Doxorubicin resistance in breast cancer is driven by light at night-induced disruption of the circadian melatonin signal

The Triad of Sleep, Immunity, and Cancer: A Mediating Perspective

The triadic interplay between sleep, immunity, and cancer represents a growing area of biomedical research with significant clinical implications. This review synthesizes the current knowledge on how sleep influences immune function, the immune system's role in cancer dynamics, and the direct connections between sleep patterns and cancer risk. After a comprehensive overview of the interrelationships among these three domains, the mechanisms of sleep in immune function are described, detailing how sleep regulates the immune system, the effects of sleep duration and quality on immune responses, and the underlying molecular and cellular mechanisms. Also, the complex relationship between immunity and cancer is explored, highlighting the immune system's role in cancer prevention and progression, immune surveillance, tumor microenvironment, and the implications of immunodeficiency and immune modulation on cancer risk. The direct connections between sleep and cancer are then described, presenting epidemiological evidence linking sleep patterns to cancer risk, biological mechanisms that influence cancer development, and the role of sleep disorders in cancer prognosis. The mediating role of sleep between immunity and cancer is highlighted, proposing hypothesized pathways, summarizing evidence from experimental and clinical studies, and evaluating the impact of sleep interventions on immune function and cancer outcomes. This review concludes by discussing the clinical implications and future directions, emphasizing the potential for sleep-based interventions in cancer prevention and treatment, the integration of sleep management in oncology and immunotherapy, and outlining a future research agenda. This agenda includes understanding the mechanisms of the sleep-immunity-cancer interplay, conducting epidemiological studies on sleep and cancer risk, assessing the impact of sleep management in cancer treatment protocols, exploring sleep and tumor microenvironment interactions, and considering policy and public health implications. Through a detailed examination of these interconnected pathways, this review underscores the critical importance of sleep in modulating immune function and cancer outcomes, advocating for interdisciplinary research and clinical strategies to harness this knowledge for improved health outcomes.

Melatonin modulates tumor metabolism and mitigates metastasis

INTRODUCTION

Melatonin, originally isolated from the mammalian pineal gland, was subsequently identified in many animal cell types and in plants. While melatonin was discovered to inhibit cancer more than 5 decades ago, its anti-cancer potential has not been fully exploited despite its lack of serious toxicity over a very wide dose range, high safety margin, and its efficacy.

AREAS COVERED

This review elucidates the potential mechanisms by which melatonin interferes with tumor growth and metastasis, including its ability to alter tumor cell metabolism, inhibit epithelial-mesenchymal transition, reverse cancer chemoresistance, function synergistically with conventional cancer-inhibiting drugs while limiting many of their side effects. In contrast to its function as a potent antioxidant in normal cells, it may induce oxidative stress in cancer cells, contributing to its oncostatic actions.

EXPERT OPINION

Considering the large amount of experimental data supporting melatonin's multiple and varied inhibitory effects on numerous cancer types, coupled with the virtual lack of toxicity of this molecule, it has not been thoroughly tested as an anti-cancer agent in clinical trials. There seems to be significant resistance to such investigations, possibly because melatonin is inexpensive and non-patentable, and as a result there would be limited financial gain for its use.

An Individualized Prognostic Model in Patients with Locoregionally Advanced Nasopharyngeal Carcinoma Based on Serum Metabolomic Profiling

PURPOSE

This study aims to evaluate the value of a serum metabolomics-based metabolic signature for locoregionally advanced nasopharyngeal carcinoma (LA-NPC) patients, thereby assisting clinical decisions.

METHODS

In this retrospective study, a total of 320 LA-NPC patients were randomly divided into a training set (ca. 70%; n = 224) and a validation set (ca. 30%; n = 96). Serum samples were analyzed using widely targeted metabolomics. Univariate and multivariate Cox regression analyses were used to identify candidate metabolites related to progression-free survival (PFS). Patients were categorized into high-risk and low-risk groups based on the median metabolic risk score (Met score), and the PFS difference between the two groups was compared using Kaplan-Meier curves. The predictive performance of the metabolic signature was evaluated using the concordance index (C-index) and the time-dependent receiver operating characteristic (ROC), and a comprehensive nomogram was constructed using the Met score and other clinical factors.

RESULTS

Nine metabolites were screened to build the metabolic signature and generate the Met score, which effectively separated patients into low- and high-risk groups. The C-index in the training and validation sets was 0.71 and 0.73, respectively. The 5-year PFS was 53.7% (95% CI, 45.12-63.86) in the high-risk group and 83.0% (95%CI, 76.31-90.26) in the low-risk group. During the construction of the nomogram, Met score, clinical stage, pre-treatment EBV DNA level, and gender were identified as independent prognostic factors for PFS. The predictive performance of the comprehensive model was better than that of the traditional model.

CONCLUSION

The metabolic signature developed through serum metabolomics is a reliable prognostic indicator of PFS in LA-NPC patients and has important clinical significance.

The neural addiction of cancer

The recently uncovered key role of the peripheral and central nervous systems in controlling tumorigenesis and metastasis has opened a new area of research to identify innovative approaches against cancer. Although the 'neural addiction' of cancer is only partially understood, in this Perspective we discuss the current knowledge and perspectives on peripheral and central nerve circuitries and brain areas that can support tumorigenesis and metastasis and the possible reciprocal influence that the brain and peripheral tumours exert on one another. Tumours can build up local autonomic and sensory nerve networks and are able to develop a long-distance relationship with the brain through circulating adipokines, inflammatory cytokines, neurotrophic factors or afferent nerve inputs, to promote cancer initiation, growth and dissemination. In turn, the central nervous system can affect tumour development and metastasis through the activation or dysregulation of specific central neural areas or circuits, as well as neuroendocrine, neuroimmune or neurovascular systems. Studying neural circuitries in the brain and tumours, as well as understanding how the brain communicates with the tumour or how intratumour nerves interplay with the tumour microenvironment, can reveal unrecognized mechanisms that promote cancer development and progression and open up opportunities for the development of novel therapeutic strategies. Targeting the dysregulated peripheral and central nervous systems might represent a novel strategy for next-generation cancer treatment that could, in part, be achieved through the repurposing of neuropsychiatric drugs in oncology.

Circadian disruption: from mouse models to molecular mechanisms and cancer therapeutic targets

The circadian clock is a timekeeping system for numerous biological rhythms that contribute to the regulation of numerous homeostatic processes in humans. Disruption of circadian rhythms influences physiology and behavior and is associated with adverse health outcomes, especially cancer. However, the underlying molecular mechanisms of circadian disruption-associated cancer initiation and development remain unclear. It is essential to construct good circadian disruption models to uncover and validate the detailed molecular clock framework of circadian disruption in cancer development and progression. Mouse models are the most widely used in circadian studies due to their relatively small size, fast reproduction cycle, easy genome manipulation, and economic practicality. Here, we reviewed the current mouse models of circadian disruption, including suprachiasmatic nuclei destruction, genetic engineering, light disruption, sleep deprivation, and other lifestyle factors in our understanding of the crosstalk between circadian rhythms and oncogenic signaling, as well as the molecular mechanisms of circadian disruption that promotes cancer growth. We focused on the discoveries made with the nocturnal mouse, diurnal human being, and cell culture and provided several circadian rhythm-based cancer therapeutic strategies.

