Stromal CD38 regulates outgrowth of primary melanoma and generation of spontaneous metastasis

Identification of a metabolism-linked genomic signature for prognosis and immunotherapeutic efficiency in metastatic skin cutaneous melanoma

Metastatic skin cutaneous melanoma (MSCM) is the most rapidly progressing/invasive skin-based malignancy, with median survival rates of about 12 months. It appears that metabolic disorders accelerate disease progression. However, correlations between metabolism-linked genes (MRGs) and prognosis in MSCM are unclear, and potential mechanisms explaining the correlation are unknown. The Cancer Genome Atlas (TCGA) was utilized as a training set to develop a genomic signature based on the differentially expressed MRGs (DE-MRGs) between primary skin cutaneous melanoma (PSCM) and MSCM. The Gene Expression Omnibus (GEO) was utilized as a validation set to verify the effectiveness of genomic signature. In addition, a nomogram was established to predict overall survival based on genomic signature and other clinic-based characteristics. Moreover, this study investigated the correlations between genomic signature and tumor micro-environment (TME). This study established a genomic signature consisting of 3 genes (CD38, DHRS3, and TYRP1) and classified MSCM patients into low and high-risk cohorts based on the median risk scores of MSCM cases. It was discovered that cases in the high-risk cohort had significantly lower survival than cases in the low-risk cohort across all sets. Furthermore, a nomogram containing this genomic signature and clinic-based parameters was developed and demonstrated high efficiency in predicting MSCM case survival times. Interestingly, Gene Set Variation Analysis results indicated that the genomic signature was involved in immune-related physiological processes. In addition, this study discovered that risk scoring was negatively correlated with immune-based cellular infiltrations in the TME and critical immune-based checkpoint expression profiles, indicating that favorable prognosis may be influenced in part by immunologically protective micro-environments. A novel 3-genomic signature was found to be reliable for predicting MSCM outcomes and may facilitate personalized immunotherapy.

Identification of G4 motifs of various stem cell markers and their biophysical and biochemical characterization

Regulatory regions in the human genome, enriched in guanine-rich DNA sequences have a remarkable enrichment of G-rich sequences having a tendency to fold into G-quadruplex structures. To identify the G-quadruplex forming motifs in regulatory regions of stem cell markers, gene sequences of various stem cell markers were downloaded and analyzed to see the abundance of G-rich sequences. We observed the enrichment of G-rich sequences in stem cell markers (CD13, CD19, CD24 and CD38) which could possibly play a critical role in its regulation. We used Circular Dichroism (CD), UV-Thermal denaturation (UV-Tm) and polyacrylamide gel electrophoresis (PAGE) to demonstrate the formation of a G-quadruplex by G-rich sequences present in these stem cell markers. We observed that these G-rich sequences containing minimum consecutive G3 stretch separated by loop length ranging from one to three bases long adopt G-quadruplexes with different molecularity involving two-strands, three-strand and four-strand with parallel and antiparallel conformation. Interestingly, we proposed the formation of three-stranded G-quadruplex by CD13 in 100 mM Na+, CD19 in 100 mM K+, 100 mM K+ with 40 wt% PEG 200, and CD38 in 100 mM K+ + 40 wt% PEG 200. The formation of such diverse G-quadruplex structures in the regulatory regions leaves the fair possibility of recognition by regulatory factors to modulate the gene expression. First time, this study may give insight into the structural polymorphism of G4 forming motifs in different stem cell markers to design the best suitable ligand and to target them for therapeutic development.Communicated by Ramaswamy H. Sarma.

Proteomic profiling of cutaneous melanoma explains the aggressiveness of distant organ metastasis

Despite recent developments in managing metastatic melanomas, patients' overall survival remains low. Therefore, the current study aims to understand better the proteome-wide changes associated with melanoma metastasis that will assist with identifying targeted therapies. The latest development in mass spectrometry-based proteomics, together with extensive bioinformatics analysis, was used to investigate the molecular changes in 60 formalin-fixed and paraffin-embedded samples of primary and lymph nodes (LN) and distant organ metastatic melanomas. A total of 4631 proteins were identified, of which 72 and 453 were significantly changed between the LN and distant organ metastatic melanomas compared to the primary lesions (adj. p-value <0.05). An increase in proteins such as SLC9A3R1, CD20 and GRB2 and a decrease in CST6, SERPINB5 and ARG1 were associated with regional LN metastasis. By contrast, increased metastatic activities in distant organ metastatic melanomas were related to higher levels of CEACAM1, MC1R, AKT1 and MMP3-9 and decreased levels of CDKN2A, SDC1 and SDC4 proteins. Furthermore, machine learning analysis classified the lesions with up to 92% accuracy based on their metastatic status. The findings from this study provide up to date proteome-level information about the progression of melanomas to regional LN and distant organs, leading to the identification of protein signatures with potential for clinical translation.

