arrest and apoptosis in diffuse large B-cell lymphoma by regulating the PI3K/AKT/mTOR pathway

ObjectiveThe initial therapeutic approach for diffuse large B-cell lymphoma (DLBCL) entails a rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) regimen. However, 40% of patients exhibit suboptimal responses, with some experiencing relapse and refractory conditions. This study aimed to explore novel therapeutic strategies and elucidate their underlying mechanisms in DLBCL.MethodsBioinformatics techniques were employed to scrutinize correlations between the HDAC1, HDAC2, HDAC3, HDAC10, BTK, MYC, TP53, and BCL2 genes in DLBCL. In vitro experiments were conducted using DB and SU-DHL-4 cells treated with chidamide, orelabrutinib, and a combination of both. Cell viability was assessed by cell counting kit-8. Cell apoptosis and the cell cycle were determined using flow cytometry. Reactive oxygen species (ROS) production and mitochondrial function were assessed through ROS and JC-1 staining. RNA sequencing and western blot analyses were conducted to elucidate the molecular mechanisms underlying the combined action of chidamide and orelabrutinib in DLBCL cells.ResultsThis investigation revealed markedly enhanced antiproliferative effects when chidamide was combined with orelabrutinib. Compusyn software analysis indicated a synergistic effect of chidamide and orelabrutinib in inhibiting DLBCL cell proliferation, with a combination index (CI) < 1. This synergy further manifested as augmented cell cycle arrest, apoptosis induction, the downregulation of cell cycle-associated and antiapoptotic proteins, and the upregulation of proapoptotic proteins. Furthermore, the western blot and RNA-Seq findings suggested that combining chidamide and orelabrutinib modulated the PI3K/AKT/mTOR signaling pathway, thereby promoting DLBCL cell cycle arrest and apoptosis.ConclusionThe findings of this study provide a compelling justification for the clinical utilization of chidamide and orelabrutinib to treat relapsed/refractory DLBCL.

Targeting ZDHHC21/FASN axis for the treatment of diffuse large B-cell lymphoma

S-palmitoylation is essential for cancer development via regulating protein stability, function and subcellular location, yet the roles S-palmitoylation plays in diffuse large B-cell lymphoma (DLBCL) progression remain enigmatic. In this study, we uncovered a novel function of the palmitoyltransferase ZDHHC21 as a tumor suppressor in DLBCL and identified ZDHHC21 as a key regulator of fatty acid synthetase (FASN) S-palmitoylation for the first time. Specifically, ZDHHC21 was downregulated in DLBCL, and its expression level was associated with the clinical prognosis of patients with DLBCL. In vitro and in vivo experiments suggested that ZDHHC21 suppressed DLBCL cell proliferation. Mechanistically, ZDHHC21 interacted with FASN and mediated its palmitoylation at Cys1317, resulting in a decrease in FASN protein stability and fatty acid synthesis, consequently leading to the inhibition of DLBCL cell growth. Of note, an FDA-approved small-molecule compound lanatoside C interacted with ZDHHC21, increased ZDHHC21 protein stability and decreased FASN expression, which contributed to the suppression of DLBCL growth in vitro and in vivo. Our results demonstrate that ZDHHC21 strongly represses DLBCL cell proliferation by mediating FASN palmitoylation, and suggest that targeting ZDHHC21/FASN axis is a potential therapeutic strategy against DLBCL.

M6A-related lncRNAs as potential biomarkers and the lncRNA ELFN1-AS1/miR-182-5p/BCL-2 regulatory axis in diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid subtype. However, unsatisfactory survival outcomes remain a major challenge, and the underlying mechanisms are poorly understood. N6-methyladenosine (m6A), the most common internal modification of eukaryotic mRNA, participates in cancer pathogenesis. In this study, m6A-associated long non-coding RNAs (lncRNA) were retrieved from publicly available databases. Univariate, LASSO, and multivariate Cox regression analyses were performed to establish an m6A-associated lncRNA model specific to DLBCL. Kaplan-Meier curves, principal component analysis, functional enrichment analyses and nomographs were used to study the risk model. The underlying clinicopathological characteristics and drug sensitivity predictions against the model were identified. Risk modelling based on the three m6A-associated lncRNAs was an independent prognostic factor. By regrouping patients using our model-based method, we could differentiate patients more accurately for their response to immunotherapy. In addition, prospective compounds that can target DLBCL subtypes have been identified. The m6A-associated lncRNA risk-scoring model developed herein holds implications for DLBCL prognosis and clinical response prediction to immunotherapy. In addition, we used bioinformatic tools to identify and verify the ceRNA of the m6A-associated lncRNA ELFN1-AS1/miR-182-5p/BCL-2 regulatory axis. ELFN1-AS1 was highly expressed in DLBCL and DLBCL cell lines. ELFN1-AS1 inhibition significantly reduced the proliferation of DLBCL cells and promoted apoptosis. ABT-263 inhibits proliferation and promotes apoptosis in DLBCL cells. Invitro and invivo studies have shown that ABT-263 combined with si-ELFN1-AS1 can inhibit DLBCL progression.

