Ecto-5'-nucleotidase (CD73): an emerging role as prognostic factor in allergic sensitization

Over the years, the importance of the epithelium in the assessment of allergic sensitization and development of allergic diseases has increased. Sensitization to allergens appears to be influenced by genetic and external environmental factors. However, not all subjects exposed to environmental factors that damage epithelial cells suffer from allergic diseases. On this basis, identifying the signaling pathways that characterize the different phenotypes and endotypes of allergy is of high priority for a successful personalized therapy. Ecto-5'-nucleotidase/CD73 is a membrane-bound enzyme responsible for extracellular adenosine accumulation from AMP derived, in turn, from the hydrolysis of extracellular ATP. Current knowledge suggests that CD73 expression and enzymatic activity at epithelial barriers would be of fundamental importance to control the first defense against allergens, by preserving both physical and immunological epithelial barrier functions. Here, we highlight evidence for a crucial role of CD73 in features of allergic sensitization and the potential of this enzyme as prognostic marker and target of therapeutic intervention.

The CD73 is induced by TGF-β1 triggered by nutrient deprivation and highly expressed in dedifferentiated human melanoma

CD73 is the key enzyme in the generation of extracellular adenosine, a mediator involved in tumor progression, tumor immune escape and resistance to anti-cancer therapeutics. Microenvironmental conditions influence the expression of CD73 in tumor cells. However how CD73 expression and activity is regulated in a stress condition of lower nutrient availability are largely unknown. Our results indicate that serum starvation leads to a marked up-regulation of CD73 expression on A375 melanoma cells in a time-dependent manner. The cell-surface expression of CD73 is associated with an increased release of TGF-β1 by starved cells. Blockade of TGF-β1 receptors or TGFβ/SMAD3 signaling pathway significantly reduce the expression of CD73 induced by starvation. Treatment of cells with rTGF-β1 up-regulates the expression of CD73 in a concentration-dependent manner, confirming the role of this pathway in regulating CD73 in melanoma A375 cells. The increased expression of CD73 is associated with enhanced AMPase activity, which is selectively reduced by inhibitors of CD73 activity, APCP and PSB-12489. Pharmacological blockade of CD73 significantly inhibits invasion of melanoma cells in a transwell system. Furthermore, using multiplex immunofluorescence imaging we found that, within human melanoma metastases, tumor cells at the dedifferentiated stage show the highest CD73 protein expression. In summary, our data provide new insights into the mechanism regulating the expression/activity of CD73 in melanoma cells in a condition of lower availability of nutrients, which is a common feature of the tumor microenvironment. Within human metastatic melanoma tissues elevated protein expression of CD73 is associated with an invasive-like phenotype.

Signaling Pathways in Inflammation and Its Resolution: New Insights and Therapeutic Challenges

Tissue inflammation is a dynamic process that develops step by step, in response to an injury, to preserve tissue integrity [...].

3D printed macroporous scaffolds of PCL and inulin-g-P(D,L)LA for bone tissue engineering applications

Bone repair and tissue-engineering (BTE) approaches require novel biomaterials to produce scaffolds with required structural and biological characteristics and enhanced performances with respect to those currently available. In this study, PCL/INU-PLA hybrid biomaterial was prepared by blending of the aliphatic polyester poly(ε-caprolactone) (PCL) with the amphiphilic graft copolymer Inulin-g-poly(D,L)lactide (INU-PLA) synthetized from biodegradable inulin (INU) and poly(lactic acid) (PLA). The hybrid material was suitable to be processed using fused filament fabrication 3D printing (FFF-3DP) technique rendering macroporous scaffolds. PCL and INU-PLA were firstly blended as thin films through solvent-casting method, and then extruded by hot melt extrusion (HME) in form of filaments processable by FFF-3DP. The physicochemical characterization of the hybrid new material showed high homogeneity, improved surface wettability/hydrophilicity as compared to PCL alone, and right thermal properties for FFF process. The 3D printed scaffolds exhibited dimensional and structural parameters very close to those of the digital model, and mechanical performances compatible with the human trabecular bone. In addition, in comparison to PCL, hybrid scaffolds showed an enhancement of surface properties, swelling ability, and in vitro biodegradation rate. In vitro biocompatibility screening through hemolysis assay, LDH cytotoxicity test on human fibroblasts, CCK-8 cell viability, and osteogenic activity (ALP evaluation) assays on human mesenchymal stem cells showed favorable results.

The combination of mesoglycan and VEGF promotes skin wound repair by enhancing the activation of endothelial cells and fibroblasts and their cross-talk

Skin wound healing requires accurate therapeutic topical managements to accelerate tissue regeneration. Here, for the first time, we found that the association mesoglycan/VEGF has a strong pro-healing activity. In detail, this combination induces angiogenesis in human endothelial cells promoting in turn fibroblasts recruitment. These ones acquire a notable ability to invade the matrigel coating and to secrete an active form of metalloproteinase 2 in presence of endothelial cells treated with mesoglycan/VEGF. Next, by creating intrascapular lesions on the back of C57Bl6 mice, we observed that the topical treatments with the mesoglycan/VEGF promotes the closure of wounds more than the single substances beside the control represented by a saline solution. As revealed by eosin/hematoxylin staining of mice skin biopsies, treatment with the combination mesoglycan/VEGF allows the formation of a well-structured matrix with a significant number of new vessels. Immunofluorescence analyses have revealed the presence of endothelial cells at the closed region of wounds, as evaluated by CD31, VE-cadherin and fibronectin staining and of activated fibroblasts assessed by vimentin, col1A and FAP1α. These results encourage defining the association mesoglycan/VEGF to activate endothelial and fibroblast cell components in skin wound healing promoting the creation of new vessels and the deposition of granulation tissue.

A2A Receptor Contributes to Tumor Progression in P2X7 Null Mice

ATP and adenosine are key constituents of the tumor niche where they exert opposite and complementary roles. ATP can be released in response to cell damage or actively released by tumor cells and subsequently degraded into adenosine, which accumulates within the tumor microenvironment. Notably, while ATP promotes immune eradicating responses mainly via the P2X7 receptor (P2X7R), extracellular adenosine acts as a potent immune suppressor and facilitates neovascularization thanks to the A2A receptor (A2AR). To date, studies exploring the interplay between P2X7R and A2AR in the tumor microenvironment are as yet missing. Here, we show that, in C57/bl6 P2X7 null mice inoculated with B16-F10 melanoma cells, several pro-inflammatory cytokines, including interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin 12 (IL-12), interleukin 17 (IL-17), interferon gamma (IFN-γ) were significantly decreased, while the immune suppressant transforming growth factor beta (TGF-β) was almost three-fold increased. Interestingly, tumors growing in P2X7-null mice upregulated tumor-associated and splenic A2AR, suggesting that immunosuppression linked to lack of the P2X7R might depend upon A2AR overexpression. Immunohistochemical analysis showed that tumor cells’ A2AR expression was increased, especially around necrotic areas, and that vascular endothelial growth factor (VEGF) and the endothelial marker CD31 were upregulated. A2AR antagonist SCH58261 treatment reduced tumor growth similarly in the P2X7 wild type or null mice strain. However, SCH58261 reduced VEGF only in the P2X7 knock out mice, thus supporting the hypothesis of an A2AR-mediated increase in vascularization observed in the P2X7-null host. SCH58261 administration also significantly reduced intratumor TGF-β levels, thus supporting a key immune suppressive role of A2AR in our model. Altogether, these results indicate that in the absence of host P2X7R, the A2AR favors tumor growth via immune suppression and neovascularization. This study shows a novel direct correlation between P2X7R and A2AR in oncogenesis and paves the way for new combined therapies promoting anti-cancer immune responses and reducing tumor vascularization.

