The impact of different extracellular matrices on melatonin effect in proliferation and stemness properties of ovarian cancer cells

Melatonin: Current evidence on protective and therapeutic roles in gynecological diseases

Melatonin, a potent antioxidant and free radical scavenger, has been demonstrated to be effective in gynecological conditions and female reproductive cancers. This review consolidates the accumulating evidence on melatonin's multifaceted protective effects in different pathological contexts. In gynecological conditions such as endometriosis, polycystic ovary syndrome (PCOS), and uterine leiomyoma, melatonin has shown promising effects in reducing oxidative stress, inflammation, and hormonal imbalances. It inhibits adhesion molecules' production, and potentially mitigates leukocyte adherence and inflammatory responses. Melatonin's regulatory effects on hormone production and insulin sensitivity in PCOS individuals make it a promising candidate for improving oocyte quality and menstrual irregularities. Moreover, melatonin exhibits significant antitumor effects by modulating various signaling pathways, promoting apoptosis, and suppressing metastasis in breast cancers and gynecological cancers, including ovarian, endometrial, and cervical cancers. Furthermore, melatonin's protective effects are suggested to be mediated by interactions with its receptors, estrogen receptors and other nuclear receptors. The regulation of clock-related genes and circadian clock systems may also contribute to its inhibitory effects on cancer cell growth. However, more comprehensive research is warranted to fully elucidate the underlying molecular mechanisms and establish melatonin as a potential therapeutic agent for these conditions.

Angiogenesis, coagulation, and fibrinolytic markers in acute promyelocytic leukemia (NB4): An evaluation of melatonin effects

Melatonin is a powerful biological agent that has been shown to inhibit angiogenesis and also exerts anti-inflammatory effects. It is well known that new blood vessel formation (angiogenesis) has become an urgent issue in leukemia as well as solid tumors. Acute promyelocytic leukemia (APL) is a form of liquid cancer that manifests increased angiogenesis in the bone marrow of patients. Despite high-rate curable treatment with all-trans-retinoic acid (ATRA) and recently arsenic-trioxide (ATO), early death because of hemorrhage, coagulopathy, and Disseminated intravascular coagulation (DIC) remains still a concerning issue in these patients. It is, therefore, urgent to seek treatment strategies with antiangiogenic capabilities that also diminish coagulopathy and hyperfibrinolysis in APL patients. In this study, a coculture system with human umbilical vein endothelial cells (HUVECs) and NB4 APL cells was used to investigate the direct effect of melatonin on angiogenesis and its possible action on tissue factor (TF) and tissue-type plasminogen activator-1 (TPA-1) expression. Our experiments revealed that HUVEC-induced angiogenesis by cocultured NB4 cells was suppressed when melatonin alone or in combination with ATRA was added to the incubation medium. Melatonin at concentrations of 1 mM inhibited tube formation of HUVECs and also decreased interleukin-6 secretion and VEGF mRNA expression in HUVEC and NB4 cells. Taken together, the results of this study demonstrate that melatonin inhibits accelerated angiogenesis of HUVECs and ameliorates the coagulation and fibrinolysis indices stimulated by coculturing with NB4 cells.

Melatonin as a Therapeutic Agent for the Inhibition of Hypoxia-Induced Tumor Progression: A Description of Possible Mechanisms Involved

Hypoxia has an important role in tumor progression via the up-regulation of growth factors and cellular adaptation genes. These changes promote cell survival, proliferation, invasion, metastasis, angiogenesis, and energy metabolism in favor of cancer development. Hypoxia also plays a central role in determining the resistance of tumors to chemotherapy. Hypoxia of the tumor microenvironment provides an opportunity to develop new therapeutic strategies that may selectively induce apoptosis of the hypoxic cancer cells. Melatonin is well known for its role in the regulation of circadian rhythms and seasonal reproduction. Numerous studies have also documented the anti-cancer properties of melatonin, including anti-proliferation, anti-angiogenesis, and apoptosis promotion. In this paper, we hypothesized that melatonin exerts anti-cancer effects by inhibiting hypoxia-induced pathways. Considering this action, co-administration of melatonin in combination with other therapeutic medications might increase the effectiveness of anti-cancer drugs. In this review, we discussed the possible signaling pathways by which melatonin inhibits hypoxia-induced cancer cell survival, invasion, migration, and metabolism, as well as tumor angiogenesis.

