Melatonin as a Selective Estrogen Enzyme Modulator

Melatonin and Its Role in the Epithelial-to-Mesenchymal Transition (EMT) in Cancer

The epithelial-to-mesenchymal transition (EMT) is a cell-biological program that occurs during the progression of several physiological processes and that can also take place during pathological situations such as carcinogenesis. The EMT program consists of the sequential activation of a number of intracellular signaling pathways aimed at driving epithelial cells toward the acquisition of a series of intermediate phenotypic states arrayed along the epithelial-mesenchymal axis. These phenotypic features include changes in the motility, conformation, polarity and functionality of cancer cells, ultimately leading cells to stemness, increased invasiveness, chemo- and radioresistance and the formation of cancer metastasis. Amongst the different existing types of the EMT, type 3 is directly involved in carcinogenesis. A type 3 EMT occurs in neoplastic cells that have previously acquired genetic and epigenetic alterations, specifically affecting genes involved in promoting clonal outgrowth and invasion. Markers such as E-cadherin; N-cadherin; vimentin; and transcription factors (TFs) like Twist, Snail and ZEB are considered key molecules in the transition. The EMT process is also regulated by microRNA expression. Many miRNAs have been reported to repress EMT-TFs. Thus, Snail 1 is repressed by miR-29, miR-30a and miR-34a; miR-200b downregulates Slug; and ZEB1 and ZEB2 are repressed by miR-200 and miR-205, respectively. Occasionally, some microRNA target genes act downstream of the EMT master TFs; thus, Twist1 upregulates the levels of miR-10b. Melatonin is an endogenously produced hormone released mainly by the pineal gland. It is widely accepted that melatonin exerts oncostatic actions in a large variety of tumors, inhibiting the initiation, progression and invasion phases of tumorigenesis. The molecular mechanisms underlying these inhibitory actions are complex and involve a great number of processes. In this review, we will focus our attention on the ability of melatonin to regulate some key EMT-related markers, transcription factors and micro-RNAs, summarizing the multiple ways by which this hormone can regulate the EMT. Since melatonin has no known toxic side effects and is also known to help overcome drug resistance, it is a good candidate to be considered as an adjuvant drug to conventional cancer therapies.

Influence of Melatonin Treatment on Emotion, Sleep, and Life Quality in Perimenopausal Women: A Clinical Study

Method

100 healthy perimenopausal women were recruited and randomly assigned to two groups, with 50 subjects in each group. In the control group, placebo was administrated daily for 3 cycles (4 weeks of treatment for 1 cycle and drug withdrawals for 1 week). The study group received 3 mg oral melatonin treatment daily in the same period of time. All subjects completed the study. We compared the uterine volume, endometrial thickness, LH (luteinizing hormone), FSH (follicle generating hormone), E2 (estradiol), and melatonin levels during daytime between the two groups before and after the study. Moreover, perimenopause syndrome, sleep, mood, and QoL were analyzed at the baseline and 3 cycles by the questionnaires of the Kupperman index, the Pittsburgh sleep quality index (PSQI), the Hamilton anxiety scale (HAMA), and the Hamilton depression scale (HAMD), as well as menopausal QoL (MENQOL), respectively. Any adverse reactions experienced by the subjects were also compared in the study. Finally, 91 participants (92%) completed the whole study, 47 and 44 in the study and control groups, respectively, and their data were considered in subsequent analyses.

Results

After therapy, the two groups were similar in the uterine volume and endometrial thickness. In contrast to the control group, the study group showed notably decreased LH and FSH levels. No notable difference was discovered in E2 and melatonin levels between the two groups in the study. Moreover, the study group exhibited a significantly lower score in the Kupperman index, PSQI, HAMA, HAMD, and MENQOL scale than the control group. Moreover, the two groups had no notable difference in adverse reactions.

Conclusion

Melatonin was a useful treatment to relieve climacteric symptoms and improve sleep, mood, and life quality in perimenopausal women without obvious adverse reactions.