Lactic Acidosis in Patients with Solid Cancer

Significance: Cancer-associated tissue-specific lactic acidosis stimulates and mediates tumor invasion and metastasis and is druggable. Rarely, malignancy causes systemic lactic acidosis, the role of which is poorly understood. Recent Advances: The understanding of the role of lactate has shifted dramatically since its discovery. Long recognized as only a waste product, lactate has become known as an alternative metabolism substrate and a secreted nutrient that is exchanged between the tumor and the microenvironment. Tissue-specific lactic acidosis is targeted to improve the host body's anticancer defense and serves as a tool that allows the targeting of anticancer compounds. Systemic lactic acidosis is associated with poor survival. In patients with solid cancer, systemic lactic acidosis is associated with an extremely poor prognosis, as revealed by the analysis of 57 published cases in this study. Although it is considered a pathology worth treating, targeting systemic lactic acidosis in patients with solid cancer is usually inefficient. Critical Issues: Research gaps include simple questions, such as the unknown nuclear pH of the cancer cells and its effects on chemotherapy outcomes, pH sensitivity of glycosylation in cancer cells, in vivo mechanisms of response to acidosis in the absence of lactate, and overinterpretation of in vitro results that were obtained by using cells that were not preadapted to acidic environments. Future Directions: Numerous metabolism-targeting anticancer compounds induce lactatemia, lactic acidosis, or other types of acidosis. Their potential to induce acidic environments is largely overlooked, although the acidosis might contribute to a substantial portion of the observed clinical effects. Antioxid. Redox Signal. 37, 1130-1152.

Pro-Apoptotic and Anti-Migration Properties of a Thiazoline-Containing Platinum(II) Complex in MDA-MB-231 Breast Cancer Cells: The Role of Melatonin as a Synergistic Agent

Triple-negative breast cancer (TNBC) is an aggressive cancer insensitive to hormonal and human epidermal growth factor receptor 2 (HER2)-targeted therapies and has a poor prognosis. Therefore, there is a need for the development of convenient anticancer strategies for the management of TNBC. In this paper, we evaluate the antitumoral potential of a platinum(II) complex coordinated with the ligand 2-(3,5-diphenylpyrazol-1-yl)-2-thiazoline (DPhPzTn), hereafter PtDPhPzTn, against the TNBC cell line MDA-MB-231, and compared its effect with both cisplatin and its less lipophilic counterpart PtPzTn, the latter containing the ligand 2-(pyrazol-1-yl)-2-thiazoline (PzTn). Then, the putative potentiating actions of melatonin, a naturally occurring antioxidant with renowned antitumor properties, on the tumor-killing ability of PtDPhPzTn were also checked in TNBC cells. Our results show that PtDPhPzTn presented enhanced cytotoxicity compared to both the classical drug cisplatin and PtPzTn. In addition, PtDPhPzTn was able to induce apoptosis, being more selective for MDA-MB-231 cells when compared to non-tumor breast epithelial MCF10A cells. Likewise, PtDPhPzTn produced moderate S phase arrest and greatly impaired the migration ability of MDA-MB-231 cells. Most importantly, the co-stimulation of TNBC cells with PtDPhPzTn and melatonin substantially enhanced apoptosis and markedly improved the anti-migratory action compared to PtDPhPzTn alone. Altogether, our findings provide evidence that PtDPhPzTn and melatonin could be potentially applied to breast cancer treatment as powerful synergistic agents.

Melatonin as an oncostatic agent: Review of the modulation of tumor microenvironment and overcoming multidrug resistance

Multi drug resistance (MDR) generally limits the efficacy of chemotherapy in cancer patients and can be categorized into primary or acquired resistance. Melatonin (MLT), a lipophilic hormone released from pineal gland, is a molecule with oncostatic effects. Here, we will briefly review the contribution of different microenvironmental components including fibroblasts, immune and inflammatory cells, stem cells and vascular endothelial cells in tumor initiation, progression and development. Then, the mechanisms by which MLT can potentially affect these elements and regulate drug resistance will be presented. Finally, we will explain how different studies have used novel strategies incorporating MLT to suppress cancer resistance against therapeutics.

Exposure to artificial light at night: A common link for obesity and cancer?

Exposure to artificial light at night (ALAN) has been associated with disruption of the circadian system, which has been pointed out to have detrimental effects on health. Exposure to outdoor ALAN is very frequent in industrialised countries due to nocturnal light pollution and the relevant involvement of the total workforce in shift work and night work. Ecological and epidemiologic studies highlight the association between exposure to ALAN and several diseases, mainly obesity and cancer. More recently, also indoor ALAN exposure has been investigated. Among several multifactorial mechanisms linking ALAN exposure and health risks, suppression of melatonin secretion plays a pivotal role leading to alterations in circadian rhythm patterns, that are detrimental in terms of appetite regulation, and dysfunctions in metabolic signalling and cell growth in cancer. In addition, gut dysbiosis, inflammation, hypovitaminosis D, imbalance in cytokine secretion and levels are responsible for the multiple relationship linking circadian dysregulation due to ALAN exposure and obesity, and cancer. Therefore, the current manuscript summarises human and basic studies pointing out the impact of ALAN exposure on health, mostly focusing on obesity and cancer. Based on extant evidence, prevention strategies for obesity and cancer should be prompted, targeting exposure to ALAN.

Sleep Disruption and Cancer: Chicken or the Egg?

Sleep is a nearly ubiquitous phenomenon across the phylogenetic tree, highlighting its essential role in ensuring fitness across evolutionary time. Consequently, chronic disruption of the duration, timing, or structure of sleep can cause widespread problems in multiple physiological systems, including those that regulate energy balance, immune function, and cognitive capacity, among others. Many, if not all these systems, become altered throughout the course of cancer initiation, growth, metastatic spread, treatment, and recurrence. Recent work has demonstrated how changes in sleep influence the development of chronic diseases, including cancer, in both humans and animal models. A common finding is that for some cancers (e.g., breast), chronic disruption of sleep/wake states prior to disease onset is associated with an increased risk for cancer development. Additionally, sleep disruption after cancer initiation is often associated with worse outcomes. Recently, evidence suggesting that cancer itself can affect neuronal circuits controlling sleep and wakefulness has accumulated. Patients with cancer often report difficulty falling asleep, difficulty staying asleep, and severe fatigue, during and even years after treatment. In addition to the psychological stress associated with cancer, cancer itself may alter sleep homeostasis through changes to host physiology and via currently undefined mechanisms. Moreover, cancer treatments (e.g., chemotherapy, radiation, hormonal, and surgical) may further worsen sleep problems through complex biological processes yet to be fully understood. This results in a “chicken or the egg” phenomenon, where it is unclear whether sleep disruption promotes cancer or cancer reciprocally disrupts sleep. This review will discuss existing evidence for both hypotheses and present a framework through which the interactions between sleep and cancer can be dissociated and causally investigated.