Evolving roles of CD38 metabolism in solid tumour microenvironment

Given that plenty of clinical findings and reviews have already explained in detail on the progression of CD38 in multiple myeloma and haematological system tumours, here we no longer give unnecessary discussion on the above progression. Though therapeutic antibodies have been regarded as a greatest breakthrough in multiple myeloma immunotherapies due to the durable anti-tumour responses in the clinic, but the role of CD38 in the immunologic regulation and evasion of non-hematopoietic solid tumours are just initiated and controversial. Therefore, we will focus on the bio-function of CD38 enzymatic substrates or metabolites in the variety of non-hematopoietic malignancies and the potential therapeutic value of targeting the CD38-NAD+ or CD38-cADPR/ADPR signal axis. Though limited, we review some ongoing researches and clinical trials on therapeutic approaches in solid tumour as well.

Paracrine ADP Ribosyl Cyclase-Mediated Regulation of Biological Processes

ADP-ribosyl cyclases (ADPRCs) catalyze the synthesis of the Ca2+-active second messengers Cyclic ADP-ribose (cADPR) and ADP-ribose (ADPR) from NAD+ as well as nicotinic acid adenine dinucleotide phosphate (NAADP+) from NADP+. The best characterized ADPRC in mammals is CD38, a single-pass transmembrane protein with two opposite membrane orientations. The first identified form, type II CD38, is a glycosylated ectoenzyme, while type III CD38 has its active site in the cytosol. The ectoenzymatic nature of type II CD38 raised long ago the question of a topological paradox concerning the access of the intracellular NAD+ substrate to the extracellular active site and of extracellular cADPR product to its intracellular receptors, ryanodine (RyR) channels. Two different transporters, equilibrative connexin 43 (Cx43) hemichannels for NAD+ and concentrative nucleoside transporters (CNTs) for cADPR, proved to mediate cell-autonomous trafficking of both nucleotides. Here, we discussed how type II CD38, Cx43 and CNTs also play a role in mediating several paracrine processes where an ADPRC+ cell supplies a neighboring CNT-and RyR-expressing cell with cADPR. Recently, type II CD38 was shown to start an ectoenzymatic sequence of reactions from NAD+/ADPR to the strong immunosuppressant adenosine; this paracrine effect represents a major mechanism of acquired resistance of several tumors to immune checkpoint therapy.

CD38: An important regulator of T cell function

Cluster of differentiation 38 (CD38) is a multifunctional extracellular enzyme on the cell surface with NADase and cyclase activities. CD38 is not only expressed in human immune cells, such as lymphocytes and plasma cells, but also is abnormally expressed in a variety of tumor cells, which is closely related to the occurrence and development of tumors. T cells are one of the important immune cells in the body. As NAD consuming enzymes, CD38, ART2, SIRT1 and PARP1 are closely related to the number and function of T cells. CD38 may also influence the activity of ART2, SIRT1 and PARP1 through the CD38-NAD⁺ axis to indirectly affect the number and function of T cells. Thus, CD38-NAD⁺ axis has a profound effect on T cell activity. In this paper, we reviewed the role and mechanism of CD38⁺ CD4⁺ T cells / CD38⁺ CD8⁺ T cells in cellular immunity and the effects of the CD38-NAD⁺ axis on T cell activity. We also summarized the relationship between the CD38 expression level on T cell surface and disease prediction and prognosis, the effects of anti-CD38 monoclonal antibodies on T cell activity and function, and the role of anti-CD38 chimeric antigen receptor (CAR) T cell therapy in tumor immunity. This will provide an important theoretical basis for a comprehensive understanding of the relationship between CD38 and T cells.

