Antitumor effects of rafoxanide in diffuse large B cell lymphoma via the PTEN/PI3K/Akt and JNK/c-Jun pathways

AIMS

Diffuse large B-cell lymphoma (DLBCL) is one of the most aggressive lymphoid malignancies, which remains incurable, thus warranting the development of new therapies. Our previous study determined that rafoxanide is very effective in treating multiple myeloma (MM). In the present study, we tried to evaluate the effects of rafoxanide on DLBCL, as well as the potential underlying molecular mechanisms.

MAIN METHODS

We used CCK-8 assay and flow cytometry to assess cell viability and apoptosis. The proteins and pathways associated with apoptosis and proliferation were evaluated through western blot, and xenograft mice were used as the experimental animal model. We also used the TUNEL assay and immunofluorescence for further analyses.

KEY FINDINGS

Treatment with different doses of rafoxanide significantly inhibited cell viability and apoptosis. Additionally, the compound induced cell cycle arrest, reduced mitochondrial membrane potential (Δψm), and stimulated reactive oxygen species (ROS) generation without the influence of normal peripheral blood monocytes (PBMCs). As expected, rafoxanide played a role in regulating these proteins and the PTEN/PI3K/AKT and JNK/c-Jun pathways. Furthermore, immunofluorescence and western blot results showed that rafoxanide upregulated H2AX phosphorylation and then inhibited DNA repair in DLBCL. In the xenograft mouse model, tumor volumes were reduced after intraperitoneal injection with rafoxanide. We also observed that TUNEL positive cells were remarkably increased in rafoxanide-treated tumor tissues.

SIGNIFICANCE

These results collectively provide a novel choice to regular treatment for DLBCL patients with poor prognosis.

Heterogeneous Pattern of Dependence on Anti-Apoptotic BCL-2 Family Proteins upon CHOP Treatment in Diffuse Large B-Cell Lymphoma

Expression of the anti-apoptotic B-cell lymphoma 2 (BCL-2) protein in patients with diffuse large B-cell lymphoma (DLBCL) strongly correlates with resistance to standard therapy with cyclophosphamide, vincristine, doxorubicin, prednisolone, and rituximab (R-CHOP). Although studies focus mainly on the contribution of BCL-2, here we also investigate the contribution of other anti-apoptotic proteins to CHOP-therapy resistance in DLBCL. Functional dynamic BCL-2 homology (BH)3 profiling was applied to DLBCL cell lines upon CHOP treatment or single CHOP compounds. Cell-specific anti-apoptotic dependencies were validated with corresponding BH3-mimetics. We found high expression of anti-apoptotic BCL-2, MCL-1, and BCL-XL in DLBCL cell lines and patients. CHOP treatment resulted in both enhanced and altered anti-apoptotic dependency. Enhanced sensitivity to different BH3-mimetics after CHOP treatment was confirmed in specific cell lines, indicating heterogeneity of CHOP-induced resistance in DLBCL. Analysis of single CHOP compounds demonstrated that similar changes could also be induced by doxorubicin or vincristine, providing evidence for clinical combination therapies of doxorubicin or vincristine with BH3-mimetics in DLBCL. In conclusion, we show for the first time that CHOP treatment induces increased anti-apoptotic dependency on MCL-1 and BCL-XL, and not just BCL-2. These results provide new perspectives for the treatment of CHOP-resistant DLBCL and underline the potential of BH3 profiling in predicting therapy outcomes.

STAT3 Activation Is Associated with Interleukin-10 Expression and Survival in Primary Central Nervous System Lymphoma

BACKGROUND

The findings from several studies have confirmed that signal transducer and activator of transcription 3 (STAT3) is constitutively phosphorylated in primary central nervous system lymphoma (PCNSL). However, the underlying mechanism and prognostic significance of STAT3 activation have not yet been clarified.

METHODS

The expression of STAT3, phosphorylated STAT3 (p-STAT3), and interleukin (IL)-10 was examined in 32 PCNSL samples using immunohistochemistry. The relationship between IL-10 expression and STAT3 phosphorylation was determined. In addition, the associations of the expression of these proteins with the clinical factors and survival were analyzed.