FKBP3 aggravates the malignant phenotype of diffuse large B-cell lymphoma by PARK7-mediated activation of Wnt/β-catenin signalling.

Diffuse large B-cell lymphoma (DLBCL) is difficult to treat due to the high recurrence rate and therapy intolerance, so finding potential therapeutic targets for DLBCL is critical. FK506-binding protein 3 (FKBP3) contributes to the progression of various cancers and is highly expressed in DLBCL, but the role of FKBP3 in DLBCL and its mechanism are not clear. Our study demonstrated that FKBP3 aggravated the proliferation and stemness of DLBCL cells, and tumour growth in a xenograft mouse model. The interaction between FKBP3 and parkinsonism associated deglycase (PARK7) in DB cells was found using co-immunoprecipitation assay. Knockdown of FKBP3 enhanced the degradation of PARK7 through increasing its ubiquitination modification. Forkhead Box O3 (FOXO3) belongs to the forkhead family of transcription factors and inhibits DLBCL, but the underlying mechanism has not been reported. We found that FOXO3 bound the promoter of FKBP3 and then suppressed its transcription, eventually weakening DLBCL. Mechanically, FKBP3 activated Wnt/β-catenin signalling pathway mediated by PARK7. Together, FKBP3 increased PARK7 and then facilitated the malignant phenotype of DLBCL through activating Wnt/β-catenin pathway. These results indicated that FKBP3 might be a potential therapeutic target for the treatment of DLBCL.

Long non-coding RNA SNHG17 may function as a competitive endogenous RNA in diffuse large B-cell lymphoma progression by sponging miR-34a-5p.

We investigated the functional mechanism of long non-coding small nucleolar host gene 17 (SNHG17) in diffuse large B-cell lymphoma (DLBCL). lncRNAs related to the prognosis of patients with DLBCL were screened to analyze long non-coding small nucleolar host gene 17 (SNHG17) expression in DLBCL and normal tissues, and a nomogram established for predicting DLBCL prognosis. SNHG17 expression in B-cell lymphoma cells was detected using qPCR. The effects of SNHG17 with/without doxorubicin on the proliferation and apoptosis of DoHH2 and Daudi were detected. The effects of combined SNHG17 and doxorubicin were analyzed. The regulatory function of SNHG17 in DLBCL was investigated using a mouse tumor xenotransplantation model. RNA sequencing was used to analyze the signaling pathways involved in SNHG17 knockdown in B-cell lymphoma cell lines. The target relationships among SNHG17, microRNA, and downstream mRNA biomolecules were detected. A higher SNHG17 level predicted a lower survival rate. SNHG17 was highly expressed in DLBCL patient tissues and cell lines. We established a prognostic model containing SNHG17 expression, which could effectively predict the overall survival rate of DLBCL patients. SNHG17 knockdown inhibited the proliferation and induced the apoptosis of B-cell lymphoma cells, and the combination of SNHG17 and doxorubicin had a synergistic effect. SNHG17, miR-34a-5p, and ZESTE gene enhancer homolog 2 (EZH2) had common hypothetical binding sites, and the luciferase reporter assay verified that miR-34a-5p was the direct target of SNHG17, and EZH2 was the direct target of miR-34a-5p. The carcinogenic function of SNHG17 in the proliferation and apoptosis of DLBCL cells was partially reversed by a miR-34a-5p inhibitor. SNHG17 increases EZH2 levels by inhibiting miR-34a-5p. Our findings indicate SNHG17 as critical for promoting DLBCL progression by regulating the EZH2 signaling pathway and sponging miR-34a-5p. These findings provide a new prognostic marker and therapeutic target for the prognosis and treatment of DLBCL.

