Melatonin down-regulates MDM2 gene expression and enhances p53 acetylation in MCF-7 cells

PRMT1 promotes Warburg effect by regulating the PKM2/PKM1 ratio in non-small cell lung cancer

Abnormal epigenetic modifications are involved in the regulation of Warburg effect in tumor cells. Protein arginine methyltransferases (PRMTs) mediate arginine methylation and have critical functions in cellular responses. PRMTs are deregulated in a variety of cancers, but their precise roles in Warburg effect in cancer is largely unknown. Experiments from the current study showed that PRMT1 was highly expressed under conditions of glucose sufficiency. PRMT1 induced an increase in the PKM2/PKM1 ratio through upregulation of PTBP1, in turn, promoting aerobic glycolysis in non-small cell lung cancer (NSCLC). The PRMT1 level in p53-deficient and p53-mutated NSCLC remained relatively unchanged while the expression was reduced in p53 wild-type NSCLC under conditions of glucose insufficiency. Notably, p53 activation under glucose-deficient conditions could suppress USP7 and further accelerate the polyubiquitin-dependent degradation of PRMT1. Melatonin, a hormone that inhibits glucose intake, markedly suppressed cell proliferation of p53 wild-type NSCLC, while a combination of melatonin and the USP7 inhibitor P5091 enhanced the anticancer activity in p53-deficient NSCLC. Our collective findings support a role of PRMT1 in the regulation of Warburg effect in NSCLC. Moreover, combination treatment with melatonin and the USP7 inhibitor showed good efficacy, providing a rationale for the development of PRMT1-based therapy to improve p53-deficient NSCLC outcomes.

DTX3L Accelerates Pancreatic cancer Progression via FAK/PI3K/AKT Axis

DTX3L (Deltex E3 ubiquitin ligase 3 L) is an E3 ubiquitin ligase, a member of the deltex family. It is also known as B-lymphoma and BAL-associated protein (BBAP). DTX3L has been proven to play an important role in various tumor development; however, its role in pancreatic cancer remains unknown. So, we analyzed the DTX3L expression in pancreatic cancer based on the TCGA database and verified it in our samples by qRT‑PCR and western blot. We identified that DTX3L was highly expressed in pancreatic cancer, and its expression level was significantly negatively correlated with patients' survival. Using CCK8, colony formation, transwell, and wound healing assays, we found that upregulated DTX3L promotes pancreatic cancer cell proliferation, invasion, and migration. Mechanically, DTX3L combined with EGFR (epidermal growth factor receptor) and prevented the ubiquitination degradation of it. Upregulated EGFR activated the FAK/PI3K/Akt pathway and promoted the progression of pancreatic cancer. Moreover, we found that DTX3L can weaken pancreatic cancer cells' sensitivity to chemotherapy using the orthotopic implant tumor model. In conclusion, DTX3L accelerates pancreatic cancer progression by EGFR dependent FAK/PI3K/Akt pathway activation and may become a potential target for pancreatic cancer treatment.

The cross talk of ubiquitination and chemotherapy tolerance in colorectal cancer

Ubiquitination, a highly adaptable post-translational modification, plays a pivotal role in maintaining cellular protein homeostasis, encompassing cancer chemoresistance-associated proteins. Recent findings have indicated a potential correlation between perturbations in the ubiquitination process and the emergence of drug resistance in CRC cancer. Consequently, numerous studies have spurred the advancement of compounds specifically designed to target ubiquitinates, offering promising prospects for cancer therapy. In this review, we highlight the role of ubiquitination enzymes associated with chemoresistance to chemotherapy via the Wnt/β-catenin signaling pathway, epithelial-mesenchymal transition (EMT), and cell cycle perturbation. In addition, we summarize the application and role of small compounds that target ubiquitination enzymes for CRC treatment, along with the significance of targeting ubiquitination enzymes as potential cancer therapies.

Potent pigmentation inhibitory activity of incensole-enriched frankincense volatile oil-identification, efficacy and mechanism

BACKGROUND

Frankincense volatile oil (FVO) has long been considered a side product in pharmaceutical industry since frankincense of large molecular weight is the prime target. However, the volatile oil recycled in the extract process might contain a series of functional actives, serving as promising ingredients in the cosmetic field.

METHODS

Gas chromatography-mass spectrometer was utilized to determine the species and amount of active ingredients in FVO. Subsequently, zebrafish models were used to evaluate pigmentation inhibition, ROS elimination and neutrophil activation. In vitro DPPH test was also conducted to consolidate the anti-oxidation efficacy. Based on the test results, network pharmacology was incorporated, where GO and KEGG enrichment analyses were performed to discover the interrelations between active ingredients.

RESULTS

About 40 actives molecules were identified, including incensole, acetate incensole, and acetate incensole oxide. The FVO demonstrated great depigmentation activity by suppressing melanin synthesis, as well as providing free radical scavenging and anti-inflammation effect. In network pharmacology analysis, 192 intersected targets were identified. By enrichment analysis and network construction, a series of whitening signal pathways, and hub genes, containing STAT3，MAPK3，MAPK1 were identified.

CONCLUSION

The current study quantified the components of FVO, evaluated its efficacy in skin depigmentation, and give pioneering insights on the possible mechanism. The results confirmed that the FVO could serve as whitening agent in topical uses.

Deciphering the Role of Melatonin-Related Signatures in Tumor Immunity and the Prognosis of Clear Cell Renal Cell Carcinoma

Methods

Adopting multiomics data from TCGA and other public datasets, we analysed the expression, mutation, and prognostic evaluation in multiple cancers. ccRCC patients were categorized into two subgroups by an unsupervised cluster algorithm: melatonin-pattern cancer subtype 1 (MPCS1) and subtype 2 (MPCS2). We then explored the immune microenvironment, immune therapy response, and tumor metabolic pathways between the two subtypes. The clinical characteristics, genomic mutation landscape, and molecular inhibitor response were further investigated. Finally, a melatonin regulator-related prognostic model was constructed to predict patient prognosis in ccRCC.

Results

We found that melatonin regulators were dysregulated depending on distinct cancer types, which were associated with genomic variation. The two subtypes indicated different clinical characteristics and biological processes in ccRCC. MPCS2, an aggressive subtype, led an advanced clinical stage and poorer survival of ccRCC patients. The activated oncogenic signaling pathway and metabolic signatures were responsible for cancer progression in the MPCS2 subtype. The MPCS2 subgroup suggested a higher tumor mutational burden and immune dysfunction state, resulting in a lower response to immunotherapy. The copy number variations of MPCS2 were significantly more frequent than those of MPCS1. In addition, the two subgroups exhibited distinct drug responsiveness, with MPCS2 being less responsive to multiple drugs. Finally, we established a subtype biomarker-based prognostic risk model that exhibited satisfactory performance in ccRCC patients.

Conclusion

Melatonin regulator-related features could remodel functional pathways and the tumor immune microenvironment through genomic mutations and pathway regulation. Melatonin regulator-associated molecular subtypes enhance the understanding of the molecular characteristics of renal cancer and can guide clinical treatment. Activating the melatonergic system axis may improve the effect of immunotherapy for ccRCC.

Melatonin and 5-fluorouracil combination chemotherapy: opportunities and efficacy in cancer therapy

Combined chemotherapy is a treatment method based on the simultaneous use of two or more therapeutic agents; it is frequently necessary to produce a more effective treatment for cancer patients. Such combined treatments often improve the outcomes over that of the monotherapy approach, as the drugs synergistically target critical cell signaling pathways or work independently at different oncostatic sites. A better prognosis has been reported in patients treated with combination therapy than in patients treated with single drug chemotherapy. In recent decades, 5-fluorouracil (5-FU) has become one of the most widely used chemotherapy agents in cancer treatment. This medication, which is soluble in water, is used as the first line of anti-neoplastic agent in the treatment of several cancer types including breast, head and neck, stomach and colon cancer. Within the last three decades, many studies have investigated melatonin as an anti-cancer agent; this molecule exhibits various functions in controlling the behavior of cancer cells, such as inhibiting cell growth, inducing apoptosis, and inhibiting invasion. The aim of this review is to comprehensively evaluate the role of melatonin as a complementary agent with 5-FU-based chemotherapy for cancers. Additionally, we identify the potential common signaling pathways by which melatonin and 5-FU interact to enhance the efficacy of the combined therapy. Video abstract.