Disrupting circadian rhythms promotes cancer-induced inflammation in mice

Disruption of circadian rhythms occurs in rotating shift-work, jetlag, and in individuals with irregular sleep schedules. Circadian disruption is known to alter inflammatory responses and impair immune function. However, there is limited understanding of how circadian disruption modulates cancer-induced inflammation. Inflammation is a hallmark of cancer and is linked to worse prognosis and impaired brain function in cancer patients. Here, we investigated the effect of circadian disruption on cancer-induced inflammation in an orthotopic breast cancer model. Using a validated chronic jetlag protocol that advances the light-cycle by 8 ​h every 2 days to disrupt circadian rhythms, we found that circadian disruption alters cancer-induced inflammation in a tissue-specific manner, increasing inflammation in the body and brain while decreasing inflammation within the tumor tissue. Circadian disruption did not affect inflammation in mice without tumors, suggesting that the impact of circadian disruption may be particularly detrimental in the context of underlying inflammatory conditions, such as cancer. Importantly, circadian disruption did not affect tumor burden, suggesting that increased inflammation was not a result of increased cancer progression. Overall, these findings identify the importance of healthy circadian rhythms for limiting cancer-induced inflammation.

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Circadian disruption enhances cancer-induced inflammation in the body and brain.

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The profile of inflammatory cytokines altered by circadian disruption is tissue specific.

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Changes in inflammatory profiles by circadian ​disruption are not due to enhanced tumor burden.

Nocturnal lighting in animal research should be replicable and reflect relevant ecological conditions

In nature, light is a key driver of animal behaviour and physiology. When studying captive or laboratory animals, researchers usually expose animals to a period of darkness, to mimic night. However, ‘darkness’ is often poorly quantified and its importance is generally underappreciated in animal research. Even small differences in nocturnal light conditions can influence biology. When light levels during the dark phase are not reported accurately, experiments can be impossible to replicate and compare. Furthermore, when nocturnal light levels are unrealistically dark or bright, the research is less ecologically relevant. Such issues are exacerbated by huge differences in the sensitivity of different light meters, which are not always described in study methods. We argue that nocturnal light levels need to be reported clearly and precisely, particularly in studies of animals housed indoors (e.g. ‘<0.03 lux’ rather than ‘0 lux’ or ‘dark’), and that these light levels should reflect conditions that the animal would experience in a natural context.

miR-26b-5p suppresses chemoresistance in breast cancer by targeting serglycin

Chemoresistance is a crucial barrier to limit the therapeutic outcome of breast cancer (BC), and the mechanism underlying chemoresistance development in BC is not fully understood. In this study, we aimed to investigate the potential involvement of miR-26b-5p/serglycin (SRGN) axis in BC drug resistance. The expression level of SRGN in drug-resistant BC cells was investigated by western blotting analysis, real-time quantitative PCR (qRT-PCR), immunohistochemical staining, and ELISA. Its expression between chemoresistant and sensitive patient samples was compared by qRT-PCR. Bioinformatics tool and dual-luciferase reporter assay were employed to identify miR-26b-5p as a regulator of SRGN. Functional assays were performed to examine cell proliferation, cell viability, apoptosis, migration, and invasion ability in vitro. Xenograft tumorigenesis experiment was conducted to evaluate the tumor suppressor effect of miR-26b-5p on chemoresistant BC cells. SRGN expression was significantly upregulated in both chemoresistant BC cell lines and chemoresistant patient samples. miR-26b-5p was identified as an upstream regulator of SRGN. Overexpression of miR-26b-5p downregulated SRGN expression, overcame chemoresistance, and suppressed cell proliferation, migration, and invasion in BC cells. Overexpression of miR-26b-5p also suppressed the tumorigenesis of chemoresistant BC cells in vivo. Mechanistically, the downregulation of SRGN by miR-26b-5p decreased the expression of breast cancer drug-resistant protein and multidrug-resistant protein 1 in chemoresistant BC cells. Our study identified miR-26b-5p as a tumor suppressor which targets SRGN to sensitize BC cells to chemotherapeutics. These results suggest that miR-26b-5p and SRGN may serve as potential biomarkers and targets for BC chemotherapy.

A Method for Perfusion of Tissue-Isolated Human Tumor Xenografts in Nude Rats to Investigate the Oncostatic Role of the Physiological Nocturnal Melatonin Signal

The tissue-isolated human tumor perfusion methodology enables the elucidation of physiological melatonin's oncostatic impact on cancer metabolism and physiology. Here we describe an apparatus and surgical technique for perfusing tissue-isolated human tumor xenografts in nude rats in situ that ensures continuous blood flow to and from the tissue. This system and methodology have proven quite successful in examining the receptor-mediated oncostatic effects of the physiological nocturnal melatonin signal on metabolism and physiology in a variety of epithelial and mesenchymal human tumors.

A Method for Growing Tissue-Isolated Human Tumor Xenografts in Nude Rats for Melatonin/Cancer Studies

The tissue-isolated tumor model permits the investigation of melatonin's influence on human tumor growth and metabolism in laboratory rats in vivo. Here we describe a unique surgical technique for implanting and growing human tumor xenografts on a vascular stalk composed of the nude rat epigastric artery and vein that provides a continuous blood supply from a single source to the tissue-isolated tumor while insuring the absence of extraneous vascular connections. A variety of human tumor types may be implanted and grown utilizing this unique model that may provide a plethora of scientific data from a single tumor examined.

Effects of melatonin and doxorubicin on primary tumor and metastasis in breast cancer model

BACKGROUND

Melatonin exerts oncostatic effects on breast cancer via immunomodulation and anti-oxidation. Doxorubicin is an effective chemotherapeutic agent, but parallel studies also provide ample evidence of an off-target effect of Doxorubicin in breast cancer patients.

OBJECTIVE

Combinatorial use of doxorubicin and melatonin has not been comprehensively analyzed in breast cancer models. We hypothesized that the anti-oxidative, anti-proliferative and anti-inflammatory effects of melatonin could ameliorate the off-target effects of doxorubicin in breast cancer patients and enhance the anti-tumoral effects of doxorubicin. The goal of the study is to test this hypothesis in cancer cell lines and xenografted mice.

METHODS

The effects of Melatonin and doxorubicin on the cell viability were evaluated in 4T1-Brain Metastatic Tumor (4TBM). Furthermore, the effects of melatonin and doxorubicin on the primary tumors and systemic metastasis were evaluated in the xenografted mice. Lung and liver tissues were removed and metastasis analyses were performed. The levels of p65, phospho-STAT3, CD11b+, GR1+, Ki67, and cleaved caspase-3 proteins were determined with immunohistochemistry and western blot analysis. We examined the effects of melatonin and Melatonin+Doxorubicin combination therapy on 4TBM cells.

RESULTS

Our results showed that doxorubicin inhibited the proliferation of metastatic breast cancer cells while melatonin did not affect cells. Tumor growth and metastasis were markedly suppressed in melatonin alone and combination with doxorubicin. The expression of CD11b+ and GR1+ proteins which are indicators of myeloid-derived suppressor cells (MDSCs) were noted to be reduced in both primary tumor and metastatic tissues in melatonin and doxorubicin groups.

CONCLUSION

The combination of melatonin with doxorubicin reduced primary tumor growth and distant metastasis. Based on these results, melatonin is a promising candidate for combinatory use with conventional chemotherapeutics for breast cancer treatment.