RESULTS

Expression of STAT3, p-STAT3, and IL-10 was detected in 28 (87.5%), 17 (53.1%), and 25 (78.1%) samples, respectively. IL-10 expression was significantly associated with STAT3 phosphorylation in PCNSL (P = 0.033). STAT3 phosphorylation and IL-10 expression were associated with the presence of multiple brain lesions (P = 0.004 and P = 0.027, respectively), suggesting that STAT3 activation might enhance the intracranial spread of tumors in PCNSL. The 2-year overall survival and progression-free survival (PFS) rates were 67.8% and 35.5%, respectively. Kaplan-Meier survival analysis demonstrated that STAT3 phosphorylation, IL-10 expression, and multiple brain lesions were significantly associated with PFS in those with PCNSL (P = 0.009, P = 0.030, and P = 0.040, respectively). However, Cox regression analysis indicated that only STAT3 phosphorylation was significantly associated with shorter PFS (hazard ratio, 3.22; 95% confidence interval, 1.24-8.37; P = 0.016).

CONCLUSION

Our results have indicated that STAT3 activation is closely related to IL-10 expression and that p-STAT3 might be a novel biomarker predictive of poor survival in those with PCNSL.

Immunohistochemical overexpression of BCL-2 protein predicts an inferior survival in patients with primary central nervous system diffuse large B-cell lymphoma

This study was designed to analyze the clinical characteristics and prognostic value of c-MYC and BCL-2 proteins expression in patients with primary central nervous system diffuse large B-cell lymphoma (PCNS-DLBCL).82 patients newly diagnosed with PCNS-DLBCL, from January 2008 to November 2018, were enrolled in this study. Clinical characteristics, immunohistochemical features, laboratory examinations, and treatment outcome were analyzed among these patients.Among these 82 cases, 45 were males (54.9%) and 37 were females (45.1%). Age ranged from 16 to 78 years old, and 29 patients (35.4%) were elder than 60 years old, with median age at 57 years old. According to Hans classification, 25 were accounted for origin of germinal center B-cell (GCB) subtype (30.5%) and 49 were accounted for non-GCB subtype (59.8%), respectively. Eight patients were unclassified due to lack of detailed pathological results. The median survival of these 82 patients was 30 months, and 1-year, 3-year, and 5-year overall survival (OS) rate was 59.7%, 44.6%, and 34.1%, respectively. Patients treated with sequential HD-MTX based chemotherapies showed a superior prognosis than those without. In combination with rituximab, the outcome was further improved. The median OS was 55 months in HD-MTX + R group, 27 months in HD-MTX group, and 9 months in other groups, respectively. Univariate analysis identified age ≥60, ECOG score ≥ 2 points, and overexpression of BCL-2 protein (≥85%) were adverse prognostic factors for OS. Co-expression of c-MYC (≥40%) and BCL-2 (≥50%) proteins was associated with poor ECOG score, high Ki-67 expression, and trended towards an inferior outcome. Gender, lesion location, number of lesions, lactic dehydrogenase (LDH), cell of origin, BCL-6 protein expression, expression of c-MYC protein alone and Ki-67 ≥85% had no significant impact on OS.In patients with PCNS-DLBCL, age ≥60 years old, ECOG score ≥2 points, and overexpression of BCL-2 protein (≥85%) were associated with a poor survival. HD-MTX based chemotherapies in combination with rituximab could improve the prognosis.

Classifying DLBCL Subtypes for Optimal Treatment

DLBCL is the most common subtype of non-Hodgkin lymphoma, representing about 30% to 40% of cases. Patients are typically diagnosed with an excisional lymph node biopsy or a biopsy of another affected organ. When pathologists look under the microscope, they can see a diffused proliferation of large neoplastic B cells. These B cells are identified by flow cytometry or immunohistochemistry that identifies pan-B-cell antigens such as CD19, CD20, and CD79a, as well as CD45. DLBCL is known to be an aggressive lymphoma, but it is also known to be both clinically and molecularly heterogeneous.[1] Patients can have a range of clinical presentations, with disease of only one lymph node to more advanced-stage disease with extranodal sites of involvement. Just like patients can have a range of clinical presentations, outcomes can also be extremely variable, with approximately 60% of patients being cured with frontline chemotherapy. The remaining patients with refractory or relapsed disease have much poorer outcomes.

