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

CXCR4: from B-cell development to B cell-mediated diseases

Chemokine receptors are members of the G protein-coupled receptor superfamily. The C-X-C chemokine receptor type 4 (CXCR4), one of the most studied chemokine receptors, is widely expressed in hematopoietic and immune cell populations. It is involved in leukocyte trafficking in lymphoid organs and inflammatory sites through its interaction with its natural ligand CXCL12. CXCR4 assumes a pivotal role in B-cell development, ranging from early progenitors to the differentiation of antibody-secreting cells. This review emphasizes the significance of CXCR4 across the various stages of B-cell development, including central tolerance, and delves into the association between CXCR4 and B cell-mediated disorders, from immunodeficiencies such as WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome to autoimmune diseases such as systemic lupus erythematosus. The potential of CXCR4 as a therapeutic target is discussed, especially through the identification of novel molecules capable of modulating specific pockets of the CXCR4 molecule. These insights provide a basis for innovative therapeutic approaches in the field.

T-cell immunoglobulin mucin molecule-3, transformation growth factor β, and chemokine-12 and the prognostic status of diffuse large B-cell lymphoma

BACKGROUND

The effects of T-cell immunoglobulin mucin molecule-3 (Tim-3), transforming growth factor β (TGF-β), and chemokine-12 (CXCL12) expression on the prognosis of patients with diffuse large B-cell lymphoma (DLBCL) have not been elucidated.

AIM

To examine the correlation between Tim-3, TGF-β and CXCL12 expression and DLBCL prognosis.

METHODS

Lymph node tissues of 97 patients with DLBCL and 93 normal-response hyperplastic lymph node tissues treated from January 2017 to May 2019 were selected as the DLBCL and control groups, respectively. The expression of Tim-3, TGF-β, and CXCL12 was detected immunohistochemically. Patients were followed up for 3 years, and progression-free survival was recorded. Cox multifactorial analysis was performed to analyze the risk factors for poor prognosis.

RESULTS

The positive expression rates of Tim-3, TGF-β, and CXCL12 were higher in DLBCL tissues than in non-cancerous (control) tissues (P < 0.05). One-year post-surgery, the positive expression rates of Tim-3, TGF-β, and CXCL12 were higher in patients with effective treatment than in those with ineffective treatment (P < 0.05). The 3-year progression-free survival of 97 patients with DLBCL was 67.01% (65/97). Univariate analysis revealed that clinical stage, bone marrow infiltration, International Prognostic Index (IPI) score, Tim-3 positivity, TGF-β positivity, and CXCL12 positivity were associated with poor prognosis (P < 0.05). Multivariate Cox regression analysis demonstrated that clinical stage III–IV, bone marrow infiltration, mediate-to-high-risk IPI scores, Tim-3 positivity, TGF-β positivity, and CXCL12 positivity were independent risk factors affecting prognosis (P < 0.05).

CONCLUSION

DLBCL tissues exhibit high positive expression of Tim-3, TGF-β, and CXCL12, and a high expression of all three indicates a poor prognosis.

STAT3 Promotes Cell Proliferation by Potentiating the CCL4 Transcriptional Activity in Diffuse Large B-Cell Lymphoma

STAT3 is a transcription factor and a candidate therapeutic option for human cancers. However, the underlying mechanism of STAT3 in the pathogenesis of diffuse large B-cell lymphoma (DLBCL) has yet to be established. We studied here whether STAT3 contributes to CCL4 transcription elevation in DLBCL. Our established protein-protein interactions (PPI) network revealed the overexpression of STAT3 and CCL4 in DLBCL. Mechanistically, STAT3 activated CCL4 transcription to induce the Wnt/β-catenin pathway. The prognostic analysis exhibited that the overall survival of patients with high STAT3 and CCL4 were poorer than those with low STAT3 and CCL4 expression. In addition, silencing of STAT3 reverted the malignant phenotype in DLBCL cells. CCL4 overexpression partly weakened the si-STAT3-mediated anti-tumor effects on DLBCL cells. Tumor xenograft models showed that si-STAT3 inhibited tumor growth in vivo and decreased proliferative and mitogenic activities in tumor tissues, findings that were consistent with the in vitro data. Hence, this study provides new evidence that STAT3 and CCL4 may be new prognostic biomarkers and therapeutic targets for treating DLBCL.