Lack of Ecto-5′-Nucleotidase Protects Sensitized Mice against Allergen Challenge

Ecto-5′-nucleotidase (CD73), the ectoenzyme that together with CD39 is responsible for extracellular ATP hydrolysis and adenosine accumulation, regulates immune/inflammatory processes by controlling innate and acquired immunity cell functions. We previously demonstrated that CD73 is required for the assessment of a controlled allergic sensitization, in mice. Here, we evaluated the response to aerosolized allergen of female-sensitized mice lacking CD73 in comparison with their wild type counterpart. Results obtained show, in mice lacking CD73, the absence of airway hyperreactivity in response to an allergen challenge, paralleled by reduced airway CD23⁺B cells and IL4⁺T cells pulmonary accumulation together with reduced mast cells accumulation and degranulation. Our findings indicate CD73 as a potential therapeutic target for allergic asthma.

Exosomal CD73 from serum of patients with melanoma suppresses lymphocyte functions and is associated with therapy resistance to anti-PD-1 agents

BACKGROUND

CD73 is an ectonucleotidase producing the immunosuppressor mediator adenosine. Elevated levels of circulating CD73 in patients with cancer have been associated with disease progression and poor response to immunotherapy. Immunosuppressive pathways associated with exosomes can affect T-cell function and the therapeutic efficacy of anti-programmed cell-death protein 1 (anti-PD-1) therapy. Here, we conducted a retrospective pilot study to evaluate levels of exosomal CD73 before and early during treatment with anti-PD-1 agents in patients with melanoma and its potential contribution to affect T-cell functions and to influence the clinical outcomes of anti-PD-1 monotherapy.

METHODS

Exosomes were isolated by mini size exclusion chromatography from serum of patients with melanoma (n=41) receiving nivolumab or pembrolizumab monotherapy. Expression of CD73 and programmed death-ligand 1 (PD-L1) were evaluated on exosomes enriched for CD63 by on-bead flow cytometry. The CD73 AMPase activity was evaluated by mass spectrometry, also in the presence of selective inhibitors of CD73. Interferon (IFN)-γ production and granzyme B expression were measured in CD3/28 activated T cells incubated with exosomes in presence of the CD73 substrate AMP. Levels of CD73 and PD-L1 on exosomes were correlated with therapy response. Exosomes isolated from healthy subjects were used as control.

RESULTS

Isolated exosomes carried CD73 on their surface, which is enzymatically active in producing adenosine. Incubation of exosomes with CD3/28 activated T cells in the presence of AMP resulted in a significant reduction of IFN-γ release, which was reversed by the CD73 inhibitor APCP or by the selective A2A adenosine receptor antagonist ZM241385. Expression levels of exosomal CD73 from serum of patients with melanoma were not significantly different from those in healthy subjects. Early on-treatment, expression levels of both CD73 and PD-L1 on exosomes isolated from patients receiving pembrolizumab or nivolumab monotherapy were significantly increased compared with baseline. Early during therapy exosomal PD-L1 increased in responders, while exosomal CD73 resulted significantly increased in non-responders.

CONCLUSIONS

CD73 expressed on exosomes from serum of patients with melanoma produces adenosine and contributes to suppress T-cell functions. Early on-treatment, elevated expression levels of exosomal CD73 might affect the response to anti-PD-1 agents in patients with melanoma who failed to respond to therapy.

Serum CD73 is a prognostic factor in patients with metastatic melanoma and is associated with response to anti-PD-1 therapy

Background

Inhibitors of immune checkpoint programmed cell death protein 1 (PD-1) receptor on T cells have shown remarkable clinical outcomes in metastatic melanoma. However, most patients are resistant to therapy. Production of extracellular adenosine, via CD73-mediated catabolism of AMP, contributes to suppress T-cell-mediated responses against cancer. In this study, we analyzed the expression and activity of soluble CD73 in sera of patients with melanoma undergoing anti-PD-1± cytotoxic T-lymphocyte-associated antigen 4 therapy.

Methods

Soluble CD73 expression and activity were retrospectively analyzed in serum of a total of 546 patients with melanoma from different centers before starting treatment (baseline) with anti-PD-1 agents, nivolumab or pembrolizumab, and compared with those of 96 healthy subjects. The CD73 activity was correlated with therapy response and survival of patients.

Results

Patients with melanoma show significantly higher CD73 activity and expression than those observed in healthy donors (p<0.0001). Elevated pretreatment levels of CD73 activity were associated with non-response to therapy with nivolumab or pembrolizumab. During treatment, levels of soluble CD73 activity remain unchanged from baseline and still stratify clinical responders from non-responders. High levels of serum CD73 enzymatic activity associate with reduced overall survival (OS; HR=1.36, 95% CI 1.03 to 1.78; p=0.03) as well as progression-free survival (PFS; HR=1.42, 95% CI 1.13 to 1.79, p=0.003). Further, the multivariate Cox regression analysis indicates that serum CD73 activity is an independent prognostic factor besides serum lactate dehydrogenase levels and the presence of brain metastases for both OS (p=0.009) and PFS (p=0.001).

Conclusion

Our data indicate the relevance of serum CD73 in patients with advanced melanoma receiving anti-PD-1 therapy and support further investigation on targeting CD73 in combination with anti-PD-1 antibodies.

Adenosine Signaling in the Tumor Microenvironment

Adenosine, deriving from ATP released by dying cancer cells and then degradated in the tumor environment by CD39/CD73 enzyme axis, is linked to the generation of an immunosuppressed niche favoring the onset of neoplasia. Signals delivered by extracellular adenosine are detected and transduced by G-protein-coupled cell surface receptors, classified into four subtypes: A₁, A_2A, A_2B, and A₃. A critical role of this nucleoside is emerging in the modulation of several immune and nonimmune cells defining the tumor microenvironment, providing novel insights about the development of novel therapeutic strategies aimed at undermining the immune-privileged sites where cancer cells grow and proliferate.

Exacerbation of Allergic Airway Inflammation in Mice Lacking ECTO-5'-Nucleotidase (CD73)

The airways are a target tissue of type I allergies and atopy is the main etiological factor of bronchial asthma. A predisposition to allergy and individual response to allergens are dependent upon environmental and host factors. Early studies performed to clarify the role of extracellular adenosine in the airways highlighted the importance of adenosine-generating enzymes CD73, together with CD39, as an innate protection system against lung injury. In experimental animals, deletion of CD73 has been associated with immune and autoimmune diseases. Our experiments have been performed to investigate the role of CD73 in the assessment of allergic airway inflammation following sensitization. We found that in CD73^−/− mice sensitization, induced by subcutaneous ovalbumin (OVA) administration, increased signs of airway inflammation and atopy developed, characterized by high IgE plasma levels and increased pulmonary cytokines, reduced frequency of lung CD4⁺CD25+Foxp3+ T cells, but without bronchial hyperreactivity, compared to sensitized wild type mice. Our results provide evidence that the lack of CD73 causes an uncontrolled allergic sensitization, suggesting that CD73 is a key molecule at the interface between innate and adaptive immune response. The knowledge of host immune factors controlling allergic sensitization is of crucial importance and might help to find preventive interventions that could act before an allergy develops.