Decoding the Role of MDM2 as a Potential Ubiquitin E3 Ligase and Identifying the Therapeutic Efficiency of Alkaloids against MDM2 in Combating Glioblastoma

Glioblastomas (GBMs) represent the most aggressive form of brain tumor arising from the malignant transformation of astrocytes. Despite various advancements, treatment options remain limited to chemotherapy and radiotherapy followed by surgery giving an overall survival of 14-15 months. These therapies are somewhere restricted in giving a better survival and cure. There is a need for new therapeutics that could potentially target GBM based on molecular pathways and pathology. Here, ubiquitin E3 ligases can be used as targets as they bind a wide array of substrates and therefore can be attractive targets for new inhibitors. Through this study, we have tried to sort various ubiquitin E3 ligases based on their expression, pathways to which these ligases are associated, and mutational frequencies, and then we tried to screen potent inhibitors against the most favorable E3 ligase as very few studies are available concerning inhibition of E3 ligase in GBM. Our study found MDM2 to be the most ideal E3 ligase and further we tried to target MDM2 against various compounds under the alkaloid class. Molecular Docking and MD simulations combined with ADMET properties and BBB scores revealed that only evodiamine and sanguinarine were effective in inhibiting MDM2. We also tried to give a proposed mechanism of how these inhibitors mediate the p53 signaling in GBM. Therefore, the new scaffolds predicted by the computational approach could help in designing promising therapeutic agents targeting MDM2 in glioblastoma.

Melatonin protects against visible light-induced oxidative stress and promotes the implantation potential of mouse blastocyst in vitro

Improvement of embryo culture media using antioxidant agents could help to improve embryo quality against environmental factors such as visible light and could overcome implantation failures. The usefulness of the melatonin against the effect of light on the expression of the primary implantation receptors, ErbB1 and ErbB4 on pre-implantation mouse embryo was investigated. Two-cell mouse embryos were exposed to the 1600 LUX light for 30 min then randomly divided into 3 groups including: Melatonin-Treated; Luzindole Treated and Simple media as a Control group. After 72-96  The expanded blastocysts were examined for morphological quality of the embryos by Hoechst and propidium iodide staining and for the expression of ErbB1 and ErbB4 by Real-time PCR and immunocytochemistry. The expression of the Sirt3 gene was also assayed. Furthermore, intracellular reactive oxygen species (ROS) levels and the total antioxidant capacity (TAC) were examined by DCFH-DA fluorescence intensity and radical cation respectively. The number of cells in the inner cell mass (ICM) and outer cell mass (OCM) were elevated significantly in the Melatonin-treated group suggesting increased viability and proliferation. Furthermore, we found that melatonin significantly increased the expression levels of ErbB1, ErbB4, and Sirt3 genes, and the protein expression of ErbB1, ErbB4 correlated with intracellular ROS levels and TAC significantly increased after melatonin treatment. Together, these results demonstrate that melatonin could be helpful to improve preimplantation embryos through its effects in decreasing ROS levels and increasing expression of implantation-related genes.

Role of Melatonin in Cancer: Effect on Clock Genes

The circadian clock is a regulatory system, with a periodicity of approximately 24 h, that generates rhythmic changes in many physiological processes. Increasing evidence links chronodisruption with aberrant functionality in clock gene expression, resulting in multiple diseases, including cancer. In this context, tumor cells have an altered circadian machinery compared to normal cells, which deregulates the cell cycle, repair mechanisms, energy metabolism and other processes. Melatonin is the main hormone produced by the pineal gland, whose production and secretion oscillates in accordance with the light:dark cycle. In addition, melatonin regulates the expression of clock genes, including those in cancer cells, which could play a key role in the numerous oncostatic effects of this hormone. This review aims to describe and clarify the role of clock genes in cancer, as well as the possible mechanisms of the action of melatonin through which it regulates the expression of the tumor's circadian machinery, in order to propose future anti-neoplastic clinical treatments.

Oncostatic activities of melatonin: Roles in cell cycle, apoptosis, and autophagy

Melatonin, the major secretory product of the pineal gland, not only regulates circadian rhythms, mood, and sleep but also has actions in neoplastic processes which are being intensively investigated. Melatonin is a promising molecule which considered a differentiating agent in some cancer cells at both physiological and pharmacological concentrations. It can also reduce invasive and metastatic status through receptors MT1 and MT2 cytosolic binding sites, including calmodulin and quinone reductase II enzyme, and nuclear receptors related to orphan members of the superfamily RZR/ROR. Melatonin exerts oncostatic functions in numerous human malignancies. An increasing number of studies report that melatonin reduces the invasiveness of several human cancers such as prostate cancer, breast cancer, liver cancer, oral cancer, lung cancer, ovarian cancer, etc. Moreover, melatonin's oncostatic activities are exerted through different biological processes including antiproliferative actions, stimulation of anti-cancer immunity, modulation of the cell cycle, apoptosis, autophagy, the modulation of oncogene expression, and via antiangiogenic effects. This review focuses on the oncostatic activities of melatonin that targeted cell cycle control, with special attention to its modulatory effects on the key regulators of the cell cycle, apoptosis, and telomerase activity.

Molecular and cellular mechanisms of melatonin in breast cancer

Breast cancer is considered as one of the most important health problems due to its poor prognosis and high rate of mortality and new diagnosed cases. Annually, a great number of deaths are reported in men and women; this means that despite all the improvements in cancer diagnosis and treatment, still, an intense need for more effective approaches exists. Melatonin is a multivalent compound which has a hand in several cellular and molecular processes and therefore, is an appropriate candidate for treatment of many diseases like cancer. Currently, considerable properties of this agent have oriented the research towards investigating its effects specifically in breast cancer. In this review, we gathered a bunch of evidence in order to give a new sight for breast cancer treatment utilizing melatonin. We expect that in coming years, melatonin will become one of the most common therapeutic drugs with lesser side-effects than other chemotherapeutic drugs.

The potential anti-cancer effects of melatonin on breast cancer

Melatonin is the primary hormone of the pineal gland that is secreted at night. It regulates many physiological functions, including the sleep-wake cycle, gonadal activity, free radical scavenging, immunomodulation, neuro-protection, and cancer progression. The precise functions of melatonin are mediated by guanosine triphosphate (GTP)-binding protein (G-protein) coupled melatonin receptor 1 (MT1) and MT2 receptors. However, nuclear receptors are also associated with melatonin activity. Circadian rhythm disruption, shift work, and light exposure at night hamper melatonin production. Impaired melatonin level promotes various pathophysiological changes, including cancer. In our modern society, breast cancer is a serious problem throughout the world. Several studies have been indicated the link between low levels of melatonin and breast cancer development. Melatonin has oncostatic properties in breast cancer cells. This indolamine advances apoptosis, which arrests the cell cycle and regulates metabolic activity. Moreover, melatonin increases the treatment efficacy of cancer and can be used as an adjuvant with chemotherapeutic agents.

Melatonin as a Smart Protector of Pregnancy in Dairy Cows

The experimental objective was to examine the role of melatonin and its pathways in the maintenance of pregnancy in lactating dairy cows. Blood samples were collected at days 0, 16 and 32 after timed AI from cows (n = 200) in order to consider plasma melatonin concentrations and to conduct AOPP (advanced oxidation products of proteins) and TBARS (thiobarbituric acid reactive substances) tests. Luminal endometrial cells were collected at day 16 using a Cytobrush in all cows to determine mRNA expressions of melatonin receptor 1 (MT1), mouse double minute 2 (MDM2), MDM2 binding protein (MTBP), BCL2-associated X, apoptosis Regulator (BAX), p53 upregulated modulator of apoptosis (PUMA, gene symbol BBC3), mucin 1 (MUC1) and leukemia inhibitory factor (LIF). Plasma concentrations of melatonin were significantly greater in pregnant cows diagnosed pregnant at day 16 who sustained pregnancy to day 32 compared to nonpregnant cows at day 16, or pregnant at day 16 and who lost embryos by days 32. Concentrations of AOPP and TBARS were greater in nonpregnant cows at day 16 or pregnant at day 16 and who lost embryos by days 32 compared to those diagnosed pregnant at day 16 and who sustained pregnancy to day 32. In pregnant cows, endometrial mRNA expressions of MDM2, MTBP, MTR1 and LIF were higher compared to pregnant-embryo-loss cows (p < 0.05). In contrast, mRNA expressions of BBC3 and MUC1 were greater at day 16 in pregnant-embryo-loss cows compared to pregnant cows (p < 0.05). In conclusion, melatonin status is a modulator of embryo well-being and maintenance of pregnancy in lactating dairy cows.