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.

CXCL12-PLGA/Pluronic Nanoparticle Internalization Abrogates CXCR4-Mediated Cell Migration

Chemokine-induced chemotaxis mediates physiological and pathological immune cell trafficking, as well as several processes involving cell migration. Among them, the role of CXCL12/CXCR4 signaling in cancer and metastasis is well known, and CXCR4 has been often targeted with small molecule-antagonists or short CXCL12-derived peptides to limit the pathological processes of cell migration and invasion. To reduce CXCR4-mediated chemotaxis, we adopted a different approach. We manufactured poly(lactic acid-co-glycolic acid) (PLGA)/Pluronic F127 nanoparticles through microfluidics-assisted nanoprecipitation and functionalized them with streptavidin to docking a biotinylated CXCL12 to be exposed on the nanoparticle surface. Our results show that CXCL12-decorated nanoparticles are non-toxic and do not induce inflammatory cytokine release in THP-1 monocytes cultured in fetal bovine and human serum-supplemented media. The cell internalization of our chemokine receptor-targeting particles increases in accordance with CXCR4 expression in FBS/medium. We demonstrated that CXCL12-decorated nanoparticles do not induce cell migration on their own, but their pre-incubation with THP-1 significantly decreases CXCR4⁺-cell migration, thereby antagonizing the chemotactic action of CXCL12. The use of biodegradable and immune-compatible chemokine-mimetic nanoparticles to reduce cell migration opens the way to novel antagonists with potential application in cancer treatments and inflammation.

Aberrant CXCR4 Signaling at Crossroad of WHIM Syndrome and Waldenstrom's Macroglobulinemia

Given its pleiotropic functions, including its prominent role in inflammation, immune responses and cancer, the C-X-C chemokine receptor type 4 (CXCR4) has gained significant attention in recent years and has become a relevant target in drug development. Although the signaling properties of CXCR4 have been extensively studied, several aspects deserve deeper investigations. Mutations in the C-term tail of the CXCR4 gene cause WHIM syndrome, a rare congenital immunodeficiency associated by chronic leukopenia. Similar mutations have also been recently identified in 30% of patients affected by Waldenstrom’s macroglobulinaemia, a B-cell neoplasia with bone marrow accumulation of malignant cells. An ample body of work has been generated to define the impact of WHIM mutations on CXCR4 signaling properties and evaluate their role on pathogenesis, diagnosis, and response to therapy, although the identity of disease-causing signaling pathways and their relevance for disease development in different genetic variants are still open questions. This review discusses the current knowledge on biochemical properties of CXCR4 mutations to identify their prototypic signaling profile potentially useful to highlighting novel opportunities for therapeutic intervention.

Molecular imaging in lymphoma beyond 18F-FDG-PET: understanding the biology and its implications for diagnostics and therapy

Mature lymphoproliferative diseases are a heterogeneous group of neoplasms arising from different stages of B-cell and T-cell development. With improved understanding of the molecular processes in lymphoma and novel treatment options, arises a growing need for the molecular characterisation of tumours. Molecular imaging with single-photon-emission CT and PET using specific radionuclide tracers can provide whole-body information to investigate cancer biology, to evaluate phenotypic heterogeneity, to identify resistance to targeted therapy, and to assess the biodistribution of drugs in patients. In this Review, we evaluate the existing literature on molecular imaging in lymphoma, other than ¹⁸F-fluordeoxyglucose molecular imaging. The aim is to examine the contribution of molecular imaging to the understanding of the biology of lymphoma and to discuss potential implications for the diagnostics and therapy of this disease. Finally, we discuss possible applications for molecular imaging of patients with lymphoma in the clinical context.

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.