CDCA2 Is a Predictive Marker and Mediator of Bortezomib Response in Diffuse Large B-Cell Lymphoma

Objective: In recent years randomized phase III clinical trials have attempted to improve first-line R-CHOP treatment of diffuse large B-cell lymphoma (DLBCL) through addition or substitution of drugs. Bortezomib treatment has shown significant clinical efficacy in other B-cell malignancies, and the REMoDL-B trial testing R-CHOP vs. RB-CHOP in DLBCL patients stratified by cell of origin revealed at 60 months follow-up that ABC and molecular high-grade patients significantly benefitted in clinical outcome. This study aims at identifying predictive markers of bortezomib response combined with functional investigation of their biological impact in DLBCL irrespective of molecular subtypes. Methods: Data from the REMoDL-B trial including 450 patients in each treatment arm was retrospectively analyzed. We fitted a multivariate Cox regression model testing all expressed genes with overall survival as outcome and an interaction term between gene expression and treatment arms (R-CHOP and RB-CHOP) as covariates, including their main effects. For the top candidate, CDCA2, survival was visualized using Kaplan-Meier analysis of patients stratified by median expression. Functional examination of CDCA2 was performed by applying CRISPR/Cas9 genome editing. Knockout of CDCA2 was conducted in two DLBCL cell lines, representing ABC and GCB cell of origin, and effect on proliferation, cell cycle distribution, and drug response was examined in MTS-assays and by flow cytometry. A DLBCL xenograft mouse model was established with CDCA2 knockout and control DLBCL cells, respectively, and time to tumor formation and death was monitored and tumors molecularly characterized. Results: DLBCL patients with high expression of CDCA2 have superior outcome when treated with RB-CHOP in comparison to R-CHOP (p=0.0097), whereas no difference in outcome was observed for patients with low CDCA2 expression (p=0.086) (Figure 1), supporting high expression of CDCA2 as a predictive marker of bortezomib response irrespective of cell of origin subclassification. Knockout of CDCA2 decreased DLBCL cell proliferation rate and affected the cell cycle transition between the G1 and S-phase, resulting in an increased percentage of cells in G1 compared to the scramble control. Bortezomib dose-response analysis revealed reduced sensitivity in CDCA2 knockout cells compared to the control (Figure 2A). In addition, CDCA2 knockout cells were also less sensitive to carfilzomib, a 2 nd generation proteasome inhibitor. In combinatory drug experiments comparing CHOP and B-CHOP, CDCA2 knockout cells demonstrated higher relative resistance compared to controls cells when exposed to B-CHOP than CHOP (Figure 2B+C), illustrating CDCA2 to be cardinal and specifically mediating the bortezomib response. In DLBCL xenograft models, CDCA2 knockout tumors displayed reduced growth rate in comparison to control tumors. Due to the substantial tumor burden, control DLBCL xenografted mice had shorter survival time than CDCA2 knockout DLBCL mice (Figure 2D). Conclusion: DLBCL patients with high expression levels of CDCA2 benefitted the most from addition of bortezomib to R-CHOP. In functional studies, the loss of CDCA2 increased cellular resistance to bortezomib in both single- and combinational drug studies.

Targeting YTHDF2 inhibits tumorigenesis of diffuse large B-cell lymphoma through ACER2-mediated ceramide catabolism

