Antitumoral Activity of the Universal Methyl Donor S-Adenosylmethionine in Glioblastoma Cells.

Glioblastoma (GBM), the most frequent and lethal brain cancer in adults, is characterized by short survival times and high mortality rates. Due to the resistance of GBM cells to conventional therapeutic treatments, scientific interest is focusing on the search for alternative and efficient adjuvant treatments. S-Adenosylmethionine (AdoMet), the well-studied physiological methyl donor, has emerged as a promising anticancer compound and a modulator of multiple cancer-related signaling pathways. We report here for the first time that AdoMet selectively inhibited the viability and proliferation of U87MG, U343MG, and U251MG GBM cells. In these cell lines, AdoMet induced S and G2/M cell cycle arrest and apoptosis and downregulated the expression and activation of proteins involved in homologous recombination DNA repair, including RAD51, BRCA1, and Chk1. Furthermore, AdoMet was able to maintain DNA in a damaged state, as indicated by the increased γH2AX/H2AX ratio. AdoMet promoted mitotic catastrophe through inhibiting Aurora B kinase expression, phosphorylation, and localization causing GBM cells to undergo mitotic catastrophe-induced death. Finally, AdoMet inhibited DNA repair and induced cell cycle arrest, apoptosis, and mitotic catastrophe in patient-derived GBM cells. In light of these results, AdoMet could be considered a potential adjuvant in GBM therapy.

Advances in "adiponcosis": Insights in the inner mechanisms at the base of adipose and tumour tissues interplay.

The epidemic spread of obesity is nowadays recognized as a global health and economic burden, arising great interest in the scientific community. The rate of adult obesity steadily increases concomitantly with the cancer incidence. As has been comprehensively reported, obesity is included among the multiple cancer risk factors and can progressively cause and/or exacerbate certain cancer types, as colorectal and breast cancers. The term adiponcosis was forged precisely to emphasize the interconnection between obesity and cancer onset and progression. The underlying mechanisms of adiponcosis have not been fully elucidated yet, may vary on cancer type, and depend on body fat distribution. It has been proposed that insulin resistance and related chronic hyperinsulinemia, increased insulin-like growth factors production, chronic inflammation or increased bioavailability of steroid hormones could be responsible of cancer hallmarks. Additionally, it has been suggested that adipose tissue-derived hormones, cytokines and adipokines, such as leptin, adiponectin and inflammatory markers, may reflect mechanisms linked to tumorigenesis. This review summarizes the current evidence on pathways, hormones, cytokines and low-chronic inflammation subtending adiponconsis, focusing on breast and colorectal cancers. In addition, we analyzed the lifestyle interventions that could attenuate the driving forces of obesity-related cancer incidence and progression. Moreover, current targets and drugs, their pros and cons, as well as new mechanisms and targets with promising therapeutic potential in cancer are discussed. Depicting this complex interconnection will provide insights for establishing new therapeutic approaches to halt the obesity impacts and thwart cancer onset and progression.

Cannabinoids in the Modulation of Oxidative Signaling.

Cannabis sativa-derived compounds, such as delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), and components of the endocannabinoids system, such as N-arachidonoylethanolamide (anandamide, AEA) and 2-arachidonoylglycerol (2-AG), are extensively studied to investigate their numerous biological effects, including powerful antioxidant effects. Indeed, a series of recent studies have indicated that many disorders are characterized by alterations in the intracellular antioxidant system, which lead to biological macromolecule damage. These pathological conditions are characterized by an unbalanced, and most often increased, reactive oxygen species (ROS) production. For this study, it was of interest to investigate and recapitulate the antioxidant properties of these natural compounds, for the most part CBD and THC, on the production of ROS and the modulation of the intracellular redox state, with an emphasis on their use in various pathological conditions in which the reduction of ROS can be clinically useful, such as neurodegenerative disorders, inflammatory conditions, autoimmunity, and cancers. The further development of ROS-based fundamental research focused on cannabis sativa-derived compounds could be beneficial for future clinical applications.

Impacts of Environmental Pollution on Brain Tumorigenesis.

