The interplay of CD150 and CD180 receptor pathways contribute to the pathobiology of chronic lymphocytic leukemia B cells by selective inhibition of Akt and MAPK signaling

MD-1 downregulation is associated with reduced cell surface CD180 expression in CLL

CD180 is a toll-like receptor that is highly expressed in complex with the MD-1 satellite molecule on the surface of B cells. In chronic lymphocytic leukaemia (CLL) however, the expression of CD180 is highly variable and overall, significantly reduced when compared to normal B cells. We have recently shown that reduced CD180 expression in CLL lymph nodes is associated with inferior overall survival. It was therefore important to better understand the causes of this downregulation through investigation of CD180 at the transcriptional and protein expression levels. Unexpectedly, we found CD180 RNA levels in CLL cells (n = 26) were comparable to those of normal B cells (n = 13), despite heterogeneously low expression of CD180 on the cell surface. We confirmed that CD180 RNA is translated into CD180 protein since cell surface CD180-negative cases presented with high levels of intracellular CD180 expression. Levels of MD-1 RNA were, however, significantly downregulated in CLL compared to normal controls. Together, these data suggest that changes in CD180 cell surface expression in CLL are not due to transcriptional downregulation, but defective post-translational stabilisation of the receptor due to MD-1 downregulation.

Comprehensive analysis of signaling lymphocyte activation molecule family as a prognostic biomarker and correlation with immune infiltration in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is a common type of kidney cancer and accounts for 2-3% of all cancer cases. Furthermore, a growing number of immunotherapy approaches are being used in antitumor treatment. Signaling lymphocyte activation molecule family (SLAMF) members have been well studied in several cancers, whereas their roles in ccRCC have not been investigated. The present study comprehensively assessed the molecular mechanisms of SLAMF members in ccRCC, performed using The Cancer Genome Atlas database, with analysis of gene transcription, prognosis, biological function, clinical features, tumor-associated immune cells and the correlation with programmed cell death protein 1/programmed death-ligand 1 immune checkpoints. Simultaneously, the Tumor Immune Dysfunction and Exclusion algorithm was used to predict the efficacy of immune checkpoint blockade (ICB) therapy in patients with high and low SLAMF expression levels. The results demonstrated that all SLAMF members were highly expressed in ccRCC, and patients with high expression levels of SLAMF1, 4, 7 and 8 had a worse prognosis that those with low expression. SLAMF members were not only highly associated with immune activation but also with immunosuppressive agents. The level of immune cell infiltration was associated with the prognosis of patients with ccRCC with high SLAMF expression. Moreover, high ICB response rates were observed in patients with high expression levels of SMALF1 and 4. In summary, SLAMF members may serve as future potential biomarkers for predicting the prognosis of ccRCC and emerge as a novel immunotherapy target.

SOLUBLE CD150 ISOFORM LEVEL IN PLASMA OF CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS

BACKGROUND

SLAMF1/CD150 is an active player in B cell signaling networks in chronic lymphocytic leukemia (CLL). CD150-mediated signaling initiates through a homophilic CD150 binding, which spans the adjacent cells, or the interaction with the soluble CD150 isoform (sCD150). The expression of sCD150 isoform at the mRNA and protein levels ex vivo was confirmed. However, it is unclear whether sCD150 isoform present in the blood plasma of CLL patients is a factor in the constitutive activation of CD150+ cells. The aim of this study was to develop an ELISA assay for the specific sCD150 evaluation and assess the sCD150 levels in the blood plasma of CLL patients with different CD150 expression on B cells.

MATERIALS AND METHODS

Blood plasma samples and peripheral blood mononuclear cells from 40 previously untreated CLL patients were analyzed. An ELISA method, ex vivo drug sensitivity assay, and a cell viability assay were used.

RESULTS

The sCD150 isoform was found in all studied plasma samples of CLL patients at different levels regardless of the cell surface CD150 expression status of B cells and sCD150 mRNA expression. CLL cases with low levels of the cell surface CD150 expression in B cells are characterized by high levels of sCD150 in blood plasma in contrast to the CLL cases with high cell surface CD150 expression on B cells. The elevated levels of sCD150 in blood plasma are associated with a better sensitivity of malignant B cells to cyclophosphamide and bendamustine.

CONCLUSIONS

The sCD150 isoform is actively secreted by CLL B cells with its accumulation in blood plasma, which may be regarded as an additional factor in the CLL clinicopathologic variability.

