Clinical significance of chemokine receptor CXCR4 and mammalian target of rapamycin (mTOR) expression in patients with diffuse large B-cell lymphoma

Recent advances in CD5+ diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL), the most common non-Hodgkin's lymphoma (NHL), is substantially heterogeneous. Approximately 5-10% of DLBCLs express CD5, which makes CD5+ DLBCL a rare subgroup. Different studies have shown that CD5+ DLBCL patients are often older and female and have higher lactate dehydrogenase levels, an Eastern Cooperative Oncology Group (ECOG) performance status > 1, and higher International Prognostic Index (IPI) scores. Moreover, patients often have advanced stage disease with a high incidence of central nervous system (CNS) relapse and bone marrow involvement. CD5+ DLBCL cells are more likely to express MYC, BCL-2, and MUM-1, less likely to express CD10, and most belong to the activated B-cell-like (ABC) subtype. The potential mechanisms underlying the poor prognosis of CD5+ DLBCL patients may be related to CD5-mediated B-cell receptor (BCR)-dependent and -independent pathways. The efficacy of the traditional rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) regimen is unsatisfactory in CD5+ DLBCL patients. Despite supporting evidence from retrospective studies, it is currently unclear whether dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin plus rituximab (DA-EPOCH-R) can improve outcomes in this population. Several new drugs, such as Bruton tyrosine kinase inhibitors (BTKi), BCL-2 inhibitors, and CXCR4 antagonists, as well as immunotherapy, may help to improve the prognosis of CD5+ DLBCL patients, but additional clinical explorations are needed to determine the optimal therapeutic strategy for this disease.

A novel anoikis-related signature predicts prognosis risk and treatment responsiveness in diffuse large B-cell lymphoma

BACKGROUND

Although anoikis plays a role in cancer metastasis and aggressiveness, it has rarely been reported in diffuse large B cell lymphoma (DLBCL).

METHODS

We obtained RNA sequencing data and matched clinical data from the GEO database. An anoikis-related genes (ARGs)-based risk signature was developed in GSE10846 training cohort and validated in three other cohorts. Additionally, we predicted half-maximal inhibitory concentration (IC50) of drugs based on bioinformatics method and obtained the actual IC50 to some chemotherapy drugs via cytotoxicity assay.

RESULTS

The high-risk group, as determined by our signature, was associated with worse prognosis and an immunosuppressive environment in DLBCL. Meanwhile, the nomogram based on eight variables had more accurate ability in forecasting the prognosis than the international prognostic index in DLBCL. The prediction of IC50 indicated that DLBCL patients in the high-risk group were more sensitive to doxorubicin, IPA-3, lenalidomide, gemcitabine, and CEP.701, while patients in the low-risk group were sensitive to cisplatin and dasatinib. Consistent with the prediction, cytotoxicity assay suggested the higher sensitivity to doxorubicin and gemcitabine and the lower sensitivity to dasatinib in the high-risk group in DLBCL.

CONCLUSION

The ARG-based signature may provide a promising direction for prognosis prediction and treatment optimization for DLBCL patients.

Binding site hotspot map of PI3Kα and mTOR in the presence of selective and dual ATP-competitive inhibitors

The PI3K/Akt/mTOR signaling pathway plays a pivotal role in cellular metabolism, growth and survival. PI3Kα hyperactivation impairs downstream signaling, including mTOR regulation, and are linked to poor prognosis and refractory cancer treatment. To support multi-target drug discovery, we took advantage from existing PI3Kα and mTOR crystallographic structures to map similarities and differences in their ATP-binding pockets in the presence of selective or dual inhibitors. Molecular dynamics and MM/PBSA calculations were employed to study the binding profile and identify the relative contribution of binding site residues. Our analysis showed that while varying parameters of solute and solvent dielectric constant interfered in the absolute binding free energy, it had no effect in the relative per residue contribution. In all complexes, the most important interactions were observed within 3-3.5 Å from inhibitors, responding for ∼75-100% of the total calculated interaction energy. While closest residues are essential for the strength of the binding of all ligands, more distant residues seem to have a larger impact on the binding of the dual inhibitor, as observed for PI3Kα residues Phe934, Lys802 and Asp805 and, mTOR residues Leu2192, Phe2358, Leu2354, Lys2187 and Tyr2225. A detailed description of individual residue contribution in the presence of selective or dual inhibitors is provided as an effort to improve the understanding of molecular mechanisms controlling multi-target inhibition. This work provides key information to support further studies seeking the rational design of potent PI3K/mTOR dual inhibitors for cancer treatment.Communicated by Ramaswamy H. Sarma.