Melatonin: Regulation of Prion Protein Phase Separation in Cancer Multidrug Resistance

The unique ability to adapt and thrive in inhospitable, stressful tumor microenvironments (TME) also renders cancer cells resistant to traditional chemotherapeutic treatments and/or novel pharmaceuticals. Cancer cells exhibit extensive metabolic alterations involving hypoxia, accelerated glycolysis, oxidative stress, and increased extracellular ATP that may activate ancient, conserved prion adaptive response strategies that exacerbate multidrug resistance (MDR) by exploiting cellular stress to increase cancer metastatic potential and stemness, balance proliferation and differentiation, and amplify resistance to apoptosis. The regulation of prions in MDR is further complicated by important, putative physiological functions of ligand-binding and signal transduction. Melatonin is capable of both enhancing physiological functions and inhibiting oncogenic properties of prion proteins. Through regulation of phase separation of the prion N-terminal domain which targets and interacts with lipid rafts, melatonin may prevent conformational changes that can result in aggregation and/or conversion to pathological, infectious isoforms. As a cancer therapy adjuvant, melatonin could modulate TME oxidative stress levels and hypoxia, reverse pH gradient changes, reduce lipid peroxidation, and protect lipid raft compositions to suppress prion-mediated, non-Mendelian, heritable, but often reversible epigenetic adaptations that facilitate cancer heterogeneity, stemness, metastasis, and drug resistance. This review examines some of the mechanisms that may balance physiological and pathological effects of prions and prion-like proteins achieved through the synergistic use of melatonin to ameliorate MDR, which remains a challenge in cancer treatment.

Melatonin prevents cyclophosphamide-induced primordial follicle loss by inhibiting ovarian granulosa cell apoptosis and maintaining AMH expression

Cyclophosphaty -45mide (Cyc) chemotherapy in young female cancer patients is associated with an increased risk of premature ovarian insufficiency (POI). This study was designed to investigate the protective role of melatonin (Mel) as an adjuvant against Cyc-induced POI. Female mice received a single intraperitoneal (i.p.) dose of Cyc (75 mg/kg). Mel protection was achieved in mice after i.p. injection of melatonin (50 mg/kg) every 24 h for four consecutive days prior to chemotherapy initiation and for 14 additional days. Ovarian reserve testing, hormonal assays for follicle-stimulating hormone, luteinizing hormone, and anti-Müllerian hormone (AMH), assessment of the oxidative stress status, and measurement of the relative expression of genes in PTEN/AKT/FOXO3a and mitochondrial apoptosis pathways were performed. The results showed that treatment with 50 mg/kg Mel significantly prevented Cyc-induced over-activation of primordial follicles by maintaining the plasma level of AMH and subsequently preventing litter size reduction in mice treated with Cyc chemotherapy. Importantly, Mel treatment significantly prevented ovarian granulosa cell loss by inhibiting the mitochondrial apoptotic pathway. Identifying the protective actions of Mel against Cyc-induced primordial follicle loss has important implications for fertility maintenance in young cancer patients undergoing chemotherapy.

Melatonin is a potential oncostatic agent to inhibit HepG2 cell proliferation through multiple pathways

CONTEXT

Chemotherapy is a cornerstone in the treatment of hepatocellular carcinoma (HCC). Melatonin is a pineal hormone that targets various cancers, however, its antitumor pathways are still not fully elucidated.

OBJECTIVE

This study investigated melatonin's antitumor molecular mechanisms to inhibit the proliferation of HepG2 cells.

MATERIALS AND METHODS

HepG2 Cells were classified into cells without treatment as a control group and cells treated with melatonin (5.4 mmol/L) for 48 h. Proliferating cell nuclear antigen (PCNA) and marker of proliferation Ki-67 were estimated using immunohistochemical analysis. Apoptosis and cell cycle were evaluated using flow cytometric analysis. Apoptotic markers were detected using RT-qPCR assay. Antioxidants and oxidative stress biomarkers were performed using a colorimetric assay.

RESULTS

Melatonin produced a remarkable steady decrease in the viability of HepG2 cells at a concentration range between 5-20 mmol/L. Melatonin suppressed cell proliferation in the G2/M phase of the cell cycle (34.97 ± 0.92%) and induced apoptosis (12.43 ± 0.73%) through up-regulating p21 and p53 that was confirmed by the reduction of PCNA and Ki-67 expressions. Additionally, melatonin repressed angiogenesis evidenced by the down-regulation of angiopoietin-2, vascular endothelial growth factor receptor-2 expressions (0.42-fold change), and the level of CD133. Moreover, melatonin augmented the oxidative stress manifested by a marked increase of 4-hydroxynonenal levels with a reduction of glutathione content and superoxide dismutase activity.

DISCUSSION AND CONCLUSION

Melatonin inhibits proliferation and angiogenesis and induced apoptosis and oxidative stress in HepG2 cells. These results indicate the oncostatic effectiveness of melatonin on liver cancer.

Combinations of Calcitriol with Anticancer Treatments for Breast Cancer: An Update

Preclinical, clinical, and epidemiological studies indicate that vitamin D3 (VD) deficiency is a risk factor for the development of breast cancer. Underlying mechanisms include the ability of calcitriol to induce cell differentiation, inhibit oncogenes expression, and modify different signaling pathways involved in the control of cell proliferation. In addition, calcitriol combined with different kinds of antineoplastic drugs has been demonstrated to enhance their beneficial effects in an additive or synergistic fashion. However, a recognized adjuvant regimen based on calcitriol for treating patients with breast cancer has not yet been fully established. Accordingly, in the present work, we review and discuss the preclinical and clinical studies about the combination of calcitriol with different oncological drugs, aiming to emphasize its main therapeutic benefits and opportunities for the treatment of this pathology.

Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders

Biomolecular condensates are membraneless organelles (MLOs) that form dynamic, chemically distinct subcellular compartments organizing macromolecules such as proteins, RNA, and DNA in unicellular prokaryotic bacteria and complex eukaryotic cells. Separated from surrounding environments, MLOs in the nucleoplasm, cytoplasm, and mitochondria assemble by liquid-liquid phase separation (LLPS) into transient, non-static, liquid-like droplets that regulate essential molecular functions. LLPS is primarily controlled by post-translational modifications (PTMs) that fine-tune the balance between attractive and repulsive charge states and/or binding motifs of proteins. Aberrant phase separation due to dysregulated membrane lipid rafts and/or PTMs, as well as the absence of adequate hydrotropic small molecules such as ATP, or the presence of specific RNA proteins can cause pathological protein aggregation in neurodegenerative disorders. Melatonin may exert a dominant influence over phase separation in biomolecular condensates by optimizing membrane and MLO interdependent reactions through stabilizing lipid raft domains, reducing line tension, and maintaining negative membrane curvature and fluidity. As a potent antioxidant, melatonin protects cardiolipin and other membrane lipids from peroxidation cascades, supporting protein trafficking, signaling, ion channel activities, and ATPase functionality during condensate coacervation or dissolution. Melatonin may even control condensate LLPS through PTM and balance mRNA- and RNA-binding protein composition by regulating N6-methyladenosine (m6A) modifications. There is currently a lack of pharmaceuticals targeting neurodegenerative disorders via the regulation of phase separation. The potential of melatonin in the modulation of biomolecular condensate in the attenuation of aberrant condensate aggregation in neurodegenerative disorders is discussed in this review.

