Tannic acid elicits selective antitumoral activity in vitro and inhibits cancer cell growth in a preclinical model of glioblastoma multiforme.

Glioblastoma is a devastating tumor affecting the central nervous system with infiltrative capacity, high proliferation rate and chemoresistance. Therefore, it is urgent to find new therapeutic alternatives that improve this prognosis. Herein, we focused on tannic acid (TA) a polyphenol with antioxidant and antiproliferative activities. In this work, the antitumor and antioxidant effects of TA on rat (C6) glioblastoma cells and their cytotoxicity relative to primary astrocyte cultures were evaluated in vitro. Cells were exposed to TA of 6.25 to 75 µM for 24, 48 and/or 72 h. In addition, colony formation, migration and cell adhesion were analyzed and flow cytometry was used to analyze cell death and cell cycle. Next, the action of TA was evaluated in a preclinical glioblastoma model performed on Wistar rats. In this protocol, the animals were treated with a dose of 50 mg/kg/day TA for 15 days. Our results demonstrated that TA induced in vitro selective antiglioma activity, not demonstrating cytotoxicity in astrocyte culture. It induced cell death by apoptosis and cell cycle arrest, reducing formation and size of colonies, cell migration/adhesion and showing to be a potential antioxidant. Interestingly, the antiglioma effect was also observed in vivo, as TA decreased tumor volume by 55%, accompanied by an increase in the area of intratumoral necrosis and infiltration of lymphocytes without causing systemic damage. To the best of our knowledge, this is the first study to report TA activity in a GBM preclinical model. Thus, this natural compound is promising as a treatment for glioblastoma.

Improved photostability and cytotoxic effect of coenzyme Q10 by its association with vitamin E acetate in polymeric nanocapsules.

The present study showed the development of nanocapsules containing the association of the coenzyme Q10 and vitamin E acetate and the evaluation of their effect on in vitro cells culture of malignant glioma and melanoma. In order to investigate if nanocapsules are able to protect coenzyme Q10 from degradation under UVC radiation, a photostability study was carried out. For this, three concentrations of vitamin E acetate were evaluated (1%, 2%, or 3%). Nanocapsules presented suitable physicochemical characteristics and were able to protect coenzyme Q10 from photodegradation. In addition, this protection was influenced by higher vitamin E acetate concentrations, attributing to this oil an important role on coenzyme Q10 photostabilization. Regarding to in vitro citotoxicity assay, nanocapsules containing coenzyme Q10 and 2% vitamin E significantly reduced glioma and melanoma cell viability in 61% and 66%, respectively. In this sense, these formulations represent interesting platforms for the delivery of coenzyme Q10 and vitamin E acetate, presenting effect on the reduction of malignant cells viability.

Methionine and methionine sulfoxide treatment induces M1/classical macrophage polarization and modulates oxidative stress and purinergic signaling parameters.

Methionine is an essential amino acid involved in critical metabolic process, and regulation of methionine flux through metabolism is important to supply this amino acid for cell needs. Elevation in plasma methionine commonly occurs due to mutations in methionine-metabolizing enzymes, such as methionine adenosyltransferase. Hypermethioninemic patients exhibit clinical manifestations, including neuronal and liver disorders involving inflammation and tissue injury, which pathophysiology is not completely established. Here, we hypothesize that alterations in macrophage inflammatory response may contribute to deleterious effects of hypermethioninemia. To this end, macrophage primary cultures were exposed to methionine (1 mM) and/or its metabolite methionine sulfoxide (0.5 mM), and M1/proinflammatory or M2/anti-inflammatory macrophage polarization was evaluated. In addition, inflammation-related pathways including oxidative stress parameters, as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities; reactive oxygen species (ROS) production, and purinergic signaling, as ATP/ADP/AMPase activities, were investigated. Methionine and/or methionine sulfoxide induced M1/classical macrophage activation, which is related to proinflammatory responses characterized by increased iNOS activity and TNF-α release. Further experiments showed that treatments promoted alterations on redox state of macrophages by differentially modulated SOD and CAT activities and ROS levels. Finally, methionine and/or methionine sulfoxide treatment also altered the extracellular nucleotide metabolism, promoting an increase of ATPase/ADPase activities in macrophages. In conclusion, these findings contribute to better understand the participation of proinflammatory responses in cell injury observed in hypermethioninemic patients.

Glioma sensitive or chemoresistant to temozolomide differentially modulate macrophage protumor activities.