Pollutants consist of several components, known as direct or indirect mutagens, that can be associated with the risk of tumorigenesis. The increased incidence of brain tumors, observed more frequently in industrialized countries, has generated a deeper interest in examining different pollutants that could be found in food, air, or water supply. These compounds, due to their chemical nature, alter the activity of biological molecules naturally found in the body. The bioaccumulation leads to harmful effects for humans, increasing the risk of the onset of several pathologies, including cancer. Environmental components often combine with other risk factors, such as the individual genetic component, which increases the chance of developing cancer. The objective of this review is to discuss the impact of environmental carcinogens on modulating the risk of brain tumorigenesis, focusing our attention on certain categories of pollutants and their sources.

Cannabinoids: Therapeutic Use in Clinical Practice.

Medical case reports suggest that cannabinoids extracted from Cannabis sativa have therapeutic effects; however, the therapeutic employment is limited due to the psychotropic effect of its major component, Δ9-tetrahydrocannabinol (THC). The new scientific discoveries related to the endocannabinoid system, including new receptors, ligands, and mediators, allowed the development of new therapeutic targets for the treatment of several pathological disorders minimizing the undesirable psychotropic effects of some constituents of this plant. Today, FDA-approved drugs, such as nabiximols (a mixture of THC and non-psychoactive cannabidiol (CBD)), are employed in alleviating pain and spasticity in multiple sclerosis. Dronabinol and nabilone are used for the treatment of chemotherapy-induced nausea and vomiting in cancer patients. Dronabinol was approved for the treatment of anorexia in patients with AIDS (acquired immune deficiency syndrome). In this review, we highlighted the potential therapeutic efficacy of natural and synthetic cannabinoids and their clinical relevance in cancer, neurodegenerative and dermatological diseases, and viral infections.

Molecular Mechanism of Cannabinoids in Cancer Progression.

Cannabinoids are a family of heterogeneous compounds that mostly interact with receptors eliciting several physiological effects both in the central and peripheral nervous systems and in peripheral organs. They exert anticancer action by modulating signaling pathways involved in cancer progression; furthermore, the effects induced by their use depend on both the type of tumor and their action on the components of the endocannabinoid system. This review will explore the mechanism of action of the cannabinoids in signaling pathways involved in cancer proliferation, neovascularisation, migration, invasion, metastasis, and tumor angiogenesis.

N6-Isopentenyladenosine Hinders the Vasculogenic Mimicry in Human Glioblastoma Cells through Src-120 Catenin Pathway Modulation and RhoA Activity Inhibition.

BACKGROUND: Vasculogenic mimicry (VM) is a functional microcirculation pattern formed by aggressive tumor cells. Thus far, no effective drugs have been developed to target VM. Glioblastoma (GBM) is the most malignant form of brain cancer and is a highly vascularized tumor. Vasculogenic mimicry represents a means whereby GBM can escape anti-angiogenic therapies. METHODS: Here, using an in vitro tube formation assay on Matrigel, we evaluated the ability of N6-isopentenyladenosine (iPA) to interfere with vasculogenic mimicry (VM). RhoA activity was assessed using a pull-down assay, while the modulation of the adherens junctions proteins was analyzed by Western blot analysis. RESULTS: We found that iPA at sublethal doses inhibited the formation of capillary-like structures suppressing cell migration and invasion of U87MG, U343MG, and U251MG cells, of patient-derived human GBM cells and GBM stem cells. iPA reduces the vascular endothelial cadherin (VE-cadherin) expression levels in a dose-dependent manner, impairs the vasculogenic mimicry network by modulation of the Src/p120-catenin pathway and inhibition of RhoA-GTPase activity. CONCLUSIONS: Taken together, our results revealed iPA as a promising novel anti-VM drug in GBM clinical therapeutics.

The Endocannabinoid System: A Target for Cancer Treatment.

In recent years, the endocannabinoid system has received great interest as a potential therapeutic target in numerous pathological conditions. Cannabinoids have shown an anticancer potential by modulating several pathways involved in cell growth, differentiation, migration, and angiogenesis. However, the therapeutic efficacy of cannabinoids is limited to the treatment of chemotherapy-induced symptoms or cancer pain, but their use as anticancer drugs in chemotherapeutic protocols requires further investigation. In this paper, we reviewed the role of cannabinoids in the modulation of signaling mechanisms implicated in tumor progression.