CD5+ diffuse large B-cell lymphoma has heterogeneous clinical features and poor prognosis: a single-center retrospective study in China

Objective

De novo CD5-positive (CD5+) diffuse large B-cell lymphoma (DLBCL) has different clinical characteristics compared with CD5-negative (CD5−) DLBCL. However, few studies have been reported in Chinese cohorts. We investigated the clinical features and prognosis of patients with CD5+ DLBCL and summarized the related literature.

Methods

Data from 245 patients with newly diagnosed DLBCL were retrospectively assessed.

Results

Thirty-one and 214 patients were diagnosed with CD5+ DLBCL or CD5− DLBCL, respectively. In the CD5+ DLBCL group, there were significantly higher proportions of patients with older age (≥60 years), International Prognostic Index (IPI) ≥3, Eastern Cooperative Oncology Group (ECOG) scores ≥ 2, bone marrow involvement, positive B-cell lymphoma 2 expression, and positive MYC expression. Survival analysis showed that CD5+ DLBCL had a markedly poorer 2-year progression-free survival than CD5− DLBCL (18.2% vs. 56.2%). Univariate analysis indicated that age ≥60 years, ECOG score ≥ 2, IPI ≥ 3, B symptoms, and no rituximab-based treatment were poor predictive factors for overall survival (OS). Multivariate analysis revealed that B symptoms and no rituximab-based treatment, but not positive CD5 expression, were independent factors for OS.

Conclusions

Patients with CD5+ DLBCL had heterogeneous clinical characteristics and poor survival. The development of more targeted and effective therapies is needed.

Identification of CXCR4 Upregulation in Diffuse Large B-Cell Lymphoma Associated with Prognostic Significance and Clinicopathological Characteristics

Background

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous malignant lymphoma with distinct characteristics. Patients with treatment failure after the standard immunochemotherapy have worse prognosis, which implies the necessity to uncover novel targets. The C-X-C chemokine receptor 4 (CXCR4) overexpression has been identified in several hematopoietic malignancies. However, the expression signatures and prognostic significance of CXCR4 in DLBCL associated with clinicopathological features remain unclear.

Methods

Gene expression profiles of DLBCL were obtained from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Then, a meta-analysis with an integrated bioinformatic analysis was performed to assess the relationship between CXCR4 expression and clinicopathological features of DLBCL. Finally, experimental verification including immunohistochemical (IHC) staining and real-time quantitative PCR (qPCR) was carried out using patient samples. In vitro cell line viability tests were conducted using CXCR4 inhibitor WZ811.

Results

DLBCL patients with activated B-cell-like (ABC) subtype have higher expression level of CXCR4 with worse survival. Differential expressed genes in the CXCR4-upregulation group were enriched in canonical pathways associated with oncogenesis. DLBCL with CXCR4 upregulation had lower degree of CD8⁺ T cell infiltration. TIMER analysis demonstrated that the CXCR4 expression was positively correlated with the expression of CD5, MYC, NOTCH1, PDCD1, CD274, mTOR, FOXO1, and hnRNPA2B1 in DLBCL. IHC study in patient samples showed the positive correlation between CXCR4 and nongerminal center B-cell (non-GCB) subtype and mTOR expression. Meanwhile, quantitative polymerase chain reaction results revealed that high CXCR4 mRNA level was correlated to double-hit DLBCL. Finally, cell viability test showed that WZ811 exerted antiproliferation effect in DLBCL cell lines in a dose-dependent manner.

Conclusion

CXCR4 was upregulated in ABC-DLBCL associated with worse prognosis. Our analysis predicted CXCR4 as a potential target for DLBCL treatment, which may serve as an inhibitor both on BCR signaling and nuclear export warranting further investigation in clinical trials.

Somatostatin Receptors and Chemokine Receptor CXCR4 in Lymphomas: A Histopathological Review of Six Lymphoma Subtypes

Background

Somatostatin receptors (SSTR) and chemokine receptor CXCR4 are expressed in lymphomas, while the abundance is known to be heterogeneous in different subtypes of lymphomas. Targeting tumor cells expressing these receptors might add to therapeutic opportunities while radiolabeled ligands for both imaging and therapy have been developed. The aim of this study was to establish SSTR subtype 2, 3 and 5 and also CXCR4 status immunohistochemically in six different lymphoma subtypes: diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), mantle cell lymphoma (MCL), mucosa-associated marginal B-cell lymphoma (MALT), Hodgkin lymphoma (HL) and peripheral T-cell lymphoma (PTCL).

