New paradigms in chronic intestinal inflammation and colon cancer: role of melatonin

IP3R1-mediated MAMs formation contributes to mechanical trauma-induced hepatic injury and the protective effect of melatonin

INTRODUCTION

There is a high morbidity and mortality rate in mechanical trauma (MT)-induced hepatic injury. Currently, the molecular mechanisms underlying liver MT are largely unclear. Exploring the underlying mechanisms and developing safe and effective medicines to alleviate MT-induced hepatic injury is an urgent requirement. The aim of this study was to reveal the role of mitochondria-associated ER membranes (MAMs) in post-traumatic liver injury, and ascertain whether melatonin protects against MT-induced hepatic injury by regulating MAMs.

METHODS

Hepatic mechanical injury was established in Sprague-Dawley rats and primary hepatocytes. A variety of experimental methods were employed to assess the effects of melatonin on hepatic injury, apoptosis, MAMs formation, mitochondrial function and signaling pathways.

RESULTS

Significant increase of IP3R1 expression and MAMs formation were observed in MT-induced hepatic injury. Melatonin treatment at the dose of 30 mg/kg inhibited IP3R1-mediated MAMs and attenuated MT-induced liver injury in vivo. In vitro, primary hepatocytes cultured in 20% trauma serum (TS) for 12 h showed upregulated IP3R1 expression, increased MAMs formation and cell injury, which were suppressed by melatonin (100 μmol/L) treatment. Consequently, melatonin suppressed mitochondrial calcium overload, increased mitochondrial membrane potential and improved mitochondrial function under traumatic condition. Melatonin's inhibitory effects on MAMs formation and mitochondrial calcium overload were blunted when IP3R1 was overexpressed. Mechanistically, melatonin bound to its receptor (MR) and increased the expression of phosphorylated ERK1/2, which interacted with FoxO1 and inhibited the activation of FoxO1 that bound to the IP3R1 promoter to inhibit MAMs formation.

CONCLUSION

Melatonin prevents the formation of MAMs via the MR-ERK1/2-FoxO1-IP3R1 pathway, thereby alleviating the development of MT-induced liver injury. Melatonin-modulated MAMs may be a promising therapeutic therapy for traumatic hepatic injury.

The potential influence of melatonin on mitochondrial quality control: a review

Mitochondria are critical for cellular energetic metabolism, intracellular signaling orchestration and programmed death regulation. Therefore, mitochondrial dysfunction is associated with various pathogeneses. The maintenance of mitochondrial homeostasis and functional recovery after injury are coordinated by mitochondrial biogenesis, dynamics and autophagy, which are collectively referred to as mitochondrial quality control. There is increasing evidence that mitochondria are important targets for melatonin to exert protective effects under pathological conditions. Melatonin, an evolutionarily conserved tryptophan metabolite, can be synthesized, transported and metabolized in mitochondria. In this review, we summarize the important role of melatonin in the damaged mitochondria elimination and mitochondrial energy supply recovery by regulating mitochondrial quality control, which may provide new strategies for clinical treatment of mitochondria-related diseases.

Melatonin as a potential treatment for septic cardiomyopathy

Septic cardiomyopathy (SCM) is a common complication of sepsis contributing to high mortality rates. Its pathophysiology involves complex factors, including inflammatory cytokines, mitochondrial dysfunction, oxidative stress, and immune dysregulation. Despite extensive research, no effective pharmacological agent has been established for sepsis-induced cardiomyopathy. Melatonin, a hormone with diverse functions in the body, has emerged as a potential agent for SCM through its anti-oxidant, anti-inflammatory, anti-apoptotic, and cardioprotective roles. Through various molecular levels of its mechanism of action, it counterattacks the adverse event of sepsis. Experimental studies have mentioned that melatonin protects against many cardiovascular diseases and exerts preventive effects on SCM. Moreover, melatonin has been investigated in combination with other drugs such as antibiotics, resveratrol, and anti-oxidants showing synergistic effects in reducing inflammation, anti-oxidant, and improving cardiac function. While preclinical studies have demonstrated positive results, clinical trials are required to establish the optimal dosage, route of administration, and treatment duration for melatonin in SCM. Its safety profile, low toxicity, and natural occurrence in the human body provide a favorable basis for its clinical use. This review aims to provide an overview of the current evidence of the use of melatonin in sepsis-induced cardiomyopathy (SICM). Melatonin appears to be promising as a possible treatment for sepsis-induced cardiomyopathy and demands further investigation.

Pharmacotechnical, Physico-Chemical, and Antioxidant Evaluation of Newly Developed Capsule Formulations

The excess of free radicals causes numerous imbalances in the body that lead to premature aging, the degradation of internal structures, and the appearance of numerous pathologies responsible for the increased risk of premature death. The present work aims to evaluate the physical, chemical, pharmacotechnical, and antioxidant activity of newly achieved capsule formulations. These two formulations were F1_a.i., which contains melatonin:biotin:coenzyme Q10 (weight ratio of 1:2:60), and F2_a.i., which contains quercetin:resveratrol:biotin:coenzyme Q10 (weight ratio of 10:10:1:10). The adequate selection of the excipient types and amounts for final capsule formulations (F1_c.c., F2_c.c.) was based on preformulation studies performed on the powders containing active ingredients. The antioxidant activity assessed using three methods (ABTS, DPPH, and FRAP) compared with acid ascorbic as a positive control demonstrated that the F2_c.c. formulation possesses the strongest antioxidant capacity. The results confirmed the suitable formulation and the accurate selection of the types and amounts of active ingredients, as well as the auxiliary excipients used in newly developed capsule formulations as supplements with an excellent antioxidant effect on the human body.

Study of a First Approach to the Controlled Fermentation for Lambic Beer Production

Non-Saccharomyces yeasts represent a great source of biodiversity for the production of new beer styles, since they can be used in different industrial areas, as pure culture starters, in co-fermentation with Saccharomyces, and in spontaneous fermentation (lambic and gueuze production, with the main contribution of Brettanomyces yeast). The fermentation process of lambic beer is characterized by different phases with a characteristic predominance of different microorganisms in each of them. As it is a spontaneous process, fermentation usually lasts from 10 months to 3 years. In this work, an attempt was made to perform a fermentation similar to the one that occurred in this process with lactic bacteria, Saccharomyces yeast and Brettanomyces yeast, but controlling their inoculation and therefore decreasing the time necessary for their action. For this purpose, after the first screening in 100 mL where eight Brettanomyces yeast strains from D.O. "Ribeira Sacra" (Galicia) were tested, one Brettanomyces bruxellensis strain was finally selected (B6) for fermentation in 1 L together with commercial strains of Saccharomyces cerevisiae S-04 yeast and Lactobacillus brevis lactic acid bacteria in different sequences. The combinations that showed the best fermentative capacity were tested in 14 L. Volatile compounds, lactic acid, acetic acid, colour, bitterness, residual sugars, ethanol, melatonin and antioxidant capacity were analysed at different maturation times of 1, 2, 6 and 12 months. Beers inoculated with Brettanomyces yeast independently of the other microorganisms showed pronounced aromas characteristic of the Brettanomyces yeast. Maturation after 12 months showed balanced beers with "Brett" aromas, as well as an increase in the antioxidant capacity of the beers.

Extracellular Nicotinamide Phosphoribosyltransferase as a Surrogate Marker of Prominent Malignant Potential in Colonic Polyps: A 2-Year Prospective Study

BACKGROUND/AIMS

The implications of extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a cancer metabokine, in colonic polyps remain uncertain.

METHODS

A 2-year prospective cohort study of patients who underwent colonoscopy was conducted. Biochemical parameters and serum eNAMPT levels were analyzed at baseline and every 24 weeks postpolypectomy. NAMPT-associated single-nucleotide polymorphisms (SNPs), including rs61330082, rs2302559, rs10953502, and rs23058539, were assayed.

