Cancer-associated immune cells and their modulation by melatonin.

OBJECTIVES: Rapidly growing evidence suggests that immune cells play a key role in determining tumor progression. Tumor cells are surrounded by a microenvironment composed of different cell populations including immune cells. The cross talk between tumor cells and the neighboring microenvironment is an important factor to take into account while designing tumor therapies. Despite significant advances in immunotherapy strategies, a relatively small proportion of patients have successfully responded to them. Therefore, the search for safe and efficient drugs, which could be used alongside conventional therapies to boost the immune system against tumors, is an ongoing need. In the present work, the modulatory effects of melatonin on different components of tumor immune microenvironment are reviewed. METHODS: A thorough literature review was performed in PubMed, Scopus, and Web of Science databases. All published papers in English on tumor immune microenvironment and the relevant modulatory effects of melatonin were scrutinized. RESULTS: Melatonin modulates macrophage polarization and prevents M2 induction. Moreover, it prevents the conversion of fibroblasts into cancer-associated fibroblasts (CAFs) and prevents cancer cell stemness. In addition, it can affect the payload composition of tumor-derived exosomes (TEXs) and their secretion levels to favor a more effective anti-tumor immune response. Melatonin is a safe molecule that affects almost all components of the tumor immune microenvironment and prevents them from being negatively affected by the tumor. CONCLUSION: Based on the effects of melatonin on normal cells, tumor cells and microenvironment components, it could be an efficient compound to be used in combination with conventional immune-targeted therapies to increase their efficacy.

Therapeutic targets of cancer drugs: Modulation by melatonin.

The biological functions of melatonin range beyond the regulation of the circadian rhythm. With regard to cancer, melatonin's potential to suppress cancer initiation, progression, angiogenesis and metastasis as well as sensitizing malignant cells to conventional chemo- and radiotherapy are among its most interesting effects. The targets at which melatonin initiates its anti-cancer effects are in common with those of a majority of existing anti-cancer agents, giving rise to the notion that this molecule is a pleiotropic agent sharing many features with other antineoplastic drugs in terms of their mechanisms of action. Among these common mechanisms of action are the regulation of several major intracellular pathways including mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK) and protein kinase B (AKT/PKB) signaling. The important mediators affected by melatonin include cyclins, nuclear factor-κB (NF-κB), heat shock proteins (HSPs) and c-Myc, all of which can serve as potential targets for cancer drugs. Melatonin also exerts some of its anti-cancer effects via inducing epigenetic modifications, DNA damage and mitochondrial disruption in malignant cells. The regulation of these mediators by melatonin mitigates tumor growth and invasiveness via modulating their downstream responsive genes, housekeeping enzymes, telomerase reverse transcriptase, apoptotic gene expression, angiogenic factors and structural proteins involved in metastasis. Increasing our knowledge on how melatonin affects its target sites will help find ways of exploiting the beneficial effects of this ubiquitously-acting molecule in cancer therapy. Acknowledging this, here we reviewed the most studied target pathways attributed to the anti-cancer effects of melatonin, highlighting their therapeutic potential.

Caffeine attenuates seizure and brain mitochondrial disruption induced by Tramadol: the role of adenosinergic pathway.

Tramadol (TR) is an analgesic drug used to treat moderate-to-severe pain but it induces seizure even at therapeutic doses. The exact mechanism of TR-inducing seizure is not clear but inhibition of the serotonin, GABA, and nitrous oxide (NOS) pathways are the commonly proposed mechanisms. Adenosinergic system has a crucial function in the modulation of seizure. Also, oxidative damage is an unavoidable effect of the seizure. This study was conducted to evaluate the role of the adenosinergic system on the seizure and oxidative stress biomarkers induced by TR using antagonist of the adenosinergic receptors in the Albino mice. For that purpose, generated clonic seizure, as seizure threshold, was evaluated by TR. Caffeine (CAF; 8 mg/kg, i.p.), a nonselective antagonist of adenosine receptors, was administered 1 hour before the seizure induction. The seizure threshold significantly increased by CAF-treated group when compared to TR group (p < 0.001). Oxidative stress biomarkers such as reactive oxygen species, protein carbonyl content, and lipid peroxidation significantly decreased and glutathione content significantly increased by CAF in brain mitochondria compared to the TR group, whereas oxidative biomarkers significantly increased in the TR group compared to the control group. The results of the present study suggested that the adenosinergic system is involved in seizure induced by TR and meanwhile, inhibition of adenosine receptors can decrease the TR seizure threshold and also decrease the induced oxidative damage in the brain mitochondria.