Material and Methods

This study included a total of 103 lymphoma patients (24 DLBCL, 22 FL, 18 HL, 9 MALT, 20 MCL and 10 PTCL) diagnosed in the Southwest hospital district of Finland during 2010-2019. SSTR 2, 3 and 5 and CXCR4 expression was analyzed immunohistochemically (IHC) in lymphoma samples obtained from local archival Biobank tissue repository. Immunopositivity of each receptor was scored on a four-point scale accounting for staining intensity and proportion of positively stained tumor cells.

Results

Of different SSTR subtypes SSTR2 immunopositivity was most common and seen predominantly at the cell membrane of the malignant cells in 46-56% of DLBCL, HL and FL. CXCR4 co-expression was frequently present in these cases. SSTR3 and SSTR5 IHC were negative in DLBCL and FL but in HL SSTR expression was more heterogenous and SSTR3 and SSTR5 positivity was found in cytoplasm in 35% and 25% of cases. 2/4 blastoid MCL variants and one pleomorphic MCL variant had positive CXCR4 IHC whilst all other MCL cases (85%) were negative for all receptors. 30% (n=3) of the PTCL patients had positive SSTR5 IHC and CXCR4. MALT lymphomas were negative for all receptors.

Conclusion

SSTR2 and CXCR4 are found in DLBCL, FL and HL and co-expression of these receptors is common. Although in general expression of SSTRs and CXCR4 is heterogenous and very low in some subtypes such as MCL and MALT there are also patients with abundant expression. The latter are candidates for trials studying SSTR2 and/or CXCR4 based treatments in the future.

Different chemokine profile between systemic and testicular diffuse large B-cell lymphoma

Although treatment for diffuse large B-cell lymphoma (DLBCL) has taken some notable steps in the 2000s, there are still subgroups of patients suffering from high mortality and relapse rates. To further improve treatment outcomes, it is essential to discover new mechanisms of chemotherapy resistance and create new treatment approaches to overcome them. In the present study, we analyzed the expression of chemokines and their ligands in systemic and testicular DLBCL. From our biopsy sample set of 21 testicular and 28 systemic lymphomas, we were able to demonstrate chemokine profile differences and identify associations with clinical risk factors. High cytoplasmic CXCL13 expression had correlations with better treatment response, lower disease-related mortality, and limited stage. This study suggests that active CXCR5/CXCL13 signaling could overtake the CXCR4/CXCL12 axis, resulting in a better prognosis.

Increased mTOR activation in idiopathic multicentric Castleman disease

Idiopathic multicentric Castleman disease (iMCD) is a rare and poorly understood hematologic disorder characterized by lymphadenopathy, systemic inflammation, cytopenias, and life-threatening multiorgan dysfunction. Interleukin-6 (IL-6) inhibition effectively treats approximately one-third of patients. Limited options exist for nonresponders, because the etiology, dysregulated cell types, and signaling pathways are unknown. We previously reported 3 anti-IL-6 nonresponders with increased mTOR activation who responded to mTOR inhibition with sirolimus. We investigated mTOR signaling in tissue and serum proteomes from iMCD patients and controls. mTOR activation was increased in the interfollicular space of iMCD lymph nodes (N = 26) compared with control lymph nodes by immunohistochemistry (IHC) for pS6, p4EBP1, and p70S6K, known effectors and readouts of mTORC1 activation. IHC for pS6 also revealed increased mTOR activation in iMCD compared with Hodgkin lymphoma, systemic lupus erythematosus, and reactive lymph nodes, suggesting that the mTOR activation in iMCD is not just a product of lymphoproliferation/inflammatory lymphadenopathy. Further, the degree of mTOR activation in iMCD was comparable to autoimmune lymphoproliferative syndrome, a disease driven by mTOR hyperactivation that responds to sirolimus treatment. Gene set enrichment analysis of serum proteomic data from iMCD patients (n = 88) and controls (n = 42) showed significantly enriched mTORC1 signaling. Finally, functional studies revealed increased baseline mTOR pathway activation in peripheral monocytes and T cells from iMCD remission samples compared with healthy controls. IL-6 stimulation augmented mTOR activation in iMCD patients, which was abrogated with JAK1/2 inhibition. These findings support mTOR activation as a novel therapeutic target for iMCD, which is being investigated through a trial of sirolimus (NCT03933904).