Recognition by natural killer cells of N6-isopentenyladenosine-treated human glioma cell lines.

Cancer cell stress induced by cytotoxic agents promotes antitumor immune response. Here, we observed that N6-isopentenyladenosine (iPA), an isoprenoid modified adenosine with a well established anticancer activity, was able to induce a significant upregulation of cell surface expression of natural killer (NK) cell activating receptor NK Group 2 member D (NKG2D) ligands on glioma cells in vitro and xenografted in vivo. Specifically suboptimal doses of iPA (0.1 and 1 µM) control the selective upregulation of UL16-binding protein 2 on p53wt-expressing U343MG and that of MICA/B on p53mut-expressing U251MG cells. This event made the glioblastoma cells a potent target for NK cell-mediated recognition through a NKG2D restricted mechanism. p53 siRNA-mediated knock-down and pharmacological inhibition (pifithrin-α), profoundly prevented the iPA action in restoring the immunogenicity of U343MG cells through a mechanism that is dependent upon p53 status of malignancy. Furthermore, accordingly to the preferential recognition of senescent cells by NK cells, we found that iPA treatment was critical for glioma cells entry in premature senescence through the induction of S and G2/M phase arrest. Collectively, our results indicate that behind the well established cytotoxic and antiangiogenic effects, iPA can also display an immune-mediated antitumor activity. The indirect engagement of the innate immune system and its additional activity in primary derived patient's glioma cell model (GBM17 and GBM37), fully increase its translational relevance and led to the exploitation of the isoprenoid pathway for a valid therapeutic intervention in antiglioma research.

PPARα Antagonist AA452 Triggers Metabolic Reprogramming and Increases Sensitivity to Radiation Therapy in Human Glioblastoma Primary Cells.

Glioblastoma (GB) is the most common cancer in the brain and with an increasing incidence. Despite major advances in the field, there is no curative therapy for GB to date. Many solid tumors, including GB, experienced metabolic reprogramming in order to sustain uncontrolled proliferation, hypoxic conditions, and angiogenesis. PPARs, member of the steroid hormone receptor superfamily, are particularly involved in the control of energetic metabolism, particularly lipid metabolism, which has been reported deregulated in gliomas. PPARα was previously indicated by us as a potential therapeutic target for this neoplasm, due to the malignancy grade dependency of its expression, being particularly abundant in GB. In this work, we used a new PPARα antagonist on patient-derived GB primary cells, with particular focus on the effects on lipid metabolism and response to radiotherapy. The results obtained demonstrated that blocking PPARα results in cell death induction, increase of radiosensitivity, and decrease of migration. Therefore, AA452 is proposed as a new adjuvant for the gold standard therapies for GB, opening the possibility for preclinical and clinical trials for this class of compounds. J. Cell. Physiol. 232: 1458-1466, 2017. © 2016 Wiley Periodicals, Inc.

Antiglioma effects of N6-isopentenyladenosine, an endogenous isoprenoid end product, through the downregulation of epidermal growth factor receptor.

Malignant gliomas are highly dependent on the isoprenoid pathway for the synthesis of lipid moieties critical for cell proliferation. The isoprenoid derivative N6-isopentenyladenosine (iPA) displays pleiotropic biological effects, including a direct anti-tumor activity in several tumor models. The antiglioma effects of iPA was then explored in U87MG cells both in vitro and grafted in mice and the related molecular mechanism confirmed in primary derived patients' glioma cells. iPA powerfully inhibited tumor cell growth and induced caspase-dependent apoptosis through a mechanism involving a marked accumulation of the pro-apoptotic BIM protein and inhibition of EGFR. Indeed, activating AMPK following conversion into its iPAMP active form, iPA stimulated EGFR phosphorylation and ubiquitination along a proteasome-mediated pathway which was responsible for receptor degradation and its downstream signaling pathways inhibition, including the STAT3, ERK and AKT cascade. The inhibition of AMPK by compound C prevented iPA-mediated phosphorylation of EGFR, known to precede receptor loss. As expected the block of EGFR degradation, by exposure to the proteasome inhibitor MG132, significantly reduced iPA-induced cell death. Given the importance of receptor degradation in iPA-mediated cytotoxicity, we also documented that the EGFR expression levels in a panel of primary glioma cells confers them a high sensitivity to iPA treatment. In conclusion our study provides the first evidence of iPA antiglioma effect. Indeed, as glioma is driven by aberrant signaling of growth factor receptors, particularly the EGFR, iPA, alone or in association with EGFR targeted therapies, might be a promising therapeutic tool to achieve a potent anti-tumoral effect.