RESULTS

Of 532 patients, 80 (15%) had prominent malignant potential (PMP) in colonic polyps, including villous adenomas (n = 18, 3.3%), adenomas with high-grade dysplasia (n = 33, 6.2%), and adenocarcinomas (n = 29, 5.5%). Baseline associations were as follows: colonic polyp pathology (p < 0.001), total cholesterol (p = 0.019), and neutrophil-to-lymphocyte ratio (p = 0.023) with eNAMPT levels; and age (p < 0.001), polyp size (p < 0.001), and eNAMPT levels (p < 0.001) with polyp pathology. Higher baseline eNAMPT levels were noted in patients harboring polyps with PMP than in patients without PMP (p < 0.001), and baseline eNAMPT levels significantly predicted PMP (cutoff: >4.238 ng/mL, p < 0.001). Proportions of eNAMPT-positive glandular and stromal cells were higher in polyps with PMP than in polyps without PMP (64.55 ± 11.94 vs. 14.82 ± 11.45%, p = 0.025). eNAMPT levels decreased within 48 weeks postpolypectomy (p = 0.01) and remained stable afterward regardless of PMP until 96 weeks postpolypectomy. However, those with PMP had a higher degree of eNAMPT decline within 24 weeks (p = 0.046). All investigated SNPs were in linkage disequilibrium with each other but were not associated with eNAMPT levels.

CONCLUSION

With a link to inflammation and lipid metabolism, along with its decreasing trend after polypectomy, serum eNAMPT may serve as a surrogate marker of PMP in colonic polyps. In situ probing of the NAMPT-associated pathway holds promise in attenuating PMP, as much of the eNAMPT likely originates from colonic polyps.

Lachancea thermotolerans, an Innovative Alternative for Sour Beer Production

The interest in and growth of craft beer has led to an intense search for new beers and styles. The revival of traditional styles has sometimes been hampered by the use of microorganisms such as lactic acid bacteria. Therefore, studies on alternative yeasts for the production of this style of beer have increased. In this work and together with previous studies carried out with yeasts isolated from Madrid agriculture (from grapes, must, wine, vineyards and wineries), the capacity of 10 yeast strains, belonging to the genus Lachancea thermotolerans, for the production of sour beer has been determined. For this purpose, different fermentation scale-ups (100 mL, 1 L and 100 L) have been performed and their fermentation capacity, aroma compound production (33 volatile compounds by GC), organoleptic profile (trained tasting panel and consumers), melatonin production (HPLC) and antioxidant capacity have been studied. Beer fermented with yeast strain CLI 1232 showed a balanced acidity with a fruity aromatic profile and honey notes. On the other hand, the beer fermented with strain 1-8B also showed a balanced acidity, but less fruity and citric flavour than CLI 1232 strain. Finally, the yeast strain selected by the consumers (CLI 1232) was used for beer production at industrial scale and the market launch of a sour beer.

Melatonin Can Modulate Neurodegenerative Diseases by Regulating Endoplasmic Reticulum Stress

As people age, their risks of developing degenerative diseases such as cancer, diabetes, Parkinson's Disease (PD), Alzheimer's Disease (AD), rheumatoid arthritis, and osteoporosis are generally increasing. Millions of people worldwide suffer from these diseases as they age. In most countries, neurodegenerative diseases are generally recognized as the number one cause afflicting the elderly. Endoplasmic reticulum (ER) stress has been suggested to be associated with some human neurological diseases, such as PD and AD. Melatonin, a neuroendocrine hormone mainly synthesized in the pineal gland, is involved in pleiotropically biological functions, including the control of the circadian rhythm, immune enhancement, and antioxidant, anti-aging, and anti-tumor effects. Although there are many papers on the prevention or suppression of diseases by melatonin, there are very few papers about the effects of melatonin on ER stress in neurons and neurodegenerative diseases. This paper aims to summarize and present the effects of melatonin reported so far, focusing on its effects on neurons and neurodegenerative diseases related to ER stress. Studies have shown that the primary target molecule of ER stress for melatonin is CHOP, and PERK and GRP78/BiP are the secondary target molecules. Therefore, melatonin is crucial in protecting neurons and treating neurodegeneration against ER stress.

Melatonin as an Antioxidant Agent in Stroke: An Updated Review

Stroke is a devastating disease associated with high mortality and disability worldwide, and is generally classified as ischemic or hemorrhagic, which share certain similar pathophysiological processes. Oxidative stress is a critical factor involved in stroke-induced injury, which not only directly damages brain tissue, but also enhances a series of pathological signaling cascades, contributing to inflammation, brain edema, and neuronal death. To alleviate these serious secondary brain injuries, neuroprotective agents targeting oxidative stress inhibition may serve as a promising treatment strategy. Melatonin is a hormone secreted by the pineal gland, and has various properties, such as antioxidation, anti-inflammation, circadian rhythm modulation, and promotion of tissue regeneration. Numerous animal experiments studying stroke have confirmed that melatonin exerts considerable neuroprotective effects, partially via anti-oxidative stress. In this review, we introduce the possible role of melatonin as an antioxidant in the treatment of stroke based on the latest published studies of animal experiments and clinical research.

Heterophyllin B an Active Cyclopeptide Alleviates Dextran Sulfate Sodium-induced Colitis by Modulating Gut Microbiota and Repairing Intestinal Mucosal Barrier via AMPK Activation

SCOPE

Advances in pathology broaden our perception of the intimate interaction between gut microbiota dysbiosis and the pathogenesis of ulcerative colitis (UC), but the potential modulating roles remain to be elucidated.

METHODS AND RESULTS

DSS-induced colitis was used to investigate the effect of Heterophyllin B (HB), a typical active cyclopeptide extracted from Pseudostellaria heterophylla, on colitis and gut microbiota. Administration of HB substantially mitigated the symptoms of UC as evidenced by increasing body weight and colon length, as well as decreased macrophages infiltration in the colon. Meanwhile, HB significantly alleviated intestinal mucosal barrier dysfunction by reducing the production of inflammatory cytokines, while all the mentioned beneficial effects were significantly eliminated by co-treatment with compound C, a selective AMPK inhibitor. In addition, 16S rDNA gene analyses and fecal microbiota transplantation also revealed that HB dramatically prevented against UC by reshaping intestinal dysbiosis, especially elevated the relative abundance of Akkermansia muciniphila.

CONCLUSION

These findings illustrated that HB prominently improved intestinal epithelial homeostasis via activating AMPK and ameliorated the colonic inflammation in a gut microbiota-dependent manner, which provide evidence for microbial contribution to UC pathogenesis and suggesting a novel approach for colitis prevention. This article is protected by copyright. All rights reserved.

New Approaches for the Fermentation of Beer: Non-Saccharomyces Yeasts from Wine

Non-Saccharomyces yeasts represent a very attractive alternative for the production of beers with superior sensory quality since they are able to enhance the flavour of beer. Furthermore, they can produce beers with low ethanol content due to the weak fermentative capacity of a large percentage of non-Saccharomyces species. The objective of this study was to evaluate the ability of 34 non-Saccharomyces yeast strains isolated from Madrilenian agriculture to produce a novel ale beer. The non-Saccharomyces yeast strains were screened at two scales in the laboratory. In the first screening, those with undesirable aromas were discarded and the selected strains were analysed. Thirty-three volatile compounds were analysed by GC, as well as melatonin production by HPLC, for the selected strains. Thirteen strains were then fermented at a higher scale in the laboratory for sensory evaluation. Only yeast strains of the species Schizosaccharomyces pombe and Lachancea thermotolerans were able to complete fermentation. Species such as Torulaspora delbrueckii, Metschnikowia pulcherrima, Wickerhamomyces anomalus, Hanseniaspora vineae, and Hanseniaspora guilliermondii could be used both for production of low ethanol beers and co-fermentation with a Saccharomyces yeast to improve the organoleptic characteristics of the beer. In addition, for these strains, the levels of melatonin obtained were higher than the concentrations found for Saccharomyces strains subjected to the same study conditions. The selected strains can be used in future trials to further determine their viability under different conditions and for different purposes.