The CXCR4-CXCL12-Axis Is of Prognostic Relevance in DLBCL and Its Antagonists Exert Pro-Apoptotic Effects In Vitro

In tumor cells of more than 20 different cancer types, the CXCR4-CXCL12-axis is involved in multiple key processes including proliferation, survival, migration, invasion, and metastasis. Since data on this axis in diffuse large B cell lymphoma (DLBCL) are inconsistent and limited, we comprehensively studied the CXCR4-CXCL12-axis in our DLBCL cohort as well as the effects of CXCR4 antagonists on lymphoma cell lines in vitro. In DLBCL, we observed a 140-fold higher CXCR4 expression compared to non-neoplastic controls, which was associated with poor clinical outcome. In corresponding bone marrow biopsies, we observed a correlation of CXCL12 expression and lymphoma infiltration rate as well as a reduction of CXCR4 expression in remission of bone marrow involvement after treatment. Additionally, we investigated the effects of three CXCR4 antagonists in vitro. Therefore, we used AMD3100 (Plerixafor), AMD070 (Mavorixafor), and WKI, the niacin derivative of AMD070, which we synthesized. WK1 demonstrated stronger pro-apoptotic effects than AMD070 in vitro and induced expression of pro-apoptotic genes of the BCL2-family in CXCR4-positive lymphoma cell lines. Finally, WK1 treatment resulted in the reduced expression of JNK-, ERK1/2- and NF-κB/BCR-target genes. These data indicate that the CXCR4-CXCL12-axis impacts the pathogenesis of DLBCL and represents a potential therapeutic target in aggressive lymphomas.

Repurposing dasatinib for diffuse large B cell lymphoma

To repurpose compounds for diffuse large B cell lymphoma (DLBCL), we screened a library of drugs and other targeted compounds approved by the US Food and Drug Administration on 9 cell lines and validated the results on a panel of 32 genetically characterized DLBCL cell lines. Dasatinib, a multikinase inhibitor, was effective against 50% of DLBCL cell lines, as well as against in vivo xenografts. Dasatinib was more broadly active than the Bruton kinase inhibitor ibrutinib and overcame ibrutinib resistance. Tumors exhibiting dasatinib resistance were commonly characterized by activation of the PI3K pathway and loss of PTEN expression as a specific biomarker. PI3K suppression by mTORC2 inhibition synergized with dasatinib and abolished resistance in vitro and in vivo. These results provide a proof of concept for the repurposing approach in DLBCL, and point to dasatinib as an attractive strategy for further clinical development in lymphomas.

A Pooled Analysis of The Clinical Utilities of Long Non-Coding RNA Based Molecular Signature for Diffuse Large B Cell Lymphoma

BACKGROUND

Long non-coding RNAs (lncRNAs) have been highlighted as promising biomarkers for several types of malignancies. The current meta-analysis sought to investigate the clinical value of lncRNA-based molecular signatures as biomarkers for diagnosis, subtype classification, and prognosis in diffuse large B cell lymphoma (DLBCL).

METHODS

A systematic search of the online databases was carried out and data were retrieved by pairs of independent reviewers. Effect sizes of the diagnostic parameters were combined using a quantitative meta-analysis. In the prognostic analysis, hazard ratio (HR) with 95% confidence interval (CI) for the primary endpoints of overall survival (OS) and progression-free survival (PFS) were meta-analyzed.

RESULTS

Our data exhibited that lncRNA expression profiling harvested a pooled sensitivity of 0.87 (95% CI: 0.78 - 0.92), specificity of 0.84 (95% CI: 0.75 - 0.90), and AUC of 0.92 in distinguishing DLBCL cases from cancer-free participants. For subtype classification, lncRNA signature could discriminate germinal center B-cell-like (GCB) and activated B-cell-like (ABC) DLBCL cases with an estimated sensitivity of 0.92 (95% CI: 0.89 - 0.95), specificity of 0.89 (95% CI: 0.83 - 0.93) and AUC of 0.96. Prognostic analysis manifested that altered lncRNA profiles predicted unfavorable clinical outcomes of DLBCL in OS (univariate analysis: HR = 1.45, 95% CI: 1.14 - 1.83, p < 0.001). Further subgroup study stratified by clinicopathological features revealed that the LDH level, IPI score, subtype, and testing pattern of lncRNAs were markedly correlated with the OS in DLBCL.

CONCLUSIONS

Collectively, our data uncover that lncRNA expression profiling retains a relatively high accuracy in the diagnosis and classification of DLBCL. Altered levels of lncRNAs are also closely associated with worse OS and appeared to be powerful predictors in forecasting prognosis in DLBCL.

