Role of Melatonin in Cancer: Effect on Clock Genes

The Common Hallmarks and Interconnected Pathways of Aging, Circadian Rhythms, and Cancer: Implications for Therapeutic Strategies

The intricate relationship between cancer, circadian rhythms, and aging is increasingly recognized as a critical factor in understanding the mechanisms underlying tumorigenesis and cancer progression. Aging is a well-established primary risk factor for cancer, while disruptions in circadian rhythms are intricately associated with the tumorigenesis and progression of various tumors. Moreover, aging itself disrupts circadian rhythms, leading to physiological changes that may accelerate cancer development. Despite these connections, the specific interplay between these processes and their collective impact on cancer remains inadequately explored in the literature. In this review, we systematically explore the physiological mechanisms of circadian rhythms and their influence on cancer development. We discuss how core circadian genes impact tumor risk and prognosis, highlighting the shared hallmarks of cancer and aging such as genomic instability, cellular senescence, and chronic inflammation. Furthermore, we examine the interplay between circadian rhythms and aging, focusing on how this crosstalk contributes to tumorigenesis, tumor proliferation, and apoptosis, as well as the impact on cellular metabolism and genomic stability. By elucidating the common pathways linking aging, circadian rhythms, and cancer, this review provides new insights into the pathophysiology of cancer and identifies potential therapeutic strategies. We propose that targeting the circadian regulation of cancer hallmarks could pave the way for novel treatments, including chronotherapy and antiaging interventions, which may offer important benefits in the clinical management of cancer.

The role of circadian rhythm regulator PERs in oxidative stress, immunity, and cancer development

The complex interaction between circadian rhythms and physiological functions is essential for maintaining human health. At the heart of this interaction lies the PERIOD proteins (PERs), pivotal to the circadian clock, influencing the timing of physiological and behavioral processes and impacting oxidative stress, immune functionality, and tumorigenesis. PER1 orchestrates the cooperation of the enzyme GPX1, modulating mitochondrial dynamics in sync with daily rhythms and oxidative stress, thus regulating the mechanisms managing energy substrates. PERs in innate immune cells modulate the temporal patterns of NF-κB and TNF-α activities, as well as the response to LPS-induced toxic shock, initiating inflammatory responses that escalate into chronic inflammatory conditions. Crucially, PERs modulate cancer cell behaviors including proliferation, apoptosis, and migration by influencing the levels of cell cycle proteins and stimulating the expression of oncogenes c-Myc and MDM2. PER2/3, as antagonists in cancer stem cell biology, play important roles in differentiating cancer stem cells and in maintaining their stemness. Importantly, the expression of Pers serve as a significant factor for early cancer diagnosis and prognosis. This review delves into the link between circadian rhythm regulator PERs, disruptions in circadian rhythm, and oncogenesis. We examine the evidence that highlights how dysfunctions in PERs activities initiate cancer development, aid tumor growth, and modify cancer cell metabolism through pathways involved in oxidative stress and immune system. Comprehending these connections opens new pathways for the development of circadian rhythm-based therapeutic strategies, with the aims of boosting immune responses and enhancing cancer treatments.

Effects of melatonin on planaria head regeneration are dependent on both timing and duration of exposure

Melatonin is a multifunctional biomolecule with demonstrated stimulatory, inhibitory, and antioxidant effects, including both receptor-mediated and receptor-independent mechanisms of action. One of its more perplexing effects is the disruption of regeneration in planaria. Head regeneration in planaria is a remarkable phenomenon in which stem cells (neoblasts) migrate to the wound site, proliferate, then differentiate into all functional tissue types within days of injury. We investigated how both the timing and duration of melatonin exposure affect head regeneration in the planaria Phagocata gracilis (Haldeman). Our results demonstrate that P. gracilis is capable of recovery from the melatonin-induced delay of regeneration and reveal the time required to recover to control levels. Further, we found evidence of regenerative stage-specific responses to discontinuous melatonin exposure, including non-inhibitory effects. Further exploration of melatonin's effects on regeneration can be targeted to specific regenerative processes, and the possibility of multiple mechanisms of action should be recognized.