IntroductionEpigenetic alterations play crucial roles in diffuse large B-cell lymphoma (DLBCL). Disturbances in lipid metabolism contribute to tumor progression. However, studies in epigenetics, especially its critical regulator YTH N6-methyladenosine RNA binding protein 2 (YTHDF2), on lipid metabolism regulation in DLBCL are unidentified. ObjectivesElucidate the prognostic value and biological functions of YTHDF2 in DLBCL and illuminate the underlying epigenetic regulation mechanism of lipid metabolism by YTHDF2 in DLBCL development. MethodsThe expression and clinical value of YTHDF2 in DLBCL were performed in public databases and clinical specimens. The biological functions of YTHDF2 in DLBCL were determined in vivo and in vitro through overexpression and CRISPR/Cas9-mediated knockout of YTHDF2. RNA sequencing, lipidomics, methylated RNA immunoprecipitation sequencing, RNA immunoprecipitation-qPCR, luciferase activity assay, and RNA stability experiments were used to explore the potential mechanism by which YTHDF2 contributed to DLBCL progression. ResultsYTHDF2 was highly expressed in DLBCL, and related to poor prognosis. YTHDF2 overexpression exerted a tumor-promoting effect in DLBCL, and knockdown of YTHDF2 restricted DLBCL cell proliferation, arrested cell cycle in the G2/M phase, facilitated apoptosis, and enhanced drug sensitivity to ibrutinib and venetoclax. In addition, YTHDF2 knockout drastically suppressed tumor growth in xenograft DLBCL models. Furthermore, a regulatory role of YTHDF2 in ceramide metabolism was identified in DLBCL cells. Exogenous ceramide effectively inhibited the malignant phenotype of DLBCL cells in vitro. The binding of YTHDF2 to m6A sites on alkaline ceramidase 2 (ACER2) mRNA promoted its stability and expression. Enhanced ACER2 expression hydrolyzed ceramides, disrupting the balance between ceramide and sphingosine-1-phosphate (S1P), activating the ERK and PI3K/AKT pathways, and leading to DLBCL tumorigenesis. ConclusionThis study demonstrated that YTHDF2 contributed to the progression of DLBCL by regulating ACER2-mediated ceramide metabolism in an m6A-dependent manner, providing novel insights into targeted therapies.

HK2 contributes to the proliferation, migration, and invasion of diffuse large B-cell lymphoma cells by enhancing the ERK1/2 signaling pathway.

Hexokinase 2 (HK2) has been associated with carcinogenic growth in numerous kinds of malignancies as essential regulators during the processing of glucose. This study aimed to explore the effects of HK2 on diffuse large B-cell lymphoma (DLBCL) cells via the ERK1/2 signaling. Expressions of HK2 and ERK1/2 were examined in DLBCL cell lines using quantitative reverse transcription polymerase chain reaction and western blotting. HK2 and ERK1/2 were attenuated through HK2 small-interfering RNA (siRNA) and ERK inhibitor FR180204, respectively, in U2932 and SU-DHL-4 cells. Cell Counting Kit-8, clone formation, transwell, and flow cytometry assays were used in evaluating the effects of HK2 and ERK1/2 on cell proliferation, migration, and apoptosis. Moreover, a xenograft model was created to assess the roles of HK2 in vivo. HK2 and ERK1/2 were evidently up-regulated in DLBCL cell lines. HK2 knockdown and FR180204 markedly suppressed the proliferation and clonogenesis of U2932 and SU-DHL-4 cells and promoted cell apoptosis in vitro. We also found that HK2 silencing suppressed tumor growth in vivo. Notably, HK2 knockdown inactivated the ERK1/2 signaling pathway both in vitro and in vivo. These data indicate that inhibition of HK2 may suppress the proliferation, migration, and invasion of DLBCL cells, partly via inhibiting the ERK1/2 signaling pathway.

Determination and mechanism of Xiao-Ai Jie-Du decoction against diffuse large B-cell lymphoma: In silico and In vitro studies