Hesperidin and its aglycone hesperetin in breast cancer therapy: A review of recent developments and future prospects

Breast cancer (BC) has high incidence and mortality rates, making it a major global health issue. BC treatment has been challenging due to the presence of drug resistance and the limited availability of therapeutic options for triple-negative and metastatic BC, thereby urging the exploration of more effective anti-cancer agents. Hesperidin and its aglycone hesperetin, two flavonoids from citrus species, have been extensively evaluated for their anti-cancer potentials. In this review, available literatures on the chemotherapeutic and chemosensitising activities of hesperidin and hesperetin in preclinical BC models are reported. The safety and bioavailability of hesperidin and hesperetin as well as the strategies to enhance their bioavailability are also discussed. Overall, hesperidin and hesperetin can inhibit cell proliferation, migration and BC stem cells as well as induce apoptosis and cell cycle arrest in vitro. They can also inhibit tumour growth, metastasis and neoplastic changes in tissue architecture in vivo. Moreover, the co-administration of hesperidin or hesperetin with doxorubicin, letrozole or tamoxifen can enhance the efficacies of these clinically available agents. These chemotherapeutic and chemosensitising activities of hesperidin and hesperetin have been linked to several mechanisms, including the modulation of signalling pathways, glucose uptake, enzymes, miRNA expression, oxidative status, cell cycle regulatory proteins, tumour suppressor p53, plasma and liver lipid profiles as well as DNA repair mechanisms. However, poor water solubility, extensive phase II metabolism and apical efflux have posed limitations to the bioavailability of hesperidin and hesperetin. Various strategies for bioavailability enhancement have been studied, including the utilisation of nano-based drug delivery systems and the co-administration of hesperetin with other flavonoids. In particular, nanoformulated hesperidin and hesperetin possess greater chemotherapeutic and chemosensitising activities than free compounds. Despite promising preclinical results, further safety and efficacy evaluation of hesperidin and hesperetin as well as their nanoformulations in clinical trials is required to ascertain their potentials to be developed as clinically useful agents for BC treatment.

Recent Advances in Functional Carbon Quantum Dots for Antitumour

Carbon quantum dots (CQDs) are an emerging class of quasi-zero-dimensional photoluminescent nanomaterials with particle sizes less than 10 nm. Owing to their favourable water dispersion, strong chemical inertia, stable optical performance, and good biocompatibility, CQDs have become prominent in biomedical fields. CQDs can be fabricated by “top-down” and “bottom-up” methods, both of which involve oxidation, carbonization, pyrolysis and polymerization. The functions of CQDs include biological imaging, biosensing, drug delivery, gene carrying, antimicrobial performance, photothermal ablation and so on, which enable them to be utilized in antitumour applications. The purpose of this review is to summarize the research progress of CQDs in antitumour applications from preparation and characterization to application prospects. Furthermore, the challenges and opportunities of CQDs are discussed along with future perspectives for precise individual therapy of tumours.

Melatonin-A New Prospect in Prostate and Breast Cancer Management

Cancer is a known cause of mortality globally. The management of cancer has been influenced periodically by diverse scientific research for early detection to promote remission and improve quality of life. One of these advancements is the prospect of melatonin (n-acetyl-5-methoxytryptamine) in managing prostate and breast cancers. Melatonin exerts its oncostatic effect by inhibiting angiogenesis, preventing cancer spread and growth, and improving the sensitivity of cancer cells to radiation and chemotherapy in both prostate and breast cancer. This review aims to highlight some of the current studies on melatonin's effect on prostate and breast cancers. We reviewed articles and two randomized controlled trials (RCT) that highlighted the mechanism of melatonin in combating tumorigenesis of these cancers. Articles and RCT studies were obtained by searching PubMed using regular and Medical Subject Heading (MeSH) keyword search strategy. The majority of the articles reviewed supported the use of melatonin in cancer management since inhibition of angiogenesis, cancer proliferation, invasion of normal cells by tumor cells, and improvement in chemotherapeutic and radiation therapy were achieved with its use. In addition, melatonin was also protective against prostate and breast cancers in the general population. Despite the benefits of melatonin in cancer management, most of the studies done were in vivo and in vitro studies, and more studies in human subjects are encouraged to confirm the positive therapeutic use of melatonin.

Roles of circadian clocks in cancer pathogenesis and treatment

Circadian clocks are ubiquitous timing mechanisms that generate approximately 24-h rhythms in cellular and bodily functions across nearly all living species. These internal clock systems enable living organisms to anticipate and respond to daily changes in their environment in a timely manner, optimizing temporal physiology and behaviors. Dysregulation of circadian rhythms by genetic and environmental risk factors increases susceptibility to multiple diseases, particularly cancers. A growing number of studies have revealed dynamic crosstalk between circadian clocks and cancer pathways, providing mechanistic insights into the therapeutic utility of circadian rhythms in cancer treatment. This review will discuss the roles of circadian rhythms in cancer pathogenesis, highlighting the recent advances in chronotherapeutic approaches for improved cancer treatment.

Circadian Rhythms, Disease and Chronotherapy

Circadian clocks are biological timing mechanisms that generate 24-h rhythms of physiology and behavior, exemplified by cycles of sleep/wake, hormone release, and metabolism. The adaptive value of clocks is evident when internal body clocks and daily environmental cycles are mismatched, such as in the case of shift work and jet lag or even mistimed eating, all of which are associated with physiological disruption and disease. Studies with animal and human models have also unraveled an important role of functional circadian clocks in modulating cellular and organismal responses to physiological cues (ex., food intake, exercise), pathological insults (e.g. virus and parasite infections), and medical interventions (e.g. medication). With growing knowledge of the molecular and cellular mechanisms underlying circadian physiology and pathophysiology, it is becoming possible to target circadian rhythms for disease prevention and treatment. In this review, we discuss recent advances in circadian research and the potential for therapeutic applications that take patient circadian rhythms into account in treating disease.

Melatonin Inhibits Osteoclastogenesis and Osteolytic Bone Metastasis: Implications for Osteoporosis

Osteoblasts and osteoclasts are major cellular components in the bone microenvironment and they play a key role in the bone turnover cycle. Many risk factors interfere with this cycle and contribute to bone-wasting diseases that progressively destroy bone and markedly reduce quality of life. Melatonin (N-acetyl-5-methoxy-tryptamine) has demonstrated intriguing therapeutic potential in the bone microenvironment, with reported effects that include the regulation of bone metabolism, acceleration of osteoblastogenesis, inhibition of osteoclastogenesis and the induction of apoptosis in mature osteoclasts, as well as the suppression of osteolytic bone metastasis. This review aims to shed light on molecular and clinical evidence that points to possibilities of melatonin for the treatment of both osteoporosis and osteolytic bone metastasis. It appears that the therapeutic qualities of melatonin supplementation may enable existing antiresorptive osteoporotic drugs to treat osteolytic metastasis.

Long non-coding RNA LINC00607 silencing exerts antioncogenic effects on thyroid cancer through the CASP9 Promoter methylation

Thyroid cancer (TC) was the most frequent thyroid malignant tumour, accounting for about 1% of all malignant tumours. Some long non-coding RNAs (lncRNAs) have been reported to exert essential tumour promotion effects, while caspase-9 (CASP9) gene could play a promotive role in the cell apoptosis in TC. However, whether they have a specific effect on TC remains unclear. Hence, this study aims to explore the relationship between LINC00607 and CASP9, and its effect in TC. LINC00607 expression in the TC tissues and cell lines was determined. Then, we explored the combination effect between a LINC00607 and a methylation inhibitor 5-Aza-dc in doxorubicin-resistant ARO cells using colony formation assay, flow cytometry, WST-1 and EdU assay, as well as in vivo tumour growth assay. Besides, the dual-luciferase reporter gene assay, RIP, ChIP, methylation-specific PCR and BSP method were employed to detect the relationship between LINC00607 and CASP9 and its methylation. LINC00607 expression was up-regulated in the doxorubicin-resistant TC cell lines and tissues and negatively correlated to the poor prognosis of TC patients. Knockdown of LINC00607 suppressed doxorubicin resistance, proliferation and colony formation, and promoted cell apoptosis of TC cells in vitro, as well as suppressed tumour growth in vivo, whereas LINC00607 overexpression was observed to exercise the opposite effects. Notably, it was also revealed that LINC00607 down-regulated the CASP9 expression by promoting CASP9 promoter methylation. In conclusion, LINC00607 could inhibit the apoptosis and augment the doxorubicin resistance of TC cells by decreasing CASP9 expression, which might provide a novel therapeutic target for TC treatment.