Radiomitigation by Melatonin in C57BL/6 Mice: Possible Implications as Adjuvant in Radiotherapy and Chemotherapy

BACKGROUND/AIM

Melatonin (N-acetyl-5-methoxytryptamine), a chief secretory molecule of the pineal gland, has multiple properties, and numerous clinical investigations regarding its actions are in progress. This study investigated the radiomitigative role of melatonin in C57BL/6 mice.

MATERIALS AND METHODS

Melatonin (100 mg/kg) was orally administered once daily starting at 1 h on day 1 and subsequently every 24 h until day 7 after whole-body irradiation (WBI) and survival was monitored for 30 days. The bone marrow, spleen, and intestine were studied to evaluate the mitigative potential of melatonin after radiation-induced damage.

RESULTS

Melatonin significantly improved the survival upto 60% and 90% after 9 Gy (lethal) and 7.5 Gy (sub-lethal) WBI, respectively. Melatonin alleviated WBI-induced myelosuppression and pancytopenia, and increased white blood cell, red blood cell, platelet, and lymphocyte (CD4⁺ and CD8⁺) counts in peripheral blood. Bone marrow and spleen cellularity were restored through enhanced haematopoiesis. Melatonin ameliorated the damage in the small intestine, and promoted recovery of villi length, crypts number, and goblet cell count.

CONCLUSION

Melatonin mitigates the radiation-induced injury in the gastrointestinal and haematopoietic systems. The observed radiomitigative properties of melatonin can also be useful in the context of adjuvant therapy for cancer and radiotherapy.

Korean Red Ginseng exerts anti-inflammatory and autophagy-promoting activities in aged mice

BACKGROUND

Korean Red Ginseng (KRG) is a traditional herb that has several beneficial properties including anti-aging, anti-inflammatory, and autophagy regulatory effects. However, the mechanisms of these effects are not well understood. In this report, the underlying mechanisms of anti-inflammatory and autophagy-promoting effects were investigated in aged mice treated with KRG-water extract (WE) over a long period.

METHODS

The mechanisms of anti-inflammatory and autophagy-promoting activities of KRG-WE were evaluated in kidney, lung, liver, stomach, and colon of aged mice using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), quantitative RT-PCR (qRT-PCR), and western blot analysis.

RESULTS

KRG-WE significantly suppressed the mRNA expression levels of inflammation-related genes such as interleukin (IL)-1β, IL-8, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein-1 (MCP-1), and IL-6 in kidney, lung, liver, stomach, and colon of the aged mice. Furthermore, KRG-WE downregulated the expression of transcription factors and their protein levels associated with inflammation in lung and kidney of aged mice. KRG-WE also increased the expression of autophagy-related genes and their protein levels in colon, liver, and stomach.

CONCLUSION

The results suggest that KRG can suppress inflammatory responses and recover autophagy activity in aged mice.

Potentiating the Benefits of Melatonin through Chemical Functionalization: Possible Impact on Multifactorial Neurodegenerative Disorders

Although melatonin is an astonishing molecule, it is possible that chemistry will help in the discovery of new compounds derived from it that may exceed our expectations regarding antioxidant protection and perhaps even neuroprotection. This review briefly summarizes the significant amount of data gathered to date regarding the multiple health benefits of melatonin and related compounds. This review also highlights some of the most recent directions in the discovery of multifunctional pharmaceuticals intended to act as one-molecule multiple-target drugs with potential use in multifactorial diseases, including neurodegenerative disorders. Herein, we discuss the beneficial activities of melatonin derivatives reported to date, in addition to computational strategies to rationally design new derivatives by functionalization of the melatonin molecular framework. It is hoped that this review will promote more investigations on the subject from both experimental and theoretical perspectives.

Biosynthetic Pathway and the Potential Role of Melatonin at Different Abiotic Stressors and Developmental Stages in Tolypocladium guangdongense

Melatonin, a bioactive compound and an important signaling molecule produced in plants and animals, is involved in many biological processes. However, its function and synthetic pathways in fungi are poorly understood. Here, the samples from Tolypocladium guangdongense, a highly valued edible fungus with functional food properties, were collected under different experimental conditions to quantify the levels of melatonin and its intermediates. The results showed that the intracellular melatonin content was markedly improved by Congo red (CR), cold, and heat stresses; the levels of intracellular melatonin and its intermediates increased at the primordial (P) and fruiting body (FB) stages. However, the levels of most intermediates exhibited a notable decrease under CR stress. Several genes related to melatonin synthesis, excluding AADC (aromatic-L-amino-acid decarboxylase), were markedly upregulated at an early stage of CR stress but downregulated later. Compared to the mycelial stage, those genes were significantly upregulated at the P and FB stages. Additionally, exogenous melatonin promoted resistance to several abiotic stressors and P formation in T. guangdongense. This study is the first to report melatonin biosynthesis pathway in macro-fungi. Our results should help in studying the diversity of melatonin function and melatonin-synthesis pathways and provide a new viewpoint for melatonin applications in the edible-medicinal fungus.

The Link between Circadian Clock Genes and Autophagy in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), a progressive respiratory disease, is characterized by the alveolar epithelium injury and persistent airway inflammation. It is documented that oscillation and dysregulated expression of circadian clock genes, like Bmal1, Per1, and Per2, involved in COPD pathogenies, including chronic inflammation and imbalanced autophagy level, and targeting the associations of circadian rhythm and autophagy is promising strategies in the management and treatment of COPD. Herein, we reviewed the mechanisms of the circadian clock and the unbalance of the autophagic level in COPD, as well as the link between the two, so as to provide further theoretical bases for the study on the pathogenesis of COPD.

Molecular targets for the management of gastrointestinal cancer using melatonin, a natural endogenous body hormone

Gastrointestinal cancer is one of the most common cancers globally. Melatonin, a natural endogenous body hormone, has been of interest for years, due to its anti-cancer characteristics, such as antiproliferative, antimetastatic, and cytotoxic as well as apoptotic induction. Through regulating several proteins such as melatonin upregulated mRNAs and proteins of downregulated Bcl-2-associated X protein (Bax), and B-cell lymphoma 2 (Bcl-2), as well as cytoplasmic protein such as calcium-binding proteins calmodulin or tubulin, and nuclear receptors, including RORα/RZR, and acts by non-receptor-regulated mechanisms, melatonin can exert anti-cancer efficacy. Moreover, melatonin modulates angiogenesis by targeting mRNA and protein expression of endothelin-converting enzyme (ECE-1) protein. In the present review, we address in vivo, in vitro and clinical reports on its anti-cancer efficacies, and the molecular mechanisms of action responsible for these effects. We advance the possibility of therapeutic melatonin administration for cancer therapy.

Synergistic potential of dual andrographolide and melatonin targeting of metastatic colon cancer cells: Using the Chou-Talalay combination index method

Colorectal cancer (CRC) mortality has diminished for decades due to new and improved treatment profiles. However, CRC still ranks as the third most diagnosed cancer in the US. Therefore, a new therapeutic approach is needed to overcome colospheroids inhibition and drug resistance. It is well documented that andrographolide (AGP) and melatonin (MLT) have anti-carcinogenic properties. Our goal was to evaluate their synergistic effects on metastatic colon cancer cells (mCRC) and colospheroids. HT-29 and HCT-15 mCRC cells were simultaneously treated with serial dilutions of AGP and MLT for 24, 48 and 72 h. Cell viability was monitored using the MTT assay. The Chou-Talalay method for drug combination is based on the median effect equation, providing a theoretical basis for the combination index and the isobologram equation. This allows quantitative determination of drug interactions using the CompuSyn software, where CI < 1, = 1, and >1 indicates synergistic, additive, and antagonistic effects respectively. Our results demonstrate that AGP and MLT in combination show synergism with CI values of 0.35293 and 0.34152 for HT-29 and HCT-15 respectively and a fractional inhibition of Fa = 0.50-0.90, as shown by the Fa-CI plot and isobologram. The synergism value was validated in colospheroids (HT-29-s and HCT-15-s) based on morphology, viability, and colony formation and in 5-FU drug resistant cell (HT-29R and HCT-116R) viability. The mechanism(s) of decreased cell viability are due to the induction of ER stress proteins and angiogenic inhibition. Our results provide rationale for using AGP in combination with MLT on mCRC.