Immuno-Modulatory and Anti-Inflammatory Effects of Dihydrogracilin A, a Terpene Derived from the Marine Sponge Dendrilla membranosa.

We assessed the immunomodulatory and anti-inflammatory effects of 9,11-dihydrogracilin A (DHG), a molecule derived from the Antarctic marine sponge Dendrilla membranosa. We used in vitro and in vivo approaches to establish DHG properties. Human peripheral blood mononuclear cells (PBMC) and human keratinocytes cell line (HaCaT cells) were used as in vitro system, whereas a model of murine cutaneous irritation was adopted for in vivo studies. We observed that DHG reduces dose dependently the proliferative response and viability of mitogen stimulated PBMC. In addition, DHG induces apoptosis as revealed by AnnexinV staining and downregulates the phosphorylation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), signal transducer and activator of transcription (STAT) and extracellular signal-regulated kinase (ERK) at late time points. These effects were accompanied by down-regulation of interleukin 6 (IL-6) production, slight decrease of IL-10 and no inhibition of tumor necrosis factor-alpha (TNF-α) secretion. To assess potential properties of DHG in epidermal inflammation we used HaCaT cells; this compound reduces cell growth, viability and migration. Finally, we adopted for the in vivo study the croton oil-induced ear dermatitis murine model of inflammation. Of note, topical use of DHG significantly decreased mouse ear edema. These results suggest that DHG exerts anti-inflammatory effects and its anti-edema activity in vivo strongly supports its potential therapeutic application in inflammatory cutaneous diseases.

Anti Proliferative and Pro Apoptotic Effects of Flavonoid Quercetin Are Mediated by CB1 Receptor in Human Colon Cancer Cell Lines.

Quercetin, the major constituent of flavonoid and widely present in fruits and vegetables, is an attractive compound for cancer prevention due to its beneficial anti proliferative effects, showing a crucial role in the regulation of apoptosis and cell cycle signaling. In vitro studies have demonstrated that quercetin specifically influences colon cancer cell proliferation. Our experiments, using human colon adenocarcinoma cells, confirmed the anti proliferative effect of quercetin and gave intriguing new insight in to the knowledge of the mechanisms involved. We observed a significant increase in the expression of the endocannabinoids receptor (CB1-R) after quercetin treatment. CB1-R can be considered an estrogen responsive receptor and quercetin, having a structure similar to that of the estrogens, can interact with CB1-R leading to the regulation of cell growth. In order to clarify the contribution of the CB1-R to the quercetin action, we investigated some of the principal molecular pathways that are inhibited or activated by this natural compound. In particular we detected the inhibition of the major survival signals like the PI3K/Akt/mTOR and an induction of the pro apoptotic JNK/JUN pathways. Interestingly, the metabolism of ß-catenin was modified by flavonoid both directly and through activated CB1-R. In all the experiments done, the quercetin action has proven to be reinforced by anandamide (Met-F-AEA), a CB1-R agonist, and partially counteracted by SR141716, a CB1-R antagonist. These findings open new perspectives for anticancer therapeutic strategies.

Anandamide drives cell cycle progression through CB1 receptors in a rat model of synchronized liver regeneration.