Abstract 4517: Targeting Notch1 via adenosine A2A receptor to modulate tumor immunity

One of the hallmarks of cancer is the ability to evade the host immune system and this is achieved through different mechanisms. Several studies have showed that the accumulation of adenosine in the tumor microenvironment suppresses T-cell functions, thus helping the tumor to evade the immune system. Finding a way to counteract adenosine-mediated immune suppression might greatly enhance the host endogenous immune response against cancer and the efficacy of adoptive immunotherapies. To achieve this, we need to understand how adenosine regulates T-cell functions. In a collaborative project, our group recently showed that stimulation of adenosine A2A receptor (A2AR) reduces T-cell receptor (TCR)-signaling and consequently Notch1 activation and expression in CD8+ T-cells, which are critical to cancer immunity. This suggests that A2AR stimulation suppresses CD8+ T-cell function through inhibition of TCR-induced Notch1, which is required for the activation and function of CD8+ T-cells. Based on these observations, we hypothesized that while stimulation of A2AR suppresses CD8+ T-cells, inhibition of A2AR should protect CD8+ T-cells from the adenosine-mediated immune suppression. Notch1 is likely to be critical in this process since it was shown that ectopic expression of Notch1 intracellular domain prevents the adenosine-mediated immune suppression in CD8+ T-cells. Therefore, we aim to investigate the effect of A2AR inhibition on TCR activation and Notch1 to evaluate the A2AR-Notch axis as a novel immunotherapeutic target. Our data show that pharmacological inhibition of A2AR with a selective antagonist induces tumor cell death and increases the number of CD8+ T-cells in tumor-derived spheroids from a mouse triple-negative breast cancer (TNBC) model. The effect of A2AR inhibition appears to be immune-mediated since the same agent did not induce cell death in tumor-derived spheroids from immunocompromised mice. Along the same lines, we show that, inhibition of A2AR restored Notch1 activation and proliferation in primary murine CD8+ T-cells, but did not affect Notch1 and proliferation in TNBC cell lines. This effect is likely to be strictly dependent on Notch since A2AR inhibition failed to rescue CD8+ T-cell proliferation from the suppressive effect of gamma-secretase inhibition. It is not yet known how A2AR regulates Notch1, however, our latest preliminary results suggest that A2AR stimulation might promote the endosomal degradation of Notch1, whereas, A2AR inhibition might switch Notch1 fate from endosomal degradation to activation. Further investigation is needed to establish how A2AR regulates Notch1 and whether A2AR inhibition can protect CD8+ T-cell function in vivo in the tumor microenvironment. Overall our current data provides a rationale for the evaluation of A2AR antagonists as a Notch-modulating immunotherapy.

Citation Format: Giulia Monticone, Fokhrul M. Hossain, Deniz A. Ucar, Samarpan Majumder, Claudia Sorrentino, Paulo C. Rodriguez, Rosa A. Sierra, Antonio Pannuti, Stephen Hatfield, Barbara A. Osborne, Lisa M. Minter, Silvana Morello, Lucio Miele. Targeting Notch1 via adenosine A2A receptor to modulate tumor immunity [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4517.

Frequency of circulating CD8+CD73+T cells is associated with survival in nivolumab-treated melanoma patients

BACKGROUND

PD-1 blocking agents, such as nivolumab, have demonstrated clear anti-tumor effects and clinical benefits in a subset of patients with advanced malignancies. Nonetheless, more efforts are needed to identify reliable biomarkers for outcome, to correctly select patients who will benefit from anti-PD-1 treatment. The aim of this study was to investigate the role of peripheral CD8+T cells expressing CD73, involved in the generation of the immune suppressive molecule adenosine, in predicting outcome after nivolumab treatment in advanced melanoma patients.

METHODS

PBMCs from 100 melanoma patients treated with nivolumab were collected at National Cancer Institute "G. Pascale" of Naples. Frequencies of CD8+ lymphocytes phenotypes were assessed by flow cytometry at baseline before nivolumab treatment, along with clinical characteristics and blood count parameters. Healthy controls (n = 20) were also analysed. Percentages of baseline T cells expressing PD-1 and CD73 were correlated with outcome after nivolumab treatment.

RESULTS

Melanoma patients presented a lower frequency of total circulating CD8+ lymphocytes than control subjects (p = 0.008). Patients with low baseline percentage of circulating CD8+PD-1+CD73+ lymphocytes (< 2.3%) had better survival (22.4 months vs 6.9 months, p = 0.001). Patients (39%) with clinical benefit from nivolumab therapy presented a significantly lower frequency of circulating CD8+PD-1+CD73+ lymphocytes than patients who progressed to nivolumab treatment (p = 0.02).

CONCLUSIONS

Our observations suggest that baseline CD73 expression on circulating CD8+PD-1+ lymphocytes appear a promising biomarker of response to anti-PD-1 treatment in melanoma patients. Further investigations are needed for validation and for clarifying its role as prognostic or predictive marker.

Zinc and Calcium Cations Combination in the Production of Floating Alginate Beads as Prednisolone Delivery Systems

The aim of this research was to verify the application of alginate in combination with Ca²⁺ and Zn²⁺ ions to produce a floating and prolonged release system for the oral administration of prednisolone. Hollow and floating gel-beads were designed using prilling/ionotropic gelation as the microencapsulation technique, zinc acetate in the gelling solution as the alginate external crosslinker, and calcium carbonate in the feed as the internal crosslinking agent able to generate gas when in contact with the acidic zinc acetate solution. To achieve this goal, drug/alginate solutions were opportunely combined with different amounts of calcium carbonate. The effect of the addition of calcium carbonate into the feed solution on buoyancy, encapsulation efficiency, morphology, size distribution, as well as in vitro drug release profile of the alginate particles was studied. Moreover, the ability of the floating beads to modulate in vivo the anti-inflammatory response was assayed using the carrageenan-induced acute oedema in rat paw. The proposed strategy allowed obtaining alginate beads with extremely high encapsulation efficiency values (up to 94%) and a very porous inner matrix conferring buoyancy in vitro in simulated gastric fluid up to 5 h. Moreover, in vivo, the best formulation, F4, resulted in the ability to prolong the anti-inflammatory effect up to 15 h compared with raw prednisolone.

Low copper availability limits Helicobacter infection in mice

Copper is an essential element for all living organisms; however, it becomes toxic at high concentrations due to its ability to participate in many redox reactions. This vital micronutrient balance plays an important role in the battle between host and pathogen, due to its use by the host to intoxicate pathogens. In this study, we explore the effects of copper deprivation on Helicobacter infection in mice using the copper chelator tetrathiomolybdate. Our results reveal that Helicobacter infection significantly reduces copper concentration in mice stomachs without affecting its circulating levels. Moreover, in copper-deprived mice, bacteria hardly colonize the epithelium and mice show less gastric damage in comparison with the infected ones. However, when the copper chelator is administered after infection, the condition of the mouse stomachs declines. This could be explained by the lower copper availability in tetrathiomolybdate-treated mice, which would reduce macrophages' action against the pathogen. In this scenario, we observe that the protective factor trefoil factor 1 is induced upon copper-deprived conditions, probably contributing to the inefficacy of infection, whereas, when the chelator is administered after infection, the gene is already silenced by bacteria and cannot be restored. In conclusion, our data suggest that Helicobacter takes advantage of gastric copper reducing its availability for the host and that copper levels have an impact on the outcome of infection.