Exposure to long-term source-specific transportation noise and incident breast cancer: A pooled study of eight Nordic cohorts

BACKGROUND

Environmental noise is an important environmental exposure that can affect health. An association between transportation noise and breast cancer incidence has been suggested, although current evidence is limited. We investigated the pooled association between long-term exposure to transportation noise and breast cancer incidence.

METHODS

Pooled data from eight Nordic cohorts provided a study population of 111,492 women. Road, railway, and aircraft noise were modelled at residential addresses. Breast cancer incidence (all, estrogen receptor (ER) positive, and ER negative) was derived from cancer registries. Hazard ratios (HR) were estimated using Cox Proportional Hazards Models, adjusting main models for sociodemographic and lifestyle variables together with long-term exposure to air pollution.

RESULTS

A total of 93,859 women were included in the analyses, of whom 5,875 developed breast cancer. The median (5th-95th percentile) 5-year residential road traffic noise was 54.8 (40.0-67.8) dB Lden, and among those exposed, the median railway noise was 51.0 (41.2-65.8) dB Lden. We observed a pooled HR for breast cancer (95 % confidence interval (CI)) of 1.03 (0.99-1.06) per 10 dB increase in 5-year mean exposure to road traffic noise, and 1.03 (95 % CI: 0.96-1.11) for railway noise, after adjustment for lifestyle and sociodemographic covariates. HRs remained unchanged in analyses with further adjustment for PM2.5 and attenuated when adjusted for NO2 (HRs from 1.02 to 1.01), in analyses using the same sample. For aircraft noise, no association was observed. The associations did not vary by ER status for any noise source. In analyses using <60 dB as a cutoff, we found HRs of 1.08 (0.99-1.18) for road traffic and 1.19 (0.95-1.49) for railway noise.

CONCLUSIONS

We found weak associations between road and railway noise and breast cancer risk. More high-quality prospective studies are needed, particularly among those exposed to railway and aircraft noise before conclusions regarding noise as a risk factor for breast cancer can be made.

Melatonin in Health and Disease: A Perspective for Livestock Production

Mounting evidence in the literature indicates an important role of endogenous and exogenous melatonin in driving physiological and molecular adaptations in livestock. Melatonin has been extensively studied in seasonally polyestrous animals whereby supplementation studies have been used to adjust circannual rhythms in herds of animals under abnormal photoperiodic conditions. Livestock undergo multiple metabolic and physiological adaptation processes throughout their production cycle which can result in decreased immune response leading to chronic illness, weight loss, or decreased production efficiency; however, melatonin’s antioxidant capacity and immunostimulatory properties could alleviate these effects. The cardiovascular system responds to melatonin and depending on receptor type and localization, melatonin can vasodilate or vasoconstrict several systemic arteries, thereby controlling whole animal nutrient partitioning via vascular resistance. Increased incidences of non-communicable diseases in populations exposed to circadian disruption have uncovered novel pathways of neurohormones, such as melatonin, influence health, and disease. Perturbations in immune function can negatively impact the growth and development of livestock which has been examined following melatonin supplementation. Specifically, melatonin can influence nutrient uptake, circulating nutrient profiles, and endocrine profiles controlling economically important livestock growth and development. This review focuses on the physiological, cellular, and molecular implications of melatonin on the health and disease of domesticated food animals.

The Effect of Melatonin Intake on Survival of Patients with Breast Cancer-A Population-Based Registry Study

Previous research has demonstrated the antitumoral effects of melatonin on breast cancer in both in vitro and in vivo studies. The aim of the present study was to investigate whether melatonin has a favorable effect on the survival of patients diagnosed with early breast cancer. This retrospective registry-based study included all patients diagnosed with breast cancer in Sweden between 2005 and 2015. Data were linked to the Swedish Prescribed Drug Registry and the Swedish Cause of Death Registry. A multivariate Cox regression model, including patient age, tumor size, tumor grade, ER status, HER2 status, nodal status and defined daily doses (DDDs) of melatonin, was used to analyze breast-cancer-specific survival as well as overall survival. Of the 37,075 included patients, 926 (2.5%) were prescribed melatonin, with a median DDD of 30. Melatonin was found to have a protective effect on breast-cancer-specific survival (BCSS) in the univariate analysis (HR: 0.736, 95% CI: 0.548-0.989, p = 0.042), but when adjusting for known prognostic factors in the multivariate analysis, this beneficial effect disappeared (HR: 1.037, 95% CI: 0.648-1.659, p = 0.879). Melatonin was not proven to have a favorable effect on the survival of patients diagnosed with early breast cancer in this retrospective registry study.