The endocannabinoid system, through cannabinoid receptor signaling by endocannabinoids, is involved in a wide range of functions and physiopathological conditions. To date, very little is known concerning the role of the endocannabinoids in the control and regulation of cell proliferation. An anti-proliferative action of CB1 signaling blockade in neurogenesis and angiogenesis argues in favor of proliferation-promoting functions of endocannabinoids through CB1 receptors when pro-growth signals are present. Furthermore, liver regeneration, a useful in vivo model of synchronized cell proliferation, is characterized by a peak of anandamide that elicits through CB1 receptor, the expression of critical mitosis genes. The aim of this study was to focus on the timing of endocannabinoid signaling changes during the different phases of the cell cycle, exploiting the rat liver regeneration model following partial hepatectomy, the most useful to study synchronized cell cycle in vivo. Hepatic regeneration led to increased levels of anandamide and endocannabinoid-like molecules oleoylethanolamide (OEA) and palmitoylethanolamide (PEA) in the G1 phase of the cell cycle, with a concomitant increase in CB1 mRNA levels, whose protein expression peaked later during the S phase. Blocking of CB1 receptor with a low dose of the selective antagonist/inverse agonist SR141716 (0.7 mg/kg/dose) affected cell cycle progression reducing the expression of PCNA, and through the inhibition of pERK and pSTAT3 pathways. These results support the notion that the signaling mediated by anandamide through CB1 receptor may be important for the entry and progression of cells into the cell cycle and hence for their proliferation under mitogenic signals.

Antiangiogenic effects of N6-isopentenyladenosine, an endogenous isoprenoid end product, mediated by AMPK activation.

N6-isopentenyladenosine (iPA), an end product of the mevalonate pathway with an isopentenyl chain, is already known to exert a suppressor effect against various tumors. In this work, we investigated whether iPA also directly interferes with the angiogenic process, which is fundamental to tumor growth and progression. To this end, using human umbilical vein endothelial cells (HUVECs) as a suitable in vitro model of angiogenesis, we evaluated their viability, proliferation, migration, invasion, tube formation in response to iPA, and molecular mechanisms involved. Data were corroborated in mice by using a gel plug assay. iPA dose- and time-dependently inhibited all the neoangiogenesis stages, with an IC50 of 0.98 µM. We demonstrated for the first time, by liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS), that iPA was monophosphorylated into 5'-iPA-monophosphate (iPAMP) by the adenosine kinase (ADK) inside the cells. iPAMP is the active form that inhibits angiogenesis through the direct activation of AMP-kinase (AMPK). Indeed, all effects were completely reversed by pretreatment with 5-iodotubercidin (5-Itu), an ADK inhibitor. The isoprenoid intermediate isopentenyl pyrophosphate (IPP), which shares the isopentenyl moiety with iPA, was ineffective in the inhibition of angiogenesis, thus showing that the iPA structure is specific for the observed effects. In conclusion, iPA is a novel AMPK activator and could represent a useful tool for the treatment of diseases where excessive neoangiogenesis is the underlying pathology.

Pharmacological actions of statins: a critical appraisal in the management of cancer.

Statins, among the most commonly prescribed drugs worldwide, are cholesterol-lowering agents used to manage and prevent cardiovascular and coronary heart diseases. Recently, a multifaceted action in different physiological and pathological conditions has been also proposed for statins, beyond anti-inflammation and neuroprotection. Statins have been shown to act through cholesterol-dependent and -independent mechanisms and are able to affect several tissue functions and modulate specific signal transduction pathways that could account for statin pleiotropic effects. Typically, statins are prescribed in middle-aged or elderly patients in a therapeutic regimen covering a long life span during which metabolic processes, aging, and concomitant novel diseases, including cancer, could occur. In this context, safety, toxicity, interaction with other drugs, and the state of health have to be taken into account in subjects treated with statins. Some evidence has shown a dichotomous effect of statins with either cancer-inhibiting or -promoting effects. To date, clinical trials failed to demonstrate a reduced cancer occurrence in statin users and no sufficient data are available to define the long-term effects of statin use over a period of 10 years. Moreover, results from clinical trials performed to evaluate the therapeutic efficacy of statins in cancer did not suggest statin use as chemotherapeutic or adjuvant agents. Here, we reviewed the pharmacology of the statins, providing a comprehensive update of the current knowledge of their effects on tissues, biological processes, and pathological conditions, and we dissected the disappointing evidence on the possible future use of statin-based drugs in cancer therapy.

Statins in neurological disorders: an overview and update.