Metabolic Anti-Cancer Effects of Melatonin: Clinically Relevant Prospects

Metabolic reprogramming characterized by alterations in nutrient uptake and critical molecular pathways associated with cancer cell metabolism represents a fundamental process of malignant transformation. Melatonin (N-acetyl-5-methoxytryptamine) is a hormone secreted by the pineal gland. Melatonin primarily regulates circadian rhythms but also exerts anti-inflammatory, anti-depressant, antioxidant and anti-tumor activities. Concerning cancer metabolism, melatonin displays significant anticancer effects via the regulation of key components of aerobic glycolysis, gluconeogenesis, the pentose phosphate pathway (PPP) and lipid metabolism. Melatonin treatment affects glucose transporter (GLUT) expression, glucose-6-phosphate dehydrogenase (G6PDH) activity, lactate production and other metabolic contributors. Moreover, melatonin modulates critical players in cancer development, such as HIF-1 and p53. Taken together, melatonin has notable anti-cancer effects at malignancy initiation, progression and metastasing. Further investigations of melatonin impacts relevant for cancer metabolism are expected to create innovative approaches supportive for the effective prevention and targeted therapy of cancers.

Melatonin in Cancer Treatment: Current Knowledge and Future Opportunities

Melatonin is a pleotropic molecule with numerous biological activities. Epidemiological and experimental studies have documented that melatonin could inhibit different types of cancer in vitro and in vivo. Results showed the involvement of melatonin in different anticancer mechanisms including apoptosis induction, cell proliferation inhibition, reduction in tumor growth and metastases, reduction in the side effects associated with chemotherapy and radiotherapy, decreasing drug resistance in cancer therapy, and augmentation of the therapeutic effects of conventional anticancer therapies. Clinical trials revealed that melatonin is an effective adjuvant drug to all conventional therapies. This review summarized melatonin biosynthesis, availability from natural sources, metabolism, bioavailability, anticancer mechanisms of melatonin, its use in clinical trials, and pharmaceutical formulation. Studies discussed in this review will provide a solid foundation for researchers and physicians to design and develop new therapies to treat and prevent cancer using melatonin.

An updated review of mechanistic potentials of melatonin against cancer: pivotal roles in angiogenesis, apoptosis, autophagy, endoplasmic reticulum stress and oxidative stress

Cancers are serious life-threatening diseases which annually are responsible for millions of deaths across the world. Despite many developments in therapeutic approaches for affected individuals, the rate of morbidity and mortality is high. The survival rate and life quality of cancer patients is still low. In addition, the poor prognosis of patients and side effects of the present treatments underscores that finding novel and effective complementary and alternative therapies is a critical issue. Melatonin is a powerful anticancer agent and its efficiency has been widely documented up to now. Melatonin applies its anticancer abilities through affecting various mechanisms including angiogenesis, apoptosis, autophagy, endoplasmic reticulum stress and oxidative stress. Regarding the implication of mentioned cellular processes in cancer pathogenesis, we aimed to further evaluate the anticancer effects of melatonin via these mechanisms.

Melatonin Lowers HIF-1α Content in Human Proximal Tubular Cells (HK-2) Due to Preventing Its Deacetylation by Sirtuin 1

Although melatonin is widely known for its nephroprotective properties, there are no reports clearly pointing at its impact on the activity of hypoxia-inducible factor-1 (HIF-1), the main mediator of metabolic responses to hypoxia, in kidneys. The aim of the present study was to elucidate how melatonin affects the expression of the regulatory subunit HIF-1α in renal proximal tubules. HK-2 cells, immortalized human proximal tubular cells, were cultured under hypoxic conditions (1% O₂). Melatonin was applied at 100 μM concentration. Protein and mRNA contents were determined by Western blot and RT-qPCR, respectively. HIF-1α acetylation level was established by means of immunoprecipitation followed by Western blot. Melatonin receptors MT1 and MT2 localization in HK-2 cells was visualized using immunofluorescence confocal analysis. It was found that melatonin in HK-2 cells (1) lowered HIF-1α protein, but not mRNA, content; (2) attenuated expression of HIF-1 target genes; (3) increased HIF-1α acetylation level; and (4) diminished sirtuin 1 expression (both protein and mRNA). Sirtuin 1 involvement in the regulation of HIF-1α level was confirmed applying cells with silenced Sirt1 gene. Moreover, the presence of membrane MT1 and MT2 receptors was identified in HK-2 cells and their ligand, ramelteon, turned out to mimic melatonin action on both HIF-1α and sirtuin 1 levels. Thus, it is concluded that the mechanism of melatonin-evoked decline in HIF-1α content in renal proximal tubular cells involves increased acetylation of this subunit which results from the attenuated expression of sirtuin 1, an enzyme reported to deacetylate HIF-1α. This observation provides a new insight to the understanding of melatonin action in kidneys.

Anti-Cancer Effect of Melatonin via Downregulation of Delta-like Ligand 4 in Estrogen-Responsive Breast Cancer Cells

BACKGROUND

The Notch signaling pathway has a key role in angiogenesis and Delta - Like Ligand 4 (DLL4) is one of the main ligands of Notch involved in cell proliferation in sprouting vessels.

OBJECTIVE

In this study, we aimed to evaluate the expression of DLL4 in primary breast tumors and to examine the effect of melatonin on DLL4 expression in vitro.

METHODS

Eighty-five breast tumor and paired adjacent non-tumor tissue samples were collected. Apoptosis assay was performed on breast cancer cells to evaluate melatonin effects. Western blot and quantitative RT-PCR were used to measure DLL4 expression. Then, we investigated the effect of melatonin on the expression of DLL4 in four breast cancer cell lines at RNA and protein levels. We also performed a probabilistic neural network analysis to study genes closely associated with DLL4 expression.

RESULTS

Our results showed a significantly higher expression of DLL4 in tumor tissues compared to non-tumor tissues (P = 0.027). Melatonin treatment substantially attenuated DLL4 expression in BT474 and MCF-7 cells, but not in SK-BR-3 and MDA-MB-231 cells. Also, melatonin induced apoptosis in all four cell lines. Network analysis revealed a set of 15 genes that had close association and interaction with DLL4. DLL4 was overexpressed in breast cancer tissues as compared to the non-tumor tissues.

CONCLUSION

It can be concluded that melatonin treatment attenuated DLL4 expression only in estrogen- responsive breast cancer cells and is able to induce apoptosis in breast cancer cells.

Melatonin: A Potential Therapeutic Option for Breast Cancer

Melatonin has significant inhibitory effects in numerous cancers, especially breast cancer. In estrogen receptor (ER)-positive human breast cancer, the oncostatic actions of melatonin are mainly achieved by suppressing ER mRNA expression and ER transcriptional activity via the MT1 receptor. Melatonin also regulates the transactivation of nuclear receptors, estrogen-metabolizing enzymes, and the expression of related genes. Furthermore, melatonin suppresses tumor aerobic glycolysis, critical cell-signaling pathways relevant to cell proliferation, survival, metastasis, and overcomes drug resistance. Studies in animal and human models indicate that disruption of the circadian nocturnal melatonin signal promotes the growth, metabolism, and signaling of human breast cancer, resulting in resistance to hormone therapy and chemotherapy, which may be reversed by melatonin.

Melatonin down-regulates steroidal hormones, thymocyte apoptosis and inflammatory cytokines in middle-aged T. cruzi infected rats

Chagas disease, triggered by the flagellate protozoan Trypanosoma cruzi (T. cruzi) plays a potentially threat to historically non-endemic areas. Considerable evidence established that the immuno-endocrine balance could deeply influence the experimental T. cruzi progression inside the host's body. A high-resolution multiple reaction monitoring approach (MRM^HR) was used to study the influence of melatonin on adrenal and plasma steroidal hormones profile of T. cruzi infected Wistar rats. Young (5 weeks) and middle-aged (18 months) male Wistar rats received melatonin (5 mg/Kg, orally) during the acute Chagas disease. Corticosterone, 11-dehydrocorticosterone (11-DHC), cortisol, cortisone, aldosterone, progesterone and melatonin concentration were evaluated. Interleukin-1 alpha and β (IL-1α and β), IL-6 and transforming growth factor beta (TGF-β) were also analyzed. Our results revealed an increased production of corticosterone, cortisone, cortisol and aldosterone in middle-aged control animals, thus confirming the aging effects on the steroidal hormone profile. Serum melatonin levels were reduced with age and predominantly higher in young and middle-aged infected rats. Melatonin treatment reduced the corticosterone, 11-DHC, cortisol, cortisone, aldosterone and progesterone in response to T. cruzi infection. Decreased IL-1 α and β concentrations were also found in melatonin treated middle-aged infected animals. Melatonin treated middle-aged control rats displayed reduced concentrations of TGF-β. Melatonin levels were significantly higher in all middle-aged rats treated animals. Reduced percentages of early and late thymocyte apoptosis was found for young and middle-aged melatonin supplemented rats. Finally, our results show a link between the therapeutic and biological effects of melatonin controlling steroidal hormones pathways as well as inflammatory mediators.