Clinicopathological characteristics of diffuse large B-cell lymphoma involving small and large intestines: an analysis of 126 patients

We analyzed the clinicopathologic characteristics of 136 intestinal diffuse large B-cell lymphomas (DLBCLs) among 126 patients. The DLBCL sites were categorized as: duodenum (n = 23), ileocecal region (n = 63), other small intestine (n = 29), rectum (n = 7), and other large intestine (n = 14). Patients with DLBCLs of the ileocecal region or other small intestine frequently underwent surgery for ileus or perforations (P < 0.001), were predominantly male (P = 0.042), and had a higher incidence of limited-stage disease (P = 0.001), lower International Prognostic Index (P = 0.015), and lower incidence of lactate dehydrogenase elevation (P = 0.007) than those with DLBCLs of other regions. Half of the intestinal DLBCLs exhibited the germinal center B-cell phenotype. A low-grade B-cell lymphoma background was found in 21% of the cases; the prevalence was significantly lower in the ileocecal region (13%, P = 0.025), suggesting a higher incidence of de novo DLBCLs. Intestinal follicular lymphoma (FL) and mucosa-associated lymphoid tissue (MALT) lymphoma backgrounds were observed in 10% and 0% of the cases, respectively. Five percent (5/107) of intestinal DLBCL cases were Epstein-Barr virus-encoded RNA-1 positive. The clinicopathologic characteristics of the DLBCLs differed by region. Histologic transformation of intestinal FL was observed in around 10% of the intestinal DLBCL cases.

The utility of CD83, fascin and CD23 in the differential diagnosis of primary mediastinal large B-cell lymphoma versus classic Hodgkin lymphoma

Primary mediastinal large B-cell lymphoma (PMBL) and classic Hodgkin lymphoma (CHL) are the most common large cell lymphomas arising in the mediastinum and are thought to be closely related histogenetically. Although the distinction between PMBL and CHL is usually straightforward, in some cases it is challenging and rarely these neoplasms have intermediate features and qualify for the diagnosis of mediastinal gray zone lymphoma (GZL). CD83 and fascin are markers of CHL and CD23 is a marker of PMBL. In this study we assess the utility of this combination of these immunohistochemical markers to distinguish CHL from PMBL. We retrospectively collected cases of PMBL, CHL and GZL from three centers. Tissue sections were stained with CD83, fascin and CD23. CD83 was expressed in the neoplastic cells of 100% of CHL (22/22), 93% of GZL (16/18) and 41% of PMBL (9/22). Similarly, fascin was positive in the neoplastic cells of 100% of CHL (22/22), 86% of GZL (18/21) and 32% of PMBL (7/22). CD23 was positive in 95% of PMBL (21/22), 67% of GZL (12/18) and 9% of CHL (2/22). CD83 and fascin are sensitive markers for CHL but not specific whereas CD23 is sensitive for PMBL and uncommon in CHL. The GZL cases in this study had an intermediate immunophenotype, but the results were closer to CHL than PMBL. A large panel of immunohistochemical studies is recommended to distinguish CHL from PMBL entities and we suggest that CD83, fascin and CD23 add value to panels designed for this differential diagnosis.

Regulation of S1PR2 by the EBV oncogene LMP1 in aggressive ABC-subtype diffuse large B-cell lymphoma

The Epstein-Barr virus (EBV) is found almost exclusively in the activated B-cell (ABC) subtype of diffuse large B-cell lymphoma (DLBCL), yet its contribution to this tumour remains poorly understood. We have focused on the EBV-encoded latent membrane protein-1 (LMP1), a constitutively activated CD40 homologue expressed in almost all EBV-positive DLBCLs and which can disrupt germinal centre (GC) formation and drive lymphomagenesis in mice. Comparison of the transcriptional changes that follow LMP1 expression with those that follow transient CD40 signalling in human GC B cells enabled us to define pathogenic targets of LMP1 aberrantly expressed in ABC-DLBCL. These included the down-regulation of S1PR2, a sphingosine-1-phosphate (S1P) receptor that is transcriptionally down-regulated in ABC-DLBCL, and when genetically ablated leads to DLBCL in mice. Consistent with this, we found that LMP1-expressing primary ABC-DLBCLs were significantly more likely to lack S1PR2 expression than were LMP1-negative tumours. Furthermore, we showed that the down-regulation of S1PR2 by LMP1 drives a signalling loop leading to constitutive activation of the phosphatidylinositol-3-kinase (PI3-K) pathway. Finally, core LMP1-PI3-K targets were enriched for lymphoma-related transcription factors and genes associated with shorter overall survival in patients with ABC-DLBCL. Our data identify a novel function for LMP1 in aggressive DLBCL. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Alternative and canonical NF-kB pathways DNA-binding hierarchies networks define Hodgkin lymphoma and Non-Hodgkin diffuse large B Cell lymphoma respectively