Statins have, at present, the potential to provide a new therapeutic target for various neurological diseases. It is well established that statins reduce cholesterol levels and prevent coronary heart disease. Moreover, evidence suggest that statins have additional properties such as endothelial protection via action on the nitric oxide synthase system as well as antioxidant, anti-inflammatory and anti-platelet effects. These properties might have potential therapeutic implication not only in stroke but also in neurological disorders such as Alzheimer disease, Parkinson's disease, multiple sclerosis and primary brain tumors. In addition to their potent anti-atherosclerotic and cardio-protective effects, compelling clinical and preclinical studies delineate the neuro-protective efficacy of statins in all these neurological disorders. It is apparent from these studies that most patients with central nervous system disorders probably benefit to some extent from lipid-lowering therapy. But data are not univocal, and we must also consider the adverse effects due to the administration of lipid-lowering therapy. Thus, in these scenarios the effectiveness of statins in treating stroke, Alzheimer's disease, Parkinson disease, multiple sclerosis, and primary brain tumors have to be conclusively proven in vivo and/or in adequate clinical trials.

N6-isopentenyladenosine affects cytotoxic activity and cytokines production by IL-2 activated NK cells and exerts topical anti-inflammatory activity in mice.

N6-isopentenyladenosine (iPA) is a modified adenosine with an isopentenyl moiety derived from the mevalonate pathway which displays pleiotropic biological effects, including anti-tumor and anti-angiogenic activity. Previous evidence revealed a biphasic effect of iPA on phytohemagglutinin-stimulated lymphocytes, being pro-proliferative at low doses and anti-proliferative at high doses. Analogously, we have recently shown that low iPA concentrations (<1µM) increased the immune response of natural killer (NK) cells against cancer targets. In the present study, we evaluated the effect of iPA at high concentration (10µM) on IL-2-activated NK cells. iPA, inhibited NK cell proliferation and cytotoxicity against their conventional tumor target, human K562 cells. This inhibition was associated with decreased expression and functionality of NK cell activating receptors NKp44 and NKG2D as well as impaired cyto/chemokines secretion (RANTES, MIP-1α, TNF-α and IFN-γ). ERK/MAPK and STAT5 activation in IL-2-activated NK cells were inhibited by iPA. The results obtained in vitro were validated in vivo in the inflammatory murine model of croton oil-induced ear dermatitis. The topical application of iPA significantly reduced mouse ear oedema, thus suggesting anti-inflammatory properties of this molecule. These results show the ability of iPA to exert anti-inflammatory effects both in vitro and in vivo directly targeting NK cells, providing a novel pharmacological tool in those diseases characterized by a deregulated immune-response, such as cancer or inflammatory conditions.

Cannabidiol exerts multitarget immunomodulatory effects on PBMCs from individuals with psoriasis vulgaris.

Introduction: The involvement of endocannabinoid system (ECS) in the inflammatory cascade, and the ability of phytocannabinoids, endocannabinoids and their synthetic analogues to modulate it has become an interesting research area for new therapeutic approaches in inflammatory skin diseases. Cannabidiol (CBD) appears to be the most promising among phytocannabinoids, due to the lack of psychotropic effects and low toxicity profile. Its anti-inflammatory action has been highlighted in different preclinical models, ranging from experimental colitis to arthritis and neuroinflammation. Our aim was to evaluate CBD immune-modulatory effects in peripheral blood mononuclear cells (PBMC) of psoriasis individuals with particular attention to both innate and adaptative immune arms. Methods: We performed in vitro immune functional experiments to analyze CBD action on various immune cells active in psoriatic lesions. Results: The results showed that CBD produced a shift from Th1 to Th2 response, while boosting cytotoxic activity of Natural Killer (NK) cells. Furthermore, it also exerted a potent action on monocyte differentiation as, after CBD treatment, monocytes from psoriatic individuals were unable to migrate in response to inflammatory stimuli and to fully differentiate into mature dendritic cells. Finally, a M2 skewing of monocyte-derived macrophages by CBD also contributed to the fine tuning of the magnitude of immune responses. Conclusions: These data uncover new potential immunomodulatory properties of this cannabinoid suggesting a possible therapeutic action in the treatment of multiple inflammatory skin diseases.