The Ecto-5'-Nucleotidase/CD73 Inhibitor, α,β-Methylene Adenosine 5'-Diphosphate, Exacerbates Carrageenan-Induced Pleurisy in Rat

The ecto-5’-nucleotidase (ecto-5’NT/CD73) represents a crucial enzyme for endogenous adenosine generation. Several findings have shown that CD73 plays an important role in regulating vascular permeability and immune cell function. Adenosine 5’-(α,β-methylene)diphosphate (APCP) is a CD73 inhibitor, widely used as pharmacological tool to investigate the role of CD73/adenosine pathway in several in vitro and in vivo models, although it has been also shown to inhibit other ectoenzymes involved in adenosinergic pathway. Here, we evaluated the effect of APCP in the development of inflammation in carrageenan-induced pleurisy model. We found that treatment with APCP (400 µg/rat) significantly increased cell accumulation, exudate formation, and pro-inflammatory cytokine content into the pleural cavity in the acute phase (4 h) of inflammation, with no differences in the sub-acute phase (72 h) except for the regulation of monocyte chemotactic protein-1 levels. In addition, cells collected by pleural lavage fluids of APCP-treated rats, 4 h following carrageenan injection, showed increased ability to migrate in vitro, both in presence and in absence of N-formyl-L-methionyl-L-leucyl-L-phenylalanine as chemotactic stimulus, compared to cells obtained by control rats. Our results demonstrate that APCP exacerbates the early phase of carrageenan-induced pleurisy by controlling pleural effusion and polymorphonuclear migration in vivo and ex vivo. This effect is likely dependent upon CD73 inhibition, although an inhibitory effect of other ectoenzymes cannot be ruled out.

Enzyme activity of circulating CD73 in human serum

CD73 is an ectonucleotidase able to catabolize 5'-adenosine monophosphate (AMP) into adenosine at the extracellular level. Extracellular adenosine plays a critical role in regulating many processes under physiological and pathological conditions. In the context of cancer, the expression and activity of CD73, either in tissue and in biological fluids, is increased leading to high levels of adenosine that potently suppress T-cell mediated responses, promoting tumor progression through stimulation of adenosine receptors. Compelling evidence indicates that elevated levels of CD73-generating adenosine limit the efficacy of cancer immunotherapy. Inhibitors of ectonucleotidases and antagonists of adenosine receptors have emerged as new therapeutic tools to improve anti-tumor immune response and potentially synergize with currently used immunotherapeutic agents. Measurement of CD73 levels in serum of cancer patients is a promising approach that, although it needs to be validated, may help to select patients who will benefit from adenosine-targeting agents and predict response to immunotherapy. Here, we describe a simple and fast method to evaluate the AMPase activity of CD73 in peripheral blood that may also be applied to other biological fluids.

Adenosine A2A Receptor Stimulation Inhibits TCR-Induced Notch1 Activation in CD8+T-Cells

Notch receptors signaling is required for optimal T-cell activation and function. T-cell receptor (TCR) engagement can activate Notch receptors in T-cells in a ligand-independent fashion. In this study, we examined the role of adenosine A2A receptor (A2AR) signaling pathway in regulating the activity of Notch1 induced by TCR stimulation in CD8+T-cells. A selective A2AR agonist decreased Notch1 protein expression and Notch1 cleavage, and reduced transcripts of Notch1-target genes Hes1 and Myc in activated CD8+T-cells. Inhibition of TCR-induced Notch1 expression by an A2AR agonist was accompanied by increased cAMP concentration and mimicked by forskolin. This effect was associated with reduced IFN-γ and granzyme B production. The effect of an A2AR agonist was abrogated by a selective A2AR antagonist and absent in CD8+T-cells harvested from A2AR-/- mice. Stimulation of A2AR reduced Notch1 receptor levels by inhibiting upstream TCR signals, including ZAP70 phosphorylation, in turn impairing the generation of the active Notch1 intracellular domain (N1ICD). Direct activation of PKC with PMA and ionomycin bypassed A2AR-induced Notch1 inhibition. Overexpression of N1ICD in CD8+T-cells prevented the suppressive effects of an A2AR agonist on proliferation and cytokine release during activation. Our results identify the A2AR signaling pathway as an important regulator of TCR-induced Notch1 receptor activation in CD8+T-cells, and Notch as an important target of the immune suppressive effects of A2AR. We propose a mechanism whereby A2AR impairs CD8 T-cells function through inhibition of Notch1 receptor activation.

Notch Signaling Regulates Mitochondrial Metabolism and NF-κB Activity in Triple-Negative Breast Cancer Cells via IKKα-Dependent Non-canonical Pathways

Triple negative breast cancer (TNBC) patients have high risk of recurrence and metastasis, and current treatment options remain limited. Cancer stem-like cells (CSCs) have been linked to cancer initiation, progression and chemotherapy resistance. Notch signaling is a key pathway regulating TNBC CSC survival. Treatment of TNBC with PI3K or mTORC1/2 inhibitors results in drug-resistant, Notch-dependent CSC. However, downstream mechanisms and potentially druggable Notch effectors in TNBC CSCs are largely unknown. We studied the role of the AKT pathway and mitochondrial metabolism downstream of Notch signaling in TNBC CSC from cell lines representative of different TNBC molecular subtypes as well as a novel patient-derived model. We demonstrate that exposure of TNBC cells to recombinant Notch ligand Jagged1 leads to rapid AKT phosphorylation in a Notch1-dependent but RBP-Jκ independent fashion. This requires mTOR and IKKα. Jagged1 also stimulates mitochondrial respiration and fermentation in an AKT- and IKK-dependent fashion. Notch1 co-localizes with mitochondria in TNBC cells. Pharmacological inhibition of Notch cleavage by gamma secretase inhibitor PF-03084014 in combination with AKT inhibitor MK-2206 or IKK-targeted NF-κB inhibitor Bay11-7082 blocks secondary mammosphere formation from sorted CD90^hi or CD44⁺CD24^low (CSCs) cells. A TNBC patient-derived model gave comparable results. Besides mitochondrial oxidative metabolism, Jagged1 also triggers nuclear, NF-κB-dependent transcription of anti-apoptotic gene cIAP-2. This requires recruitment of Notch1, IKKα and NF-κB to the cIAP-2 promoter. Our observations support a model where Jagged1 triggers IKKα-dependent, mitochondrial and nuclear Notch1 signals that stimulate AKT phosphorylation, oxidative metabolism and transcription of survival genes in PTEN wild-type TNBC cells. These data suggest that combination treatments targeting the intersection of the Notch, AKT and NF-κB pathways have potential therapeutic applications against CSCs in TNBC cases with Notch1 and wild-type PTEN expression.