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Melatonin acts on the regulation of steroid hormones, apoptosis and cytokine signaling during acute T. cruzi infection;

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Middle-aged control rats have higher production of corticosterone, cortisone, cortisol and aldosterone;

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Melatonin treated middle-aged infected rats displayed reduced concentrations of IL-1 α and β;

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Melatonin levels were significantly higher in all middle-aged rats treated animals;

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Reduced percentages of early and late thymocyte apoptosis was found for young and middle-aged melatonin supplemented rats.

Melatonin: an endogenous miraculous indolamine, fights against cancer progression

PURPOSE

Melatonin is an amphipathic indolamine molecule ubiquitously present in all organisms ranging from cyanobacteria to humans. The pineal gland is the site of melatonin synthesis and secretion under the influence of the retinohypothalamic tract. Some extrapineal tissues (skin, lens, gastrointestinal tract, testis, ovary, lymphocytes, and astrocytes) also enable to produce melatonin. Physiologically, melatonin regulates various functions like circadian rhythm, sleep-wake cycle, gonadal activity, redox homeostasis, neuroprotection, immune-modulation, and anticancer effects in the body. Inappropriate melatonin secretion advances the aging process, tumorigenesis, visceral adiposity, etc. METHODS: For the preparation of this review, I had reviewed the literature on the multidimensional activities of melatonin from the NCBI website database PubMed, Springer Nature, Science Direct (Elsevier), Wiley Online ResearchGate, and Google Scholar databases to search relevant articles. Specifically, I focused on the roles and mechanisms of action of melatonin in cancer prevention.

RESULTS

The actions of melatonin are primarily mediated by G-protein coupled MT1 and MT2 receptors; however, several intracellular protein and nuclear receptors can modulate the activity. Normal levels of the melatonin protect the cells from adverse effects including carcinogenesis. Therapeutically, melatonin has chronomedicinal value; it also shows a remarkable anticancer property. The oncostatic action of melatonin is multidimensional, associated with the advancement of apoptosis, the arrest of the cell cycle, inhibition of metastasis, and antioxidant activity.

CONCLUSION

The present review has emphasized the mechanism of the anti-neoplastic activity of melatonin that increases the possibilities of the new approaches in cancer therapy.

Melatonin inhibits apoptosis in mouse Leydig cells via the retinoic acid-related orphan nuclear receptor α/p53 pathway

Melatonin is an endogenous indoleamine hormone involved in various physiological processes. However, the mechanism of melatonin in mediating Leydig cells function has not been fully explained. In this study, we investigated the mechanism through which melatonin inhibits apoptosis in mouse Leydig cells by activating the retinoic acid-related orphan nuclear receptor (ROR) α/p53 signaling pathway. We confirmed the expression and localization of RORα in mouse Leydig cells using immunofluorescence. After treatment with 10 ng/mL melatonin for 36 h, RORα mRNA and protein levels were significantly increased (P < 0.01). TUNEL and flow cytometry showed that melatonin significantly decreased the TUNEL-positive cell ratio and apoptosis rate (P < 0.05). Moreover, melatonin decreased BAX expression and increased BCL-2 expression (P < 0.05). However, the RORα inhibitor SR1001 reversed the inhibitory effects of melatonin on apoptosis (P < 0.05). Additionally, analysis of p53 expression showed that melatonin inhibited p53 mRNA and protein expression (P < 0.05), whereas SR1001 reversed these effects. p53 reversed the anti-apoptotic process involving RORα-mediated melatonin in mouse Leydig cells. Collectively, our findings suggested that melatonin inhibited apoptosis via the RORα/p53 pathway.

Melatonin Regulates Breast Cancer Progression by the lnc010561/miR-30/FKBP3 Axis

Melatonin has been recognized to slow breast cancer growth. The molecular mechanisms may involve long non-coding RNAs (lncRNAs). However, little is known on how melatonin affects lncRNA expression and function in breast cancer. We used microarrays to explore the expression profile of mRNAs and lncRNAs in melatonin-treated breast cancer cells. Kyoto encyclopedia of genes and genomes (KEGG) and Reactome pathways analysis were performed to identify the signaling pathways affected by altered expressed mRNAs after melatonin treatment. To explore the functions and mechanisms of the selected differentially expressed mRNA and lncRNA in breast cancer, we performed a series of experiments. We found that FK506-binding protein 3 (FKBP3) and lnc010561 were downregulated in melatonin-treated breast cancer cells. Knockdown of FKBP3 and lnc010561 inhibited breast cancer proliferation and invasion, and induced apoptosis. Also, lnc010561 and FKBP3 functioned as competing endogenous RNAs (ceRNAs) for miR-30. Our findings suggested that melatonin regulated breast cancer progression by the lnc010561/miR-30/FKBP3 axis. Melatonin may, therefore, function as an anticancer strategy for breast cancer.

Melatonin and (-)-Epigallocatechin-3-Gallate: Partners in Fighting Cancer

We have demonstrated previously that melatonin attenuates hepatotoxicity triggered by high doses of (−)-epigallocatechin-3-gallate (EGCG) in mice. The current work investigated the influence of melatonin on the oncostatic activity of EGCG in two cancer cell lines, wherein melatonin induced an opposite response of p21. In human tongue cancer TCA8113 cells, melatonin-induced p21 and EGCG-mediated formation of quinoproteins were positively associated with the oncostatic effects of melatonin and EGCG. Melatonin-stimulated an increase in p21 which was correlated with a pronounced nuclear translocation of thioredoxin 1 and thioredoxin reductase 1, both of which are known to induce p21 via promoting p53 trans-activation. Melatonin did not influence the EGCG-mediated increase of quinoprotein formation nor did EGCG impair melatonin-induced p21 up-regulation. Co-treatment with both agents enhanced the cell-killing effect as well as the inhibitory activities against cell migration and colony formation. It is known that p21 also plays a powerful anti-apoptotic role in some cancer cells and confers these cells with a survival advantage, making it a target for therapeutic suppression. In human hepatocellular carcinoma HepG2 cells, melatonin suppressed p21 along with the induction of pro-survival proteins, PI3K and COX-2. However, EGCG prevented against melatonin-induced PI3K and COX-2, and melatonin probably sensitized HepG2 cells to EGCG cytotoxicity via down-regulating p21, Moreover, COX-2 and HO-1 were significantly reduced only by the co-treatment, and melatonin aided EGCG to achieve an increased inhibition on Bcl2 and NFκB. These events occurring in the co-treatment collectively resulted in an enhanced cytotoxicity. In addition, the co-treatment also enhanced the inhibitory activities against cell migration and colony formation. Overall, the results gathered from these two cancer cell lines with a divergent p21 response to melatonin show that the various oncostatic activities of melatonin and EGCG together are more robust than each agent alone, suggesting that they may be useful partners in fighting cancer.

Promising Antineoplastic Actions of Melatonin

Melatonin is an endogenous indoleamine with an incredible variety of properties and activities. In recent years, an increasing number of studies have investigated this indoleamine’s interaction with cancerous cells. In particular, it seems that melatonin not only has the ability to improve the efficacy of many drugs used in chemotherapy but also has a direct inhibitory action on neoplastic cells. Many publications underlined the ability of melatonin to suppress the proliferation of various cancer cells or to modulate the expression of membrane receptors on these cells, thereby reducing tumor aggressiveness to metastasize. In addition, while melatonin has antiapoptotic actions in normal cells, in many cancer cells it has proapoptotic effects; these dichotomous actions have gained the interest of researchers. The increasing focus on melatonin in the field of oncology and the growing number of studies on this topic require a deep understanding of what we already know about the antineoplastic actions of melatonin. This information would be of value for potential use of melatonin against neoplastic diseases.