Melatonin effect on breast and ovarian cancers by targeting the PI3K/Akt/mTOR pathway

Melatonin, the hormone of the pineal gland, possesses a range of physiological functions, and recently, its anticancer effect has become more apparent. A more thorough understanding of molecular alterations in the components of several signaling pathways as new targets for cancer therapy is needed because of current innate restrictions such as drug toxicity, side effects, and acquired or de novo resistance. The PI3K/Akt/mTOR pathway is overactivated in many solid tumors, such as breast and ovarian cancers. This pathway in normal cells is essential for growth, proliferation, and survival. However, it is an undesirable characteristic in malignant cells. We have reviewed multiple studies about the effect of melatonin on breast and ovarian cancer, focusing on the PI3K/Akt/mTOR pathway. Melatonin exerts its inhibitory effects via several mechanisms. A: Downregulation of downstream or upstream components of the signaling pathway such as phosphatase and tensin homolog (PTEN), phosphatidylinositol (3,4,5)-trisphosphate kinase (PI3K), p-PI3K, Akt, p-Akt, mammalian target of rapamycin (mTOR), and mTOR complex1 (mTORC1). B: Apoptosis induction by decreasing MDM2 expression, a downstream target of Akt, and mTOR, which leads to Bad activation in addition to Bcl-XL and p53 inhibition. C: Induction of autophagy in cancer cells via activating ULK1 after mTOR inhibition, resulting in Beclin-1 phosphorylation. Beclin-1 with AMBRA1 and VPS34 promotes PI3K complex I activity and autophagy in cancer cells. The PI3K/Akt/mTOR pathway overlaps with other intracellular signaling pathways and components such as AMP-activated protein kinase (AMPK), Wnt/β-catenin, mitogen-activated protein kinase (MAPK), and other similar pathways. Cancer therapy can benefit from understanding how these pathways interact and how melatonin affects these pathways.

IL-10-induced STAT3/NF-κB crosstalk modulates pineal and extra-pineal melatonin synthesis

Immune-pineal axis activation is part of the assembly of immune responses. Proinflammatory cytokines inhibit the pineal synthesis of melatonin while inducing it in macrophages by mechanisms dependent on nuclear factor-κB (NF-κB) activation. Cytokines activating the Janus kinase/signal transducer and activator of transcription (STAT) pathways, such as interferon-gamma (IFN-γ) and interleukin-10 (IL-10), modulate melatonin synthesis in the pineal, bone marrow (BM), and spleen. The stimulatory effect of IFN-γ upon the pineal gland depends on STAT1/NF-κB interaction, but the mechanisms controlling IL-10 effects on melatonin synthesis remain unclear. Here, we evaluated the role of STAT3 and NF-κB activation by IL-10 upon the melatonin synthesis of rats' pineal gland, BM, spleen, and peritoneal cells. The results show that IL-10-induced interaction of (p)STAT3 with specific NF-κB dimmers leads to different cell effects. IL-10 increases the pineal's acetylserotonin O-methyltransferase (ASMT), N-acetylserotonin, and melatonin content via nuclear translocation of NF-κB/STAT3. In BM, the nuclear translocation of STAT3/p65-NF-κB complexes increases ASMT expression and melatonin content. Increased pSTAT3/p65-NF-κB nuclear translocation in the spleen enhances phosphorylated serotonin N-acetyltransferase ((p)SNAT) expression and melatonin content. Conversely, in peritoneal cells, IL-10 leads to NF-κB p50/p50 inhibitory dimmer nuclear translocation, decreasing (p)SNAT expression and melatonin content. In conclusion, IL-10's effects on melatonin production depend on the NF-κB subunits interacting with (p)STAT3. Thus, variations of IL-10 levels and downstream pathways during immune responses might be critical regulatory factors adjusting pineal and extra-pineal synthesis of melatonin.