Gut Bless Your Pain—Roles of the Gut Microbiota, Sleep, and Melatonin in Chronic Orofacial Pain and Depression

Background. Increased attention has been paid to the gut–brain axis recently, but little is known so far regarding how this translates into pain susceptibility. Aim. The aim of this review is to determine whether gastroenterological disorders and sleep disorders (directly or indirectly) contribute to an increased susceptibility to depression and chronic orofacial pain. Method. A search was performed in the U.S. National Library of Medicine (PubMed) database in order to find studies published before 19 December 2021. We used the following terms: gut microbiome, OR sleep quality, OR melatonin, OR GERD, OR IBS, AND: depression OR chronic pain, in different configurations. Only papers in English were selected. Given the large number of papers retrieved in the search, their findings were described and organized narratively. Results. A link exists between sleep disorders and gastroenterological disorders, which, by adversely affecting the psyche and increasing inflammation, disturb the metabolism of tryptophan and cause excessive microglial activation, leading to increased susceptibility to pain sensation and depression. Conclusions. Pain therapists should pay close attention to sleep and gastrointestinal disorders in patients with chronic pain and depression.

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

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

Sleep duration and risk of cancer incidence and mortality: a pooled analysis of six population-based cohorts in Japan

Sleep duration is emerging as an important modifiable risk factor for morbidity and mortality. We assessed the association between sleep duration and cancer incidence and mortality among Japanese adults using data from six population-based cohorts with 271 694 participants. During a total follow-up period of about 5.9 million person-years, we identified 40 751 incident cancer cases and 18 323 cancer deaths. We computed study-specific hazard ratios (HRs) and 95% confidence intervals (CIs) using Cox proportional hazards regression models and pooled the estimates using random-effects meta-analysis. Sleep duration of ≥ 10 h (vs. 7 h) was associated with increased risk of cancer incidence among women (HR 1.19, 95% CI 1.02-1.38), but not men, and increased risk of cancer mortality among men (HR 1.18, 95% CI 1.00-1.39) and women (HR 1.44, 95% CI 1.20-1.73). Sleep duration of ≤ 5 h (vs. 7 h) was not associated with cancer incidence and mortality. However, among post-menopausal women, sleep durations of both ≤ 5 h and ≥ 10 h (vs. 7 h) were associated with an increased risk of cancer mortality. Among Japanese adults, sleep duration of ≥ 10 h is associated with increased risk of cancer incidence and mortality among women and cancer mortality among men. This article is protected by copyright. All rights reserved.

Protective Role of Melatonin and Its Metabolites in Skin Aging

The skin, being the largest organ in the human body, is exposed to the environment and suffers from both intrinsic and extrinsic aging factors. The skin aging process is characterized by several clinical features such as wrinkling, loss of elasticity, and rough-textured appearance. This complex process is accompanied with phenotypic and functional changes in cutaneous and immune cells, as well as structural and functional disturbances in extracellular matrix components such as collagens and elastin. Because skin health is considered one of the principal factors representing overall “well-being” and the perception of “health” in humans, several anti-aging strategies have recently been developed. Thus, while the fundamental mechanisms regarding skin aging are known, new substances should be considered for introduction into dermatological treatments. Herein, we describe melatonin and its metabolites as potential “aging neutralizers”. Melatonin, an evolutionarily ancient derivative of serotonin with hormonal properties, is the main neuroendocrine secretory product of the pineal gland. It regulates circadian rhythmicity and also exerts anti-oxidative, anti-inflammatory, immunomodulatory, and anti-tumor capacities. The intention of this review is to summarize changes within skin aging, research advances on the molecular mechanisms leading to these changes, and the impact of the melatoninergic anti-oxidative system controlled by melatonin and its metabolites, targeting the prevention or reversal of skin aging.