Activation of the A2B adenosine receptor in B16 melanomas induces CXCL12 expression in FAP-positive tumor stromal cells, enhancing tumor progression

The A2B receptor (A2BR) can mediate adenosine-induced tumor proliferation, immunosuppression and angiogenesis. Targeting the A2BR has proved to be therapeutically effective in some murine tumor models, but the mechanisms of these effects are still incompletely understood. Here, we report that pharmacologic inhibition of A2BR with PSB1115, which inhibits tumor growth, decreased the number of fibroblast activation protein (FAP)-expressing cells in tumors in a mouse model of melanoma. This effect was associated with reduced expression of fibroblast growth factor (FGF)-2. Treatment of melanoma-associated fibroblasts with the A2BR agonist Bay60-6583 enhanced CXCL12 and FGF2 expression. This effect was abrogated by PSB1115. The A2AR agonist CGS21680 did not induce CXCL12 or FGF2 expression in tumor associated fibroblasts. Similar results were obtained under hypoxic conditions in skin-derived fibroblasts, which responded to Bay60-6583 in an A2BR-dependent manner, by stimulating pERK1/2. FGF2 produced by Bay60-6583-treated fibroblasts directly enhanced the proliferation of melanoma cells. This effect could be reversed by PSB1115 or an anti-FGF2 antibody. Interestingly, melanoma growth in mice receiving Bay60-6583 was attenuated by inhibition of the CXCL12/CXCR4 pathway with AMD3100. CXCL12 and its receptor CXCR4 are involved in angiogenesis and immune-suppression. Treatment of mice with AMD3100 reduced the number of CD31+ cells induced by Bay60-6583. Conversely, CXCR4 blockade did not affect the accumulation of tumor-infiltrating MDSCs or Tregs. Together, our data reveal an important role for A2BR in stimulating FGF2 and CXCL12 expression in melanoma-associated fibroblasts. These factors contribute to create a tumor-promoting microenvironment. Our findings support the therapeutic potential of PSB1115 for melanoma.

Soluble CD73 as biomarker in patients with metastatic melanoma patients treated with nivolumab

Background

Nivolumab is an anti-PD1 checkpoint inhibitor active in patients with advanced melanoma and as adjuvant therapy in high-risk metastatic melanoma patients.

Methods

In this single-center retrospective analysis, we investigated the CD73 enzyme activity in patients with metastatic melanoma stage IV and its correlation with the response to nivolumab. The soluble CD73 (sCD73) enzyme activity was measured in the serum of 37 melanoma patients before receiving nivolumab and the Harrel’s C index was used to find the best cut-off for this biomarker. The multivariate Cox proportional hazard model was used to evaluate the prognostic value of CD73 enzyme activity for survival and progression-free survival.

Results

Our results show that high levels of sCD73 enzyme activity were significantly associated with poor overall survival and progression-free survival in patients with metastatic melanoma. The median progression–free survival was 2.6 months [95% confidence interval (CI) 1.9–3.3] in patients with high sCD73 enzyme activity (> 27.8 pmol/min/mg protein), and 14.2 months (95% CI 4.6–23.8) in patients with lower CD73 enzyme activity, when patients were follow-up for a median of 24 months range. The median overall survival was not reached in patients with low sCD73 activity (< 27.8 pmol/min/mg protein) compared with 6.1 months (95% CI 0–14.8) in patients with higher sCD73 activity. In multivariate analyses, the sCD73 enzyme activity emerged as the strongest prognostic factor for overall survival and progression-free survival. Elevated basal levels of sCD73 enzyme activity, before starting nivolumab treatment, were associated with lower response rates to therapy.

Conclusions

We observed a significant association between the activity of sCD73 in the blood and clinical outcomes in patients with metastatic melanoma stage IV, receiving nivolumab. Although our results need to be confirmed and validated, we suggest that sCD73 might be used as serologic prognostic biomarker. Potentially evaluating sCD73 enzyme activity in the peripheral blood before treatment could help to estimate the response to nivolumab.

Gastric TFF1 Expression from Acute to Chronic Helicobacter Infection

TFF1, a mucin-associated secreted peptide of gastric mucous cells, is known as a protective agent for stomach epithelium under different stimuli, but its role upon Helicobacter infection is still not clear. In this paper we characterized TFFs expression, with particular attention to TFF1, under Helicobacter infection in gastric cell lines. A mouse model was used to distinguish TFF1 mRNA expression between acute and chronic stages of Helicobacter infection. Our results show that TFF1 expression is induced in infected cells; in addition, the inflammatory response upon Helicobacter infection is inversely associated to pre-existing TFF1 protein levels. In infected mice, TFF1 is initially upregulated in gastric antrum in the acute phase of infection, along with IL-1β and IL-6. Then, expression of TFF1 is gradually silenced when the infection becomes chronic and IFN-γ, CXCL5, and CXCL15 reach higher levels. Our data suggest that TFF1 might help cells to counteract bacteria colonization and the development of a chronic inflammation.

Quadriceps muscles activity during gait: comparison between PFPS subjects and healthy control

PURPOSE

The purpose of the study was to evaluate if during a common activity as walking, altered quadriceps muscular activity may be present in patellofemoral pain syndrome (PFPS) patients.

METHODS

Forty subjects with clinically diagnosed PFPS and forty healthy males matching in age, weight, height and level of sport activity were enrolled in the study. Subjects were asked to walk on an instrumented walking path at their self-selected speed. Force platform and motion tracking system were used for the analysis of the gait. Wireless surface EMG probes were used to evaluate quadriceps muscles activity. Rectus femoris, vastus medialis and lateralis activity percentage, onset and offset time, walking speed, cadence, step length, stride length, knee ROM during gait were measured and reported. Tegner activity questionnaire was reported.

RESULTS

Patient group showed a significant increasing in all quadriceps muscles activity when compared to the control (p < 0.05). In particular, for VM and VL muscle onset time was anticipated and offset time was postponed in PFPS group when compared with healthy group (p < 0.05). Knee range of motion during walking was significantly decreased in the patient group.

CONCLUSIONS

Young athletes with PFPS showed increased length of quadriceps muscles activity and reduced functional knee Rom while walking, comparing with healthy subjects, in particular muscular onset was anticipated in respect of the loading response event of the gait. Nonetheless, walking parameters were not affected by these alterations.

Abstract P5-13-13: Enhancing compliance with national nutrition recommendations in breast cancer survivors. Experience in an underprivileged community

BACKGROUND: To enhance compliance with national nutrition recommendations in breast cancer survivors (BCS), a 3-year program granted by the Regional Health Authority began in 2013 in an area (Seine-Saint-Denis, SSD) which is among the poorest in France.

PATIENTS AND METHODS: Ac'Santé 93 is a non-profit organization whose aim is to provide supportive care, health education and individualized assistance to patients and families, and to facilitate timely access to quality medical and psychosocial care. Vulnerability was evaluated using an 11-item standardized score (EPICES) previously investigated by French Health Examination Centers. This score is more strongly related to health status than the administrative classification of poverty (Sass, Sante Publique 2006). Vulnerability was defined by a score &gt;30 and considered as severe when &gt;40. Given the high level of poverty in the area and the incidence of financial difficulties in cancer survivors, a particular attention was paid to comparing the costs of different foods in order to promote affordable dietary changes. Between March 2013 and December 2015, 109 BCS were enrolled in a 3-month education program including 3 sessions of a professionally led support group (with dieticians and social workers).