Influence of various light regimes on some circadian rhythms of transplantable melanoma B16

BACKGROUND: Today it is known that disturbance of the lighting regime, expressed both by lengthening of the light period and its reduction, can not only affect the regulation of circadian rhythms of the organism, but also contributes to the initiation of neoplasm growth. AIM: The aim of the study was to investigate circadian rhythmicity of melatonin level, some micromorphometric indices of tumor cells and expression of genes Bmal1, Clock and Per2 in them in mice with transplanted melanoma B16. MATERIALS AND METHODS: The study was conducted on 75 mice with subcutaneously transplanted melanoma B16, divided into 3 groups: control group, in which animals were kept under fixed light regime (light/darkness 10/14 hours with light on at 8:00 and off at 18:00), group under dark deprivation conditions, with animals kept under constant light 24 hours a day and group, in which animals were kept in constant darkness. The duration of the experiment was 2 weeks. RESULTS: It was shown that under conditions of fixed light there are reliable circadian rhythms for all studied parameters, except for the nuclear-cytoplasmic ratio, the circadian rhythms of which was not revealed in any group. Constant darkness leads to rearrangement of all identified rhythms, and constant light causes destruction of all circadian rhythms except the Clock expression rhythm. CONCLUSIONS: This study shows that light disturbances, whether constant light or constant darkness, lead to significant changes in the structure of the studied circadian rhythms.

Potential of melatonin to reverse epigenetic aberrations in oral cancer: new findings

It is now an accepted principle that epigenetic alterations cause cellular dyshomeostasis and functional changes, both of which are essential for the initiation and completion of the tumor cycle. Oral carcinogenesis is no exception in this regard, as most of the tumors in the different subsites of the oral cavity arise from the cross-reaction between (epi)genetic inheritance and the huge challenge of environmental stressors. Currently, the biochemical machinery is put at the service of the tumor program, halting the cell cycle, triggering uncontrolled proliferation, driving angiogenesis and resistance to apoptosis, until the archetypes of the tumor phenotype are reached. Melatonin has the ability to dynamically affect the epigenetic code. It has become accepted that melatonin can reverse (epi)genetic aberrations present in oral and other cancers, suggesting the possibility of enhancing the oncostatic capacity of standard multimodal treatments by incorporating this indolamine as an adjuvant. First steps in this direction confirm the potential of melatonin as a countermeasure to mitigate the detrimental side effects of conventional first-line radiochemotherapy. This single effect could produce synergies of extraordinary clinical importance, allowing doses to be increased and treatments not to be interrupted, ultimately improving patients' quality of life and prognosis. Motivated by the urgency of improving the medical management of oral cancer, many authors advocate moving from in vitro and preclinical research, where the bulk of melatonin cancer research is concentrated, to systematic randomized clinical trials on large cohorts. Recognizing the challenge to improve the clinical management of cancer, our motivation is to encourage comprehensive and robust research to reveal the clinical potential of melatonin in oral cancer control. To improve the outcome and quality of life of patients with oral cancer, here we provide the latest evidence of the oncolytic activity that melatonin can achieve by manipulating epigenetic patterns in oronasopharyngeal tissue.

The Relationship between Clock Genes, Sirtuin 1, and Mitochondrial Activity in Head and Neck Squamous Cell Cancer: Effects of Melatonin Treatment