The mechanisms of cellular crosstalk between mesenchymal stem cells and natural killer cells: Therapeutic implications.

Mesenchymal stem cells (MSCs) are mesenchymal precursors of various origins, with well-known immunomodulatory effects. Natural killer (NK) cells, the major cells of the innate immune system, are critical for the antitumor and antiviral defenses; however, in certain cases, they may be the main culprits in the pathogenesis of some NK-related conditions such as autoimmunities and hematological malignancies. On the other hand, these cells seem to be the major responders in beneficial phenomena like graft versus leukemia. Substantial data suggest that MSCs can variably affect NK cells and can be affected by these cells. Accordingly, acquiring a profound understanding of the crosstalk between MSCs and NK cells and the involved mechanisms seems to be a necessity to develop therapeutic approaches based on such interactions. Therefore, in this study, we made a thorough review of the existing literature on the interactions between MSCs and NK cells with a focus on the underlying mechanisms. The current knowledge herein suggests that MSCs possess a great potential to be used as tools for therapeutic targeting of NK cells in disease context and that preconditioning of MSCs, as well as their genetic manipulation before administration, may provide a wider variety of options in terms of eliciting more specific and desirable therapeutic outcomes. Nevertheless, our knowledge regarding the effects of MSCs on NK cells is still in its infancy, and further studies with well-defined conditions are warranted herein.

Immunoregulatory role of melatonin in cancer.

Melatonin is a ubiquitous indole amine that plays a fundamental role in the regulation of the biological rhythm. Disrupted circadian rhythm alters the expression of clock genes and deregulates oncogenes, which finally promote tumor development and progression. An evidence supporting this notion is the higher risk of developing malignancies among night shift workers. Circadian secretion of the pineal hormone also synchronizes the immune system via a reciprocal association that exists between the immune system and melatonin. Immune cells are capable of melatonin biosynthesis in addition to the expression of its receptors. Melatonin induces big changes in different immune cell proportions, enhances their viability and improves immune cell metabolism in the tumor microenvironment. These effects might be directly mediated by melatonin receptors or indirectly through alterations in hormonal and cytokine release. Moreover, melatonin induces apoptosis in tumor cells via the intrinsic and extrinsic pathways of apoptosis, while it protectsthe immune cells. In general, melatonin has a profound impact on immune cell trafficking, cytokine production and apoptosis induction in malignant cells. On such a basis, using melatonin and resynchronization of sleep cycle may have potential implications in immune function enhancement against malignancies, which will be the focus of the present paper.

New thiazole-2(3H)-thiones containing 4-(3,4,5-trimethoxyphenyl) moiety as anticancer agents.

A new series of thiazole-2(3H)-thiones containing 4-(3,4,5-trimethoxyphenyl) moiety were synthesized as diaryl-heterocylic analogs of combretastatin A-4 with anticancer activity. The cytotoxicity evaluation of synthesized compounds against cancer cell lines (A549, MCF-7 and SKOV3) revealed that most of them had potent cytotoxic activity toward all tested cell lines (IC50s < 10 µg/mL). Among them, 3-(chlorobenzyl) derivatives 5c and 5d showed the best inhibitory effect on MCF-7 cells (IC50 values of 1.14 and 2.41 µg/mL, respectively). Furthermore, the ability of tubulin polymerization inhibition and apoptosis induction were evaluated for the promising compounds 5c and 5d. Results suggested that these compounds remarkably inhibit tubulin polymerization and induce apoptosis resulting in cell death. In vitro studies revealed that these compounds had no significant cytotoxicity against normal cells at the concentrations required for growth inhibition of cancer cells. In vitro biding assay and in silico docking study also confirmed the binding of prototype compound to the colchicine binding site of tubulin.

Design, synthesis and biological evaluation of flexible and rigid analogs of 4H-1,2,4-triazoles bearing 3,4,5-trimethoxyphenyl moiety as new antiproliferative agents.