Protective role of melatonin in breast cancer: what we can learn from women with blindness

PURPOSE

This review proposes an overall vision of the protective and therapeutic role of melatonin in breast cancer: from the specific cases of blind women and their reduction of breast cancer incidence to all clinical uses of the sleep hormone in breast cancer.

METHODS

We reviewed studies focused on (1) the correlation between blindness and breast cancer, (2) the correlation between melatonin and breast cancer occurrence in the general population, (3) melatonin therapeutic use in breast cancer, and (4) we discussed the properties of melatonin that could explain an anticancer effect.

RESULTS

(1) Seven studies of breast cancer risk in blind women related significant incidence decreases, up to 57%, among totally blind women. The limited number of studies and the absence of adjustment for confounding factors in most studies limit conclusions. None of these studies established melatonin profiles to determine whether blind women with a decreased breast cancer incidence produced higher levels of melatonin. (2) In the general population, 5 meta-analyses and 12 prospective-cohort studies focused on melatonin levels at recruitment and breast cancer occurrence. All reported the absence of correlation in premenopausal women, whereas in postmenopausal women, most studies showed significantly decreased risk for women with highest melatonin levels. (3) The therapeutic interest of melatonin associated with chemotherapy, radiotherapy, and hormonotherapy is poorly documented in breast cancer to conclude on a positive effect. (4) Melatonin effects on mammary carcinogenesis were only reported in in vitro and animal studies that demonstrated antiestrogenic, antioxidant, oncostatic, and immunomodulatory properties.

CONCLUSION

The preventive role of high endogenous melatonin on breast cancer as well as its beneficial therapeutic use remains to be proven.

Methotrexate Neurotoxicity Is Related to Epigenetic Modification of the Myelination Process

With the improvement of the survival rate of acute lymphoblastic leukemia (ALL) in children, some children ALL survivors reveal inferior intellectual and cognition outcome. Methotrexate (MTX), while serving as an essential component in ALL treatment, has been reported to be related to various neurologic sequelae. Using combined intrathecal (IT) and intraperitoneal (IP) MTX model, we had demonstrated impaired spatial memory function in developing rats, which can be rescued by melatonin treatment. To elucidate the impact of MTX treatment on the epigenetic modifications of the myelination process, we examined the change of neurotrophin and myelination-related transcriptomes in the present study and found combined IT and IP MTX treatment resulted in altered epigenetic modification on the myelination process, mainly in the hippocampus. Further, melatonin can restore the MTX effect through alterations of the epigenetic pathways.

A New Paradigm in the Relationship between Melatonin and Breast Cancer: Gut Microbiota Identified as a Potential Regulatory Agent

In this review we summarize a possible connection between gut microbiota, melatonin production, and breast cancer. An imbalance in gut bacterial population composition (dysbiosis), or changes in the production of melatonin (circadian disruption) alters estrogen levels. On the one hand, this may be due to the bacterial composition of estrobolome, since bacteria with β-glucuronidase activity favour estrogens in a deconjugated state, which may ultimately lead to pathologies, including breast cancer. On the other hand, it has been shown that these changes in intestinal microbiota stimulate the kynurenine pathway, moving tryptophan away from the melatonergic pathway, thereby reducing circulating melatonin levels. Due to the fact that melatonin has antiestrogenic properties, it affects active and inactive estrogen levels. These changes increase the risk of developing breast cancer. Additionally, melatonin stimulates the differentiation of preadipocytes into adipocytes, which have low estrogen levels due to the fact that adipocytes do not express aromatase. Consequently, melatonin also reduces the risk of breast cancer. However, more studies are needed to determine the relationship between microbiota, melatonin, and breast cancer, in addition to clinical trials to confirm the sensitizing effects of melatonin to chemotherapy and radiotherapy, and its ability to ameliorate or prevent the side effects of these therapies.

Metabolomic Profiles of Shift Workers and Day Workers: A Cross-Sectional Study

OBJECTIVE

The purpose of this study was to characterize the metabolomic profiles of shift workers and day workers and to discover the effect of shift work on workers' metabolic health.