The CD38 glycohydrolase and the NAD sink: implications for pathological conditions

Nicotinamide adenine dinucleotide (NAD) acts as a cofactor in several oxidation-reduction (redox) reactions and is a substrate for a number of nonredox enzymes. NAD is fundamental to a variety of cellular processes including energy metabolism, cell signaling, and epigenetics. NAD homeostasis appears to be of paramount importance to health span and longevity, and its dysregulation is associated with multiple diseases. NAD metabolism is dynamic and maintained by synthesis and degradation. The enzyme CD38, one of the main NAD-consuming enzymes, is a key component of NAD homeostasis. The majority of CD38 is localized in the plasma membrane with its catalytic domain facing the extracellular environment, likely for the purpose of controlling systemic levels of NAD. Several cell types express CD38, but its expression predominates on endothelial cells and immune cells capable of infiltrating organs and tissues. Here we review potential roles of CD38 in health and disease and postulate ways in which CD38 dysregulation causes changes in NAD homeostasis and contributes to the pathophysiology of multiple conditions. Indeed, in animal models the development of infectious diseases, autoimmune disorders, fibrosis, metabolic diseases, and age-associated diseases including cancer, heart disease, and neurodegeneration are associated with altered CD38 enzymatic activity. Many of these conditions are modified in CD38-deficient mice or by blocking CD38 NADase activity. In diseases in which CD38 appears to play a role, CD38-dependent NAD decline is often a common denominator of pathophysiology. Thus, understanding dysregulation of NAD homeostasis by CD38 may open new avenues for the treatment of human diseases.

CD38 a biomarker and therapeutic target in non-hematopoietic tumors

The type II transmembrane glycoprotein CD38 has recently been implicated in regulating metabolism and the pathogenesis of multiple conditions, including aging, inflammation and cancer. CD38 is overexpressed in several tumor cells and microenvironment tumoral cells, associated to migration, angiogenesis, cell invasion and progression of the disease. Thus, CD38 has been used as a progression marker for different cancer types as well as in immunotherapy. This review focuses on describing the involvement of CD38 in various non-hematopoietic cancers.

CD38: A Significant Regulator of Macrophage Function

Cluster of differentiation 38 (CD38) is a cell surface glycoprotein and multifunctional extracellular enzyme. As a NADase, CD38 produces adenosine through the adenosine energy pathway to cause immunosuppression. As a cell surface receptor, CD38 is necessary for immune cell activation and proliferation. The aggregation and polarization of macrophages are affected by the knockout of CD38. Intracellular NAD⁺ levels are reduced by nuclear receptor liver X receptor-alpha (LXR) agonists in a CD38-dependent manner, thereby reducing the infection of macrophages. Previous studies suggested that CD38 plays an important role in the regulation of macrophage function. Therefore, as a new marker of macrophages, the effect of CD38 on macrophage proliferation, polarization and function; its possible mechanism; the relationship between the expression level of CD38 on macrophage surfaces and disease diagnosis, treatment, etc; and the role of targeting CD38 in macrophage-related diseases are reviewed in this paper to provide a theoretical basis for a comprehensive understanding of the relationship between CD38 and macrophages.

Antibody-drug conjugates: Resurgent anticancer agents with multi-targeted therapeutic potential

Antibody-drug conjugates (ADCs) constitute a relatively new group of anticancer agents, whose first appearance took place about two decades ago, but a renewed interest occurred in recent years, following the success of anti-cancer immunotherapy with monoclonal antibodies. Indeed, an ADC combines the selectivity of a monoclonal antibody with the cell killing properties of a chemotherapeutic agent (payload), joined together through an appropriate linker. The antibody moiety targets a specific cell surface antigen expressed by tumor cells and/or cells of the tumor microenvironment and acts as a carrier that delivers the cytotoxic payload within the tumor mass. Despite advantages in terms of selectivity and potency, the development of ADCs is not devoid of challenges, due to: i) low tumor selectivity when the target antigens are not exclusively expressed by cancer cells; ii) premature release of the cytotoxic drug into the bloodstream as a consequence of linker instability; iii) development of tumor resistance mechanisms to the payload. All these factors may result in lack of efficacy and/or in no safety improvement compared to unconjugated cytotoxic agents. Nevertheless, the development of antibodies engineered to remain inert until activated in the tumor (e.g., antibodies activated proteolytically after internalization or by the acidic conditions of the tumor microenvironment) together with the discovery of innovative targets and cytotoxic or immunomodulatory payloads, have allowed the design of next-generation ADCs that are expected to possess improved therapeutic properties. This review provides an overview of approved ADCs, with related advantages and limitations, and of novel targets exploited by ADCs that are presently under clinical investigation.