The Increment of Genoprotective Effect of Melatonin due to "Autooptic" Effect versus the Genotoxicity of Mitoxantrone

Background:

Mitoxantrone is a chemotherapy anti-cancer drug, which can have side effects on healthy cells like secondary cancers. On the other side, Melatonin is a hormone that is responsible for the daily rhythm adjustment and has several properties to be anticancer and anti-inflammatory. Recently, it has been shown that all living cells produce ultraweak photon emission (UPE) spontaneously and continuously. The intensity of UPE is in the order of a few, up to 10⁴ photon/(cm² sec) (or 10⁻¹⁹ to 10⁻¹⁴ W/cm²) measurable by photodetectors. UPEs are produced from diverse natural oxidative and biochemical reactions, especially free radical reactions and the simple cessation of excited molecules. Also, it has been evidenced that UPE has a signaling role at a distance among different cell cultures.

Objective:

Here, we investigate the effect of UPE among similar cells (i.e. “Autooptic effect”) by using mirrors around the cell plate(s).

Material and Methods:

In this experimental research, the HepG2 cells were co-treated by melatonin as a genoprotective and silver nanoparticles as a carrier against mitoxantrone’s genotoxicity. Our results are analyzed based on the Comet assay method, and the genoprotective effect of melatonin is investigated in presence of (and without) mirrors against the genotoxicity of mitoxantrone. Additionally, the autooptic effect is investigated in presence of Ag nanoparticles (NPs).

Results:

The results indicated that Ag NPs with lower concentrations of melatonin made more protection as genoprotective agent, and the same results obtained by increasing access’ cells to drug.

Conclusion:

The autooptic effect could increase the genoprotective effect of melatonin.

Melatonin Reduces GSK3β-Mediated Tau Phosphorylation, Enhances Nrf2 Nuclear Translocation and Anti-Inflammation

Alzheimer’s disease is a neuropathological condition with abnormal accumulation of extracellular Amyloid-β plaques and intracellular neurofibrillary tangles of Microtubule-associated protein Tau (Tau) in the brain. In pathological conditions, Tau undergoes post-translational modifications such as hyperphosphorylation by the activity of cellular kinases, which eventually leads to protein aggregation in neurons. Melatonin is a neuro-hormone that is mainly secreted from the pineal gland and functions to modulate the cellular kinases. In our study, we have checked the neuroprotective function of Melatonin by MTT and LDH assay, where Melatonin inhibited the Tau aggregates-mediated cytotoxicity and membrane leakage in Neuro2A cells. The potency of Melatonin has also been studied for the quenching of intracellular reactive oxygen species level by DCFDA assay and caspase 3 activity. Melatonin was shown to reduce the GSK3β mRNA and subsequent protein level as well as the phospho-Tau level (pThr181 and pThr212-pSer214) in okadaic acid-induced Neuro2A cells, as observed by western blot and immunofluorescence assay. Further, Melatonin has increased the cellular Nrf2 level and its nuclear translocation as an oxidative stress response in Tauopathy. The Melatonin was found to induce pro- and anti-inflammatory cytokines levels in N9 microglia. The mRNA level of cellular kinases such as as-GSK3β, MAPK were also studied by qRT-PCR assay in Tau-exposed N9 and Neuro2A cells. The immunomodulatory effect of Melatonin was evident as it induced IL-10 and TGF-β cytokine levels and activated MAP3K level in Tau-exposed microglia and neurons, respectively. Melatonin also downregulated the mRNA level of pro-inflammatory markers, IL-1β and Cyclooxygenase-2 in N9 microglia. Together, these findings suggest that Melatonin remediated the cytokine profile of Tau-exposed microglia, reduced Tau hyperphosphorylation by downregulating GSK3β level, and alleviated oxidative stress via Nrf2 nuclear translocation.

Is Melatonin the Cornucopia of the 21st Century?

Melatonin, an indoleamine hormone produced and secreted at night by pinealocytes and extra-pineal cells, plays an important role in timing circadian rhythms (24-h internal clock) and regulating the sleep/wake cycle in humans. However, in recent years melatonin has gained much attention mainly because of its demonstrated powerful lipophilic antioxidant and free radical scavenging action. Melatonin has been proven to be twice as active as vitamin E, believed to be the most effective lipophilic antioxidant. Melatonin-induced signal transduction through melatonin receptors promotes the expression of antioxidant enzymes as well as inflammation-related genes. Melatonin also exerts an immunomodulatory action through the stimulation of high-affinity receptors expressed in immunocompetent cells. Here, we reviewed the efficacy, safety and side effects of melatonin supplementation in treating oxidative stress- and/or inflammation-related disorders, such as obesity, cardiovascular diseases, immune disorders, infectious diseases, cancer, neurodegenerative diseases, as well as osteoporosis and infertility.

Melatonin as an inducer of arecoline and their coordinated roles in anti-oxidative activity and immune responses

Arecoline is one of the main medicinal constituents in areca. Melatonin is an amine molecule with multiple functions in plants and animals. However, the interaction between arecoline and melatonin remains unknown. Herein, metabolomics analysis showed that multiple metabolites including arecoline were induced in areca by exogenous melatonin. In vitro assay demonstrated that the induced arecoline had strong antioxidant capacities, being similar to the traditional function of melatonin. Both arecoline and melatonin could significantly improve plant disease resistance against Colletotrichum kahawae and delay post-harvest physiological deterioration (PPD) of areca fruits, through modulation of the levels of jasmonic acid (JA), salicylic acid (SA), ethylene (ETH) and abscisic acid (ABA), reactive oxygen species (ROS) level as well as glycolytic activity. In addition, animal and cell assays indicated that arecoline and melatonin could commonly enhance anti-inflammatory effects through regulating ROS and hypoxia inducible factor-1α (HIF-1α). Taken together, melatonin could serve as an inducer of arecoline and they show coordinated roles in antioxidative activity and immune responses in areca and animals. This study greatly extends the knowledge of the action of melatonin in areca and animals.

Hydroxyl radical scavenging activity of melatonin and its related indolamines

The hydroxyl radical (•OH) scavenging activities of Melatonin, an endogenously produced neurohormone and its related indolamines like N-acetyl tryptophan (NAT) and N-acetyl serotonin (NAS) have been investigated using density functional theory. The mechanism involves 4 steps: initial radical addition to position-3 of the indole ring, keto-amine to enol-imine tautomerization, cyclisation, and finally, addition of a second •OH leading to a cyclic end product. Incorporation of an explicit water molecule in tautomerization step leads to a significant reduction in the barrier of this step, so that the subsequent cyclisation step becomes rate-limiting. In agreement with the very high reactivity of •OH, the initial and final addition of •OH to indolamine are found to be barrierless. Radical adduct formed in the initial step was found to be very stable due to the extensive conjugation present in the substrate. Our calculations show that melatonin is the most effective radical scavenger among the three molecules chosen. NAS was found to exhibit antiradical property comparable to that of melatonin. In contrast to the general observation of reduced antioxidant activity of tryptophan, a non-natural derivative of tryptophan used here (NAT) is found to have good radical scavenging activity. This work further implies that non-natural derivatives of indolamines might as well be useful in the detoxification of free radicals as they exhibit almost comparable antioxidant efficiency as that of melatonin.