METHODS

A total of 824 participants aged 25 to 55 years were recruited, and 485 (275 shift workers and 210 day workers) completed the study. The mean age of the shift workers was 37.32 (5.53) years old, and that of day workers was 36.50 (7.83) years old. Serum and salivary samples were collected for the detection of key biochemical indicators (melatonin, cholesterol, and low-density lipoprotein cholesterol) and for metabolome profile analyses.

RESULTS

Compared with female day workers, female shift workers had a higher BMI, waist circumference, and hip circumference. Correspondingly, we identified 76 significant metabolites (false discovery rate < 0.05) in shift workers, including L-tryptophan, acylcarnitines, and several fatty acids. Three pathways that presented significant differences were biosynthesis of unsaturated fatty acids, linoleic acid metabolism, and ubiquinone and other terpenoid-quinone biosynthesis.

CONCLUSIONS

Compared with day workers, shift workers were more prone to weight gain and central obesity and were at a higher risk for impaired lipid metabolism with disrupted circadian rhythms.

Melatonin as an Oncostatic Molecule Based on Its Anti-Aromatase Role in Breast Cancer

Breast cancer is the most common type of cancer. In the developmental stages of breast cancer, estrogens are strongly involved. As estrogen synthesis is regulated by the enzyme aromatase, targeting the activity of this enzyme represents a therapeutic option. The pineal hormone melatonin may exert a suppressive role on aromatase activity, leading to reduced estrogen biosynthesis. A melatonin-mediated decrease in the expression of aromatase promoters and associated genes would provide suitable evidence of this molecule’s efficacy as an aromatase inhibitor. Furthermore, melatonin intensifies radiation-induced anti-aromatase effects and counteracts the unwanted disadvantages of chemotherapeutic agents. In this manner, this review summarizes the inhibitory role of melatonin in aromatase action, suggesting its role as a possible oncostatic molecule in breast cancer.

Sleep deficiency and breast cancer risk among postmenopausal women in the California teachers study (CTS)

Purpose:

There is provocative, yet inconsistent, evidence that sleep deficiency may influence the development of breast cancer. The purpose of this study was to evaluate the risk of breast cancer associated with sleep deficiency among postmenopausal women in the California Teachers Study (CTS).

Methods:

We conducted a case-control study of 2,856 invasive breast cancer cases and 38,649 cancer-free controls, nested within the CTS. Self-administered questionnaires were used to ascertain several components of sleep deficiency, including quality, latency, duration, disturbance and use of sleep medications. Additionally, a Global Sleep Index (GSI) was created by summing the individual sleep components and categorizing into quartiles. Multivariable logistic regression analyses were used to estimate odds ratios and 95% confidence intervals (OR, 95% CI).

Results:

Increased breast cancer risks were associated with sleep deficiency. With the exception of duration, linear increases in risk were associated with all the other individual components of sleep deficiency (p-trend ≤0.002). The OR for the highest GSI quartile vs. lowest was 1.24, 95% CI: 1.12 – 1.38; p-trend <0.001).

Conclusions:

Sleep deficiency may be a risk factor for breast cancer. Additional prospective studies and those aimed at elucidating underlying mechanism are warranted.

17β-Estradiol augments the neuroprotective effect of agomelatine in depressive- and anxiety-like behaviors in ovariectomized rats

RATIONALE AND OBJECTIVE

Estradiol decline has been associated with depression and anxiety in post-menopausal women. Agomelatine (Ago) is an agonist of the melatonergic MT1/MT2 receptors and an antagonist of the serotonergic 5-HT2c receptors. The present study aimed to evaluate the effects of combining Ago with 17β-estradiol (E2) on ovariectomy (OVX)-induced depressive- and anxiety-like behaviors in young adult female rats.

METHODS

OVX rats were treated with Ago (40 mg/kg/day, p.o.) for 10 days starting 1 week after surgery alone or combined with two doses of E2 (40 μg/kg/day, s.c.) given before behavioral testing.