Several flexible and rigid analogs of 4H-1,2,4-triazoles (compounds 8a-g and 9a-g) bearing trimethoxyphenyl pharmacophoric unit, were designed and synthesized as potential anticancer agents. The in vitro cytotoxic assay indicated that both flexible and rigid analogs (8 and 9, respectively) can potentially inhibit the growth of cancerous cells (A549, MCF7, and SKOV3), with IC50 values less than 5.0 µM. Furthermore, compounds 10a-l as regional isomers of compounds 9 exhibited remarkable cytotoxic activity with IC50 values ranging from 0.30 to 5.0 µM. The rigid analogs 9a, 10h and 10k were significantly more potent than etoposide against MCF7, SKOV3 and A549 cells, respectively. These compounds showed high selectivity towards cancer cells over normal cells, as they had no significant cytotoxicity against L929 cells. In addition, the representative compounds 9a and 10h could inhibit the tubulin polymerization at micro-molar levels. By determining changes in the colchicine-tubulin fluorescence, it was suggested that compound 10h could bind to the tubulin at the colchicine pocket. The molecular docking study further confirmed the inhibitory activity of promising compounds 9a, 10h and 10k on tubulin polymerization through binding to the colchicine-binding site.

Doxorubicin and liposomal doxorubicin induce senescence by enhancing nuclear factor kappa B and mitochondrial membrane potential.

AIMS: Senescence is a state ensuing aging to eliminate age-associated damage with an irreversible cell-cycle arrest mechanism, which is historically believed to be one of the tumor responses to therapy. Doxorubicin as an anti-cancer drug has been used in cancer treatment for a long time. Liposomal doxorubicin (Ldox) is a liposomal formulation of doxorubicin, which increases the doxorubicin permanency. The aim of this study was to examine the toxicity of these two formulations by comparing them in terms of their ability to induce cellular senescence. MAIN METHODS: The study groups included a control group, three DOX (0.75, 0.5, 0.1 mg/kg/BW) and three Ldox groups (0.1, 0.05, 0.025 mg/kg/BW). Heart tissues were studied regarding oxidative stress assessment, mitochondrial function, inflammatory markers and biochemical and histopathological evaluation. Real-Time PCR was used for P53 and SA ß-gal expression. KEY FINDINGS: Based on the results, the highest doses of Dox and Ldox (0.75 and 0.1 mg/kg/BW respectively) significantly increased the level of inflammatory markers and according to other factors especially p53 and SA ß-gal expression, both were able to induce senescence but the changes in Ldox were less tangible than the Dox.

NLRP inflammasome as a key role player in the pathogenesis of environmental toxicants.

Exposure to environmental toxicants (ET) results in specific organ damage and auto-immune diseases, mostly mediated by inflammatory responses. The NLRP3 inflammasome has been found to be the major initiator of the associated pathologic inflammation. It has been found that ETs can trigger all the signals required for an NLRP3-mediated response. The exaggerated activation of the NLRP3 inflammasome and its end product IL-1ß, is responsible for the pathogenesis caused by many ETs including pesticides, organic pollutants, heavy metals, and crystalline compounds. Therefore, an extensive study of these chemicals and their mechanisms of inflammasome (INF) activation may provide the scientific evidence for possible targeting of this pathway by proposing possible protective agents that have been previously shown to affect INF compartments and its activation. Melatonin and polyunsaturated fatty acids (PUFA) are among the safest and the most studied of these agents, which affect a wide variety of cellular and physiological processes. These molecules have been shown to suppress the NLRP3 inflammasome mostly through the regulation of cellular redox status and the nuclear factor-κB (NF-κB) pathway, rendering them potential promising compounds to overcome ET-mediated organ damage. In the present review, we have made an effort to extensively review the ETs that exert their pathogenesis via the stimulation of inflammation, their precise mechanisms of action and the possible protective agents that could be potentially used to protect against such toxicants.

New potent antifungal triazole alcohols containing N-benzylpiperazine carbodithioate moiety: Synthesis, in vitro evaluation and in silico study.