Effects of melatonin on thymic and oxidative stress dysfunctions during Trypanosoma cruzi infection

Although the exact etiology of Chagas disease is not completely elucidated, thymic atrophy and oxidative stress are believed to be important contributors to the pathogenesis during acute Trypanosoma cruzi (T. cruzi) infection. We hypothesized that exogenous melatonin, administered by gavage (5 mg/kg, p.o., gavage) to young (5 weeks old) and middle-aged (18 months old) male Wistar rats, would modulate thymic oxidative damage and reverse the age-related thymus regression during T. cruzi acute infection. Increased levels of superoxide anion (O₂^- ) were detected in the thymus of infected animals, and treatment with melatonin reverted this response. We found reduced TBARS levels as well as a significant increase in superoxide dismutase (SOD) activity in the thymus of all middle-aged melatonin-treated animals, infected or not with T. cruzi. Furthermore, melatonin increased the thymic expression of SOD1 and SOD2 in middle-aged control animals. Nox2 expression was not affected by melatonin treatment in young or middle-aged animals. Melatonin reverted the age-related thymic regression as revealed by the increase in thymus weight, total number of thymocytes, and reduction in age-related accumulation of double-negative thymocytes. This is the first report to directly examine the effects of melatonin treatment on the thymic antioxidant/oxidant status and thymic changes during T. cruzi infection. Our results revealed new antioxidant features that turn melatonin a potentially useful compound for the treatment of Chagas disease, a condition in which an excessive oxidative damage occurs.

From Implantation to Birth: Insight into Molecular Melatonin Functions

Melatonin is a lipophilic hormone synthesized and secreted mainly in the pineal gland, acting as a neuroendocrine transducer of photoperiodic information during the night. In addition to this activity, melatonin has shown an antioxidant function and a key role as regulator of physiological processes related to human reproduction. Melatonin is involved in the normal outcome of pregnancy, beginning with the oocyte quality, continuing with embryo implantation, and finishing with fetal development and parturition. Melatonin has been shown to act directly on several reproductive events, including folliculogenesis, oocyte maturation, and corpus luteum (CL) formation. The molecular mechanism of action has been investigated through several studies which provide solid evidence on the connections between maternal melatonin secretion and embryonic and fetal development. Melatonin administration, reducing oxidative stress and directly acting on its membrane receptors, melatonin thyroid hormone receptors (MT1 and MT2), displays effects on the earliest phases of pregnancy and during the whole gestational period. In addition, considering the reported positive effects on the outcomes of compromised pregnancies, melatonin supplementation should be considered as an important tool for supporting fetal development, opening new opportunities for the management of several reproductive and gestational pathologies.

Natural products targeting the p53-MDM2 pathway and mutant p53: Recent advances and implications in cancer medicine

The p53 tumor suppressor plays a major role in controlling the initiation and development of cancer by regulating cell cycle arrest, apoptosis, senescence, and DNA repair. The MDM2 oncogene is a major negative regulator of p53 that inhibits the activity of p53 and reduces its protein stability. MDM2, p53, and the p53-MDM2 pathway represent well-documented targets for preventing and/or treating cancer. Natural products, especially those from medicinal and food plants, are a rich source for the discovery and development of novel therapeutic and preventive agents against human cancers. Many natural product-derived MDM2 inhibitors have shown potent efficacy against various human cancers. In contrast to synthetic small-molecule MDM2 inhibitors, the majority of which have been designed to inhibit MDM2-p53 binding and activate p53, many natural product inhibitors directly decrease MDM2 expression and/or MDM2 stability, exerting their anticancer activity in both p53-dependent and p53-independent manners. More recently, several natural products have been reported to target mutant p53 in cancer. Therefore, identification of natural products targeting MDM2, mutant p53, and the p53-MDM2 pathway can provide a promising strategy for the development of novel cancer chemopreventive and chemotherapeutic agents. In this review, we focus our discussion on the recent advances in the discovery and development of anticancer natural products that target the p53-MDM2 pathway, emphasizing several emerging issues, such as the efficacy, mechanism of action, and specificity of these natural products.

Combination of melatonin and rapamycin for head and neck cancer therapy: Suppression of AKT/mTOR pathway activation, and activation of mitophagy and apoptosis via mitochondrial function regulation

Head and neck squamous cell carcinoma (HNSCC) clearly involves activation of the Akt mammalian target of rapamycin (mTOR) signalling pathway. However, the effectiveness of treatment with the mTOR inhibitor rapamycin is often limited by chemoresistance. Melatonin suppresses neoplastic growth via different mechanisms in a variety of tumours. In this study, we aimed to elucidate the effects of melatonin on rapamycin-induced HNSCC cell death and to identify potential cross-talk pathways. We analysed the dose-dependent effects of melatonin in rapamycin-treated HNSCC cell lines (Cal-27 and SCC-9). These cells were treated with 0.1, 0.5 or 1 mmol/L melatonin combined with 20 nM rapamycin. We further examined the potential synergistic effects of melatonin with rapamycin in Cal-27 xenograft mice. Relationships between inhibition of the mTOR pathway, reactive oxygen species (ROS), and apoptosis and mitophagy reportedly increased the cytotoxic effects of rapamycin in HNSCC. Our results demonstrated that combined treatment with rapamycin and melatonin blocked the negative feedback loop from the specific downstream effector of mTOR activation S6K1 to Akt signalling, which decreased cell viability, proliferation and clonogenic capacity. Interestingly, combined treatment with rapamycin and melatonin-induced changes in mitochondrial function, which were associated with increased ROS production, increasing apoptosis and mitophagy. This led to increase cell death and cellular differentiation. Our data further indicated that melatonin administration reduced rapamycin-associated toxicity to healthy cells. Overall, our findings suggested that melatonin could be used as an adjuvant agent with rapamycin, improving effectiveness while minimizing its side effects.

Therapeutic potential of melatonin for breast cancer radiation therapy patients

Melatonin is an endogenous hormone primarily known for its action on the circadian rhythms. But pre-clinical studies are reporting both its radioprotective and radiosensitizing properties, possibly mediated through an interaction between melatonin and the regulation of estrogens. Melatonin pre-treatment prior to ionizing radiation was associated with a decrease in cell proliferation and an increase in p53 mRNA expression, leading to an increase in the radiosensitivity of breast cancer cells. At the same time, a decrease in radiation-induced side effects was described in breast cancer patients and in rodent models. This review examines the potential for melatonin to improve the therapeutic outcomes of breast radiation therapy, specifically estrogen receptor positive patients. Evidence suggests that melatonin may offer a novel, non-toxic and cheap adjuvant therapy to improve the existing treatment modalities. But further research is required in the clinical setting before a clear understanding of its therapeutic benefits is determined.

Melatonin exerts anti-oral cancer effect via suppressing LSD1 in patient-derived tumor xenograft models

Aberrant activation of histone lysine-specific demethylase (LSD1) increases tumorigenicity; hence, LSD1 is considered a therapeutic target for various human cancers. Although melatonin, an endogenously produced molecule, may defend against various cancers, the precise mechanism involved in its anti-oral cancer effect remains unclear. Patient-derived tumor xenograft (PDTX) models are preclinical models that can more accurately reflect human tumor biology compared with cell line xenograft models. Here, we evaluated the anticancer activity of melatonin by using LSD1-overexpressing oral cancer PDTX models. By assessing oral squamous cell carcinoma (OSCC) tissue arrays through immunohistochemistry, we examined whether aberrant LSD1 overexpression in OSCC is associated with poor prognosis. We also evaluated the action mechanism of melatonin against OSCC with lymphatic metastases by using the PDTX models. Our results indicated that melatonin, at pharmacological concentrations, significantly suppresses cell proliferation in a dose- and time-dependent manner. The observed suppression of proliferation was accompanied by the melatonin-mediated inhibition of LSD1 in oral cancer PDTXs and oral cancer cell lines. In conclusion, we determined that the beneficial effects of melatonin in reducing oral cancer cell proliferation are associated with reduced LSD1 expression in vivo and in vitro.

Melatonin Ameliorates Busulfan-Induced Spermatogonial Stem Cell Oxidative Apoptosis in Mouse Testes

AIMS

Many men endure immunosuppressive or anticancer treatments that contain alkylating agents before the age of sexual maturity, especially the increasing number of preadolescent males who undergo busulfan treatment for myeloablative conditioning before hematopoietic stem cell transplantation. Before sperm production, there are no sperm available for cryopreservation. Thus, it is necessary to identify a solution to ameliorate the busulfan-induced damage of spermatogonial stem cells (SSCs).