The role of CD180 in hematological malignancies and inflammatory disorders

Toll-like receptors play a significant role in the innate immune system and are also involved in the pathophysiology of many different diseases. Over the past 35 years, there have been a growing number of publications exploring the role of the orphan toll-like receptor, CD180. We therefore set out to provide a narrative review of the current evidence surrounding CD180 in both health and disease. We first explore the evidence surrounding the role of CD180 in physiology including its expression, function and signaling in antigen presenting cells (APCs) (dendritic cells, monocytes, and B cells). We particularly focus on the role of CD180 as a modulator of other TLRs including TLR2, TLR4, and TLR9. We then discuss the role of CD180 in inflammatory and autoimmune diseases, as well as in hematological malignancies of B cell origin, including chronic lymphocytic leukemia (CLL). Based on this evidence we produce a current model for CD180 in disease and explore the potential role for CD180 as both a prognostic biomarker and therapeutic target. Throughout, we highlight specific areas of research which should be addressed to further the understanding of CD180 biology and the translational potential of research into CD180 in various diseases.

SLAM-family receptors come of age as a potential molecular target in cancer immunotherapy

The signaling lymphocytic activation molecule (SLAM) family receptors were discovered in immune cells for the first time. The SLAM-family receptors are a significant player in cytotoxicity, humoral immune responses, autoimmune diseases, lymphocyte development, cell survival, and cell adhesion. There is growing evidence that SLAM-family receptors have been involved in cancer progression and heralded as a novel immune checkpoint on T cells. Previous studies have reported the role of SLAMs in tumor immunity in various cancers, including chronic lymphocytic leukemia, lymphoma, multiple myeloma, acute myeloid leukemia, hepatocellular carcinoma, head and neck squamous cell carcinoma, pancreas, lung, and melanoma. Evidence has deciphered that the SLAM-family receptors may be targeted for cancer immunotherapy. However, our understanding in this regard is not complete. This review will discuss the role of SLAM-family receptors in cancer immunotherapy. It will also provide an update on recent advances in SLAM-based targeted immunotherapies.

The Potential Role of RP105 in Regulation of Inflammation and Osteoclastogenesis During Inflammatory Diseases

Inflammatory diseases have a negative impact on bone homeostasis via exacerbated local and systemic inflammation. Bone resorbing osteoclasts are mainly derived from hematopoietic precursors and bone marrow monocytes. Induced osteoclastogenesis during inflammation, autoimmunity, metabolic diseases, and cancers is associated with bone loss and osteoporosis. Proinflammatory cytokines, pathogen-associated molecular patterns, or endogenous pathogenic factors induce osteoclastogenic differentiation by binding to the Toll-like receptor (TLR) family expressed on surface of osteoclast precursors. As a non-canonical member of the TLRs, radioprotective 105 kDa (RP105 or CD180) and its ligand, myeloid differentiation protein 1 (MD1), are involved in several bone metabolic disorders. Reports from literature had demonstrated RP105 as an important activator of B cells, bone marrow monocytes, and macrophages, which regulates inflammatory cytokines release from immune cells. Reports from literature had shown the association between RP105 and other TLRs, and the downstream signaling mechanisms of RP105 with different “signaling-competent” partners in immune cells during different disease conditions. This review is focused to summarize: (1) the role of RP105 on immune cells’ function and inflammation regulation (2) the potential regulatory roles of RP105 in different disease-mediated osteoclast activation and the underlying mechanisms, and (3) the different “signaling-competent” partners of RP105 that regulates osteoclastogenesis.

SLAMF1 Promotes Methotrexate Resistance via Activating Autophagy in Choriocarcinoma Cells

Objective

The acquisition of chemoresistance to methotrexate (MTX) still remains one of the major challenges for choriocarcinoma treatment. Herein, we aimed to evaluate the potential role of Signaling Lymphocytic Activation Molecule Family Member 1 (SLAMF1) as a possible regulator of chemoresistance to MTX in choriocarcinoma.

Material and Methods

MTX-resistant JEG3 and JAR sublines (JEG3/MTX, JAR/MTX) were used to study SLAMF1 function. CCK8 assay and soft agar assay were conducted to measure the cell viability and clonogenesis of choriocarcinoma cells, respectively; MDC incorporation assay was conducted for the quantification of intracellular autophagy; BrdU labeling was used to assess the proliferative potential of choriocarcinoma cells; SLAMF1 protein expression was analyzed by Western blotting.

Results

Upregulation of SLAMF1 expression was observed in MTX-resistant JEG3/MTX and JAR/MTX sublines compared to their parental JEG3 and JAR cell lines, respectively. Knockdown of SLAMF1 markedly attenuated cell viability and soft agar clonogenesis after incubation with MTX in JEG3/MTX and JAR/MTX cells. In contrast, constitutive expression of SLAMF1 rescued cell survival soft agar clonogenesis in JEG3 and JAR cells treated with MTX. Moreover, autophagy is apparently activated in MTX-resistant JEG3/MTX and JAR/MTX sublines compared to their parental cell lines. Autophagy inhibitor 3-methyladenine and bafilomycin A1 enhanced MTX-induced cytotoxicity in MTX-resistant JEG3 and JAR sublines. Further, SLAMF1 might activate autophagy-related mechanism to promote resistance to MTX in choriocarcinoma cells. Depletion of SLAMF1 suppressed autophagy and induced apoptosis in MTX-treated JEG3/MTX and JAR/MTX cells.