X-ray Crystallography-Guided Design, Antitumor Efficacy, and QSAR Analysis of Metabolically Stable Cyclopenta-Pyrimidinyl Dihydroquinoxalinone as a Potent Tubulin Polymerization Inhibitor

Small molecules that interact with the colchicine binding site in tubulin have demonstrated therapeutic efficacy in treating cancers. We report the design, syntheses, and antitumor efficacies of new analogues of pyridopyrimidine and hydroquinoxalinone compounds with improved drug-like characteristics. Eight analogues, 5j, 5k, 5l, 5m, 5n, 5r, 5t, and 5u, showed significant improvement in metabolic stability and demonstrated strong antiproliferative potency in a panel of human cancer cell lines, including melanoma, lung cancer, and breast cancer. We report crystal structures of tubulin in complex with five representative compounds, 5j, 5k, 5l, 5m, and 5t, providing direct confirmation for their binding to the colchicine site in tubulin. A quantitative structure-activity relationship analysis of the synthesized analogues showed strong ability to predict potency. In vivo, 5m (4 mg/kg) and 5t (5 mg/kg) significantly inhibited tumor growth as well as melanoma spontaneous metastasis into the lung and liver against a highly paclitaxel-resistant A375/TxR xenograft model.

CD38 and Regulation of the Immune Response Cells in Cancer

Cancer is a leading cause of death worldwide. Understanding the functional mechanisms associated with metabolic reprogramming, which is a typical feature of cancer cells, is key to effective therapy. CD38, primarily a NAD + glycohydrolase and ADPR cyclase, is a multifunctional transmembrane protein whose abnormal overexpression in a variety of tumor types is associated with cancer progression. It is linked to VEGFR2 mediated angiogenesis and immune suppression as it favors the recruitment of suppressive immune cells like Tregs and myeloid-derived suppressor cells, thus helping immune escape. CD38 is expressed in M1 macrophages and in neutrophil and T cell-mediated immune response and is associated with IFNγ-mediated suppressor activity of immune responses. Targeting CD38 with anti-CD38 monoclonal antibodies in hematological malignancies has shown excellent results. Bearing that in mind, targeting CD38 in other nonhematological cancer types, especially carcinomas, which are of epithelial origin with specific anti-CD38 antibodies alone or in combination with immunomodulatory drugs, is an interesting option that deserves profound consideration.

Prognostic value of tumor-infiltrating B lymphocytes and plasma cells in triple-negative breast cancer

Background

Recent investigations have demonstrated that the tumor microenvironment, including tumor-infiltrating lymphocytes (TILs), is an important factor in tumor growth and development. While the prognostic correlation of tumor-infiltrating T cells has been widely studied in breast cancer, that of tumor-infiltrating B cells and plasma cells has not received so much attention, especially in triple-negative breast cancer (TNBC).

Methods

We investigated 114 patients with TNBC who had surgery between 2006 and 2019 at Dokkyo Medical University Hospital. Intratumoral (i) TILs were considered to be lymphocytes within cancer cell nests and directly infiltrating tumor cells. Similarly, stromal (s) TILs were considered to be lymphocytes within the tumor stroma, but not directly infiltrating tumor cells. CD20 + , CD38 + and CD138 + staining was determined by estimating the number of positive B cells.

Results

sCD20 + TILs had prognostic significance for relapse-free survival (RFS) (p = 0.043) and overall survival (OS) (p = 0.027). The sCD38 + TILs were significantly related to favorable RFS (p = 0.042). iCD38, iCD138, and sCD138 was not significantly correlated with RFS (p = 0.065, p = 0.719, p = 0.074) or OS (p = 0.071, p = 0.689, p = 0.082).