A number of 1H-1,2,4-triazole alcohols containing N-(halobenzyl)piperazine carbodithioate moiety have been designed and synthesized as potent antifungal agents. In vitro bioassays against different Candida species including C. albicans, C. glabrata, C. parapsilosis, C. krusei, and C. tropicalis revealed that the N-(4-chlorobenzyl) derivative (6b) with MIC values of 0.063-0.5 µg/mL had the best profile of activity, being 4-32 times more potent than fluconazole. Docking simulation studies confirmed the better fitting of compound 6b in the active site of lanosterol 14α-demethylase (CYP51) enzyme, the main target of azole antifungals. Particularly, the potential of compound 6b against fluconazole-resistant isolates along with its minimal toxicity against human erythrocytes and HepG2 cells make this prototype compound as a good lead for discovery of potent and safe antifungal agents.

Does the use of melatonin overcome drug resistance in cancer chemotherapy?

Our knowledge regarding the implications of melatonin in the therapy of numerous medical conditions, including cancer is constantly expanding. Melatonin can variably affect cancer pathology via targeting several key aspects of any neoplastic condition, including the very onset of carcinogenesis as well as tumor growth, differentiation, and dissemination. Numerous studies have examined the effects of melatonin in the context of various cancers reporting the enhanced efficacy of chemo/radiotherapy in combination with this compound. Reduced sensitivity and also resistance of cancer cells to antineoplastic agents are common events which might arise as a result of genomic instability of the malignant cells. Genetic mutations provide numerous mechanisms for these cells to resist cytotoxic therapies. Melatonin, due to its pleitropic effects, is able to correct these alterations in favour of sensitization to antineoplastic agents as evident by increased response to treatment via modulating the expression and phosphorylation status of drug targets, the reduced clearance of drugs by affecting their metabolism and transport within the body, decreased survival of malignant cells via altering DNA repair and telomerase activity, and enhanced responsiveness to cell death-associated mechanisms such as apoptosis and autophagy. These effects are presumably governed by melatonin's interventions in the main signal transduction pathways such as Akt and MAPK, independent of its antioxidant properties. Possessing such a signaling altering nature, melatonin can considerably affect the drug-resistance mechanisms employed by the malignant cells in breast, lung, hepatic, and colon cancers as well as different types of leukemia which are the subject of the current review.

Atorvastatin attenuates ethanol-induced hepatotoxicity via antioxidant and anti-inflammatory mechanisms.

The aim of this study was to evaluate the role of inflammation and oxidative damage in hepatotoxicity of ethanol. Also we assessed protective effects of atorvastatin against ethanol-induced hepatotoxicity. In this study, the animals were divided into five groups: control, ethanol (10 mg/kg intraperitoneal (i.p.)), ethanol with atorvastatin (10, 20 mg/kg/day, i.p.) and ethanol-vitamin C group which received ethanol (10 mg/kg/day) plus vitamin C (200 mg/kg, i.p.) for 28 consecutive days. Then, the animals were euthanized and liver tissues were separated. Biochemical markers ALT and AST were measured. Moreover, glutathione (GSH) content, lipid peroxidation, protein carbonyl, nitric oxide and tumor necrosis factor-α (TNF-α) were evaluated. The administration of ethanol for 28 days resulted in an increase in liver damage, oxidative stress and inflammatory markers. The atorvastatin was able to prevent the ethanol-induced hepatotoxicity by decreasing the oxidative stress and inflammation processes. Our study showed the critical role of oxidative damage and inflammation in ethanol-induced hepatotoxicity that markedly was inhibited by administration of atorvastatin. Therefore, atorvastatin can be suggested for prevention of ethanol-induced hepatotoxicity.

Autophagy, its mechanisms and regulation: Implications in neurodegenerative diseases.

Autophagy is a major regulatory cellular mechanism which gives the cell an ability to cope with some of the destructive events that normally occur within a metabolically living cell. This is done by maintaining the cellular homeostasis, clearance of damaged organelles and proteins and recycling necessary molecules like amino acids and fatty acids. There is a wide array of factors that influence autophagy in the state of health and disease. Disruption of these mechanisms may not only give rise to several autophagy-related disease, but also it can occur as the result of intracellular changes induced during disease pathogenesis causing exacerbation of the disease. Our knowledge is increasing regarding the role of autophagy and its mechanisms in the pathogenesis of various neurodegenerative diseases such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, Huntington's disease and Amyotrophic lateral sclerosis. Indeed, getting to know about the pathways of autophagy and its regulation can provide the basis for designing therapeutic interventions. In the present paper, we review the pathways of autophagy, its regulation and the possible autophagy-targeting interventions for the treatment of neurodegenerative disorders.