Microorganisms: Producers of Melatonin in Fermented Foods and Beverages

Melatonin has recently been detected in fermented beverages and foods, in which microorganism metabolism is highly important. The existing literature knowledge discusses the direction for future studies in this review. Evidence shows that many species of microorganisms could synthesize melatonin. However, the actual concentrations of melatonin in fermented foods and beverages range from picograms per milliliter to nanograms per milliliter. Different types of microorganisms, different raw materials, different culture environments, the presence or absence of precursors, high or low alcohol content, and different detection methods are all possible reasons for the huge difference of melatonin levels. Thus far, there have been relatively few studies on the melatonin synthesis pathway microorganisms. Thus, referring to the synthetic pathway of plants and animals, the putative melatonin biosynthesis pathway of microorganisms is presented. It will be significant to discuss whether all species of microorganisms have the capacity to synthesize melatonin and what the biological functions of melatonin are in microorganisms. Melatonin plays a lot of important roles in microorganisms, particularly in enhancing the tolerance of environment stress. Also, the loss of melatonin concentration in commercially available fermented foods and beverages is a ubiquitous trend, and how to solve this problem is a new field to be further explored.

The circadian rhythm in intervertebral disc degeneration: an autophagy connection

There is one circadian clock in the central nervous system and another in the peripheral organs, and the latter is driven by an autoregulatory molecular clock composed of several core clock genes. The height, water content, osmotic pressure and mechanical characteristics of intervertebral discs (IVDs) have been demonstrated to exhibit a circadian rhythm (CR). Recently, a molecular clock has been shown to exist in IVDs, abolition of which can lead to stress in nucleus pulposus cells (NPCs), contributing to intervertebral disc degeneration (IDD). Autophagy is a fundamental cellular process in eukaryotes and is essential for individual cells or organs to respond and adapt to changing environments; it has also been demonstrated to occur in human NPCs. Increasing evidence supports the hypothesis that autophagy is associated with CR. Thus, we review the connection between CR and autophagy and the roles of these mechanisms in IDD.

Inhibition of autophagy triggers melatonin-induced apoptosis in glioblastoma cells

Background

Autophagy is considered to be another restorative focus for the treatment of brain tumors. Although several research have demonstrated that melatonin induces autophagy in colon cancer and hepatoma cells, there has not been any direct evidence of whether melatonin is capable of inducing autophagy in human glioma cells.

Results

In the present research, we report that melatonin or its agonist, agomelatine, induced autophagy in A172 and U87-MG glioblastoma cells for a concentration-and time-dependent way, which was significantly attenuated by treatment with luzindole, a melatonin receptor antagonist. Furthermore, by suppressing autophagy at the late-stage with bafilomycin A1 and early stage with 3-MA, we found that the melatonin-induced autophagy was activated early, and the autophagic flux was complete. Melatonin treatment alone did not induce any apoptotic changes in the glioblastoma cells, as measured by flow cytometry. Western blot studies confirmed that melatonin alone prominently upregulated the levels of Beclin 1 and LC3 II, which was accompanied by an increase in the expression of Bcl-2, whereas it had no effect on the expression of Bax in the glioblastoma cells. Remarkably, co-treatment with 3-MA and melatonin significantly enhanced the apoptotic cell population in the glioblastoma cells, along with a prominent decrease in the expression of bcl-2 and increase in the Bax expression levels, which collectively indicated that the disruption of autophagy triggers the melatonin-induced apoptosis in glioblastoma cells.

Conclusions

These results provide information indicating that melatonin may act as a common upstream signal between autophagy and apoptosis, which may lead to the development of new therapeutic strategies for glioma.

Evaluation of the therapeutic activity of melatonin and resveratrol in Inflammatory Bowel Disease: A longitudinal PET/CT study in an animal model

Inflammatory Bowel Disease (IBD) is a group of chronic disorders of the gastrointestinal tract, which two main types are Crohn's disease and ulcerative colitis. Although conventional therapeutic strategies have demonstrated to be effective in the IBD treatment, it is necessary to incorporate novel therapeutic agents that target other mechanisms involved in the pathogenesis of the disease, such as oxidative stress. For this reason, the efficacy in vivo of two antioxidant compounds, melatonin and resveratrol, has been investigated in an animal model of TNBS (2, 4, 6-trinitrobenzenesulfonic acid) induced colitis. PET/CT (Positron emission tomography/Computer Tomography) scans were performed to assess disease activity and evaluate treatment response. SUV_max (Standardized Uptake Value) values, body weight changes and histological evaluation were used as inflammatory indices to measure the efficacy of both treatments. SUV_max values increased rapidly after induction of colitis, but after the beginning of the treatment (day 3) a statistically significant decrease was observed on days 7 and 10 in treated animals compared to the non-treated group. This remission of the disease was also confirmed by histological analysis of the colon tissue using the Nancy histological index (p value < 0.05 for differences between non-treated and both groups of treated animals). Moreover, statistical analysis showed a correlation (R² = 65.52%) between SUV_max values and weight changes throughout the treatment. Overall, this study demonstrates the potential of resveratrol, and melatonin in lower extent, as therapeutic agents in the IBD treatment.

Melatonin: An important anticancer agent in colorectal cancer

Colorectal cancer is one of the most common cancers among the elderly, which is also seen in the forms of hereditary syndromes occurring in younger individuals. Numerous studies have been conducted to understand the molecular and cellular pathobiology underlying colorectal cancer. These studies have found that cellular signaling pathways are at the core of colorectal cancer pathology. Because of this, new agents have been proposed as possible candidates to accompany routine therapy regimens. One of these agents is melatonin, a neuro-hormone known best for its essential role in upholding the circadian rhythm and orchestrating the many physiologic changes it accompanies. Melatonin is shown to be able to modulate many signaling pathways involved in many essential cell functions, which if deregulated cause an accelerated pace towards cancer. More so, melatonin is involved in the regulation of immune function, tumor microenvironment, and acts as an antioxidant agent. Many studies have focused on the beneficial effects of melatonin in colorectal cancers, such as induction of apoptosis, increased sensitivity to chemotherapy agents and radiotherapy, limiting cellular proliferation, migration, and invasion. The present review aims to illustrate the known significance of melatonin in colorectal cancer and to address possible clinical use.

Melatonin Modulates the Microenvironment of Glioblastoma Multiforme by Targeting Sirtuin 1

Natural products have historically been regarded as an important resource of therapeutic agents. Resveratrol and melatonin have been shown to increase SIRT1 activity and stimulate deacetylation. Glioblastoma multiforme (GBM) is the deadliest of malignant types of tumor in the central nervous system (CNS) and their biological features make treatment difficult. In the glioma microenvironment, infiltrating immune cells has been shown to possess beneficial effects for tumor progression. We analyzed SIRT1, CCL2, VCAM-1 and ICAM-1 in human glioma cell lines by immunoblotting. The correlation between those markers and clinico-pathological grade of glioma patients were assessed by the Gene Expression Omnibus (GEO) datasets analysis. We also used monocyte-binding assay to study the effects of melatonin on monocyte adhesion to GBM. Importantly, overexpression of SIRT1 by genetic modification or treatment of melatonin significantly downregulated the adhesion molecular VCAM-1 and ICAM-1 expression in GBM. CCL2-mediated monocyte adhesion and expression of VCAM-1 and ICAM-1 were regulated through SIRT1 signaling. SIRT1 is an important modulator of monocytes interaction with GBM that gives the possibility of improved therapies for GBM. Hence, this study provides a novel treatment strategy for the understanding of microenvironment changes in tumor progression.