Melatonin and its derivative disrupt cancer stem-like phenotypes of lung cancer cells via AKT downregulation

Cancer stem cells (CSCs), a small subpopulation of tumour cells, have properties of self-renewal and multipotency, which drive cancer progression and resistance to current treatments. Compounds potentially targeting CSCs have been recently developed. This study shows how melatonin, an endogenous hormone synthesised by the pineal gland, and its derivative suppress CSC-like phenotypes of human non-small cell lung cancer (NSCLC) cell lines, H460, H23, and A549. The effects of MLT and its derivative, acetyl melatonin (ACT), on CSC-like phenotypes were investigated using assays for anchorage-independent growth, three-dimensional spheroid formation, scratch wound healing ability, and CSC marker and upstream protein signalling expression. Enriched CSC spheroids were used to confirm the effect of both compounds on lung cancer cells. MLT and ACT inhibited CSC-like behaviours by suppression of colony and spheroid formation in NSCLC cell lines. Their effects on spheroid formation were confirmed in CSC-enriched H460 cells. CSC markers, CD133 and ALDH1A1, were depleted by both compounds. The behaviour and factors associated to epithelial-mesenchymal transition, as indicated by cell migration and the protein vimentin, were also decreased by MLT and ACT. Mechanistically, MLT and ACT decreased the expression of stemness proteins Oct-4, Nanog, and β-catenin by reducing active AKT (phosphorylated AKT). Suppression of the AKT pathway was not mediated through melatonin receptors. This study demonstrates a novel role, and its underlying mechanism, for MLT and its derivative ACT in suppression of CSC-like phenotypes in NSCLC cells, indicating that they are potential candidates for lung cancer treatment.

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.

Insights on Melatonin as an Active Pharmacological Molecule in Cancer Prevention: What's New?

Along with playing an important role in circadian rhythm, melatonin is thought to play a significant role in preventing cells from damage, as well as in the inhibition of growth and in triggering apoptosis in malignant cells. Its relationship with circadian rhythms, energetic homeostasis, diet, and metabolism, is fundamental to achieve a better comprehension of how melatonin has been considered a chemopreventive molecule, though very few papers dealing with this issue. In this article, we tried to review the most recent evidence regarding the protective as well as the antitumoral mechanisms of melatonin, as related to diet and metabolic balance. From different studies, it was evident that an intracellular antioxidant defense mechanism is activated by upregulating an antioxidant gene battery in the presence of high-dose melatonin in malignant cells. Like other broad-spectrum antioxidant molecules, melatonin plays a vital role in killing tumor cells, preventing metastasis, and simultaneously keeping normal cells protected from oxidative stress and other types of tissue damage.

Current approaches in identification and isolation of cancer stem cells

Cancer stem cells (CSCs) are tumor cells with initiating ability, self-renewal potential, and intrinsic resistance to conventional therapeutics. Efficient isolation and characterization of CSCs pave the way for more comprehensive knowledge about tumorigenesis, heterogeneity, and chemoresistance. Also a better understanding of CSCs will lead to novel era of both basic and clinical cancer research, reclassification of human tumors, and development of innovative therapeutic strategies. Finding novel diagnostic and effective therapeutic strategies also enhance the success of treatment in cancer patients. There are various methods based on the characteristics of the CSCs to detect and isolate these cells, some of which have recently developed. This review summarized current techniques for effective isolation and characterization of CSCs with a focus on advantages and limitations of each method with clinical applications.

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.

Melatonin is a potential inhibitor of ovarian cancer: molecular aspects

Ovarian cancer is one of the most common causes of morbidity related to gynecologic malignancies. Possible risk factors are including hereditary ovarian cancer, obesity, diabetes mellitus, alcohol consumption, aging, and smoking. Various molecular signaling pathways including inflammation, oxidative stress, apoptosis and angiogenesis are involved in this progression of ovarian cancer. Standard treatments for recently diagnosed patients are Surgery and chemotherapy such as co-treatment with other drugs such that the exploitation of neoadjuvant chemotherapy is expanding. Melatonin (N-acetyl-5-methoxy-tryptamine), an endogenous agent secreted from the pineal gland, has anti-carcinogenic features, such as regulation of estradiol production, cell cycle modulation, stimulation of apoptosis as well as anti-angiogenetic properties, anti-inflammatory activities, significant antioxidant effects and modulation of various immune system cells and cytokines. Multiple studies have shown the significant beneficial roles of melatonin in various types of cancers including ovarian cancer. This paper aims to shed light on the roles of melatonin in ovarian cancer treatment from the standpoint of the molecular aspects.

Melatonin inhibits the migration of human gastric carcinoma cells at least in part by remodeling tight junction

The recurrence and metastasis is one of the major reasons for malignant tumor treatment failure. Melatonin, a naturally occuring hormone, could reduce the recurrence and metastasis of various tumors. However, the underlying molecular mechanisms of melatonin on tumor metastasis inhibition have not been fully elucidated. In the present study, we explored the impact of melatonin on the migratory capability of human gastric carcinoma cells using wound healing assay, and further investigated if the inhibition on migration ability of melatonin was embodied by relocating tight junction proteins zo-1 and occludin onto the cells surface to remodel tight junction structure. Immunofluorescence assay and Western blot analysis were performed to detect the expression and cell location of the tight junction proteins. The migration distance was decreased as the cells were treated with melatonin. And melatonin increased the membrane location of tight junction proteins, zo-1 and occludin, showed by immunofluorescence staining and Western blot analysis. The results we got show that melatonin makes tight junction proteins anchored more on the cells membrane to remodel cells tight junction, which increase cells adhesion and decrease motility, resulting in the inhibition of gastric cancer cells migration and metastasis ability.