RESULTS

In this study, we demonstrated that melatonin relieved the previously described SSC loss and apoptosis in mouse testes. Melatonin increased the expression of manganese superoxide dismutase (MnSOD), which regulated the production of busulfan-induced reactive oxygen species (ROS). Moreover, melatonin promoted sirtuin type 1 (SIRT1) expression. SIRT1 participated in the deacetylation of p53, which promotes p53 ubiquitin degradation. Decreased concentrations of deacetylated p53 resulted in spermatogonial cell resistance to apoptosis. Acute T cell leukemia cell assay demonstrated that melatonin does not affect busulfan-induced cancer cell apoptosis and ROS.

INNOVATION

The current evidence suggests that melatonin may alleviate the side effects of alkylating drugs, such as busulfan.

CONCLUSION

Melatonin promoted MnSOD and SIRT1 expression, which successfully ameliorated busulfan-induced SSC apoptosis caused by high concentrations of ROS and p53. Antioxid. Redox Signal. 28, 385-400.

Melatonin as a potential anticarcinogen for non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) is a leading cause of death from cancer worldwide. Melatonin, an indoleamine discovered in the pineal gland, exerts pleiotropic anticancer effects against a variety of cancer types. In particular, melatonin may be an important anticancer drug in the treatment of NSCLC. Herein, we review the correlation between the disruption of the melatonin rhythm and NSCLC incidence; we also evaluate the evidence related to the effects of melatonin in inhibiting lung carcinogenesis. Special focus is placed on the oncostatic effects of melatonin, including anti-proliferation, induction of apoptosis, inhibition of invasion and metastasis, and enhancement of immunomodulation. We suggest the drug synergy of melatonin with radio- or chemotherapy for NSCLC could prove to be useful. Taken together, the information complied herein may serve as a comprehensive reference for the anticancer mechanisms of melatonin against NSCLC, and may be helpful for the design of future experimental research and for advancing melatonin as a therapeutic agent for NSCLC.

Melatonin enhances the apoptotic effects and modulates the changes in gene expression induced by docetaxel in MCF‑7 human breast cancer cells

Results from clinical trials and multiple in vivo and in vitro studies point to melatonin as a promising adjuvant molecule with many beneficial effects when concomitantly administered with chemotherapy. Melatonin palliates side‑effects and enhances the efficacy of chemotherapeutic agents. However, the mechanisms through which melatonin regulates molecular changes induced by chemotherapeutic agents remain largely unknown. In this study, we demonstrated that melatonin enhanced the anti-proliferative and apoptotic responses to low doses of docetaxel in breast cancer cells. Importantly, these effects were more potent when melatonin was added prior to docetaxel. Treatment with 1 µM docetaxel (equivalent to the therapeutic dosage) induced changes in gene expression profiles and melatonin modulated these changes. Specifically, docetaxel downregulated TP53, cyclin-dependent kinase inhibitor 1A (CDKN1A) and cadherin 13 (CDH13), and upregulated mucin 1 (MUC1), GATA binding protein 3 (GATA3) and c-MYC, whereas melatonin counteracted these effects. Melatonin further stimulated the expression of the pro-apoptotic BAD and BAX genes, and enhanced the inhibition of the anti-apoptotic gene BCL-2 induced by docetaxel. The findings of this study suggest that melatonin is a molecule with potential for use as an adjuvant in cancer chemotherapy, which may have implications for designing clinical trials using chemotherapeutic drugs in combination with melatonin.

Melatonin: An Anti-Tumor Agent in Hormone-Dependent Cancers

Melatonin (N-acetyl-5-methoxytryptamine) is a hormone synthesized and secreted by the pineal gland mainly during the night, since light exposure suppresses its production. Initially, an implication of this indoleamine in malignant disease was described in endocrine-responsive breast cancer. Data from several clinical trials and multiple experimental studies performed both in vivo and in vitro have documented that the pineal hormone inhibits endocrine-dependent mammary tumors by interfering with the estrogen signaling-mediated transcription, therefore behaving as a selective estrogen receptor modulator (SERM). Additionally, melatonin regulates the production of estradiol through the control of the enzymes involved in its synthesis, acting as a selective estrogen enzyme modulator (SEEM). Many more mechanisms have been proposed during the past few years, including signaling triggered after activation of the membrane melatonin receptors MT-1 and MT-2, or else intracellular actions targeting molecules such as calmodulin, or binding intranuclear receptors. Similar results have been obtained in prostate (regulation of enzymes involved in androgen synthesis and modulation of androgen receptor levels and activity) and ovary cancer. Thus, tumor metabolism, gene expression, or epigenetic modifications are modulated, cell growth is impaired and angiogenesis and metastasis are inhibited. In the last decade, many more reports have demonstrated that melatonin is a promising adjuvant molecule with many potential beneficial consequences when included in chemotherapy or radiotherapy protocols designed to treat endocrine-responsive tumors. Therefore, in this state-of-the-art review, we aim to compile the knowledge about the oncostatic actions of the indoleamine in hormone-dependent tumors, and the latest findings concerning melatonin actions when administered in combination with radio- or chemotherapy in breast, prostate, and ovary cancers. As melatonin has no toxicity, it may be well deserve to be considered as an endogenously generated agent helpful in cancer prevention and treatment.

The potential therapeutic effect of melatonin on human ovarian cancer by inhibition of invasion and migration of cancer stem cells

There is an urgent need to identify targeting molecules to control invasion and metastasis in cancer patients. We first isolated cancer stem cells (CSCs) from SKOV3 ovarian cancer cells and then investigated the role of melatonin in invasiveness and migration of CSCs compared to SKOV3 cells. The proportion of CSCs in SKOV3 cells was as low as 1.28% with overexpression of both CD133 and CD44. The ability of spheroid formation along with SOX2 overexpression revealed a high self-renewal potential in isolated cells. Melatonin (3.4 mM) inhibited proliferation of CSCs by 23% which was confirmed by a marked decrease in protein expression of Ki67, as a proliferation marker. Applying luzindole, a melatonin receptor 1, 2 inhibitor, partially abolished anti-proliferative effect of melatonin. Melatonin also decreased Epithelial mesenchymal transition (EMT) related gene expressions including ZEB1, ZEB2, snail and vimentin with increase in E-cadherin as a negative EMT regulator. Incubation of CSCs with melatonin showed a marked decrease in matrix metalloproteinase 9 (MMP9) expression and activity. Melatonin also inhibited CSCs migration in a partially receptor dependent and PI3k and MAPK independent manner. Melatonin can be considered as an important adjuvant to control invasion and metastasis especially in patients with high melatonin receptor expression.

The role of melatonin on chemotherapy-induced reproductive toxicity

Objectives

Reproductive malfunctions after chemotherapy still are a reason of reducing fertility and need specialized intensive care. The aim of this review was to investigate the effect of melatonin on the reproductive system under threatening with chemotherapeutic drugs.

Methods

To find the role of melatonin in the reproductive system during chemotherapy, a full systematic literature search was carried out based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in the electronic databases up to 17 April 2017 using search terms in the titles and abstracts. A total of 380 articles are screened according to our inclusion and exclusion criteria. Finally, 18 articles were included in this study.

Key findings

It has been cleared that melatonin has bilateral effects on reproductive cells. Melatonin protects normal cells via mechanisms, including decrease in oxidative stress, apoptosis, inflammation and modulating mitochondrial function, and sexual hormones. Furthermore, melatonin with antiproliferative properties and direct effects on its receptors improves reproductive injury and function during chemotherapy. On the other hand, melatonin sensitizes the effects of chemotherapeutic drugs and enhances chemotherapy-induced toxicity in cancerous cells through increasing apoptosis, oxidative stress and mitochondrial malfunction.

Conclusions

The study provides evidence of the bilateral role of melatonin in the reproductive system during chemotherapy.

Melatonin, mitochondria, and the cancer cell

The long-recognized fact that oxidative stress within mitochondria is a hallmark of mitochondrial dysfunction has stimulated the development of mitochondria-targeted antioxidant therapies. Melatonin should be included among the pharmacological agents able to modulate mitochondrial functions in cancer, given that a number of relevant melatonin-dependent effects are triggered by targeting mitochondrial functions. Indeed, melatonin may modulate the mitochondrial respiratory chain, thus antagonizing the cancer highly glycolytic bioenergetic pathway of cancer cells. Modulation of the mitochondrial respiratory chain, together with Ca2+ release and mitochondrial apoptotic effectors, may enhance the spontaneous or drug-induced apoptotic processes. Given that melatonin may efficiently counteract the Warburg effect while stimulating mitochondrial differentiation and mitochondrial-based apoptosis, it is argued that the pineal neurohormone could represent a promising new perspective in cancer treatment strategy.