Multiple interactions between melatonin and non-coding RNAs in cancer biology

The melatonin hormone secreted by the pineal gland is involved in physiological functions such as growth and maturation, circadian cycles, and biological activities including antioxidants, anti-tumor, and anti-ischemia. Melatonin not only interacts with proteins but also has functional effects on regulatory RNAs such as long non-coding RNAs (lncRNAs) and microRNAs (miRNAs). In this study, we overview various physiological and pathological conditions affecting melatonin through lncRNA and miRNA. The information compiled herein will serve as a solid foundation to formulate ideas for future mechanistic studies on melatonin. It will also provide a chance to more clarify the emerging functions of the non-coding transcriptome.

Melatonin inhibits triple-negative breast cancer progression through the Lnc049808-FUNDC1 pathway

Melatonin has been reported to have tumor-suppressive effects via comprehensive molecular mechanisms, and long non-coding RNAs (lncRNAs) may participate in this process. However, the mechanism by which melatonin affects the function of lncRNAs in triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer, is still unknown. Therefore, we aimed to investigate the differentially expressed mRNAs and lncRNAs in melatonin-treated TNBC cells and the interaction mechanisms. Microarray analyses were performed to identify differentially expressed mRNAs and lncRNAs in TNBC cell lines after melatonin treatment. To explore the functions and underlying mechanisms of the mRNAs and lncRNAs candidates, a series of in vitro experiments were conducted, including CCK-8, Transwell, colony formation, luciferase reporter gene, and RNA immunoprecipitation (RIP) assays, and mouse xenograft models were established. We found that after melatonin treatment, FUNDC1 and lnc049808 downregulated in TNBC cell lines. Knockdown of FUNDC1 and lnc049808 inhibited TNBC cell proliferation, invasion, and metastasis. Moreover, lnc049808 and FUNDC1 acted as competing endogenous RNAs (ceRNAs) for binding to miR-101. These findings indicated that melatonin inhibited TNBC progression through the lnc049808-FUNDC1 pathway and melatonin could be used as a potential therapeutic agent for TNBC.

Melatonin as an Adjuvant to Antiangiogenic Cancer Treatments

Melatonin is a hormone with different functions, antitumor actions being one of the most studied. Among its antitumor mechanisms is its ability to inhibit angiogenesis. Melatonin shows antiangiogenic effects in several types of tumors. Combination of melatonin and chemotherapeutic agents have a synergistic effect inhibiting angiogenesis. One of the undesirable effects of chemotherapy is the induction of pro-angiogenic factors, whilst the addition of melatonin is able to overcome these undesirable effects. This protective effect of the pineal hormone against angiogenesis might be one of the mechanisms underlying its anticancer effect, explaining, at least in part, why melatonin administration increases the sensitivity of tumors to the inhibitory effects exerted by ordinary chemotherapeutic agents. Melatonin has the ability to turn cancer totally resistant to chemotherapeutic agents into a more sensitive chemotherapy state. Definitely, melatonin regulates the expression and/or activity of many factors involved in angiogenesis which levels are affected (either positively or negatively) by chemotherapeutic agents. In addition, the pineal hormone has been proposed as a radiosensitizer, increasing the oncostatic effects of radiation on tumor cells. This review serves as a synopsis of the interaction between melatonin and angiogenesis, and we will outline some antiangiogenic mechanisms through which melatonin sensitizes cancer cells to treatments, such as radiotherapy or chemotherapy.

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 and its mechanism of action in the female reproductive system and related malignancies

Melatonin (N-acetyl-5-methoxytryptamine), the main product of pineal gland in vertebrates, is well known for its multifunctional role which has great influences on the reproductive system. Recent studies documented that melatonin is a powerful free radical scavenger that affects the reproductive system function and female infertility by MT1 and MT2 receptors. Furthermore, cancer researches indicate the influence of melatonin on the modulation of tumor cell signaling pathways resulting in growth inhibitor of the both in vivo/in vitro models. Cancer adjuvant therapy can also benefit from melatonin through therapeutic impact and decreasing the side effects of radiation and chemotherapy. This article reviews the scientific evidence about the influence of melatonin and its mechanism of action on the fertility potential, physiological alteration, and anticancer efficacy, during experimental and clinical studies.

Reversible Lysine Specific Demethylase 1 (LSD1) Inhibitors: A Promising Wrench to Impair LSD1

As a flavin adenine dinucleotide (FAD)-dependent monoamine oxidase, lysine specific demethylase 1 (LSD1/KDM1A) functions as a transcription coactivator or corepressor to regulate the methylation of histone 3 lysine 4 and 9 (H3K4/9), and it has emerged as a promising epigenetic target for anticancer treatment. To date, numerous inhibitors targeting LSD1 have been developed, some of which are undergoing clinical trials for cancer therapy. Although only two reversible LSD1 inhibitors CC-90011 and SP-2577 are in the clinical stage, the past decade has seen remarkable advances in the development of reversible LSD1 inhibitors. Herein, we provide a comprehensive review about structures, biological evaluation, and structure-activity relationship (SAR) of reversible LSD1 inhibitors.

RORα Regulates Odontoblastic Differentiation and Mediates the Pro-Odontogenic Effect of Melatonin on Dental Papilla Cells

Dental papilla cells (DPCs), precursors of odontoblasts, are considered promising seed cells for tissue engineering. Emerging evidence suggests that melatonin promotes odontoblastic differentiation of DPCs and affects tooth development, although the precise mechanisms remain unknown. Retinoid acid receptor-related orphan receptor α (RORα) is a nuclear receptor for melatonin that plays a critical role in cell differentiation and embryonic development. This study aimed to explore the role of RORα in odontoblastic differentiation and determine whether melatonin exerts its pro-odontogenic effect via RORα. Herein, we observed that RORα was expressed in DPCs and was significantly increased during odontoblastic differentiation in vitro and in vivo. The overexpression of RORα upregulated the expression of odontogenic markers, alkaline phosphatase (ALP) activity and mineralized nodules formation (p < 0.05). In contrast, odontoblastic differentiation of DPCs was suppressed by RORα knockdown. Moreover, we found that melatonin elevated the expression of odontogenic markers, which was accompanied by the upregulation of RORα (p < 0.001). Utilising small interfering RNA, we further demonstrated that RORα inhibition attenuated melatonin-induced odontogenic gene expression, ALP activity and matrix mineralisation (p < 0.01). Collectively, these results provide the first evidence that RORα can promote odontoblastic differentiation of DPCs and mediate the pro-odontogenic effect of melatonin.