New Insights on the Emerging Genomic Landscape of CXCR4 in Cancer: A Lesson from WHIM

Deciphering the molecular alterations leading to disease initiation and progression is currently crucial to identify the most relevant targets for precision therapy in cancer patients. Cancers express a complex chemokine network influencing leucocyte infiltration and angiogenesis. Moreover, malignant cells also express a selective repertoire of chemokine receptors that sustain their growth and spread. At present, different cancer types have been shown to overexpress C-X-C chemokine receptor type 4 (CXCR4) and to respond to its ligand C-X-C motif chemokine 12 (CXCL12). The CXCL12/CXCR4 axis influences cancer biology, promoting survival, proliferation, and angiogenesis, and plays a pivotal role in directing migration of cancer cells to sites of metastases, making it a prognostic marker and a therapeutic target. More recently, mutations in the C-terminus of CXCR4 have been identified in the genomic landscape of patients affected by Waldenstrom's macroglobulinemia, a rare B cell neoplasm. These mutations closely resemble those occurring in Warts, Hypogammaglobulinemia, Immunodeficiency, and Myelokathexis (WHIM) syndrome, an immunodeficiency associated with CXCR4 aberrant expression and activity and with chemotherapy resistance in clinical trials. In this review, we summarize the current knowledge on the relevance of CXCR4 mutations in cancer biology, focusing on its importance as predictors of clinical presentation and response to therapy.

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.

CXCR4 upregulation is an indicator of sensitivity to B-cell receptor/PI3K blockade and a potential resistance mechanism in B-cell receptor-dependent diffuse large B-cell lymphomas

B-cell receptor (BCR) signaling pathway components represent promising treatment targets in multiple B-cell malignancies including diffuse large B-cell lymphoma (DLBCL). In in vitro and in vivo model systems, a subset of DLBCLs depend upon BCR survival signals and respond to proximal BCR/phosphoinositide 3 kinase (PI3K) blockade. However, single-agent BCR pathway inhibitors have had more limited activity in patients with DLBCL, underscoring the need for indicators of sensitivity to BCR blockade and insights into potential resistance mechanisms. Here, we report highly significant transcriptional upregulation of C-X-C chemokine receptor 4 (CXCR4) in BCR-dependent DLBCL cell lines and primary tumors following chemical spleen tyrosine kinase (SYK) inhibition, molecular SYK depletion or chemical PI3K blockade. SYK or PI3K inhibition also selectively upregulated cell surface CXCR4 protein expression in BCR-dependent DLBCLs. CXCR4 expression was directly modulated by fork-head box O1 via the PI3K/protein kinase B/forkhead box O1 signaling axis. Following chemical SYK inhibition, all BCR-dependent DLBCLs exhibited significantly increased stromal cell-derived factor-1α (SDF-1α) induced chemotaxis, consistent with the role of CXCR4 signaling in B-cell migration. Select PI3K isoform inhibitors also augmented SDF-1α induced chemotaxis. These data define CXCR4 upregulation as an indicator of sensitivity to BCR/PI3K blockade and identify CXCR4 signaling as a potential resistance mechanism in BCR-dependent DLBCLs.

A CXCR4-targeted nanocarrier achieves highly selective tumor uptake in diffuse large B-cell lymphoma mouse models

One-third of diffuse large B-cell lymphoma patients are refractory to initial treatment or relapse after rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone chemotherapy. In these patients, CXCR4 overexpression (CXCR4⁺) associates with lower overall and disease-free survival. Nanomedicine pursues active targeting to selectively deliver antitumor agents to cancer cells; a novel approach that promises to revolutionize therapy by dramatically increasing drug concentration in target tumor cells. In this study, we intravenously administered a liganded protein nanocarrier (T22-GFP-H6) targeting CXCR4⁺ lymphoma cells in mouse models to assess its selectivity as a nanocarrier by measuring its tissue biodistribution in cancer and normal cells. No previous protein-based nanocarrier has been described as specifically targeting lymphoma cells. T22-GFP-H6 achieved a highly selective tumor uptake in a CXCR4⁺ lymphoma subcutaneous model, as detected by fluorescent emission. We demonstrated that tumor uptake was CXCR4-dependent because pretreatment with AMD3100, a CXCR4 antagonist, significantly reduced tumor uptake. Moreover, in contrast to CXCR4⁺ subcutaneous models, CXCR4^– tumors did not accumulate the nanocarrier. Most importantly, after intravenous injection in a disseminated model, the nanocarrier accumulated and internalized in all clinically relevant organs affected by lymphoma cells with negligible distribution to unaffected tissues. Finally, we obtained antitumor effect without toxicity in a CXCR4⁺ lymphoma model by administration of T22-DITOX-H6, a nanoparticle incorporating a toxin with the same structure as the nanocarrier. Hence, the use of the T22-GFP-H6 nanocarrier could be a good strategy to load and deliver drugs or toxins to treat specifically CXCR4-mediated refractory or relapsed diffuse large B-cell lymphoma without systemic toxicity.

