Effects of clopidogrel bisulfate on B16-F10 cells and tumor development in a murine model of melanoma.

Metastatic melanoma is a very aggressive skin cancer. Platelets are constituents of the tumor microenvironment and, when activated, contribute to cancer progression, especially metastasis and inflammation. P2Y12 is an adenosine diphosphate receptor that triggers platelet activation. Inhibition of P2Y12 by clopidogrel bisulfate (CB) decreases platelet activation, which is also controlled by the extracellular concentration and the metabolism of purines by purinergic enzymes. We evaluated the effects of CB on the viability and proliferation of cultured B16-F10 cells. We also used a metastatic melanoma model with C57BL-6 mice to evaluate cancer development and purine metabolism modulation in platelets. B16-F10 cells were administered intraperitoneally to the mice. Two days later, the animals underwent a 12-day treatment with CB (30 mg/kg by gavage). We have found that CB reduced cell viability and proliferation in B16-F10 culture in 72 h at concentrations above 30 µm. In vivo, CB decreased tumor nodule counts and lactate dehydrogenase levels and increased platelet purine metabolism. Our results showed that CB has significant effects on melanoma progression.

Istradefylline modulates purinergic enzymes and reduces malignancy-associated factors in B16F10 melanoma cells.

ATP and adenosine exert pivotal roles in the development, maintenance, and metastatic spreading of melanoma. The action of such key melanoma tumor microenvironment (TME) constituents might be complementary or opposed, and their effects are not exclusive to immune cells but also to other host cells and tumor cells. The effects of ATP are controlled by the axis CD39/73, resulting in adenosine, the main actor in the TME, and A2A is the crucial mediator of its effects. We evaluated ATP and adenosine signaling through A2A on B16F10 melanoma cells using istradefylline (IST) (antiparkinsonian A2A antagonist) and caffeine (CAF) treatments after exposure to ATP and adenosine. Adenosine increased melanoma cell viability and proliferation in a concentration-dependent manner. ATP increases viability only as a substrate by CD39 to produce adenosine. Both IST and CAF are toxic to B16F10 cells, but only IST potentialized paclitaxel-induced cytotoxic effects, even decreasing its IC50 value. IST positively modulated CD39 and CD73 expression. CD39 activity was increased, and E-ADA was reduced, indicating that the melanoma cells promoted compensatory feedback in the production and maintenance of adenosine levels. A2A antagonism by IST reduced the factors associated with malignancy, like migration, adhesion, colony formation, and the capacity to produce melanin. Moreover, IST significantly increases nitric oxide (NO) production, which correlates to a decline in melanoma cell viability by apoptotic events. Altogether, our results suggest that adenosine signaling through A2A is essential for B16F10 cells, and its inhibition by IST causes compensatory purinergic enzymatic modulations. Furthermore, IST is a promising therapy that provides new ways to improve current melanoma treatments.

Antioxidant, hepatoprotective, genoprotective, and cytoprotective effects of quercetin in a murine model of arthritis.

Rheumatoid arthritis is a highly debilitating inflammatory autoimmune disease which is characterized by joint destruction. The present study sought to investigate the effect of quercetin in rats with complete Freund's adjuvant-induced arthritis. Animals were divided into control/saline, control/quercetin (5 mg/kg, 25 mg/kg, and 50 mg/kg) arthritis/saline, and arthritis/quercetin (5 mg/kg, 25 mg/kg, and 50 mg/kg); the treatments were administered for 45 days. Biochemical, oxidative stress, genotoxicity, and cytotoxicity parameters were evaluated. All doses of quercetin reduced the levels of aspartate aminotransferase, thiobarbituric acid-reactive substances, and reactive oxygen species; however, only treatment with 25 or 50 mg/kg increased catalase activity. Total thiol and reduced glutathione levels were not significantly affected by the induction nor by the treatments. Genotoxicity assessed by DNA damage, and cytotoxicity through picogreen assay, decreased after treatments with quercetin. Our results present evidence of the antioxidant, cytoprotective, genoprotective and hepatoprotective, and effects of quercetin, demonstrating its potential as a candidate for coadjuvant therapy.

Tucumã (Astrocaryum aculeatum) prevents memory loss and oxidative imbalance in the brain of rats with hyperlipidemia.

Hyperlipidemia generates deposition of lipids, inflammation, and oxidative damage in cells and tissues, including those of the brain. Tucumã (Astrocaryum aculeatum) fruits contain bioactive compounds with antioxidant and anti-inflammatory effects. We evaluated the action of Tucumã extract on memory and brain cortex redox balance in hyperlipidemic rats. For 30 days, Wistar rats received Tucumã extract (250 mg/kg). Then, hyperlipidemia was induced by intraperitoneal administration of Poloxamer-407. Twenty-four hours later, the object recognition index was measured. The animals were euthanized for sample collection 36 hr postinduction. Hyperlipidemic animals showed memory loss and an imbalance between reactive species and intrinsic antioxidants. We found that Tucumã prevented memory loss and protein and lipid oxidative damage and prompted a better antioxidant response in the cerebral cortex of rats with hyperlipidemia. These findings suggest a neuroprotective effect and nutraceutical potential of Tucumã. PRACTICAL APPLICATIONS: In the present work, we demonstrated that induced hyperlipidemia in rats caused memory loss and redox unbalance, both factors prevented by the administration of Tucumã (Astrocaryum aculeatum) extract. Two aims were fulfilled with these results. The first was to show that hyperlipidemia affected brain function through oxidative damage and concerned basic research. The second was to offer a therapy that prevented this harm and could be applied in the clinic. Tucumã has ethnopharmacological importance through the consumption of fruits or the administration of extracts and oils by a population that was shown to enjoy improved health and longevity. Here, we show evidence that Tucumã contributes to the maintenance of brain health by preventing memory loss and oxidative damage, a nutraceutical supplement that may aid the prevention of vascular, inflammatory, and brain diseases.

ATP signaling and NTPDase in Systemic Lupus Erythematosus (SLE).

Systemic lupus erythematosus (SLE) is an autoimmune and inflammatory disease with periods of exacerbation and remission. SLE is characterized by the irreversible breakdown of immunological self-tolerance, where there is deregulation of multiple aspects of the immune system. SLE immune dysfunction is characterized by activation of autoreactive T lymphocytes, and hyperactivity of B lymphocytes with consequent production of several autoantibodies. ATP is a purinergic mediator released into the extracellular space in response to cell and tissue damage which operates as a danger signal to modulate immune and inflammatory responses. ATP binds to P2 receptors and its levels are regulated by NTPDase (CD39). SLE patients exhibit increased levels of ATP which binds to P2X receptors resulting in activation of the inflammasome and consequent release of IL-1ß and IL-18, cytokines associated with disease pathogenesis. CD39 is upregulated in SLE representing an important immunoregulatory mechanism by controlling inflammation and favoring the production of adenosine. The aim of this review is to clarify the effects of ATP on the modulation of the inflammatory process and immune responses via P2 receptors as well as the role of NTPDase in the immunopathogenesis of SLE.