Melatonin as a multifunctional anti-cancer molecule: Implications in gastric cancer.

Gastric cancer (GC) is a predominant malignancy with a high mortality rate affecting a large population worldwide. The etiology of GC is multifactorial spanning from various genetic determinants to different environmental causes. Current tretaments of GC are not efficient enough and require improvements to minimize the adverse effects. Melatonin, a naturally occurring compound with known potent inhibitory effects on cancer cells is one of the major candidates which can be recruited herein. Here we reviewed the articles conducted on the therapeutic effects of melatonin in gastric cancer in various models. The results are classified according to different aspects of cancer pathogenesis and the molecular mechanisms by which melatonin exerts its effects. Melatonin could be used to combat GC exploiting its effects on multiple aspects of its pathogenesis, including formation of cancer cells, tumor growth and angiogenesis, differentiation and metastasis as well as enhancing the anti-tumor immunity. Melatonin is a pleiotropic anti-cancer molecule that affects malignant cells via multiple mechanisms. It has been shown to benefit cancer patients indirectly by reducing side effects of current therapies which have been discussed in this review. This field of research is still underdeveloped and may serve as an interesting subject for further studies aiming at the molecular mechanisms of melatonin and novel treatments.

Synergism effects of pioglitazone and Urtica dioica extract in streptozotocin-induced nephropathy via attenuation of oxidative stress.

OBJECTIVES: Hyperglycemia promotes oxidative stress that plays a crucial role in the pathogenesis of Diabetic nephropathy (DN). In this study, we investigated the synergism effects of hydroalcoholic extract of Urtica dioica and pioglitazone (PIO) on the prevention of DN in streptozotocin induced-diabetic mice. MATERIALS AND METHODS: Forty-two mice were divided into six groups as follows: non-diabetic control group, DMSO group (as solvent), diabetic group and four treatment groups which received U. dioica, pioglitazone, U. dioica plus pioglitazone and vitE. Diabetes was induced by a single dose of streptozotocin (STZ) (200 mg/kg body wt, IP) diluted in citrate buffer (pH= 4.6). After 4 weeks treatment, all animals were anaesthetized and blood was collected for serum urea and creatinine levels assessment in plasma and kidney tissue were excised for evaluation of oxidative stress markers. RESULTS: Treatment with U. dioica significantly inhibited increase in serum urea and creatinine in plasma that were observed in diabetic mice. Furthermore, the elevated level of oxidative stress markers (glutathione oxidation, lipid peroxidation (LPO), protein carbonyl) in renal supernatant of diabetic mice was inhibited by U. dioica treatment. Interestingly, U. dioica promoted beneficial effects of PIO in reducing STZ-induced hyperglycemia, renal damage and oxidative stress markers. CONCLUSION: Our findings showed that PIO plus U. dioica have synergism protective effects against STZ-induced nephropathy that can be a candidate as a therapeutic approach in order to treatment of DN.

A Systematic and Mechanistic Review on the Phytopharmacological Properties of Alhagi Species.

Alhagi species are well known in Iran (locally known as Khar Shotor) and other parts of Asia as a popular folk medicine. Recent research has shown extensive pharmacological effects of these species. This paper is a comprehensive review of the phytopharmacological effects and traditional uses of Alhagi species and their active constituents with special attention to the responsible mechanisms, effective dosages and routes of administration. The Alhagi species studied in this paper include: A. maurorum, A. camelorum, A. persarum, A. pseudoalhagi, and A. kirgisorum. In order to include all the up to date data, the authors went through several databases including the Web of Science, Embase, etc. The findings were critically reviewed and sorted on the basis of relevance to the topic. Tables have been used to clearly present the ideas and discrepancies were settled through discussion. Alhagi species have significant biomedical properties which can be exploited in clinical use. Proantocyanidin isolated from A. pseudoalhagi has significant biochemical effects on blood factors. Among Alhagi species, A. camelorum and A. maurorum possess the highest anti-microbial activity. Most of the effects observed with A. maurorum are dose-dependent. This paper indicates with emphasis that Alhagi species are safe and rich sources of biologically active compounds with low toxicity. Since DNA damage has been observed following the ingestion of specific concentrations of A. pseudalhagi, care should be taken during administration of the plant for therapeutic use. Further studies are required to confirm the safety and quality of these plants to be used by clinicians as therapeutic agents.