Conclusions

The present study demonstrated that a high density of sCD20 + TILs was significantly related to favorable prognosis in both RFS and OS. Increased sCD38 + TILs in TNBC were correlated with a significantly favorable prognosis in RFS. These results indicate that TILs–B may have a profound influence on the clinical outcome of TNBC.

Constitutive low expression of antiviral effectors sensitizes melanoma cells to a novel oncolytic virus

STAT1 is a critical effector and a target gene of interferon (IFN) signaling, and thus a central mediator of antiviral responses. As both a mediator and a target of IFN signals, STAT1 expression reports on, and determines IFN activity. Gene expression analyses of melanoma patient samples revealed varied levels of STAT1 expression, which highly correlated with expression of >700 genes. The ability of oncolytic viruses to exploit tumor-induced defects to antiviral responses suggests that oncolytic viruses may efficiently target a subset of melanomas, yet these should be defined. We modeled this scenario with murine B16F10 melanomas, immortalized skin fibroblasts as controls and a novel oncolytic virus, EHDV-TAU. In B16F10 cells, constitutive low expression of STAT1 and its target genes, which included intracellular pattern recognition receptors (PRRs), correlated with their inability to mount IFN-based antiviral responses upon EHDV-TAU challenge, and with potency of EHDV-TAU-induced oncolysis. This underexpression of interferon stimulated genes (ISGs) and PRRs, and the inability of EHDV-TAU to induce their expression, were reversed by epigenetic modifiers, suggesting epigenetic silencing as a basis for their underexpression. Despite their inability to mount IFN/STAT-based responses upon viral infection, EHDV-TAU infected B16F10 cells secreted immune-stimulatory chemokines. Accordingly, in vivo, EHDV-TAU enhanced intratumoral infiltration of cytotoxic T-cells and reduced growth of local and distant tumors. We propose that "STAT1 signatures" should guide melanoma virotherapy treatments, and that oncolytic viruses such as EHDV-TAU have the potential to exploit the cellular context of low-STAT1 tumors.

CD38 in cancer-associated fibroblasts promotes pro-tumoral activity

Primary and metastatic melanoma progression are supported by a local microenvironment comprising, inter alia, of cancer-associated fibroblasts (CAFs). We previously reported in orthotropic/syngeneic mouse models that the stromal ectoenzyme CD38 participates in melanoma growth and metastasis. The results presented here suggest that CD38 is a novel regulator of CAFs' pro-tumorigenic functions. Orthotopic co-implantation of CD38 deficient fibroblasts and B16F10 melanoma cells limited tumor size, compared with CD38-expressing fibroblasts. Intrinsically, CAF-CD38 promoted migration of primary fibroblasts toward melanoma cells. Further, in vitro paracrine effects of CAF-CD38 fostered tumor cell migration and invasion as well as endothelial cell tube formation. Mechanistically, we report that CAF-CD38 drives the protein expression of an angiogenic/pro-metastatic signature, which includes VEGF-A, FGF-2, CXCL-12, MMP-9, and HGF. Data suggest that CAF-CD38 fosters tumorigenesis by enabling the production of pro-tumoral factors that promote cell invasion, migration, and angiogenesis.

Host CD39 Deficiency Affects Radiation-Induced Tumor Growth Delay and Aggravates Radiation-Induced Normal Tissue Toxicity