Melatonin May Increase Anticancer Potential of Pleiotropic Drugs

Melatonin (N-acetyl-5-methoxytryptamine) is not only a pineal hormone, but also an ubiquitary molecule present in plants and part of our diet. Numerous preclinical and some clinical reports pointed to its multiple beneficial effects including oncostatic properties, and as such, it has become one of the most aspiring goals in cancer prevention/therapy. A link between cancer and inflammation and/or metabolic disorders has been well established and the therapy of these conditions with so-called pleiotropic drugs, which include non-steroidal anti-inflammatory drugs, statins and peroral antidiabetics, modulates a cancer risk too. Adjuvant therapy with melatonin may improve the oncostatic potential of these drugs. Results from preclinical studies are limited though support this hypothesis, which, however, remains to be verified by further research.

The role of Her2-Nrf2 axis in induction of oxaliplatin resistance in colon cancer cells

Nuclear factor erythroid 2-related factor 2 (Nrf2) plays a pivotal role in promoting chemoresistance by regulation of antioxidants and detoxification enzymes. Her2 is a member of tyrosine kinase receptor family with a key function in resistance of cancer cells to chemotherapeutics. The aim of this study was to investigate the possible cross talk between Nrf2 and Her2 mediated signaling pathways in development of oxaliplatin resistance in colon cancer cells. We first generated oxaliplatin-resistant LS174T and SW480 colon cancer cells with different Her2 expression levels by employing IC50 concentrations followed by a resting period. We evaluated the viability and apoptosis of the cells by MTT and flow cytometry assays, respectively. Nrf2 and Her2 gene expression levels were examined by qRT-PCR. The morphology analysis and combination index calculation were performed using the ImagJ and CompuSyn softwares, respectively. Development of resistant cells revealed a marked increase in half maximal inhibitory concentration (IC50) value from 3.95 ± 0.92 μM to 29.27 ± 3.13 μM in SW480 cells and 377 ± 46 nM to 9.59 ± 0.76 μM in LS174T cells with a significant change in morphology of the cells from elongated to small round shape (p < 0.05). Her2 expression level was increased in both types of resistant cells, but the Nrf2 expression was increased in LS174T resistant (LS174T/Res) cells and decreased in SW480/Res cells which were consistent with the level of resistance in these cells (25 fold increase in IC50 value in LS174T/Res cells versus 7 fold increase in this value in SW480/Res cells). Inhibition of either Nrf2 or Her2 alone and in combination caused a significant increase in oxaliplatin-induced cytotoxicity and apoptosis with maximum effects in SW480/Res cells with low Her2 and Nrf2 expression levels. Altogether, our results suggest that inhibition of Nrf2 signaling in colon cancer patients with Her2 overexpression can be considered as an important strategy to overcome oxaliplatin resistance.

miR-590-3p mediates melatonin-induced cell apoptosis by targeting septin 7 in the human osteoblast cell line hFOB 1.19

The present study aimed to investigate the association between septin 7 (SEPT7) and melatonin-induced apoptosis in the human fetal osteoblastic cell line hFOB 1.19. MicroRNA (miR)‑590‑3p was identified by identifying overlapping miRNAs that target SEPT7, across different databases (miRDB, DIANA and Targetscan). Apoptosis was assessed via flow cytometric analysis. Small interfering RNA of SEPT7 and a miR‑590‑3p inhibitor were used for gene silencing and the efficiency was assessed by reverse transcription‑quantitative polymerase chain reaction. Western blotting was used to measure the expression of proteins associated with pathways mediating endoplasmic reticulum stress and melatonin‑induced apoptosis. The present study identified that SEPT7 was a potential target of miR‑590‑3p and demonstrated that SEPT7 is associated with mediating the pro‑apoptotic effect of miR‑590‑3p in human osteoblast cell line hFOB 1.19. High concentrations of melatonin may result in the inhibition of miR‑590‑3p expression, leading to the upregulation of target genes that promote apoptosis.