Circadian clock protein CRY1 prevents paclitaxel‑induced senescence of bladder cancer cells by promoting p53 degradation

Bladder cancer is a common tumor type of the urinary system, which has high levels of morbidity and mortality. The first‑line treatment is cisplatin‑based combination chemotherapy, but a significant proportion of patients relapse due to the development of drug resistance. Therapy‑induced senescence can act as a 'back‑up' response to chemotherapy in cancer types that are resistant to apoptosis‑based anticancer therapies. The circadian clock serves an important role in drug resistance and cellular senescence. The aim of the present study was to investigate the regulatory effect of the circadian clock on paclitaxel (PTX)‑induced senescence in cisplatin‑resistant bladder cancer cells. Cisplatin‑resistant bladder cancer cells were established via long‑term cisplatin incubation. PTX induced apparent senescence in bladder cancer cells as demonstrated via SA‑β‑Gal staining, but this was not observed in the cisplatin‑resistant cells. The cisplatin‑resistant cells entered into a quiescent state with prolonged circadian rhythm under acute PTX stress. It was identified that the circadian protein cryptochrome1 (CRY1) accumulated in these quiescent cisplatin‑resistant cells, and that CRY1 knockdown restored PTX‑induced senescence. Mechanistically, CRY1 promoted p53 degradation via increasing the binding of p53 with its ubiquitin E3 ligase MDM2 proto‑oncogene. These data suggested that the accumulated CRY1 in cisplatin‑resistant cells could prevent PTX‑induced senescence by promoting p53 degradation.

Light Pollution and Cancer

For many individuals in industrialized nations, the widespread adoption of electric lighting has dramatically affected the circadian organization of physiology and behavior. Although initially assumed to be innocuous, exposure to artificial light at night (ALAN) is associated with several disorders, including increased incidence of cancer, metabolic disorders, and mood disorders. Within this review, we present a brief overview of the molecular circadian clock system and the importance of maintaining fidelity to bright days and dark nights. We describe the interrelation between core clock genes and the cell cycle, as well as the contribution of clock genes to oncogenesis. Next, we review the clinical implications of disrupted circadian rhythms on cancer, followed by a section on the foundational science literature on the effects of light at night and cancer. Finally, we provide some strategies for mitigation of disrupted circadian rhythms to improve health.

Melatonin, an ubiquitous metabolic regulator: functions, mechanisms and effects on circadian disruption and degenerative diseases

The last four decades, we assist to an increasing scientific interest on melatonin, a circadian hormone, a metabolic regulator which influences not only plants' metabolism and their defense against pathogens but mostly the animals and humans' metabolic pathways, their response to circadian disruption, stress and burnout syndrome. In humans, as a hormonal regulator, produced in the pineal grand as well in mitochondria, melatonin is involved in different, complex intracellular signaling pathways, with antioxidant and immune stimulating effects, proving to act as a circadian synchronizer, as a preventive and therapeutic agent in many degenerative diseases, and especially in hormone-dependent cancers. Preclinical or clinical studies showed recently the mechanisms involved in regulating the cellular activity, its role in aging and circadian disturbances and impact on degenerative diseases. Melatonin proved to have an anti-inflammatory, antiapoptotic and powerful antioxidant effect by subtle mechanisms in mitochondrial metabolic pathways. This overview includes recent and relevant literature data related to the impact of endogenous and exogeneous melatonin on the prevention of cancer progression and treatment of various degenerative diseases. Metabolomics, an emerging new omics' technology, based on high performance liquid chromatography coupled with mass spectrometry is presented as an encouraging technique to fingerprint and realize a precise evaluation and monitoring of the turnover of melatonin and its metabolites in different pathological circumstances.

Circadian disruption, melatonin rhythm perturbations and their contributions to chaotic physiology

The aim of this report is to summarize the data documenting the vital nature of well-regulated cellular and organismal circadian rhythms, which are also reflected in a stable melatonin cycle, in supporting optimal health. Cellular fluctuations in physiology exist in most cells of multicellular organisms with their stability relying on the prevailing light:dark cycle, since it regulates, via specialized intrinsically-photoreceptive retinal ganglion cells (ipRGC) and the retinohypothalamic tract, the master circadian oscillator, i.e., the suprachiasmatic nuclei (SCN). The output message of the SCN, as determined by the light:dark cycle, is transferred to peripheral oscillators, so-called slave cellular oscillators, directly via the autonomic nervous system with its limited distribution. and indirectly via the pineal-derived circulating melatonin rhythm, which contacts every cell. Via its regulatory effects on the neuroendocrine system, particularly the hypothalamo-pituitary-adrenal axis, the SCN also has a major influence on the adrenal glucocorticoid rhythm which impacts neurological diseases and psychological behaviors. Moreover, the SCN regulates the circadian production and secretion of melatonin. When the central circadian oscillator is disturbed, such as by light at night, it passes misinformation to all organs in the body. When this occurs the physiology of cells becomes altered and normal cellular functions are compromised. This physiological upheaval is a precursor to pathologies. The deterioration of the SCN/pineal network is often a normal consequence of aging and its related diseases, but in today's societies where manufactured light is becoming progressively more common worldwide, the associated pathologies may also be occurring at an earlier age.

Melatonin inhibits Warburg-dependent cancer by redirecting glucose oxidation to the mitochondria: a mechanistic hypothesis

Melatonin has the ability to intervene in the initiation, progression and metastasis of some experimental cancers. A large variety of potential mechanisms have been advanced to describe the metabolic and molecular events associated with melatonin's interactions with cancer cells. There is one metabolic perturbation that is common to a large number of solid tumors and accounts for the ability of cancer cells to actively proliferate, avoid apoptosis, and readily metastasize, i.e., they use cytosolic aerobic glycolysis (the Warburg effect) to rapidly generate the necessary ATP required for the high metabolic demands of the cancer cells. There are several drugs, referred to as glycolytic agents, that cause cancer cells to abandon aerobic glycolysis and shift to the more conventional mitochondrial oxidative phosphorylation for ATP synthesis as in normal cells. In doing so, glycolytic agents also inhibit cancer growth. Herein, we hypothesize that melatonin also functions as an inhibitor of cytosolic glycolysis in cancer cells using mechanisms, i.e., downregulation of the enzyme (pyruvate dehydrogenase kinase) that interferes with the conversion of pyruvate to acetyl CoA in the mitochondria, as do other glycolytic drugs. In doing so, melatonin halts the proliferative activity of cancer cells, reduces their metastatic potential and causes them to more readily undergo apoptosis. This hypothesis is discussed in relation to the previously published reports. Whereas melatonin is synthesized in the mitochondria of normal cells, we hypothesize that this synthetic capability is not present in cancer cell mitochondria because of the depressed acetyl CoA; acetyl CoA is necessary for the rate limiting enzyme in melatonin synthesis, arylalkylamine-N-acetyltransferase. Finally, the ability of melatonin to switch glucose oxidation from the cytosol to the mitochondria also explains how tumors that become resistant to conventional chemotherapies are re-sensitized to the same treatment when melatonin is applied.

Molecular avenues in targeted doxorubicin cancer therapy

In recent, intra- and inter-tumor heterogeneity is seen as one of key factors behind success and failure of chemotherapy. Incessant use of doxorubicin (DOX) drug is associated with numerous post-treatment debacles including cardiomyopathy, health disorders, reversal of tumor and formation of secondary tumors. The module of cancer treatment has undergone evolutionary changes by achieving crucial understanding on molecular, genetic, epigenetic and environmental adaptations by cancer cells. Therefore, there is a paradigm shift in cancer therapeutic by employing amalgam of peptide mimetic, small RNA mimetic, DNA repair protein inhibitors, signaling inhibitors and epigenetic modulators to achieve targeted and personalized DOX therapy. This review summarizes on recent therapeutic avenues that can potentiate DOX effects by removing discernible pitfalls among cancer patients.