RESULTS: Ten BCS were lost for follow-up before the end of the program; 54 BCS attended all the sessions. Mean age was 52. Median vulnerability score was 51.8 (0-93.48) and 59% of patients had a score &gt;30. Dietary intakes were assessed at baseline, and 1 and 6 mos. after the last session. At 1 mo. 65% BCS had knowledge of healthy dietary choices and 63% were ready to translate it into practice. Of note, 47% BCS decided to enroll in a tailored 1-year physical activity program or planned to do it, although it was not the aim of the study. At 6 mos. 52% of BCS still had knowledge of healthy diet and 49% of turned it into practice. However, only 12% were still practicing physical activity. Barriers were reported in 67% BCS and included asthenia or other treatment side effects (40%), anxiety or depression (27%), reluctance of relatives (20%), social isolation (20%) or cost (18%). Semi-directive interviews revealed unexpected benefits from this program such as empowerment, socialization or improvement of body image.

CONCLUSION: A short-term dietary intervention is feasible in vulnerable BCS living in an underserved area and improves adherence to higher quality diet in a meaningful number of patients. In spite of the attention paid to the affordability of dietary modifications, numerous barriers still exist in this population, the main one being treatment related side effects, including fatigue. Furthermore, compliance to a tailored physical activity program spontaneously decreases over time.

Citation Format: Zelek L, Festa A, Bodere C, Morello S. Enhancing compliance with national nutrition recommendations in breast cancer survivors. Experience in an underprivileged community [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-13-13.

Prednisolone Delivery Platforms: Capsules and Beads Combination for a Right Timing Therapy

In this work, a platform of alginate beads loaded with Prednisolone in hypromellose/gellan gum capsules (F6/Cps) able to delay steroidal anti-inflammatory drug (SAID) release as needed for chronotherapy of rheumatoid arthritis is proposed. Rheumatoid arthritis, showing a worsening in symptoms in the morning upon waking, is a pathology that can benefit from chronotherapy. With the aim to maximize prednisolone therapeutic action allowing the right timing of glucocorticoid therapy, different engineered microparticles (gel-beads) were manufactured using prilling (laminar jet break-up) as micro-encapsulation technique and Zn-alginate as gastroresistant carrier. Starting from various feed solutions and process parameters, the effect of the variables on particles size, morphology, solid state properties and drug release was studied. The optimization of operative and prilling/ionotropic gelation variables led to microspheres with almost spherical shape and a narrow dimensional range. The feed solution with the highest alginate (2.5% w/v) amount and drug/polymer ratio (1:5 w/w) gave rise to the highest encapsulation efficiency (78.5%) as in F6 formulation. As to drug release, F6 exhibited an interesting dissolution profile, releasing about 24% of the drug in simulated gastric fluid followed by a more sustained profile in simulated intestinal fluid. #F6, acting as a gastro-resistant and delayed release formulation, was selected for in vivo studies on male Wistar rats by means of a carrageenan-induced oedema model. Finally, this efficacious formulation was used as core material for the development of a final dosage form: F6/Cps allowed to significantly reduce prednisolone release in simulated gastric fluid (12.6%) and delayed drug release up to about 390 minutes.

Adenosine signalling mediates the anti-inflammatory effects of the COX-2 inhibitor nimesulide

Extracellular adenosine formation from ATP is controlled by ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase/CD39) and ecto-5'-nucleotidase (e-5NT/CD73); the latter converts AMP to adenosine and inorganic phosphate, representing the rate limiting step controlling the ratio between extracellular ATP and adenosine. Evidence that cellular expression and activity of CD39 and CD73 may be subject to changes under pathophysiological conditions has identified this pathway as an endogenous modulator in several diseases and was shown to be involved in the molecular mechanism of drugs, such as methotrexate, salicylates , interferon-β. We evaluated whether CD73/adenosine/A2A signalling pathway is involved in nimesulide anti-inflammatory effect, in vivo and in vitro. We found that the adenosine A2A agonist, 4-[2-[[6-amino-9-(N-ethyl-β-d-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid hydrochloride (CGS21680, 2mg/kg ip.), inhibited carrageenan-induced rat paw oedema and the effect was reversed by co-administration of the A2A antagonist -(2-[7-amino-2-[2-furyl][1,2,4]triazolo[2,3-a][1,3,5]triazin-5-yl-amino]ethyl)phenol (ZM241385; 3mg/kg i.p.). Nimesulide (5mg/kg i.p.) anti-inflammatory effect was inhibited by pre-treatment with ZM241385 (3mg/kg i.p.) and by local administration of the CD73 inhibitor, adenosine 5'-(α,β-methylene)diphosphate (APCP; 400μg/paw). Furthermore, we found increased activity of 5'-nucleotidase/CD73 in paws and plasma of nimesulide treated rats, 4h following oedema induction. In vitro, the inhibitory effect of nimesulide on nitrite and prostaglandin E2 production by lipopolysaccharide-activated J774 cell line was reversed by ZM241385 and APCP. Furthermore, nimesulide increased CD73 activity in J774 macrophages while it did not inhibit nitrite accumulation by lipopolysaccharide-activated SiRNA CD73 silenced J774 macrophages. Our data demonstrate that the anti-inflammatory effect of nimesulide in part is mediated by CD73-derived adenosine acting on A2A receptors.

Biomechanical evaluation of medial patello-femoral ligament reconstruction: comparison between a double-bundle converging tunnels technique versus a single-bundle technique

BACKGROUND

Several MPFL reconstructions are commonly performed for recurrent patellar dislocation, but misleading data are currently available in the literature on the ability of the different techniques to re-create a functioning ligament.

MATERIALS AND METHODS

In this study, we showed the biomechanical properties of two different procedures for MPFL reconstruction using a natural orientation during uniaxial tensile testing. Eighteen fresh-frozen human knees were randomly assigned to two groups of nine each. In the group A, the reconstruction was performed using a double converging tunnels technique and in the group B was used a single-tunnel technique with semitendinosus autograft. The specimens were loaded in natural orientation using an Instron tensile test machine, and the stiffness and ultimate load were determined.

RESULTS

The ultimate load was 213 ± 90 and 171 ± 51 N using our double-bundle technique (group A) and the single-bundle technique (group B), respectively. One (11 %) specimen failed at the patellar side due to patellar fracture in the group B. There was no statistical significant difference (p > 0.05) between the two groups in terms of stiffness and ultimate load.

CONCLUSION

This study is the first biomechanical evaluation of the MPFL reconstructions in natural orientation. Both the procedures achieved safe fixation of the graft at the femoral attachment; however, the single-bundle technique reported 11 % of failure at the patellar side due to patellar fracture. In addition, the double-bundle technique can better restore the anatomy of the native ligament.

