Migration and Adhesion of B-Lymphocytes to Specific Microenvironments in Mantle Cell Lymphoma: Interplay between Signaling Pathways and the Epigenetic Landscape

Loss of CCL28 and CXCL17 Expression and Increase in CCR1 Expression May Be Related to Malignant Transformation of LGBLEL into Lymphoma

To investigate the differential expression of the chemokine signaling pathway in lacrimal gland benign lymphoepithelial lesion (LGBLEL) and lacrimal lymphoma, providing insights into the mechanisms underlying malignant transformation and aiding clinical differentiation. Transcriptome analysis was conducted on patients with LGBLEL, lymphoma, and orbital cavernous hemangioma (CH). Three cases of LGBLEL and three cases of lymphoma were randomly selected as control and experimental groups, respectively. A real-time quantitative polymerase chain reaction (RT-qPCR) was used to validate genes associated with the chemokine signaling pathway. Immunohistochemical (IHC) staining and quantitative Western blotting (WB) were performed for precise protein quantification. Transcriptome analysis revealed differential expression of the chemokine signaling pathway between the LGBLEL and lymphoma groups, identifying ten differentially expressed genes: CCL17, VAV2, CXCR5, NRAS, HCK, RASGRP2, PREX1, GNB5, ADRBK2, and CCL22. RT-qPCR showed that, compared to the lymphoma group, the LGBLEL group had significantly higher expression of CCL28, CXCL17, HCK, GNB5, NRAS, and VAV2 (p = 0.001, <0.001, <0.001, <0.001, =0.020, <0.001, respectively) and lower expression of CCR1 (p = 0.002). IHC staining and quantitative analysis confirmed significant differences in protein expression between the groups for CCL28, CCR1, CXCL17, HCK, GNB5, NRAS, and VAV2 (p = 0.003, 0.011, 0.001, 0.024, 0.005, 0.019, and 0.031, respectively). While IHC provided localization, WB offered greater precision. WB revealed that, compared to the lymphoma group, the LGBLEL group exhibited significantly higher expression of CCL28, CXCL17, HCK, GNB5, NRAS, and VAV2 (p = 0.012, 0.005, 0.009, 0.011, 0.008, and 0.003, respectively) and lower expression of CCR1 (p = 0.014). The chemokine signaling pathway plays a role in the malignant transformation of LGBLEL. The decreased expression of CCL28 and CXCL17, coupled with the increased expression of CCR1, may be linked to the progression of LGBLEL into lymphoma.

BACH1 Loss Exerts Antitumor Effects on Mantle Cell Lymphoma Cells via Inducing a Tumor-Intrinsic Innate Immune Response and Cell-Cycle Arrest

BTB and CNC homology 1 (BACH1) is a transcription repressor that regulates multiple physiological processes, including intracellular heme homeostasis and immune responses. Increasing lines of evidence indicate that BACH1 reshapes metastasis and metabolism of human solid tumors. However, its potential roles in mantle cell lymphoma (MCL) remain largely unknown. Here, we found that silencing BACH1 in MCL cells induced markedly cell-cycle arrest and cell apoptosis, whereas overexpression of BACH1 exhibited the opposite patterns. Increased BACH1 levels not only promoted tumor growth and dispersal in xenografts, but also conferred a long-term poor prognosis in patients with MCL. Interestingly, RNA sequencing analysis revealed noncanonical function of BACH1 in regulation of type I interferon (IFNI) response, DNA replication and repair, and cell cycle. Mechanistically, zinc finger and BTB domain containing 20 (ZBTB20) and HMG-box transcription factor 1 (HBP1) were for the first time identified as two novel downstream targets repressed by BACH1 in MCL cells. Further double-knockdown functional assays confirmed that loss of BACH1 induced ZBTB20-mediated IFNα production and HBP1-mediated cell-cycle arrest, indicating that BACH1-centered regulatory network may be a novel targetable vulnerability in MCL cells.