The circadian clock is a regulatory system, with a periodicity of approximately 24 h, which generates rhythmic changes in many physiological processes, including mitochondrial activity. Increasing evidence links chronodisruption with aberrant functionality in clock gene expression, resulting in multiple diseases such as cancer. Melatonin, whose production and secretion oscillates according to the light-dark cycle, is the principal regulator of clock gene expression. In addition, the oncostatic effects of melatonin correlate with an increase in mitochondrial activity. However, the direct links between circadian clock gene expression, mitochondrial activity, and the antiproliferative effects of melatonin in cancers, including head and neck squamous cell carcinoma (HNSCC), remain largely unknown. In this study, we analyzed the effects of melatonin on HNSCC cell lines (Cal-27 and SCC9), which were treated with 500 and 1000 µM melatonin. We found that the antiproliferative effect of melatonin is not mediated by the Bmal1 clock gene. Additionally, high doses of melatonin were observed to result in resynchronization of oscillatory circadian rhythm genes (Per2 and Sirt1). Surprisingly, the resynchronizing effect of melatonin on Per2 and Sirt1 did not produce alterations in the oscillation of mitochondrial respiratory activity. These results increase our understanding of the possible antiproliferative mechanisms in melatonin in the treatment of head and neck squamous cell carcinoma and suggest that its antiproliferative effects are independent of clock genes but are directly related to mitochondrial activity.

Incidence disparities of obstructive sleep apnea-associated lung cancer by gender; Korean National Health Insurance data analysis

Introduction

Obstructive sleep apnea (OSA) is known to increase the risk of various cancers. By analyzing the Korea National Health Insurance Service (KNHIS) registry, the impact of OSA on the lung cancer incidence was analyzed in a retrospective cohort group.

Methods

A retrospective cohort of adult patients newly registered with OSA in the KNHIS data from 2007 to 2017 was included and observed until December 2019 (12 years). The main outcome measure was newly diagnosed lung cancer. The control group was set with age and sex that matched those in the OSA group.

Results

The hazard ratio (HR) of OSA for lung cancer incidence showed a significantly reduced HR of 0.87 (95% CI, 0.82-0.93). The observed significance of this finding was limited to male OSA patients [HR, 0.84 (95% CI, 0.78-0.90)], while no significant association was found in female OSA patients [HR, 1.05 (95% CI, 0.91-1.21)], irrespective of their age.

Discussion

OSA patients have a lower risk of developing lung cancer, but this risk reduction is gender-specific, as female OSA patients do not show a reduction in hazard ratio.

Circadian rhythms and cancer

Circadian rhythms are autonomous oscillators developed by the molecular circadian clock, essential for coordinating internal time with the external environment in a 24-h daily cycle. In mammals, this circadian clock system plays a major role in all physiological processes and severely affects human health. The regulation of the circadian clock extends beyond the clock genes to involve several clock-controlled genes. Hence, the aberrant expression of these clock genes leads to the downregulation of important targets that control the cell cycle and the ability to undergo apoptosis. This may lead to genomic instability and promotes carcinogenesis. Alteration in the clock genes and their modulation is recognized as a new approach for the development of effective treatment against several diseases, including cancer. Until now, there has been a lack of understanding of circadian rhythms and cancer disease. For that, this chapter aims to represent the core components of circadian rhythms and their function in cancer pathogenesis and progression. In addition, the clinical impacts, current clock drugs, and potential therapeutic targets have been discussed.

Role of Natural and Synthetic Compounds in Modulating NRF2/KEAP1 Signaling Pathway in Prostate Cancer

Prostate cancer is the second most common cancer in men worldwide. Prostate cancer can be treated by surgery or active surveillance when early diagnosed but, when diagnosed at an advanced or metastatic stage, radiation therapy or androgen-deprivation therapy is needed to reduce cancer progression. However, both of these therapies can cause prostate cancer resistance to treatment. Several studies demonstrated that oxidative stress is involved in cancer occurrence, development, progression and treatment resistance. The nuclear factor erythroid 2-related factor 2 (NRF2)/KEAP1 (Kelch-Like ECH-Associated Protein 1) pathway plays an important role in protecting cells against oxidative damage. Reactive oxygen species (ROS) levels and NRF2 activation can determine cell fate. In particular, toxic levels of ROS lead physiological cell death and cell tumor suppression, while lower ROS levels are associated with carcinogenesis and cancer progression. On the contrary, a high level of NRF2 promotes cell survival related to cancer progression activating an adaptive antioxidant response. In this review, we analyzed the current literature regarding the role of natural and synthetic compounds in modulating NRF2/KEAP1 signaling pathway in prostate cancer.