Melatonin as a potential inhibitor of colorectal cancer: Molecular mechanisms

Colorectal cancer (CRC) is a prevalent disease and a major cause of mortality in the world. Several factors including population aging, poor dietary habits, obesity, insufficient physical activity, and smoking can explain its increased prevalence. CRC is a heterogeneous disease both histopathologically and in term of its molecular and genetic aspects. Melatonin a derivative of tryptophan, is synthesized and released from pineal gland but it is also found in numerous extrapineal tissues including retina, testes, lymphocytes, Harderian gland, gastrointestinal tract, etc. This molecule has several tasks which enhance physiological functions such as antioxidant, antiaging, immunomodulatory, and tumor inhibition. Multiple immunocytochemical studies reported melatonin in the intestinal mucosa where its concentration is greater than in the blood. These findings suggest that melatonin may have a potential inhibitory role in CRC progression. The purpose of this review is to examine the effects of melatonin in molecular pathogenesis and signaling pathways of CRC.

The emergence of melatonin in oncology: Focus on colorectal cancer

Within the last few decades, melatonin has increasingly emerged in clinical oncology as a naturally occurring bioactive molecule with substantial anticancer properties and a pharmacological profile optimal for joining the currently available pharmacopeia. In addition, extensive experimental data shows that this chronobiotic agent exerts oncostatic effects throughout all stages of tumor growth, from initial cell transformation to mitigation of malignant progression and metastasis; additionally, melatonin alleviates the side effects and improves the welfare of radio/chemotherapy-treated patients. Thus, the support of clinicians and oncologists for the use of melatonin in both the treatment and proactive prevention of cancer is gaining strength. Because of its epidemiological importance and symptomatic debut in advanced stages of difficult clinical management, colorectal cancer (CRC) is a preferential target for testing new therapies. In this regard, the development of effective forms of clinical intervention for the improvement of CRC outcome, specifically metastatic CRC, is urgent. At the same time, the need to reduce the costs of conventional anti-CRC therapy results is also imperative. In light of this status quo, the therapeutic potential of melatonin, and the direct and indirect critical processes of CRC malignancy it modulates, have aroused much interest. To illuminate the imminent future on CRC research, we focused our attention on the molecular mechanisms underlying the multiple oncostatic actions displayed by melatonin in the onset and evolution of CRC and summarized epidemiological evidence, as well as in vitro, in vivo and clinical findings that support the broadly protective potential demonstrated by melatonin.

Protective stabilization of mitochondrial permeability transition and mitochondrial oxidation during mitochondrial Ca2+ stress by melatonin's cascade metabolites C3-OHM and AFMK in RBA1 astrocytes

Cyclic 3-hydroxymelatonin (C3-OHM) and N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) are two major cascade metabolites of melatonin. We previously showed melatonin provides multiple levels of mitochondria-targeted protection beyond as a mitochondrial antioxidant during ionomycin-induced mitochondrial Ca²⁺ (mCa²⁺ ) stress in RBA1 astrocytes. Using noninvasive laser scanning fluorescence coupled time-lapse digital imaging microscopy, this study investigated whether C3-OHM and AFMK also provide mitochondrial levels of protection during ionomycin-induced mCa²⁺ stress in RBA1 astrocytes. Interestingly, precise temporal and spatial dynamic live mitochondrial images revealed that C3-OHM and AFMK prevented specifically mCa²⁺ -mediated mitochondrial reactive oxygen species (mROS) formation and hence mROS-mediated depolarization of mitochondrial membrane potential (△Ψ_m ) and permanent lethal opening of the MPT (p-MPT). The antioxidative effects of AFMK, however, were less potent than that of C3-OHM. Whether C3-OHM and AFMK targeted directly the MPT was investigated under a condition of "oxidation free-Ca²⁺ stress" using a classic antioxidant vitamin E to remove mCa²⁺ -mediated mROS stress and the potential antioxidative effects of C3-OHM and AFMK. Intriguingly, two compounds still effectively postponed "oxidation free-Ca²⁺ stress"-mediated depolarization of △Ψ_m and p-MPT. Measurements using a MPT pore-specific indicator Calcein further identified that C3-OHM and AFMK, rather than inhibiting, stabilized the MPT in its transient protective opening mode (t-MPT), a critical mechanism to reduce overloaded mROS and mCa²⁺ . These multiple layers of mitochondrial protection provided by C3-OHM and AFMK thus crucially allow melatonin to extend its metabolic cascades of mitochondrial protection during mROS- and mCa²⁺ -mediated MPT-associated apoptotic stresses and may provide therapeutic benefits against astrocyte-mediated neurodegeneration in the CNS.

Phytomelatonin: Recent advances and future prospects

Melatonin (MEL) has been revealed as a phylogenetically conserved molecule with a ubiquitous distribution from primitive photosynthetic bacteria to higher plants, including algae and fungi. Since MEL is implicated in numerous plant developmental processes and stress responses, the exploration of its functions in plant has become a rapidly progressing field with the new paradigm of involvement in plants growth and development. The pleiotropic involvement of MEL in regulating the transcripts of numerous genes confirms its vital involvement as a multi-regulatory molecule that architects many aspects of plant development. However, the cumulative research in plants is still preliminary and fragmentary in terms of its established functions compared to what is known about MEL physiology in animals. This supports the need for a comprehensive review that summarizes the new aspects pertaining to its functional role in photosynthesis, phytohormonal interactions under stress, cellular redox signaling, along with other regulatory roles in plant immunity, phytoremediation, and plant microbial interactions. The present review covers the latest advances on the mechanistic roles of phytomelatonin. While phytomelatonin is a sovereign plant growth regulator that can interact with the functions of other plant growth regulators or hormones, its qualifications as a complete phytohormone are still to be established. This review also showcases the yet to be identified potentials of phytomelatonin that will surely encourage the plant scientists to uncover new functional aspects of phytomelatonin in plant growth and development, subsequently improving its status as a potential new phytohormone.

Melatonin and its metabolites vs oxidative stress: From individual actions to collective protection

Oxidative stress (OS) represents a threat to the chemical integrity of biomolecules including lipids, proteins, and DNA. The associated molecular damage frequently results in serious health issues, which justifies our concern about this phenomenon. In addition to enzymatic defense mechanisms, there are compounds (usually referred to as antioxidants) that offer chemical protection against oxidative events. Among them, melatonin and its metabolites constitute a particularly efficient chemical family. They offer protection against OS as individual chemical entities through a wide variety of mechanisms including electron transfer, hydrogen transfer, radical adduct formation, and metal chelation, and by repairing biological targets. In fact, many of them including melatonin can be classified as multipurpose antioxidants. However, what seems to be unique to the melatonin's family is their collective effects. Because the members of this family are metabolically related, most of them are expected to be present in living organisms wherever melatonin is produced. Therefore, the protection exerted by melatonin against OS may be viewed as a result of the combined antioxidant effects of the parent molecule and its metabolites. Melatonin's family is rather exceptional in this regard, offering versatile and collective antioxidant protection against OS. It certainly seems that melatonin is one of the best nature's defenses against oxidative damage.

Melatonin Regulates Apoptosis and Autophagy Via ROS-MST1 Pathway in Subarachnoid Hemorrhage

Compelling evidence has indicated that imbalance between apoptosis and autophagy may be involved in subarachnoid hemorrhage (SAH). We aimed to investigate the effects and mechanisms of melatonin in the homeostasis of apoptosis and autophagy. One-hundred and forty-eight male Sprague-Dawley rats were intraperitoneally injected with melatonin or vehicle 2 h after SAH induction. Western blotting and an immunofluorescent assay were performed to detect the expression of apoptosis- and autophagy-related proteins. The neuroprotective effect of melatonin attenuating SAH-induced neurological deficit and brain edema may be associated with the suppression of SAH-induced neuronal apoptosis and autophagy. Furthermore, melatonin inhibited the cleavage of mammalian sterile 20-like kinase 1 (MST1) protein by reducing reactive oxygen species (ROS) content. These effects of melatonin on regulating the homeostasis between apoptosis and autophagy could be reversed by an MST1 agonist, chelerythrine, via enhancement of MST1 cleavage. In conclusion, exogenous melatonin alleviates SAH-induced early brain injury (EBI) by suppressing excessive neuronal apoptosis and autophagy. The underlying mechanism may, at least in part, involve the ROS-MST1 pathway.