Effects of melatonin administration on embryo implantation and offspring growth in mice under different schedules of photoperiodic exposure

BACKGROUND

Embryo implantation is crucial for animal reproduction. Unsuccessful embryo implantation leads to pregnancy failure, especially in human-assisted conception. Environmental factors have a profound impact on embryo implantation. Because people are being exposed to more light at night, the influence of long-term light exposure on embryo implantation should be explored.

METHODS

The effects of long photoperiodic exposure and melatonin on embryo implantation and offspring growth were examined. Long photoperiodic exposure (18:6 h light:dark) was selected to resemble light pollution. Melatonin (10^-2, 10^-3, 10^-4, 10^-5 M) was added to the drinking water of mice starting at Day 1 (vaginal plugs) until delivery.

RESULTS

Melatonin treatment (10^-4,10^-5 M) significantly increased litter sizes compared to untreated controls (12.9 ± 0.40 and 12.2 ± 1.01 vs. 11.5 ± 0.43; P < 0.05). The most effective concentration of melatonin (10^-4 M) was selected for further investigation. No remarkable differences were found between melatonin-treated mice and controls in terms of the pups' birth weights, weaning survival rates, and weaning weights. Long photoperiodic exposure significantly reduced the number of implantation sites in treated mice compared to controls (light/dark, 12/12 h), and melatonin rescued this negative effect. Mechanistic studies revealed that melatonin enhanced the serum 17β-estradiol (E₂) levels in the pregnant mice and upregulated the expression of the receptors MT1 and MT2 and p53 in uterine tissue. All of these factors may contribute to the beneficial effects of melatonin on embryo implantation in mice.

CONCLUSION

Melatonin treatment was associated with beneficial effects in pregnant mice, especially those subjected to long photoperiodic exposure. This was achieved by enhanced embryo implantation. At the molecular level, melatonin administration probably increases the E₂ level during pregnancy and upregulates p53 expression by activating MT1/2 in the uterus. All of the changes may improve the microenvironment of the uterus and, thus, the outcomes of pregnancy.

Melatonin attenuates hypoxia-induced epithelial-mesenchymal transition and cell aggressive via Smad7/ CCL20 in glioma

Tumor recurrence in gliomas is partly attributed to increased epithelial-mesenchymal transition (EMT) and enhanced tumor cell dissemination in the adjacent brain parenchyma. Thus, exploring effective strategies for against EMT-like changes in glioma invasion and recurrence will be important for glioma treatment. In this study, we investigated the roles of melatonin in hypoxia-induced EMT suppression, and found that melatonin could significantly suppress the release of the cytokine, CCL20, from cancer cells and antagonize glioma cell metastasis and invasion under hypoxic stress in glioma cells. Furthermore, our findings show that melatonin deregulates Smad7 expression to suppress TGFβ/Smad-mediated increase in CCL20 transcript levels and CCL20-induced EMT occurrence, suggesting a potential anti-EMT therapeutic role for melatonin in malignant transformation in gliomas.

Gold-chrysophanol nanoparticles suppress human prostate cancer progression through inactivating AKT expression and inducing apoptosis and ROS generation in vitro and in vivo

Controlled releasing of regulations remains the most convenient method to deliver various drugs. In the present study, we precipitated gold nanoparticles with chrysophanol. The gold-chrysophanol into poly (DL-lactide-co-glycolide) nanoparticles was loaded and the biological activity of chrysophanol nanoparticles on human LNCap prostate cancer cells, was tested to acquire the sustained releasing property. The circular dichroism spectroscopy indicated that chrysophanol nanoparticles effectively resulted in conformational alterations in DNA and regulated different proteins associated with cell cycle arrest. The reactive oxygen species (ROS), apoptosis, cell cycle, DNA damage, Cyto-c and caspase-3 activity were analyzed, and the expression levels of different anti- and pro-apoptotic were studied using immunoblotting analysis. The cytotoxicity assay suggested that chrysophanol nanoparticles preferentially killed prostate cancer cells in comparison to the normal cells. Chrysophanol nanoparticles reduced histone deacetylases (HDACs) to suppress cell proliferation and induce apoptosis by arresting the cell cycle in sub-G phase. In addition, the cell cycle-related proteins, including p27, CHK1, cyclin D1, CDK1, p-AMP-activated protein kinase (AMPK) and p-protein kinase B (AKT), were regulated by chrysophanol nanoparticles to prevent human prostate cancer cell progression. Chrysophanol nanoparticles induced apoptosis in LNCap cells by promoting p53/ROS crosstalk to prevent proliferation. Pharmacokinetic study in mice indicated that chrysophanol nanoparticle injection showed high bioavailability compared to the free chrysophanol. Also, in vivo study revealed that chrysophanol nanoparticles obviously reduced tumor volume and weight. In conclusion, the data above suggested that chrysophanol nanoparticles might be effective to prevent human prostate cancer progression.

Melatonin: A pleiotropic molecule that modulates DNA damage response and repair pathways

DNA repair is responsible for maintaining the integrity of the genome. Perturbations in the DNA repair pathways have been identified in several human cancers. Thus, compounds targeting DNA damage response (DDR) hold great promise in cancer therapy. A great deal of effort, in pursuit of new anticancer drugs, has been devoted to understanding the basic mechanisms and functions of the cellular DNA repair machinery. Melatonin, a widely produced indoleamine in all organisms, is associated with a reduced risk of cancer and has multiple regulatory roles on the different aspects of the DDR and DNA repair. Herein, we have mainly discussed how defective components in different DNA repair machineries, including homologous recombination (HR), nonhomologous end-joining (NHEJ), base excision repair (BER), nucleotide excision repair (NER), and finally DNA mismatch repair (MMR), can contribute to the risk of cancer. Melatonin biosynthesis, mode of action, and antioxidant effects are reviewed along with the means by which the indoleamine regulates DDR at the transduction, mediation, and functional levels. Finally, we summarize recent studies that illustrate how melatonin can be combined with DNA-damaging agents to improve their efficacy in cancer therapy.

Efficacy of melatonin, IL-25 and siIL-17B in tumorigenesis-associated properties of breast cancer cell lines

Mammary tumorigenesis can be modulated by melatonin, which has oncostatic action mediated by multiple mechanisms, including the inhibition of the activity of transcription factors such as NF-κB and modulation of interleukins (ILs) expression. IL-25 is an active cytokine that induces apoptosis in tumor cells due to differential expression of its receptor (IL-17RB). IL-17B competes with IL-25 for binding to IL-17RB in tumor cells, promoting tumorigenesis. This study purpose is to address the possibility of engaging IL-25/IL-17RB signaling to enhance the effect of melatonin on breast cancer cells. Breast cancer cell lines were cultured monolayers and 3D structures and treated with melatonin, IL-25, siIL-17B, each alone or in combination. Cell viability, gene and protein expression of caspase-3, cleaved caspase-3 and VEGF-A were performed by qPCR and immunofluorescence. In addition, an apoptosis membrane array was performed in metastatic cells. Treatments with melatonin and IL-25 significantly reduced tumor cells viability at 1mM and 1ng/mL, respectively, but did not alter cell viability of a non-tumorigenic epithelial cell line (MCF-10A). All treatments, alone and combined, significantly increased cleaved caspase-3 in tumor cells grown as monolayers and 3D structures (p<0.05). Semi-quantitative analysis of apoptosis pathway proteins showed an increase of CYTO-C, DR6, IGFBP-3, IGFBP-5, IGFPB-6, IGF-1, IGF-1R, Livin, P21, P53, TNFRII, XIAP and hTRA proteins and reduction of caspase-3 (p<0.05) after melatonin treatment. All treatments reduced VEGF-A protein expression in tumor cells (p<0.05). Our results suggest therapeutic potential, with oncostatic effectiveness, pro-apoptotic and anti-angiogenic properties for melatonin and IL-25-driven signaling in breast cancer cells.