PURPOSE

Despite considerable evidence that supports the NF-kB role in the immune system and lymphomagenesis, it is unclear whether specific NF-kB dimers control a particular set of genes that account for their biological functions. Our previous work showed that Hodgkin Lymphoma (HL) is unique, among germinal center (GC)-derived lymphomas, with respect to its dependency on Rel-B to survive. In contrast, diffuse large B-Cell lymphoma (DLBCL) including both Activated B-Cell-Like and Germinal Center B-Cell-Like, requires cREL and Rel-A to survive and it is not affected by Rel-B depletion. These findings highlighted the activity of specific NF-kB subunits in different GC-derived lymphomas.

METHODS

Sequenced chromatin immunoprecipitated DNA fragments (ChIP-Seq) analysis revealed an extensive NF-kB DNA-binding network in DLBCL and HL. The ChIP-Seq data was merged with microarray analysis following the Rel-A, Rel-B or cRel knockdown to determine effectively regulated genes.

RESULTS

Downstream target analysis showed enrichment for cell cycle control, among other signatures. Rel-B and cRel controlled different genes within the same signature in HL and DLBCL, respectively. BCL2 was exclusively controlled by Rel-B in HL. Both mRNA and protein levels decreased following Rel-B depletion meanwhile there was no change upon cRel knock-down. BCL2 exogenous expression partially rescued the death induced by decreased Rel-B in HL cells.

CONCLUSION

The Rel-B hierarchical network defined HL and the cRel hierarchical network characterized DLBCL. Each Rel member performs specific functions in distinct GC-derived lymphomas. This result should be considered for the development of targeted therapies that are aimed to selectively inhibit individual NF-kB dimers.

C-X-C Chemokine Receptor 4 in Diffuse Large B Cell Lymphoma: Achievements and Challenges

Diffuse large B cell lymphoma (DLBCL), an aggressive cancer of the B cells, is the most common subtype of non-Hodgkin lymphoma (NHL) worldwide. In China, the cases of DLBCL increase yearly. C-X-C chemokine receptor 4 (CXCR4) has been implicated in the migration and trafficking of malignant B cells in several hematological malignancies, and only a few reports have been published on the role of CXCR4 in the metastasis of DLBCL. This review summarizes the relevant perspectives on the functional mechanism, prognostic significance, and therapeutic applications of the CXCL12/CXCR4 axis in DLBCL, in particular DLBCL with bone marrow involvement.

The prognostic and clinicopathological significance of PD-L1 expression in patients with diffuse large B-cell lymphoma: a meta-analysis

BACKGROUND

Programmed cell death receptor 1 ligand 1 (PD-L1) expression in various tumors, including hematologic malignancies, has recently become a research topic of great interest. We performed a meta-analysis to evaluate the prognostic and clinicopathological value of PD-L1 expressed in tumor cells of patients with diffuse large B-cell lymphoma (DLBCL).

METHODS

Relevant studies were identified from PubMed, EMBASE, Web of Science and the Cochrane Library. The hazard ratio (HR) and 95% confidence interval (95% CI) were used for analyzing survival outcomes, and the odds ratio (OR) was used for analyzing clinicopathological parameters.

RESULTS

Pooled results showed that tumor cell PD-L1 expression is associated with poor overall survival (OS) (HR = 2.128, 95% CI: 1.341-3.378, P = 0.001), the non-germinal center B-cell-like subtype (OR = 2.891, 95% CI: 2.087-4.003, P < 0.000), high international prognostic index score (3-5) (OR = 1.552, 95% CI: 1.111-2.169, P = 0.010), B symptoms (OR = 1.495, 95% Cl: 1.109-2.015, P = 0.008), positive MUM1 expression (OR = 3.365, 95% Cl: 1.578-7.175, P = 0.002) and negative BCL6 expression (OR = 0.414, 95% Cl: 0.217-0.792, P = 0.008). Sensitivity analysis showed that there was no publication bias among these studies.