Conclusion

SLAMF1 might promote MTX resistance via activating protective autophagy in choriocarcinoma cell lines. Targeting SLAMF1 might be a useful therapeutic strategy to sensitize choriocarcinoma cells to MTX-based regimens.

SLAMF1 contributes to cell survival through the AKT signaling pathway in Farage cells

SLAMF1 is often overexpressed in Epstein Barr virus (EBV)-infected B cell tumors. However, its role in the pathogenesis of EBV-infected B cell tumors remains largely unknown. Here, we generated SLAMF1-deficient EBV+ tumor cells and examined the effect of its deficiency on cell proliferation and cell survival. There were no significant differences in cell proliferation and cell cycle distribution for short periods between the SLAMF1-deficient and wild-type cells. However, the deficient cells were more resistant to an AKT inhibitor (MK-2206). When the both cells were co-cultured and repeatedly exposed to the limitations in nutrition and growth factors, the SLAMF1-deficient cells were gradually decreased. We observed that levels of phospho-AKT were differentially regulated according to the nutritional status between the SLAMF1-deficient and wild-type cells. A decrease in phospho-AKT was observed in SLAMF1-deficient cells as well as an increase in pro-apoptotic Bim just before cell passage, which may have been due to the loss of SLAMF1 under poor growth condition. Overall, SLAMF1 is not a strong survival factor, but it seems to be necessary for cell survival in unfavorable growth condition.

CD markers variations in chronic lymphocytic leukemia: New insights into prognosis

Chronic lymphocytic leukemia (CLL) is one of the most commonly occurring adult leukemias that is associated with clonal accumulation of mature apoptosis-resistant B-cells in bone marrow, peripheral blood, and specific tissues. Different pathogenesis factors can contribute to the aggression of the clinical course in this disease. Cytogenetic abnormalities and surface biomarkers of neoplastic CLL cells can be effective in the outcome of CLL, and the examination of changing CD markers expressions in the progression of CLL can be related to the prognosis of this disease. Changing expression levels of CD markers on lymphocytes and other cells in CLL patients can play a role in the aggressive clinical outcomes such as organomegaly, immunodeficiency, and advanced disease stages through their interaction with CLL microenvironment. Given the involvement of CD markers in the pathogenesis of CLL, it can be stated that recognizing the expression changes of CD markers in the cells involved in CLL can be a proper approach to evaluate prognosis among these patients.

Molecular Interactions Between Innate and Adaptive Immune Cells in Chronic Lymphocytic Leukemia and Their Therapeutic Implications

Innate immunity constitutes the first line of host defense against various anomalies in humans, and it also guides the adaptive immune response. The function of innate immune components and adaptive immune components are interlinked in hematological malignancies including chronic lymphocytic leukemia (CLL), and molecular interactions between innate and adaptive immune components are crucial for the development, progression and the therapeutic outcome of CLL. In this leukemia, genetic mutations in B cells and B cell receptors (BCR) are key driving factors along with evasion of cytotoxic T lymphocytes and promotion of regulatory T cells. Similarly, the release of various cytokines from CLL cells triggers the protumor phenotype in macrophages that further edges the CLL cells. Moreover, under the influence of various cytokines, dendritic cells are unable to mature and trigger T cell mediated antitumor response. The phenotypes of these cells are ultimately controlled by respective signaling pathways, the most notables are BCR, Wnt, Notch, and NF-κB, and their activation affects the cytokine profile that controls the pathogenesis of CLL, and challenge its treatment. There are several novel substances for CLL under clinical development, including kinase inhibitors, antibodies, and immune-modulators that offer new hopes. DC-based vaccines and CAR T cell therapy are promising tools; however, further studies are required to precisely dissect the molecular interactions among various molecular entities. In this review, we systematically discuss the involvement, common targets and therapeutic interventions of various cells for the better understanding and therapy of CLL.

SLAMF1/CD150 in hematologic malignancies: Silent marker or active player?

SLAMF1/CD150 receptor is a founder of signaling lymphocyte activation molecule (SLAM) family of cell-surface receptors. It is widely expressed on cells within hematopoietic system. In hematologic malignancies CD150 cell surface expression is restricted to cutaneous T-cell lymphomas, few types of B-cell non-Hodgkin's lymphoma, near half of cases of chronic lymphocytic leukemia, Hodgkin's lymphoma, and multiple myeloma. Differential expression among various types of hematological malignancies allows considering CD150 as diagnostical and potential prognostic marker. Moreover, CD150 may be a target for antibody-based or measles virus oncolytic therapy. Due to CD150 signaling properties it is involved in regulation of malignant cell fate decision and tumor microenvironment in Hodgkin's lymphoma and chronic lymphocytic leukemia. This review summarizes evidence for the important role of CD150 in pathogenesis of hematologic malignancies.