Overexpression of septin-7 inhibits melatonin-induced cell apoptosis in human fetal osteoblastic cells via suppression of endoplasmic reticulum stress

Our previous study demonstrated that melatonin could induce apoptosis in the human fetal osteoblastic (hFOB) 1.19 cell line via induction of endoplasmic reticulum stress (ERS), and recent studies have demonstrated that the expression of septin‑7 (SEPT7) exhibits a positive correlation with the concentration of melatonin. Western blotting demonstrated the expression level of SEPT7 was significantly upregulated in a dose‑dependent manner following treatment with differing concentrations of melatonin compared with the control groups, which did not receive any treatment. The expression of proteins associated with cell apoptosis and endoplasmic reticulum stress (ERS; pro-caspase‑3, cleaved caspase‑3, C/EBP‑homologous protein, 78 kDa glucose‑regulated protein and phosphorylated‑eukaryotic translation initiation factor 2α) were decreased following transfection with SEPT7 overexpression plasmid and increased following transfection with SEPT7 small interfering RNA compared with the control groups. The results of the present study suggest that SEPT7 inhibits melatonin‑induced cell apoptosis via suppression of ERS.

Periostin has a protective role in melatonin‑induced cell apoptosis by inhibiting the eIF2α‑ATF4 pathway in human osteoblasts

The present study aimed to investigate the role of periostin (POSTN) and high melatonin concentrations in the apoptosis of hFOB 1.19 human normal fetal osteoblastic cells. hFOB 1.19 human osteoblastic cells were stably cultured and treated in different concentrations of melatonin for different durations of action. Apoptosis was assessed quantitatively using flow cytometric analysis. The results of western blot analysis demonstrated that the treatment of cells with different concentrations of melatonin for different durations of action revealed a positive association between melatonin and the expression levels of glucose‑regulated protein (GRP)78, GRP94, phosphorylated (p‑) eukaryotic initiation factor 2α (eIF2α), activating transcription factor (ATF)4, CCAAT/enhanced binding protein homologous protein (CHOP), cleaved caspase‑3, p‑c‑Jun N‑terminal kinase (JNK) and POSTN. When POSTN was inhibited, the levels of p‑JNK, CHOP, p‑eIF2α, ATF4 and cleaved caspase‑3 were significantly increased, whereas other proteins associated with the endoplasmic reticulum stress (ERS) pathways, including ATF6 and X‑box binding protein 1 (XBP1), were not significantly altered. Reverse transcription‑quantitative polymerase chain reaction analysis was also performed to assess the relative mRNA levels of ATF4, ATF6 and XBP1. The results of the present study are the first, to the best of our knowledge, to demonstrate that melatonin induced apoptosis in hFOB 1.19 human osteoblastic cells by activating the ERS‑associated eIF2α‑ATF4 pathway and subsequently triggered the cascade effects of CHOP, caspase‑3 and JNK. POSTN may function as a protective factor for osteoblasts during this process by inhibiting the eIF2α‑ATF4 pathway.

Melatonin as a promising agent to treat ovarian cancer: molecular mechanisms

Ovarian cancer (OC) has the highest mortality rate of all gynecological cancers, and most patients develop chemoresistance after first-line treatments. Despite recent advances, the 5-year relative survival is ~45% for all OC subtypes, and invasive epithelial OC has only a 17% survival rate when diagnosed at a late stage. Identification of new efficacious molecules or biomarkers represents important opportunities in the treatment of OC. The pharmacological and physiological properties of melatonin indicate this agent could be useful against OC progression and metastasis. In normal cells, melatonin has potent antioxidant and anti-apoptotic actions. Conversely, melatonin has pro-oxidant as well as anti-proliferative, anti-angiogenic and immunomodulatory properties in many cancer types including hormone-dependent cancers. Although melatonin receptors have been identified in OC cells, the exact mechanism by which melatonin induces anticancer activities remains incompletely understood. Clinical studies have reported negative correlation between aggressiveness of OC and serum levels of melatonin, reinforcing the idea that melatonin may be a critical factor determining OC development. In vitro and in vivo studies suggest melatonin differentially regulates multiple signaling pathways in OC cells. This focused review explores the potential mechanisms of action of melatonin on cultured OC cells and in experimental models of OC in an attempt to clarify how melatonin modulates the signaling pathways involved in cancer cell apoptosis, survival, inflammation, proliferation and metabolic processes. Based on the evidence presented, we feel that melatonin, as an agent that controls cellular signals associated with malignancy, may be beneficial in combination with other therapeutics for OC treatment.

Melatonin and Hippo Pathway: Is There Existing Cross-Talk?

Melatonin is an indolic hormone that regulates a plethora of functions ranging from the regulation of circadian rhythms and antioxidant properties to the induction and maintenance of tumor suppressor pathways. It binds to specific receptors as well as to some cytosolic proteins, leading to several cellular signaling cascades. Recently, the involvement of melatonin in cancer insurgence and progression has clearly been demonstrated. In this review, we will first describe the structure and functions of melatonin and its receptors, and then discuss both molecular and epidemiological evidence on melatonin anticancer effects. Finally, we will shed light on potential cross-talk between melatonin signaling and the Hippo signaling pathway, along with the possible implications for cancer therapy.