CONCLUSIONS

Our meta-analysis supported the idea that tumor cell PD-L1 expression may represent a promising biomarker for predicting poor prognosis and is associated with adverse clinicopathologic features in DLBCL patients.

Unraveling transformation of follicular lymphoma to diffuse large B-cell lymphoma

Follicular lymphoma (FL) is an indolent but largely incurable disease. Some patients suffer histological transformation to a more aggressive subtype with poorer prognosis. This study aimed to improve our understanding of the genetics underlying FL histological transformation, and to identify genetic drivers or promoters of the transformation by elucidating the differences between FL samples from patients who did and did not transform. We conducted targeted massive parallel sequencing of 22 pre-transformed FL/transformed diffuse large B-cell lymphoma pairs and 20 diagnostic samples from non-transformed FL patients. Additionally, 22 matched samples from 11 transformed FL patients (pre-transformed FL and diffuse large B-cell lymphoma) and 9 non-transformed FLs were studied for copy number variation using SNP arrays. We identified recurrently mutated genes that were enriched at transformation, most notably LRP1B, GNA13 and POU2AF1, which have roles in B-cell differentiation, GC architecture and migration. Mutations in POU2AF1 might be associated with lower levels of expression, were more frequent in transformed FLs, and seemed to be specific to transformed- compared with de novo-diffuse large B-cell lymphomas. Pre-transformed FLs carried more mutations per sample and had greater subclonal heterogeneity than non-transformed FLs. Finally, we identified four mutated genes in FL samples that differed between patients who did and did not transform: NOTCH2, DTX1, UBE2A and HIST1H1E. The presence of mutations in these genes was associated with shorter time to transformation when mutated in the FL biopsies. This information might be useful for identifying patients at higher risk of transformation.

Clinicopathological features of HCV-positive splenic diffuse large B cell lymphoma

The hepatitis C virus (HCV) is a single-stranded RNA virus which is thought to be involved in the onset of B cell lymphoma. HCV-positive diffuse large B cell lymphoma (DLBCL) has been reported to clinically manifest in extranodal lesions (e.g., in the liver, spleen, and stomach). Here, we investigated HCV-positive and -negative primary splenic DLBCL (p-spDLBCL) and non-primary splenic DLBCL (ordinary DLBCL). Furthermore, to examine HCV lymphomagenesis, RNA in situ hybridization (ISH), RT-PCR (reverse-transcription polymerase chain reaction), and NS3 immunostaining of HCV viral nonstructural proteins were performed. HCV-positive p-spDLBCL patients presented fewer B symptoms (asymptomatic) and better performance status, with elevated presence of splenic macronodular lesions and more germinal center B cell (GCB) sub-group cases than HCV-negative p-spDLBCL patients. However, HCV-positive ordinary DLBCL patients were found to have more non-GCB sub-group cases than HCV-negative ordinary DLBCL patients. HCV-positive DLBCL patients showed 20.6% (7/34) NS3 positivity, 16.7% (1/6) HCV-RNA in situ positivity, and 22.2% (2/9) detection of HCV-RNA in tumor tissue by RT-PCR. Splenic samples were found to have a higher frequency of HCV detection than lymph node samples, thus suggesting that HCV may be closely related to lymphomagenesis, especially in splenic lymphoma.

Sleeping Beauty Screen Identifies RREB1 and Other Genetic Drivers in Human B-cell Lymphoma