Usefulness of melatonin as complementary to chemotherapeutic agents at different stages of the angiogenic process

Chemotherapeutics are sometimes administered with drugs, like antiangiogenic compounds, to increase their effectiveness. Melatonin exerts antitumoral actions through antiangiogenic actions. We studied if melatonin regulates the response of HUVECs to chemotherapeutics (docetaxel and vinorelbine). The inhibition that these agents exert on some of the processes involved in angiogenesis, such as, cell proliferation, migratory capacity or vessel formation, was enhanced by melatonin. Regarding to estrogen biosynthesis, melatonin impeded the negative effect of vinorelbine, by decreasing the activity and expression of aromatase and sulfatase. Docetaxel and vinorelbine increased the expression of VEGF-A, VEGF-B, VEGF-C, VEGFR-1, VEGFR-3, ANG1 and/or ANG-2 and melatonin inhibited these actions. Besides, melatonin prevented the positive actions that docetaxel exerts on the expression of other factors related to angiogenesis like JAG1, ANPEP, IGF-1, CXCL6, AKT1, ERK1, ERK2, MMP14 and NOS3 and neutralized the stimulating actions of vinorelbine on the expression of FIGF, FGFR3, CXCL6, CCL2, ERK1, ERK2, AKT1, NOS3 and MMP14. In CAM assay melatonin inhibited new vascularization in combination with chemotherapeutics. Melatonin further enhanced the chemotherapeutics-induced inhibition of p-AKT and p-ERK and neutralized the chemotherapeutics-caused stimulatory effect on HUVECs permeability by modifying the distribution of VE cadherin. Our results confirm that melatonin blocks proangiogenic and potentiates antiangiogenic effects induced by docetaxel and vinorelbine enhancing their antitumor effectiveness.

Effects of miR-34b/miR-892a Upregulation and Inhibition of ABCB1/ABCB4 on Melatonin-Induced Apoptosis in VCR-Resistant Oral Cancer Cells

Multidrug resistance (MDR) is the resistance of cells toward various drugs commonly used in tumor treatment. The mechanism of drug resistance in oral cancer is not completely understood. Melatonin is an endogenously produced molecule involved in active biological mechanisms including antiproliferation, oncogene expression modulation, antitumor invasion and migration, and anti-inflammatory, antioxidant, and antiangiogenic effects. Despite these functions, the effects of melatonin on vincristine (VCR)-resistant human oral cancer cells remain largely unknown. This study analyzed the role of melatonin in VCR-resistant human oral cancer cells along with the underlying mechanism. We determined that melatonin induced the apoptosis and autophagy of VCR-resistant oral cancer cells; these actions were mediated by AKT, p38, and c-Jun N-terminal kinase (JNK). Melatonin inhibited ATP-binding cassette B1 (ABCB1) and ABCB4 expression in vitro and in vivo. Melatonin reduced the drug resistance and promoted the apoptosis of VCR-resistant oral cancer cells through the upregulation of microRNA-892a (miR-892a) and miR-34b-5p expressions. The expression of miR-892a and miR-34b-5p was related to melatonin-induced apoptosis, but not autophagy. Therefore, melatonin is a potential novel chemotherapeutic agent for VCR-resistant human oral cancer cell lines.

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.

A ketogenic diet combined with melatonin overcomes cisplatin and vincristine drug resistance in breast carcinoma syngraft

OBJECTIVES

Chemotherapy is one of the major treatments of cancer. However, the emergence of resistance to chemotherapeutic agents is still a major obstacle in the successful management of resistant tumors. Therefore, development of new mechanisms to overcome drug resistance is essential and may be further developed into effective therapies that can flip the switch from drug resistance to susceptibility. The aim of this study was to evaluate a combination consisting of a ketogenic diet and melatonin to determine whether it would inhibit cisplatin- and vincristine-resistant breast cancer.

METHODS

In the in vitro part of the study, drug-resistant cell lines were treated with melatonin and real-time polymerase chain reaction was used to measure levels of gene expression involved in apoptosis and resistance. On the protein level, the activity of caspase-3 and the level of vascular endothelin growth factor protein were determined. In the in vivo part, tumor-bearing mice received one of the following treatments: ketogenic diet, melatonin, combination of melatonin and ketogenic diet, vehicle, or chemotherapy.

RESULTS

Successful inhibition of resistant cell lines was achieved by melatonin. This inhibition was mediated by induction of apoptosis, inhibition of angiogenesis, and downregulation of resistance genes. A synergistic anticancer effect was observed between melatonin and the ketogenic diet against resistant breast tumors inoculated in mice with a cure rate of 70%.

CONCLUSIONS

The combination of melatonin and a ketogenic diet represents a promising option to overcome drug resistance in cancer chemotherapy. However, further testing on the protein level using flow cytometry is important to better understand the mechanisms of action.

Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates

Artificial light at night (ALAN) is increasing exponentially worldwide, accelerated by the transition to new efficient lighting technologies. However, ALAN and resulting light pollution can cause unintended physiological consequences. In vertebrates, production of melatonin—the “hormone of darkness” and a key player in circadian regulation—can be suppressed by ALAN. In this paper, we provide an overview of research on melatonin and ALAN in vertebrates. We discuss how ALAN disrupts natural photic environments, its effect on melatonin and circadian rhythms, and different photoreceptor systems across vertebrate taxa. We then present the results of a systematic review in which we identified studies on melatonin under typical light-polluted conditions in fishes, amphibians, reptiles, birds, and mammals, including humans. Melatonin is suppressed by extremely low light intensities in many vertebrates, ranging from 0.01–0.03 lx for fishes and rodents to 6 lx for sensitive humans. Even lower, wavelength-dependent intensities are implied by some studies and require rigorous testing in ecological contexts. In many studies, melatonin suppression occurs at the minimum light levels tested, and, in better-studied groups, melatonin suppression is reported to occur at lower light levels. We identify major research gaps and conclude that, for most groups, crucial information is lacking. No studies were identified for amphibians and reptiles and long-term impacts of low-level ALAN exposure are unknown. Given the high sensitivity of vertebrate melatonin production to ALAN and the paucity of available information, it is crucial to research impacts of ALAN further in order to inform effective mitigation strategies for human health and the wellbeing and fitness of vertebrates in natural ecosystems.