BACKGROUND: Glioblastomas are the most devastating brain tumor characterized by chemoresistance development and poor prognosis. Macrophages are a component of tumor microenvironment related to glioma malignancy. The relation among inflammation, innate immunity and cancer is accepted; however, molecular and cellular mechanisms mediating this relation and chemoresistance remain unresolved. OBJECTIVE: Here we evaluated whether glioma sensitive or resistant to temozolomide (TMZ) modulate macrophage polarization and inflammatory pathways associated. The impact of glioma-macrophage crosstalk on glioma proliferation was also investigated. METHODS: GL261 glioma chemoresistance was developed by exposing cells to increasing TMZ concentrations over a period of 6months. Mouse peritoneal macrophages were exposed to glioma-conditioned medium or co-cultured directly with glioma sensitive (GL) or chemoresistant (GLTMZ). Macrophage polarization, in vitro and in vivo glioma proliferation, redox parameters, ectonucleotidase activity and ATP cytotoxicity were performed. RESULTS: GLTMZ cells were more effective than GL in induce M2-like macrophage polarization and in promote a strong immunosuppressive environment characterized by high IL-10 release and increased antioxidant potential, which may contribute to glioma chemoresistance and proliferation. Interestingly, macrophage-GLTMZ crosstalk enhanced in vitro and in vivo proliferation of chemoresistant cells, decreased ectonucleotidase activities, which was followed by increased macrophage sensitivity to ATP induced death. CONCLUSIONS: Results suggest a differential macrophage modulation by GLTMZ cells, which may favor the maintenance of immunosuppressive tumor microenvironment and glioma proliferation. GENERAL SIGNIFICANCE: The induction of immunosuppressive environment and macrophage education by chemoresistant gliomas may be important for tumor recovery after chemotherapy and could be considered to overcome chemoresistance development.

Ketoprofen-loaded polymeric nanocapsules selectively inhibit cancer cell growth in vitro and in preclinical model of glioblastoma multiforme.

Glioblastoma multiforme (GBM) is the worst and most common brain tumor, characterized by high proliferation and invasion rates. Nanoparticles of biodegradable polymers for anticancer drug delivery have attracted interest in recent years since they provide targeted delivery and may overcame the obstacle imposed by blood-brain barrier. Here we investigated the antitumoral effect of ketoprofen-loaded nanocapsules (Keto-NC) treatment on in vitro and in vivo glioma progression. We observed that Keto-NC treatment decreased selectively the cell viability of a panel of glioma cell lines, while did not exhibited toxicity to astrocytes. We further demonstrate that the treatment with sub-therapeutic dose of Keto-NC reduced the in vivo glioma growth as well as reduced the malignity characteristics of implanted tumors. Keto-NC treatment improved the weight, the locomotion/exploration behavior of glioma-bearing rats. Importantly, Keto-NC treatment neither induced mortality or peripheral damage. Finally, Ketoprofen also altered the extracellular nucleotide metabolism of peripheral lymphocytes, suggesting that antiinflammatory effects of ketoprofen could also be associated with the modulation of the adenine nucleotide metabolism in lymphocytes. Data indicate at first time the potential of Keto-NC as a promising therapeutic alterative to GBM treatment.

Synthetic 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones exhibit selective in vitro antitumoral activity and inhibit cancer cell growth in a preclinical model of glioblastoma multiforme.

Glioblastoma multiforme (GBM) is the worst form of primary brain tumor, which has a high rate of infiltration and resistance to radiation and chemotherapy, resulting in poor prognosis for patients. Recent studies show that thiazolidinones have a wide range of pharmacological properties including antimicrobial, anti-inflammatory, anti-oxidant and anti-tumor. Here, we investigate the effect antiglioma in vitro of a panel of sixteen synthetic 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones where 13 of these decreased the viability of glioma cells 30-65% (100 µM) compared with controls. The most promising compounds such as 4d, 4l, 4m and 4p promoted glioma reduction of viability greater than 50%, were further tested at lower concentrations (12.5, 25, 50 and 100 µM). Also, the data showed that the compounds 4d, 4l, 4m and 4p induced cell death primarily through necrosis and late apoptosis mechanisms. Interestingly, none of these 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones were cytotoxic for primary astrocytes, which were used as a non-transformed cell model, indicating selectivity. Our results also show that the treatment with sub-therapeutic doses of 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones (4d, 4l and 4p) reduced in vivo glioma growth as well as malignant characteristics of implanted tumors such as intratumoral hemorrhage and peripheral pseudopalisading. Importantly, 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones treatment did not induce mortality or peripheral damage to animals. Finally, 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones also changed the nitric oxide metabolism which may be associated with reduced growth and malignity characteristics of gliomas. These data indicates for the first time the therapeutic potential of synthetic 2-aryl-3-((piperidin-1-yl)ethyl)thiazolidin-4-ones to GBM treatment.

Ketoprofen-loaded pomegranate seed oil nanoemulsion stabilized by pullulan: Selective antiglioma formulation for intravenous administration.

This study aimed to prepare pomegranate seed oil nanoemulsions containing ketoprofen using pullulan as a polymeric stabilizer, and to evaluate antitumor activity against in vitro glioma cells. Formulations were prepared by the spontaneous emulsification method and different concentrations of pullulan were tested. Nanoemulsions presented adequate droplet size, polydispersity index, zeta potential, pH, ketoprofen content and encapsulation efficiency. Nanoemulsions were able to delay the photodegradation profile of ketoprofen under UVC radiation, regardless of the concentration of pullulan. In vitro release study indicates that nanoemulsions were able to release approximately 95.0% of ketoprofen in 5h. Free ketoprofen and formulations were considered hemocompatible at 1 µg/mL, in a hemolysis study, for intravenous administration. In addition, a formulation containing the highest concentration of pullulan was tested against C6 cell line and demonstrated significant activity, and did not reduce fibroblasts viability. Thus, pullulan can be considered an interesting excipient to prepare nanostructured systems and nanoemulsion formulations can be considered promising alternatives for the treatment of glioma.