Follicular lymphoma and diffuse large B-cell lymphoma (DLBCL) are the most common non-Hodgkin lymphomas distinguishable by unique mutations, chromosomal rearrangements, and gene expression patterns. Here, it is demonstrated that early B-cell progenitors express 2',3'-cyclic-nucleotide 3' phosphodiesterase (CNP) and that when targeted with Sleeping Beauty (SB) mutagenesis, Trp53R270H mutation or Pten loss gave rise to highly penetrant lymphoid diseases, predominantly follicular lymphoma and DLBCL. In efforts to identify the genetic drivers and signaling pathways that are functionally important in lymphomagenesis, SB transposon insertions were analyzed from splenomegaly specimens of SB-mutagenized mice (n = 23) and SB-mutagenized mice on a Trp53R270H background (n = 7) and identified 48 and 12 sites with statistically recurrent transposon insertion events, respectively. Comparison with human data sets revealed novel and known driver genes for B-cell development, disease, and signaling pathways: PI3K-AKT-mTOR, MAPK, NFκB, and B-cell receptor (BCR). Finally, functional data indicate that modulating Ras-responsive element-binding protein 1 (RREB1) expression in human DLBCL cell lines in vitro alters KRAS expression, signaling, and proliferation; thus, suggesting that this proto-oncogene is a common mechanism of RAS/MAPK hyperactivation in human DLBCL. IMPLICATIONS: A forward genetic screen identified new genetic drivers of human B-cell lymphoma and uncovered a RAS/MAPK-activating mechanism not previously appreciated in human lymphoid disease. Overall, these data support targeting the RAS/MAPK pathway as a viable therapeutic target in a subset of human patients with DLBCL.

Molecular High-Grade B-Cell Lymphoma: Defining a Poor-Risk Group That Requires Different Approaches to Therapy

PURPOSE

Biologic heterogeneity is a feature of diffuse large B-cell lymphoma (DLBCL), and the existence of a subgroup with poor prognosis and phenotypic proximity to Burkitt lymphoma is well known. Conventional cytogenetics identifies some patients with rearrangements of MYC and BCL2 and/or BCL6 (double-hit lymphomas) who are increasingly treated with more intensive chemotherapy, but a more biologically coherent and clinically useful definition of this group is required.

PATIENTS AND METHODS

We defined a molecular high-grade (MHG) group by applying a gene expression-based classifier to 928 patients with DLBCL from a clinical trial that investigated the addition of bortezomib to standard rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) therapy. The prognostic significance of MHG was compared with existing biomarkers. We performed targeted sequencing of 70 genes in 400 patients and explored molecular pathology using gene expression signature databases. Findings were validated in an independent data set.

RESULTS

The MHG group comprised 83 patients (9%), with 75 in the cell-of-origin germinal center B-cell-like group. MYC rearranged and double-hit groups were strongly over-represented in MHG but comprised only one half of the total. Gene expression analysis revealed a proliferative phenotype with a relationship to centroblasts. Progression-free survival rate at 36 months after R-CHOP in the MHG group was 37% (95% CI, 24% to 55%) compared with 72% (95% CI, 68% to 77%) for others, and an analysis of treatment effects suggested a possible positive effect of bortezomib. Double-hit lymphomas lacking the MHG signature showed no evidence of worse outcome than other germinal center B-cell-like cases.

CONCLUSION

MHG defines a biologically coherent high-grade B-cell lymphoma group with distinct molecular features and clinical outcomes that effectively doubles the size of the poor-prognosis, double-hit group. Patients with MHG may benefit from intensified chemotherapy or novel targeted therapies.

Prognostic value of baseline metabolic tumor volume and total lesion glycolysis in patients with lymphoma: A meta-analysis

Whether baseline metabolic tumor volume (TMTV) and total lesion glycolysis (TLG) measured by FDG-PET/CT affected prognosis of patients with lymphoma was controversial. We searched PubMed, EMBASE and Cochrane to identify studies assessing the effect of baseline TMTV and TLG on the survival of lymphoma patients. Pooled hazard ratios (HR) for overall survival (OS) and progression-free survival (PFS) were calculated, along with 95% confidence intervals (CI). Twenty-seven eligible studies including 2,729 patients were analysed. Patients with high baseline TMTV showed a worse prognosis with an HR of 3.05 (95% CI 2.55–3.64, p<0.00001) for PFS and an HR of 3.07 (95% CI 2.47–3.82, p<0.00001) for OS. Patients with high baseline TLG also showed a worse prognosis with an HR of 3.44 (95% CI 2.37–5.01, p<0.00001) for PFS and an HR of 3.08 (95% CI 1.84–5.16, p<0.00001) for OS. A high baseline TMTV was significantly associated with worse survival in DLBCL patients treated with R-CHOP (OS, pooled HR = 3.52; PFS, pooled HR = 2.93). A high baseline TLG was significantly associated with worse survival in DLBCL patients treated with R-CHOP (OS, pooled HR = 3.06; PFS, pooled HR = 2.93). The negative effect of high baseline TMTV on PFS was demonstrated in HL (pooled HR = 3.89). A high baseline TMTV was significantly associated with worse survival in ENKL patients (OS, pooled HR = 2.24; PFS, pooled HR = 3.25). A high baseline TLG was significantly associated with worse survival in ENKL patients (OS, pooled HR = 2.58; PFS, pooled HR = 2.99). High baseline TMTV or TLG predict significantly worse PFS and OS in patients with lymphoma. Future studies are warranted to explore whether TMTV or TLG could be integrated into various prognostic models for clinical decision making.