The melatonin-MT1 receptor axis modulates tumor growth in PTEN-mutated gliomas

More than 40% of glioma patients have tumors that harbor PTEN (phosphatase and tensin homologue deleted on chromosome ten) mutations; this disease is associated with poor therapeutic resistance and outcome. Such mutations are linked to increased cell survival and growth, decreased apoptosis, and drug resistance; thus, new therapeutic strategies focusing on inhibiting glioma tumorigenesis and progression are urgently needed. Melatonin, an indolamine produced and secreted predominantly by the pineal gland, mediates a variety of physiological functions and possesses antioxidant and antitumor properties. Here, we analyzed the relationship between PTEN and the inhibitory effect of melatonin in primary human glioma cells and cultured glioma cell lines. The results showed that melatonin can inhibit glioma cell growth both in culture and in vivo. This inhibition was associated with PTEN levels, which significantly correlated with the expression level of MT1 in patients. In fact, c-fos-mediated MT1 was shown to be a key modulator of the effect of melatonin on gliomas that harbor wild type PTEN. Taken together, these data suggest that melatonin-MT1 receptor complexes represent a potential target for the treatment of glioma.

Melatonin attenuated inflammatory reaction by inhibiting the activation of p38 and NF‑κB in taurocholate‑induced acute pancreatitis

The aim of the present study was to investigate the protective mechanism underlying of melatonin in severe acute pancreatitis (SAP). A total of 64 male Sprague‑Dawley rats were randomly divided into four groups: The sham operation (SO) group, SAP group, melatonin treatment (MLT) group and p38 inhibitor (SB203580) treatment (SB) group. Acute pancreatitis was induced by 5% taurocholate through retrograde infusion into the biliopancreatic ducts. The melatonin and SB203580 treatment groups were administered with MLT and SB 30 min before operation the induction of SAP. Rats in each group were euthanized at 6 and 12 h following SAP induction. Blood and pancreatic tissues were removed for inflammatory examination. Peripheral blood mononuclear cells (PBMCs) were isolated following sacrifice to measure the phosphorylation of p38 and nuclear factor‑κB (NF‑κB was measured as p65 and phosphorylation of p65). The pretreatment of melatonin significantly attenuated the severity of pancreatitis. In addition, melatonin also reduced serum amylase and proinflammatory cytokine levels, including tumor necrosis factor‑α, interleukin (IL)‑1 and IL‑6. The mean pathological scores for pancreatic tissues in the MLT group were higher than those for samples in the SO group, but were lower than those for samples in the SAP group at each time-point. Phosphorylation of p38 and p65 levels in the melatonin treatment group were lower than that in the SAP group, and higher in the SAP group than in the SO group, and the SB203580 treatment group. Furthermore, melatonin significantly inhibited the activation of p38 and NF‑κB in PBMCs. The authors revealed that melatonin may attenuate inflammatory reactions by inhibiting the activation of p38 MAPK and NF‑κB in both acute pancreatitis rats and PBMCs. SAP is a severe disease with a high risk of morbidity and mortality. It is important to attenuated inflammatory reaction in acute pancreatitis. Thus, the authors studied melatonin, which is synthesized by the pineal gland and released into the blood. Previous studies have shown that melatonin serves a protective role in the early course of human acute pancreatitis, and melatonin concentration variations are closely related to the severity of acute pancreatitis. It may be concluded that melatonin may attenuates inflammatory reactions by inhibiting the activation of p38 MAPK and NF‑κB in both acute pancreatitis rats and PBMCs.

Melatonin alters amino acid metabolism and inflammatory responses in colitis mice

Inflammatory bowel disease is a chronic inflammatory dysfunction of the gastrointestinal tract. This study explored the hypothesis that melatonin has beneficial functions in the mouse model of colitis induced by dextran sodium sulfate (DSS), with a specific focus on the expression of intestinal inflammatory cytokines and the serum levels of amino acids. The results revealed that mice with melatonin supplementation had a reduction in weight loss and disease index induced by DSS treatment. Melatonin stifled the expression of colonic IL-17 in mice with DSS-induced colitis. Melatonin also lowered the serum levels of Asp, Ser, Met, and Leu (p < 0.05), but increased those of Glu and Cys (p < 0.05). Thus, melatonin treatment is promising and may function as a potential adjuvant therapy to alleviate the clinical symptoms of patients with inflammatory bowel disease.

Melatonin increases the effect of 5-fluorouracil-based chemotherapy in human colorectal adenocarcinoma cells in vitro

Melatonin has antitumor activity via several mechanisms including its anti-proliferative and pro-apoptotic effects. Moreover, it has been proven that melatonin in combination with chemotherapeutic agents enhances chemotherapy-triggered apoptosis in several types of cancer. Therefore, this study was intended to evaluate whether melatonin is able to strengthen the anti-cancer potential of different chemotherapeutic drugs in human colorectal adenocarcinoma HT-29 cells. We found that treatment with 20 µM cisplatin (CIS) or 1 mM 5-fluorouracil (5-FU) for 72 h induced a decrease in HT-29 cell viability. Furthermore, 1 mM melatonin significantly (P < 0.05) increased the cytotoxic effects of 5-FU. Likewise, simultaneous stimulation with 1 mM melatonin and 1 mM 5-FU significantly (P < 0.05) enhanced the ratio of cells with an overproduction of intracellular reactive oxygen species and substantially augmented the population of apoptotic cells compared to the treatment with 5-FU alone. Nonetheless, melatonin only displayed moderate chemosensitizing effects in CIS-treated HT-29 cells, as suggested by a slight increment in the fraction of early apoptotic cells that was observed only after 48 h. Consistently, co-stimulation of HT-29 cells with 20 µM CIS or 1 mM 5-FU in the presence of 1 mM melatonin further increased caspase-3 activation. Apart from this, the cytostatic activity displayed by CIS due to S phase arrest was not affected by concomitant stimulation with melatonin. Overall, our results indicate that melatonin increases the sensitivity of HT-29 cells to 5-FU treatment and, consequently, the indolamine could be potentially applied to colorectal adenocarcinoma treatment as a potent chemosensitizing agent.

Melatonin suppresses hepatocellular carcinoma progression via lncRNA-CPS1-IT-mediated HIF-1α inactivation

Melatonin is the primary pineal hormone that relays light/dark cycle information to the circadian system. It was recently reported to exert intrinsic antitumor activity in various cancers. However, the regulatory mechanisms underlying the antitumor activity of melatonin are poorly understood. Moreover, a limited number of studies have addressed the role of melatonin in hepatocellular carcinoma (HCC), a major life-threatening malignancy in both sexes in Taiwan. In this study, we investigated the antitumor effects of melatonin in HCC and explored the regulatory mechanisms underlying these effects. We observed that melatonin significantly inhibited the proliferation, migration, and invasion of HCC cells and significantly induced the expression of the transcription factor FOXA2 in HCC cells. This increase in FOXA2 expression resulted in upregulation of lncRNA-CPS1 intronic transcript 1 (CPS1-IT1), which reduced HIF-1α activity and consequently resulted in the suppression of epithelial-mesenchymal transition (EMT) progression and HCC metastasis. Furthermore, the results of the in vivo experiments confirmed that melatonin exerts tumor suppressive effects by reducing tumor growth. In conclusion, our findings suggested that melatonin inhibited HCC progression by reducing lncRNA-CPS1-IT1-mediated EMT suppression and indicated that melatonin could be a promising treatment for HCC.

Pathomechanisms of Oxidative Stress in Inflammatory Bowel Disease and Potential Antioxidant Therapies

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disease whose incidence has risen worldwide in recent years. Accumulating evidence shows that oxidative stress plays an essential role in the pathogenesis and progression of IBD. This review highlights the generation of reactive oxygen species (ROS) and antioxidant defense mechanisms in the gastrointestinal (GI) tract, the involvement of oxidative stress signaling in the initiation and progression of IBD and its relationships with genetic susceptibility and the mucosal immune response. In addition, potential therapeutic strategies for IBD that target oxidative stress signaling are reviewed and discussed. Though substantial progress has been made in understanding the role of oxidative stress in IBD in humans and experimental animals, the underlying mechanisms are still not well defined. Thus, further studies are needed to validate how oxidative stress signaling is involved in and contributes to the development of IBD.