The ectonucleoside triphosphate diphosphohydrolase (CD39)/5′ ectonuclotidase (CD73)-dependent purinergic pathway emerges as promising cancer target. Yet, except for own previous work revealing a pathogenic role of CD73 and adenosine in radiation-induced lung fibrosis, the role of purinergic signaling for radiotherapy outcome remained elusive. Here we used C57BL/6 wild-type (WT), CD39 knockout (CD39^−/−), and CD73 knockout (CD73^−/−) mice and hind-leg tumors of syngeneic murine Lewis lung carcinoma cells (LLC1) to elucidate how host purinergic signaling shapes the growth of LLC1 tumors to a single high-dose irradiation with 10 Gy in vivo. In complementary in vitro experiments, we examined the radiation response of LLC1 cells in combination with exogenously added ATP or adenosine, the proinflammatory and anti-inflammatory arms of purinergic signaling. Finally, we analyzed the impact of genetic loss of CD39 on pathophysiologic lung changes associated with lung fibrosis induced by a single-dose whole-thorax irradiation (WTI) with 15 Gy. Loss of CD73 in the tumor host did neither significantly affect tumor growth nor the radiation response of the CD39/CD73-negative LLC1 tumors. In contrast, LLC1 tumors exhibited a tendency to grow faster in CD39^−/− mice compared to WT mice. Even more important, tumors grown in the CD39-deficient background displayed a significantly reduced tumor growth delay upon irradiation when compared to irradiated tumors grown on WT mice. CD39 deficiency caused only subtle differences in the immune compartment of irradiated LLC1 tumors compared to WT mice. Instead, we could associate the tumor growth and radioresistance-promoting effects of host CD39 deficiency to alterations in the tumor endothelial compartment. Importantly, genetic deficiency of CD39 also augmented the expression level of fibrosis-associated osteopontin in irradiated normal lungs and exacerbated radiation-induced lung fibrosis at 25 weeks after irradiation. We conclude that genetic loss of host CD39 alters the tumor microenvironment, particularly the tumor microvasculature, and thereby promotes growth and radioresistance of murine LLC1 tumors. In the normal tissue loss of host, CD39 exacerbates radiation-induced adverse late effects. The suggested beneficial roles of host CD39 on the therapeutic ratio of radiotherapy suggest that therapeutic strategies targeting CD39 in combination with radiotherapy have to be considered with caution.

Identification of CD38 as a potential biomarker in skin cutaneous melanoma using bioinformatics analysis

Skin cutaneous melanoma (SKCM) is the most aggressive type of skin cancer, with a high rate of metastasis and mortality; however, identification of biomarkers for the treatment of SKCM is required. Cluster of differentiation (CD)38 has emerged as an effective target for therapeutic drugs in several types of cancer, such as chronic lymphocytic leukemia and multiple myeloma. In the present study, to determine the contribution of CD38 to the diagnosis of SKCM, Gene Expression Profiling Interactive Analysis 2 and University of Alabama Cancer Database online tools were used to analyze The Cancer Genome Atlas-SKCM dataset. Moreover, Search Tool for the Retrieval of Interacting Genes/Proteins and GeneMANIA databases were used to determine protein-protein interaction networks and potential functions. To the best of our knowledge, the results of the present study indicated for the first time that high expression levels of CD38 were a favorable diagnostic factor for SKCM. Moreover, a correlation between CD38 expression levels and the survival probability of patients with SKCM was identified. Integrative analysis predicted that nine genes were correlated with CD38 in SKCM, and the similarity of these genes in SKCM expression and a survival heatmap was verified. Gene ontology enrichment analysis using the Metascape tool revealed that CD38 and its correlated genes were significantly enriched in lymphocyte activation and T cell differentiation regulation. Collectively, the bioinformatics analysis revealed that CD38 might serve as a potential diagnostic predictor for SKCM.

The Roles of CD38 and CD157 in the Solid Tumor Microenvironment and Cancer Immunotherapy

The tumor microenvironment (TME) consists of extracellular matrix proteins, immune cells, vascular cells, lymphatics and fibroblasts. Under normal physiological conditions, tissue homeostasis protects against tumor development. However, under pathological conditions, interplay between the tumor and its microenvironment can promote tumor initiation, growth and metastasis. Immune cells within the TME have an important role in the formation, growth and metastasis of tumors, and in the responsiveness of these tumors to immunotherapy. Recent breakthroughs in the field of cancer immunotherapy have further highlighted the potential of targeting TME elements, including these immune cells, to improve the efficacy of cancer prognostics and immunotherapy. CD38 and CD157 are glycoproteins that contribute to the tumorigenic properties of the TME. For example, in the hypoxic TME, the enzymatic functions of CD38 result in an immunosuppressive environment. This leads to increased immune resistance in tumor cells and allows faster growth and proliferation rates. CD157 may also aid the production of an immunosuppressive TME, and confers increased malignancy to tumor cells through the promotion of tumor invasion and metastasis. An improved understanding of CD38 and CD157 in the TME, and how these glycoproteins affect cancer progression, will be useful to develop both cancer prognosis and treatment methods. This review aims to discuss the roles of CD38 and CD157 in the TME and cancer immunotherapy of a range of solid tumor types.