IMPLICATIONS

BACH1 serves as a pleotropic regulator of tumor-intrinsic innate immune response and cell-cycle progression, disruption of which may offer a promising therapeutic strategy for MCL treatment.

GSK-J4 Inhibition of KDM6B Histone Demethylase Blocks Adhesion of Mantle Cell Lymphoma Cells to Stromal Cells by Modulating NF-κB Signaling

Multiple signaling pathways facilitate the survival and drug resistance of malignant B-cells by regulating their migration and adhesion to microenvironmental niches. NF-κB pathways are commonly dysregulated in mantle cell lymphoma (MCL), but the exact underlying mechanisms are not well understood. Here, using a co-culture model system, we show that the adhesion of MCL cells to stromal cells is associated with elevated levels of KDM6B histone demethylase mRNA in adherent cells. The inhibition of KDM6B activity, using either a selective inhibitor (GSK-J4) or siRNA-mediated knockdown, reduces MCL adhesion to stromal cells. We showed that KDM6B is required both for the removal of repressive chromatin marks (H3K27me3) at the promoter region of NF-κB encoding genes and for inducing the expression of NF-κB genes in adherent MCL cells. GSK-J4 reduced protein levels of the RELA NF-κB subunit and impaired its nuclear localization. We further demonstrated that some adhesion-induced target genes require both induced NF-κB and KDM6B activity for their induction (e.g., IL-10 cytokine gene), while others require induction of NF-κB but not KDM6B (e.g., CCR7 chemokine gene). In conclusion, KDM6B induces the NF-κB pathway at different levels in MCL, thereby facilitating MCL cell adhesion, survival, and drug resistance. KDM6B represents a novel potential therapeutic target for MCL.

CAR T-Cell therapy for the management of mantle cell lymphoma

Mantle cell lymphoma (MCL) is a subtype of Non-Hodgkin lymphoma (NHL) of mature B-cells characterized by translocation, which is typically due to excess expression of Cyclin D1. Although with the progress in our knowledge of the causes for MCL and available treatments for MCL, this cancer is still incurable. Age, male gender, rapid advancement, significant nodal involvement, elevated serum lactate dehydrogenase level, and prognostic indications including increased expression of Ki-67 and presence of TP53 mutation, are symbols of poor outcome. Advanced immunotherapy using chimeric antigen receptor (CAR)-T cells is advantageous for patients suffering from B-cell malignancies and MCL. Targeting B-cell antigens on the cell surface is a feasible approach in re-occurring (R/R) MCL because of significant responses obtained in other B-cell cancers. USFDA has approved brexucabtagene autoleucel (Tecartus, KTE-X19), a novel CAR T-cell therapy to be used in patients with MCL who have not responded to previous treatments or have relapsed. The FDA approved this new treatment depending on the outcomes of the ZUMA-2 clinical trial. Serious adverse reactions, moderate anti-tumor activity, allergen withdrawal, antigen escape, limited tumor infiltration, and trafficking are major barriers to successful CAR T-cell therapy. This review is a brief synopsis of the development of CAR T-cell therapy for MCL.

Tumor Microenvironment and Immunotherapy-Based Approaches in Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma (NHL) characterized by the translocation t(11;14) (q13;q32) and a poor response to rituximab–anthracycline-based chemotherapy. High-dose cytarabine-based regimens offer a durable response, but an important number of MCL patients are not eligible for intensive treatment and are ideal candidates for novel targeted therapies (such as BTK, proteasome or BCL2 inhibitors, Immunomodulatory Drugs (IMiDs), bispecific antibodies, or CAR-T cell therapy). On the bench side, several studies aiming to integrate the tumor within its ecosystem highlighted a critical role of the tumor microenvironment (TME) in the expansion and resistance of MCL. This led to important insights into the role of the TME in the management of MCL, including potential targets and biomarkers. Indeed, targeted agents often have a combined mechanism of action on the tumor B cell but also on the tumor microenvironment. The aim of this review is to briefly describe the current knowledge on the biology of the TME in MCL and expose the results of the different therapeutic strategies integrating the TME in this disease.