Melatonin Inhibits Glioblastoma Stem-like cells through Suppression of EZH2-NOTCH1 Signaling Axis

Glioblastoma stem-like cells (GSCs) play essential roles in glioma growth, radio- and chemo-resistance, and recurrence. Elimination of GSCs has therefore become a key strategy and challenge in glioblastoma therapy. Here, we show that melatonin, an indolamine derived from I-tryptophan, significantly inhibited viability and self-renewal ability of GSCs accompanied by a decrease of stem cell markers. We have identified EZH2-NOTCH1 signaling as the key signal pathway that regulated the effects of melatonin in the GSCs. Instead of transcriptionally silencing gene expression by generating a methylated epigenetic mark at histone 3 at lysine 27 (H3K27), EZH2 regulates NOTCH1 expression by directly binding to the NOTCH1 promoter. Moreover, correlation between the expressions of EZH2 and NOTCH intracellular domain 1 (NICD1) was observed in the clinical tumor samples, evidently supporting the existence of EZH2-NOTCH1 interaction in the gliomas and GSCs. Collectively, we demonstrated that melatonin, a potential tumor inhibitor, performs its function partly by suppressing GSC properties through EZH2-NOTCH1 signaling axis.

Bioengineered Colorectal Cancer Drugs: Orally Delivered Anti-Inflammatory Agents

Intestinal inflammation is one of the major factors that increase colorectal cancer (CRC) incidence worldwide. Inflammation in the gastrointestinal tract is directly linked to tumor development at the early stages of the disease, thus a key issue toward the prevention and the treatment of colonic neoplasia. Thus, the use of anti-inflammatory drugs has emerged first as a strategy to reduce chronic inflammation in case of many inflammatory bowel diseases (IBD), but it has proven its efficacy by reducing the risk of colonic neoplasia. This comprehensive review highlights the role of chronic inflammation, mainly in IBD, in the development of CRC including molecular and immune mechanisms that have tumorigenic effects. Multiple lines of evidence indicate that several bioactive and phytochemical compounds used as anti-inflammatory drugs have also antitumoral attributes. The uses of orally delivered cytokines and small molecules, as well as key dietary supplementation as anti-inflammatory therapeutics are discussed. In addition, comprehensive knowledge about CRC and intestinal inflammation, and the importance of the intestinal mucosal wall as a mucosal immunological barrier that comes into play during interactions with gut microbiota (pathogens and commensal), luminal secretions (bile acids, and bacterial and epithelial metabolites), and ingested chemicals (food components, high fat content, heterocyclic amines, and low intake of dietary fiber) are underscored. The multifunctionality of several anti-inflammatory drugs opens a line for their application in the treatment and prevention not only in IBD but also in CRC. Current bioengineering approaches for oral delivery of anti-inflammatory agents including cytokines, genetically modified bacteria, or small molecule inhibitors of inflammation directly contribute to the early management of CRC. Limitations of the current therapeutics, which stem from the lack of complete understanding of the complex molecular interactions between the intestinal microbiota, colonic epithelial barrier, and host immune system, are also discussed.

Light/Dark Shifting Promotes Alcohol-Induced Colon Carcinogenesis: Possible Role of Intestinal Inflammatory Milieu and Microbiota

Background: Colorectal cancer (CRC) is associated with the modern lifestyle. Chronic alcohol consumption—a frequent habit of majority of modern societies—increases the risk of CRC. Our group showed that chronic alcohol consumption increases polyposis in a mouse mode of CRC. Here we assess the effect of circadian disruption—another modern life style habit—in promoting alcohol-associated CRC. Method: TS4Cre × adenomatous polyposis coli (APC)^lox468 mice underwent (a) an alcohol-containing diet while maintained on a normal 12 h light:12 h dark cycle; or (b) an alcohol-containing diet in conjunction with circadian disruption by once-weekly 12 h phase reversals of the light:dark (LD) cycle. Mice were sacrificed after eight weeks of full alcohol and/or LD shift to collect intestine samples. Tumor number, size, and histologic grades were compared between animal groups. Mast cell protease 2 (MCP2) and 6 (MCP6) histology score were analyzed and compared. Stool collected at baseline and after four weeks of experimental manipulations was used for microbiota analysis. Results: The combination of alcohol and LD shifting accelerated intestinal polyposis, with a significant increase in polyp size, and caused advanced neoplasia. Consistent with a pathogenic role of stromal tryptase-positive mast cells in colon carcinogenesis, the ratio of mMCP6 (stromal)/mMCP2 (intraepithelial) mast cells increased upon LD shifting. Baseline microbiota was similar between groups, and experimental manipulations resulted in a significant difference in the microbiota composition between groups. Conclusions: Circadian disruption by Light:dark shifting exacerbates alcohol-induced polyposis and CRC. Effect of circadian disruption could, at least partly, be mediated by promoting a pro-tumorigenic inflammatory milieu via changes in microbiota.

Links of Autophagy Dysfunction to Inflammatory Bowel Disease Onset

INTRODUCTION

Autophagy is a cellular stress response that plays key roles in physiological processes, such as adaptation to starvation, degradation of aberrant proteins or organelles, anti-microbial defense, protein secretion, and innate and adaptive immunity. Dysfunctional autophagy is recognized as a contributing factor in many chronic inflammatory diseases, including inflammatory bowel disease (IBD). Genetic studies have identified multiple IBD-associated risk loci that include genes required for autophagy, and several lines of evidence demonstrate that autophagy is impaired in IBD patients. How dysfunctional autophagy contributes to IBD onset is currently under investigation by researchers.

KEY MESSAGES

Dysfunctional autophagy has been identified to play a role in IBD pathogenesis by altering processes that include (1) intracellular bacterial killing, (2) anti-microbial peptide secretion by Paneth cells, (3) pro-inflammatory cytokine production by macrophages, (4) antigen presentation by dendritic cells, (5) goblet cell function, and (6) the endoplasmic reticulum stress response in enterocytes. The overall effect of dysregulation of these processes varies by cell type, stimulus, as well as cellular context. Manipulation of the autophagic pathway may provide a new avenue in the search for effective therapies for IBD.

CONCLUSION

Autophagy plays multiple roles in IBD pathogenesis. A better understanding of the role of autophagy in IBD patients may provide better subclassification of IBD phenotypes and novel approaches to disease management.

Bioactive Compounds Isolated from Microalgae in Chronic Inflammation and Cancer

The risk of onset of cancer is influenced by poorly controlled chronic inflammatory processes. Inflammatory diseases related to cancer development include inflammatory bowel disease, which can lead to colon cancer, or actinic keratosis, associated with chronic exposure to ultraviolet light, which can progress to squamous cell carcinoma. Chronic inflammatory states expose these patients to a number of signals with tumorigenic effects, including nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPK) activation, pro-inflammatory cytokines and prostaglandins release and ROS production. In addition, the participation of inflammasomes, autophagy and sirtuins has been demonstrated in pathological processes such as inflammation and cancer. Chemoprevention consists in the use of drugs, vitamins, or nutritional supplements to reduce the risk of developing or having a recurrence of cancer. Numerous in vitro and animal studies have established the potential colon and skin cancer chemopreventive properties of substances from marine environment, including microalgae species and their products (carotenoids, fatty acids, glycolipids, polysaccharides and proteins). This review summarizes the main mechanisms of actions of these compounds in the chemoprevention of these cancers. These actions include suppression of cell proliferation, induction of apoptosis, stimulation of antimetastatic and antiangiogenic responses and increased antioxidant and anti-inflammatory activity.