Epigenetic inhibition of the tumor suppressor ARHI by light at night-induced circadian melatonin disruption mediates STAT3-driven paclitaxel resistance in breast cancer

Disruption of circadian time structure and suppression of circadian nocturnal melatonin (MLT) production by exposure to dim light at night (dLAN), as occurs with night shift work and/or disturbed sleep-wake cycles, is associated with a significantly increased risk of breast cancer and resistance to tamoxifen and doxorubicin. Melatonin inhibition of human breast cancer chemoresistance involves mechanisms including suppression of tumor metabolism and inhibition of kinases and transcription factors which are often activated in drug-resistant breast cancer. Signal transducer and activator of transcription 3 (STAT3), frequently overexpressed and activated in paclitaxel (PTX)-resistant breast cancer, promotes the expression of DNA methyltransferase one (DNMT1) to epigenetically suppress the transcription of tumor suppressor Aplasia Ras homolog one (ARHI) which can sequester STAT3 in the cytoplasm to block PTX resistance. We demonstrate that breast tumor xenografts in rats exposed to dLAN and circadian MLT disrupted express elevated levels of phosphorylated and acetylated STAT3, increased DNMT1, but reduced sirtuin 1 (SIRT1) and ARHI. Furthermore, MLT and/or SIRT1 administration blocked/reversed interleukin 6 (IL-6)-induced acetylation of STAT3 and its methylation of ARH1 to increase ARH1 mRNA expression in MCF-7 breast cancer cells. Finally, analyses of the I-SPY 1 trial demonstrate that elevated MT₁ receptor expression is significantly correlated with pathologic complete response following neo-adjuvant therapy in breast cancer patients. This is the first study to demonstrate circadian disruption of MLT by dLAN driving intrinsic resistance to PTX via epigenetic mechanisms increasing STAT3 expression and that MLT administration can reestablish sensitivity of breast tumors to PTX and drive tumor regression.

Deciphering the Molecular Basis of Melatonin Protective Effects on Breast Cells Treated with Doxorubicin: TWIST1 a Transcription Factor Involved in EMT and Metastasis, a Novel Target of Melatonin

Melatonin mitigates cancer initiation, progression and metastasis through inhibition of both the synthesis of estrogens and the transcriptional activity of the estradiol-ER (Estrogen receptor) complex in the estrogen-dependent breast cancer cell line MCF-7. Moreover, melatonin improves the sensitivity of MCF-7 to chemotherapeutic agents and protects against their side effects. It has been described that melatonin potentiates the anti-proliferative effects of doxorubicin; however, the molecular changes involving gene expression and the activation/inhibition of intracellular signaling pathways remain largely unknown. Here we found that melatonin enhanced the anti-proliferative effect of doxorubicin in MCF-7 but not in MDA-MB-231 cells. Strikingly, doxorubicin treatment induced cell migration and invasion, and melatonin effectively counteracted these effects in MCF-7 but not in estrogen-independent MDA-MB-231 cells. Importantly, we describe for the first time the ability of melatonin to downregulate TWIST1 (Twist-related protein 1) in estrogen-dependent but not in estrogen-independent breast cancer cells. Combined with doxorubicin, melatonin inhibited the activation of p70S6K and modulated the expression of breast cancer, angiogenesis and clock genes. Moreover, melatonin regulates the levels of TWIST1-related microRNAs, such as miR-10a, miR-10b and miR-34a. Since TWIST1 plays a pivotal role in the epithelial to mesenchymal transition, acquisition of metastatic phenotype and angiogenesis, our results suggest that inhibition of TWIST1 by melatonin might be a crucial mechanism of overcoming resistance and improving the oncostatic potential of doxorubicin in estrogen-dependent breast cancer cells.

Melatonin: A new inhibitor agent for cervical cancer treatment

Cervical cancer is one of the most common cancers between women and is known as the third leading cause of female cancer related deaths annually. Its detection in early stages allows it to be a preventable and generally treatable disease. Increasing evidence revealed, a variety of internal and external factors are associated with initiation and progression of cervical cancer pathogenesis. Human papilloma virus infection is found as a major cause of cervical cancer. Other molecular and biochemical alterations as well as genetic and epigenetic changes are related cervical cancer progression. Current treatment options often have severe side effects and toxicities thus, new adjuvant agents having synergistic effects and ability to decrease different side effects and toxicities are needed. Melatonin is an indolamine compound secreted from the pineal gland which shows wide range anticancer activities. A large amount of studies indicated inhibitory effects of melatonin against various types of cancers. In addition, experimental evidence reports inhibitory effects of melatonin as an adjuvant therapy on cervical cancer by targeting a sequence of different molecular mechanisms. Herein, for first time, we summarized anticervical cancer effects of melatonin and its underlying molecular mechanisms.

Central regulation of breast cancer growth and metastasis

Cancer is a systemic disease. In order to fully understand it, we must take a holistic view on how cancer interacts with its host. The brain monitors and responds to natural and aberrant signals arriving from the periphery, particularly those of metabolic or immune origin. As has been well described, a hallmark of cancer is marked disruption of metabolic and inflammatory processes. Depending on the salience and timing of these inputs, the brain responds via neural and humoral routes to alter whole-body physiology. These responses have consequences for tumor growth and metastasis, directly influencing patient quality of life and subsequent mortality. Additionally, environmental inputs such as light, diet, and stress, can promote inappropriate neural activity that benefits cancer. Here, I discuss evidence for brain-tumor interactions, with special emphasis on subcortical neuromodulator neural populations, and potential ways of harnessing this cross-talk as a novel approach for cancer treatment.

Mechanisms Underlying Tumor Suppressive Properties of Melatonin

There is considerable evidence that melatonin may be of use in the prevention and treatment of cancer. This manuscript will review some of the human, animal and cellular studies that provide evidence that melatonin has oncostatic properties. Confirmation that melatonin mitigates pathogenesis of cancer will be described from both direct study of its effects on carcinogenesis, and from indirect findings implicating disruption of the circadian cycle. A distinction is made between the role of melatonin in preventing the initiation of the tumorigenic pathway and the ability of melatonin to retard the progression of cancer. Melatonin appears to slow down the rate of advancement of established tumors and there is evidence that it constitutes a valuable complement to standard pharmacological and radiation treatment modalities. There are instances of the beneficial outcomes in cancer treatment which utilize a range of hormones and vitamins, melatonin being among the constituents of the mix. While these complex blends are empirically promising, they are only briefly mentioned here in view of the confounding influence of a multiplicity of agents studied simultaneously. The last section of this review examines the molecular mechanisms that potentially underlie the oncostatic effects of melatonin. Alterations in gene expression following activation of various transcription factors, are likely to be an important mediating event. These changes in gene activity not only relate to cancer but also to the aging process which underlies the onset of most tumors. In addition, epigenetic events such as modulation of histone acetylation and DNA methylation patterns throughout the lifespan of organisms need to be considered. The antioxidant and immunoregulatory roles of melatonin may also contribute to its cancer modulatory properties. Naturally, these mechanisms overlap and interact extensively. Nevertheless, in the interest of clarity and ease of reading, each is discussed as a separate topic section. The report ends with some general conclusions concerning the clinical value of melatonin which has been rather overlooked and understudied.

Melatonin for the prevention and treatment of cancer

The epidemiological studies have indicated a possible oncostatic property of melatonin on different types of tumors. Besides, experimental studies have documented that melatonin could exert growth inhibition on some human tumor cells in vitro and in animal models. The underlying mechanisms include antioxidant activity, modulation of melatonin receptors MT1 and MT2, stimulation of apoptosis, regulation of pro-survival signaling and tumor metabolism, inhibition on angiogenesis, metastasis, and induction of epigenetic alteration. Melatonin could also be utilized as adjuvant of cancer therapies, through reinforcing the therapeutic effects and reducing the side effects of chemotherapies or radiation. Melatonin could be an excellent candidate for the prevention and treatment of several cancers, such as breast cancer, prostate cancer, gastric cancer and colorectal cancer. This review summarized the anticancer efficacy of melatonin, based on the results of epidemiological,experimental and clinical studies, and special attention was paid to the mechanisms of action.

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.