Myeloid cells in the tumor microenvironment: Role of adenosine

Adenosine, deriving from ATP released by dying cancer cells and then degradated in the tumor environment by CD39/CD73 enzyme axis, is linked to the generation of an immunosuppressed niche favoring the onset of neoplasia. The effects of adenosine are mediated by four adenosine receptors, named A₁, A_2A, A_2B and A₃ that are widely expressed on several immune cell populations. A critical role of this nucleoside is emerging in the modulation of myeloid cell subsets accumulation and functions into tumor microenvironment, providing new insights that might be useful for the development of novel therapeutic approaches aimed to undermine the immune privileged sites where cancer cells grow and proliferate.

The adenosinergic system in cancer: Key therapeutic target

High amounts of adenosine are released in the tumor mass. Depending on the levels of adenosine, as well as on the receptor subtypes that are expressed by immune cells, adenosine can affect tumor growth in different fashions. Specifically targeting CD73, the rate-limiting enzyme for the extracellular generation of adenosine, or the A3 receptor offers new therapeutic strategies to limit tumor progression.

Insertion of a 59 amino acid peptide in Salmonella Typhimurium membrane results in loss of virulence in mice

We demonstrated previously that expression of a single trans-membrane region of the Δ(12) -desaturase gene of Synechocystis sp. PCC 6803 in Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) altered the membrane physical state of this pathogen, induced a significant change in the pattern of mRNA transcription of major heat shock genes, and inhibited pathogen growth inside murine macrophages. In this study, we demonstrate that injection of the modified Salmonella strain [Stm(pBAD200)] into C57Bl6j mice is safe. Survival of mice was associated with bacterial clearance, an increased number of splenic leukocytes, and high levels of interleukin-12, interferon γ and tumor necrosis factor α in spleens as well as in sera. Furthermore, Stm(pBAD200)-injected mice developed a Salmonella-specific antibody and Th1-like responses. Mice challenged with Stm(pBAD200) are protected from systemic infection with Salmonella wild-type. Similarly, mice infected with Stm(pBAD200) by the oral route survived when challenged with an oral lethal dose of Salmonella wild-type. The avirulent Stm(pBAD200) phenotype is associated with a remarkable change in the expression of the hilC, hilD, hilA, invF and phoP genes, among others, whose products are required for invasion and replication of Salmonella inside phagocytic cells. These data demonstrate the use of trans-membrane peptides to generate attenuated strains, providing a potential novel strategy to develop vaccines for both animal and human use.

Adenosine limits the therapeutic effectiveness of anti-CTLA4 mAb in a mouse melanoma model

Combination therapies for melanoma that target immune-regulatory networks are entering clinical practice, and more are under investigation in preclinical or clinical studies. Adenosine plays a key role in regulating melanoma progression. We investigated the effectiveness of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) antibody (mAb) in combination with either modulators of adenosine receptors (AR) activation or an inhibitor of adenosine production in a murine model of melanoma. We found that treatment with APCP, selective inhibitor of the adenosine-generating nucleotidase CD73, enhanced the activity of anti-CTLA4 mAb, by improving tumor immune response. Blockade of the adenosine A2a receptor (A2aR), which plays a critical role in the regulation of T-cell functions, significantly reduced melanoma growth. Most importantly, combination therapy including an A2aR antagonist with anti-CTLA4 mAb markedly inhibited tumor growth and enhanced anti-tumor immune responses. Targeting A3R and CTLA4 was not as effective in limiting melanoma growth as targeting A2aR. These data suggest that the efficacy of anti-CTLA4 melanoma therapy may be improved by targeting multiple mechanisms of immune suppression within tumor tissue, including CD73 or A2a receptor.

Targeting the adenosine A2b receptor in the tumor microenvironment overcomes local immunosuppression by myeloid-derived suppressor cells

Emerging evidence suggests that the adenosine A2b receptor (ADORA2B, also known as A2bR) plays a pivotal role in tumor progression. We have recently demonstrated that blocking A2bR stimulates T cell-mediated immunosurveillance in a melanoma model by impairing the influx of myeloid-deriver suppressor cells (MDSCs) into the tumor microenvironment. This results in robust antineoplastic effects, which can be abrogated by the adoptive transfer of MDSCs.

Therapeutic potential of a pyridoxal-based vanadium(IV) complex showing selective cytotoxicity for cancer versus healthy cells

Vanadium compounds can exert anticancer effects, partly due to inhibition of tyrosine phosphatases. Here, we report the effect of N,N'-ethylenebis (pyridoxylideneiminato) vanadium (IV) complex (Pyr2 enV(IV)), that induced 93% and 57% of cell mortality in A375 (human melanoma) and A549 (human lung carcinoma) cells, respectively; the mortality was <24% in other cancer cell lines and in human normal epidermal keratinocytes, lung cells and peripheral blood mononuclear cells. The mechanism of Pyr2 enV(IV) effect relied on apoptosis induction; this was triggered by ROS increase, followed by mitochondrial membrane depolarization. Indeed, the addition of N-acetyl cysteine to cell cultures abated Pyr2 enV(IV)-induced apoptosis. These results disclose the pro-apoptotic activity of Pyr2 enV(IV) and its mechanism, relying on intracellular ROS increase.

Adoptive immunotherapy with Cl-IB-MECA-treated CD8+ T cells reduces melanoma growth in mice

Cl-IB-MECA is a selective A3 adenosine receptor agonist, which plays a crucial role in limiting tumor progression. In mice, Cl-IB-MECA administration enhances the anti-tumor T cell-mediated response. However, little is known about the activity of Cl-IB-MECA on CD8+ T cells. The aim of this study was to investigate the effect of ex vivo Cl-IB-MECA treatment of CD8+ T cells, adoptively transferred in melanoma-bearing mice. Adoptive transfer of Cl-IB-MECA-treated CD8+ T cells or a single administration of Cl-IB-MECA (20 ng/mouse) inhibited tumor growth compared with the control group and significantly improved mouse survival. This was associated with the release of Th1-type cytokines and a greater influx of mature Langerin+ dendritic cells (LCs) into the tumor microenvironment. CD8+ T cells treated with Cl-IB-MECA released TNF-α which plays a critical role in the therapeutic efficacy of these cells when injected to mice. Indeed, neutralization of TNF-α by a specific monoclonal Ab significantly blocked the anti-tumor activity of Cl-IB-MECA-treated T cells. This was due to the reduction in levels of cytotoxic cytokines and the presence of fewer LCs. In conclusion, these studies reveal that ex vivo treatment with Cl-IB-MECA improves CD8+ T cell adoptive immunotherapy for melanoma in a TNF-α-dependent manner.

Inhibition of CD73 improves B cell-mediated anti-tumor immunity in a mouse model of melanoma

CD73 is a cell surface enzyme that suppresses T cell-mediated immune responses by producing extracellular adenosine. Growing evidence suggests that targeting CD73 in cancer may be useful for an effective therapeutic outcome. In this study, we demonstrate that administration of a specific CD73 inhibitor, adenosine 5'-(α,β-methylene)diphosphate (APCP), to melanoma-bearing mice induced a significant tumor regression by promoting the release of Th1- and Th17-associated cytokines in the tumor microenvironment. CD8+ T cells were increased in melanoma tissue of APCP-treated mice. Accordingly, in nude mice APCP failed to reduce tumor growth. Importantly, we observed that after APCP administration, the presence of B cells in the melanoma tissue was greater than that observed in control mice. This was associated with production of IgG2b within the melanoma. Depletion of CD20+ B cells partially blocked the anti-tumor effect of APCP and significantly reduced the production of IgG2b induced by APCP, implying a critical role for B cells in the anti-tumor activity of APCP. Our results also suggest that APCP could influence B cell activity to produce IgG through IL-17A, which significantly increased in the tumor tissue of APCP-treated mice. In support of this, we found that in melanoma-bearing mice receiving anti-IL-17A mAb, the anti-tumor effect of APCP was ablated. This correlated with a reduced capacity of APCP-treated mice to mount an effective immune response against melanoma, as neutralization of this cytokine significantly affected both the CD8+ T cell- and B cell-mediated responses. In conclusion, we demonstrate that both T cells and B cells play a pivotal role in the APCP-induced anti-tumor immune response.