Ethnopharmacological relevanceXiao-Ai Jie-Du decoction (XAJDD) has been used in clinical practice to treat diffuse large B-cell lymphoma (DLBCL); its prescriptions vary based on the pathogenesis of patients. Aim of the studyWe aimed to determine the core formula of XAJDD and investigate its mechanism of action against DLBCL. Materials and methodsApriori data mining of 187 clinical cases (including 421 Traditional Chinese Medicines, TCMs) was conducted to retrieve the core formula of XAJDD. Comprehensive in silico modeling was used to identify potential active components and corresponding targets. The potential targets of 16 compounds were identified based on network pharmacology using in silico modeling. Thereafter, experimental determination of the active compounds and their mechanism of action in treating DLBCL was performed using different assays (including CCK-8, Annexin V-FITC/PI double-staining, Western blot, and flow cytometry assays). ResultsThe core formula of XAJDD included six herbs: Astragalus mongholicus Bunge (Huangqi, family: Fabaceae), Scutellaria barbata D. Don (Banzhilian, family: Lamiaceae), Prunella vulgaris L. (Xiakucao, family: Lamiaceae), Smilax glabra Roxb. (Tufuling, family Smilacaceae) and Fritillaria thunbergii Miq. (Dabei, family: Liliaceae), and Curcuma zanthorrhiza Roxb. (Ezhu, family: Zingiberaceae); Databases including 62 druggable compounds and 38 DLBCL-related structural targets were constructed; ∼0.3 million data points produced by computational modeling based on potential compounds and targets six components from XAJDD, including astibin, folic acid, baicalin, kaempferol, quercetin, and luteolin, significantly inhibited DLBCL cell proliferation, induced apoptosis, and suppressed the expression of key oncogenes. ConclusionThis study provides an integrated strategy for determining the core formula of XAJDD and reveals the molecular mechanisms underlying the treatment of DLBCL, which were consistent with the principle of "monarch (Jun), minister (Chen), adjunctive (Zuo), and guide (Shi)", confirming that XAJDD may serve as a promising natural therapeutic agent against DLBCL.

PAQR3 facilitates the ferroptosis of diffuse large B-cell lymphoma via the regulation of LDLR-mediated PI3K/AKT pathway.

Progesterone and adiponectin receptor 3 (PAQR3) has been found to regulate tumor progression by mediating cell ferroptosis. However, whether PAQR3 mediates ferroptosis in diffuse large B-cell lymphoma (DLBCL) needs further investigation. The mRNA and protein levels of PAQR3 and low-density lipoprotein receptor (LDLR) were assessed by qRT-PCR and WB assays. Cell proliferation was detected by MTT assay and EdU assay. Shrunken mitochondria was counted under transmission electron microscope. Cell ferroptosis was evaluated by measuring the levels of malondialdehyde, reactive oxygen species, glutathione, Fe2+ , and the protein expression of ferroptosis-related markers. PAQR3 and LDLR interaction was confirmed by RIP assay and pull-down assay. Our study showed that PAQR3 was underexpressed, while LDLR was overexpressed in DLBCL tissues and cells. Functionally, PAQR3 overexpression or LDLR knockdown restrained DLBCL cell proliferation and enhanced ferroptosis. Mechanistically, PAQR3 reduced LDLR expression by inhibiting its mRNA stability. Meanwhile, LDLR overexpression reversed PAQR3-mediated the promoting on DLBCL cell ferroptosis, and LY294002 (PI3K/AKT inhibitor) eliminated the inhibiting effects of LDLR overexpression on DLBCL cell ferroptosis. Additionally, excessive PAQR3 reduced DLBCL tumor growth by enhancing tumor cell ferroptosis through LDLR-mediated PI3K/AKT pathway. In conclusion, our data suggested that PAQR3 restrained DLBCL progression by aggravating ferroptosis, which was achieved by inhibiting LDLR expression to repress PI3K/AKT pathway.

Hypomethylating agent decitabine sensitizes diffuse large B-cell lymphoma to venetoclax.

Despite recent advances in the therapy of diffuse large B-cell lymphoma (DLBCL), many patients are still not cured. Therefore, new therapeutic strategies are needed. The anti-apoptotic B-cell lymphoma 2 (BCL2) gene is commonly dysregulated in DLBCL due to various mechanisms such as chromosomal translocation t(14;18)(q32;q21) and copy number alterations; however, targeting BCL-2 with the selective inhibitor, venetoclax, led to response in only a minority of patients. Thus, we sought to identify a rational combination partner of venetoclax to improve its activity against DLBCL cells. Utilizing a functional assay, dynamic BH3 profiling, we found that the DNA hypomethylating agent decitabine increased mitochondrial apoptotic priming and BCL-2 dependence in DLBCL cells. RNA-sequencing analysis revealed that decitabine suppressed the pro-survival PI3K-AKT pathway and altered the mitochondria membrane composition in DLBCL cell lines. Additionally, it induced a DNA damage response and increased BAX and BAK activities. The combination of decitabine and venetoclax synergistically suppressed proliferation of DLBCL cells both in vitro and in vivo in a DLBCL cell line-derived xenograft mouse model. Our study suggests that decitabine plus venetoclax is a promising combination to explore clinically in DLBCL.