Overexpression of miR-222-3p Promotes the Proliferation and Inhibits the Apoptosis of Diffuse Large B-Cell Lymphoma Cells via Suppressing PPP2R2A

PURPOSE

This study aimed to investigate the effects of microRNA-222-3p on activated B cell-like-type diffuse large B-cell lymphoma cells and the regulatory relationship between microRNA-222-3p and phosphatase 2 regulatory subunit B alpha.

METHOD

The expression of microRNA-222-3p was detected in activated B cell-like-type diffuse large B-cell lymphoma tissues and cells by quantitative reverse transcription polymerase chain reaction. The regulatory effects of microRNA-222-3p on the proliferation, invasion, and apoptosis of activated B cell-like-type diffuse large B-cell lymphoma cells were analyzed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT), colony formation, flow cytometry, and Transwell assay. The regulatory relationship between microRNA-222-3p and phosphatase 2 regulatory subunit B alpha was determined by luciferase reporter gene and RNA pull-down assay. In addition, the effects of microRNA-222-3p on tumor growth were further analyzed in mice.

RESULTS

MicroRNA-222-3p and phosphatase 2 regulatory subunit B alpha were significantly up- and downregulated in activated B cell-like-type diffuse large B-cell lymphoma tissues and cells, respectively. Phosphatase 2 regulatory subunit B alpha was a target of microRNA-222-3p. MicroRNA-222-3p promoted the proliferation and invasion and inhibited the apoptosis of activated B cell-like-type diffuse large B-cell lymphoma cells. Phosphatase 2 regulatory subunit B alpha reversed the tumor-promoting effects of microRNA-222-3p on activated B cell-like-type diffuse large B-cell lymphoma cells. In addition, microRNA-222-3p promoted the tumor growth in mice and downregulated phosphatase 2 regulatory subunit B alpha in tumor tissues.

CONCLUSION

MicroRNA-222-3p promoted the proliferation and invasion and inhibited the apoptosis of activated B cell-like-type diffuse large B-cell lymphoma cells through suppressing phosphatase 2 regulatory subunit B alpha expression.

A Preliminary Study on Metadherin as a Potential Marker for Progression of Diffuse Large B Cell Lymphoma

AIMS

To determine if Metadherin (MTDH) expression levels are positively correlated with the clinical stage of diffuse large B-cell lymphoma (DLBCL) based on MTDH being highly expressed in other type of tumors including melanoma, malignant glioma, breast cancer, and hepatocellular carcinoma. In this study, we investigated the pathologic significance of MTDH and its potential in predicting DLBCL outcomes.

MATERIALS AND METHODS

Tissue samples from 50 patients with DLBCL and 22 patients with lymph node reactive hyperplasia were collected and evaluated using immunohistochemical staining, microscopy, and western blotting. The Kaplan-Meier method and Cox regression model were used for survival analysis of patients.

RESULTS

Our results show that the overexpression of the MTDH protein in tissues was observed in 66% of patients with DLBCL, whereas it was not overexpressed in the patients with reactive hyperplastic lymph nodes. While there was no correlation between MTDH overexpression with age, sex, presence of B symptoms, and lactate dehydrogenase (LDH) levels in patients with DLBCL, this parameter was positively correlated with clinical stages. Moreover, MTDH-negative patients had significantly better prognoses compared with the MTDH-positive patients.

CONCLUSION

Our preliminary study indicates that MTDH may play an important role in the development of DLBCL, and that MTDH overexpression is potentially associated with the clinical progression of DLBCL. In addition, high expression levels of MTDH in tissues was correlated with a poorer prognosis for patients with DLBCL. As such, MTDH may be a potential therapeutic target for specific therapy. However, research on a larger group of patients is needed to verify these preliminary results.