ROR1 associates unfavorable prognosis and promotes lymphoma growth in DLBCL by affecting PI3K/Akt/mTOR signaling pathway

The receptor-tyrosine-kinase (RTK)-like orphan receptor 1 (ROR1) is a transmembrane glycoprotein regarded as a tumor-associated antigen. ROR1 plays an important role in cancer development, but the detailed function of ROR1 in diffuse large B-cell lymphoma (DLBCL) remains unclear. In this study, we first detected ROR1 expression and evaluated the relationship between ROR1 expression and the clinicopathological characteristics of DLBCL patients. Next we employed shRNA-mediated knockdown of ROR1 in DLBCL cell line to explore the characteristics of ROR1 in DLBCL development both in vitro and in vivo. The results showed a significantly higher level of ROR1 in DLBCL tissues than in lymphatic hyperplasia tissues. High ROR1 expression was correlated with unfavorable prognosis in DLBCL patients. Furthermore, ROR1 knockdown inhibited the growth and induced the apoptosis in DLBCL cells and xenografts. In addition, shROR1 inhibited activation of the PI3K/Akt/mTOR signaling pathway, both in vitro and in vivo. Taken together, our results suggest that ROR1 is a novel prognostic marker for DLBCL survival and ROR1 significantly promotes DLBCL tumorigenesis by regulating the PI3K/Akt/mTOR signaling pathway. Targeting ROR1 may provide a promising strategy for DLBCL treatment. © 2019 BioFactors, 45(3):416-426, 2019.

The significance of chemokines in diffuse large B-cell lymphoma: a systematic review and future insights

Despite the progress made in molecular and clinical research, patients with diffuse large B-cell lymphoma (DLBCL) still have a bad prognosis. Recently, chemokines/chemokine receptors have become the subject of interest in relation to DLBCL. Studies have demonstrated the important role of chemokines/chemokine receptors in the communication between DLBCL cells and tumor microenvironment. Studies have also reported the ability of chemokines/chemokine receptors in promoting the proliferation and invasion of DLBCL cells. Here, we summarize the data on mechanisms of DLBCL supporting the involvement of chemokine/chemokine receptor changes. We focus on the available evidence regarding chemokines/chemokine receptors as biomarkers and therapeutic targets for DLBCL.

Human bone marrow-derived mesenchymal stem cells promote the growth and drug-resistance of diffuse large B-cell lymphoma by secreting IL-6 and elevating IL-17A levels

Background

The drug-resistance and relapse of diffuse large B-cell lymphoma (DLBCL), which are related to mesenchymal stem cells (MSCs), have become increasingly common. However, the underlying mechanisms remain elusive.

Methods

CCK 8 assay, colony formation assay, and xenograft mouse model were used to investigate the effects of hBMSCs on DLBCL growth. Immunohistochemistry, qRT-PCR, and ELISA were used to study the expressions of IL-6 and IL-17A. Flow cytometry was used to analyze Th17 cells and Treg cells expressions. Western blot analysis, microarray analysis, and bioinformatics analysis were used to analyze the pathways of IL-6 or IL-17A mediated DLBCL growth.

Results

HBMSCs promoted DLBCL growth by secreting IL-6 in vitro and in vivo and simultaneously upregulating IL-17A in vitro. IL-6 and IL-17A synergistically promoted the growth and drug-resistance of DLBCL cells by protecting them from spontaneous or drug-induced apoptosis in vitro. IL-6 or IL-17A activated the JAK2/STAT3 pathway or upregulated cyclin D2 via activation of PI3K/Akt signaling in vitro, respectively.

Conclusions

The present results indicated that hBMSCs might have a “dual effect” on promoting DLBCL progression and drug-resistance by secreting IL-6 and upregulating IL-17A. IL-6, IL-17A, p-STAT3, p-Akt or cyclin D2 may be potential molecular targets for overcoming drug-resistance in patients with relapsed or refractory DLBCL.