Polyinosinic-polycytidylic acid limits tumor outgrowth in a mouse model of metastatic lung cancer

Polyinosinic-polycytidylic acid (poly I:C), a TLR3 ligand, is currently being tested in human clinical trials as an adjuvant to anti-cancer vaccines and in combination with other therapies. However, little is known about its activity in established pulmonary metastasis. The aim of our study was to elucidate the effect of poly I:C (1, 10, or 100 μg/mouse) in a mouse model of B16-F10-induced metastatic lung cancer. Lung tumor growth was arrested after a single administration of poly I:C. This was associated with higher influx of mature dendritic cells (DCs), which drove toward a Th1-like, Th17-like, and cytotoxic immune environment. The interference with IFN type I receptor signaling by means of a specific mAb reversed poly I:C-mediated tumor regression due to lower presence of myeloid DCs, cytotoxic DCs (CD11c(+)CD8(+)), NKT cells, CD8(+) T cells, and Th1-like cytokines. Moreover, the adoptive transfer of poly I:C-activated bone marrow-derived DCs into tumor-bearing mice resulted in activities similar to those of the systemic administration of poly I:C on lung tumor burden. In conclusion, our data prove that poly I:C has potential anti-tumor activity in a mouse model of established pulmonary metastasis. The activation of DCs and the production of IFN type I are responsible for an effective T cytotoxic immune response against metastatic lung cancer progression after poly I:C treatment.

Lung cancer and Toll-like receptors

Lung carcinoma is one of the leading causes of death worldwide. It is a non-immunogenic cancer, resistant to immune surveillance. Toll-like receptors (TLRs) connect the innate to the adaptive immune system. Given that cancerous cells evade the immune system, the activation of TLRs could represent a potential target for cancer therapy. The induction of Th1-like and cytotoxic immunity by TLR signalling could lead to tumour cell death, resulting in tumour regression or arrest. However, basic research and clinical trials revealed that the activation of specific TLRs, such as TLR2, TLR4 and TLR9, do not have any anti-tumour activity in lung carcinoma. Increasing evidence suggests that TLRs are important regulators of tumour biology; however, little is known about their function in lung cancer. Thus, in order to develop new therapeutic approaches, further studies are needed to understand the connection between TLRs and lung cancer progression. This review focuses on the potential mechanisms by which TLR ligands can facilitate or not lung cancer and lung metastases establishment/progression.

NK1.1 cells and CD8 T cells mediate the antitumor activity of Cl-IB-MECA in a mouse melanoma model

Cl-IB-MECA, synthetic A(3) adenosine receptor agonist, is a potential anticancer agent. In this study, we have examined the effect of Cl-IB-MECA in a mouse melanoma model. Cl-IB-MECA significantly inhibited tumor growth in immune-competent mice. Notably, the number of tumor-infiltrating NK1.1(+) cells and CD8(+) T cells was significantly increased in Cl-IB-MECA-treated mice. This effect was correlated with high levels of tumor necrosis factor α (TNF-α) and interferon γ in melanoma tissue. Depletion of either CD8(+) T cells or NK1.1(+) cells completely abrogated the antitumor effect of Cl-IB-MECA. Accordingly, Cl-IB-MECA did not affect tumor growth in nude mice. In addition, we also found that the number of mature and active conventional dendritic cells at the tumor site was increased after Cl-IB-MECA administration. Moreover, Cl-IB-MECA significantly increased TNF-α and IL-12p40 release from splenic CD11c(+) cells. In conclusion, our study provides novel insights into the mechanism by which Cl-IB-MECA leads to an effective antitumor response that involves the activation of natural killer cells and CD8(+) T cells and further highlights its therapeutic potential.

Cl-IB-MECA enhances TNF-α release in peritoneal macrophages stimulated with LPS

Adenosine receptor A3 (A3R) belongs to the Gi/Gq-coupled receptor family, that leads to the intracellular cAMP reduction and intracellular calcium increase, respectively. A3R is widely expressed and it can play a crucial role in many patho-physiological conditions, including inflammation. Here we investigate the effect of Cl-IB-MECA, A3R agonist, on the production of TNF-α. We found that Cl-IB-MECA enhances LPS-induced TNF-α release in peritoneal macrophages. This effect is reduced by MRS1191, A3R antagonist and by forskolin, activator of adenylyl cyclase. pIκBα increased in LPS+Cl-IB-MECA-treated macrophages, while total IκB kinase-β (IKKβ) reduced. Indeed, p65NF-κB nuclear translocation increased in cells treated with LPS+Cl-IB-MECA. Moreover, IMD 0354, IKKβ inhibitor, significantly abrogated the effect of Cl-IB-MECA on TNF-α release. Inhibition of protein kinase C (PKC) significantly reduced Cl-IB-MECA-induced TNF-α release in LPS-stimulated macrophages. Furthermore, LY-294002, PI3K inhibitor, reduced the TNF-α production enhanced by Cl-IB-MECA, although the phosphorylation status of Akt did not change in cells treated with LPS+Cl-IB-MECA than LPS alone. In summary, these data show that Cl-IB-MECA is able to enhance TNF-α production in LPS-treated macrophages in an NF-κB- dependent manner.

Cytotoxic activity of nemorosone in human MCF-7 breast cancer cells

Estrogen receptor (ER) antagonists have been widely used for breast cancer treatment; however, patients have increasingly shown resistance and sensitivity to the high toxicity of these drugs, and identification of novel targeted therapies is therefore required. To determine whether nemorosone, a polycyclic polyisoprenylated benzophenone isolated from floral resins of Clusia rosea Jacq. and Cuban propolis samples, exerts anticancer effects on human breast cancer cells, estrogen receptor positive (ERα+) MCF-7 and estrogen receptor negative (ERα–) MDA-MB-231 and LNCaP cells were used. Cells were treated with nemorosone alone or in association with 17β-estradiol (E2) or an ER antagonist, ICI 182,780, a selective ER downregulator that completely abrogates estrogen-sensitive gene transcription. Nemorosone inhibited the cell viability of ERα+ but not of ERα– cells. In MCF-7, nemorosone induced inhibition of cell growth by blocking the cell cycle in the G0/G1 phase. Moreover, the expression of pERK1/2 and pAkt, considered to be hallmarks of the nongenomic estrogen signalling pathway, were reduced in MCF-7 cells treated with nemorosone. All these effects were enhanced by ICI 182,780. However, nemorosone was not able to interfere with E2-induced Ca2+ release. These findings suggest that nemorosone may have therapeutic application in the treatment of breast cancer because of its activity on ERα.