RESULTS

Co-administration of E2 enhanced the anti-depressant and anxiolytics effects of Ago as evidenced by decreased immobility time in the forced swimming test, as well as increased time spent in the open arms and number of entries to open arms in the elevated plus-maze. In parallel, Ago increased hippocampal norepinephrine, dopamine, melatonin, and brain-derived neurotrophic factor (BDNF). Meanwhile, Ago-treated rats exhibited reduced hippocampal nuclear factor kappa beta (NF-kB) P65 expression and pro-inflammatory cytokine level. Ago upregulated estrogen receptor (ER α and β) mRNA expression in the hippocampus of OVX rats and elevated serum estradiol levels. Co-administration of E2 with Ago synergistically decreased NF-kB P65 expression and pro-inflammatory cytokines, and increased BDNF levels.

CONCLUSION

E2 augmented the neuroprotective effect of Ago in OVX rats via its anti-inflammatory and neurotrophic effects. The combined treatment of E2 and Ago should be further investigated as a treatment of choice for depression, anxiety, and sleep disturbances associated with menopause.

Sex steroid metabolism and actions in non-small cell lung carcinoma

Despite recent development in targeted therapies, lung cancer still remains the leading cause of cancer death. Therefore, a better understanding of its pathogenesis and progression could contribute to improving the eventual clinical outcome of the patients. Results of recently published several in vitro and clinical studies indicated the possible involvement of sex steroids in both development and progression of non-small cell lung carcinoma (NSCLC). Therefore we summarized the reported clinical relevant information of the sex steroids, their receptors and steroid metabolizing enzymes related to NSCLC in this mini-review. In addition, we also reviewed the potential "endocrine therapy", targeting sex steroid actions and/or metabolism in NSCLC patients.

Melatonin Modulation of Radiation and Chemotherapeutics-induced Changes on Differentiation of Breast Fibroblasts

Melatonin exerts oncostatic actions and sensitizes tumor cells to chemotherapeutics or radiation. In our study, we investigated the effects of docetaxel, vinorelbine, and radiation on human breast fibroblasts and its modulation by melatonin. Docetaxel or vinorelbine inhibits proliferation and stimulates the differentiation of breast preadipocytes, by increasing C/EBPα and PPARγ expression and by downregulating tumor necrosis factor α (TNFα), interleukin 6 (IL-6), and IL-11 expression. Radiation inhibits both proliferation and differentiation through the downregulation of C/EBPα and PPARγ and by stimulating TNFα expression. In addition, docetaxel and radiation decrease aromatase activity and expression by decreasing aromatase promoter II and cyclooxygenases 1 and 2 (COX-1 and COX-2) expression. Melatonin potentiates the stimulatory effect of docetaxel and vinorelbine on differentiation and their inhibitory effects on aromatase activity and expression, by increasing the stimulatory effect on C/EBPα and PPARγ expression and the downregulation of antiadipogenic cytokines and COX expression. Melatonin also counteracts the inhibitory effect of radiation on differentiation of preadipocytes, by increasing C/EBPα and PPARγ expression and by decreasing TNFα expression. Melatonin also potentiates the inhibitory effect exerted by radiation on aromatase activity and expression by increasing the downregulation of promoter II, and COX-1 and COX-2 expression. Our findings suggest that melatonin modulates regulatory effects induced by chemotherapeutic drugs or radiation on preadipocytes, which makes it a promising adjuvant for chemotherapy and radiotherapy sensibilization.

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.

Profile of melatonin and its receptors and synthesizing enzymes in cumulus-oocyte complexes of the developing sheep antral follicle-a potential estradiol-mediated mechanism

BACKGROUND

Melatonin is an amine hormone that plays an important role in regulating mammalian reproduction. This study aimed to investigate the expression pattern of melatonin synthesis enzymes AANAT and HIOMT and melatonin receptors MT1 and MT2 in sheep cumulus-oocyte complexes (COCs) as well as the change of melatonin level in follicular fluid (FF) during antral follicle development. In this research, we also study the effect of β-estradiol (E2) on MT1 and MT2 expression as well as melatonin synthesis in COCs so as to lay the foundation for further exploration of the regulation mechanism of melatonin synthesis in the ovary.

METHODS

COCs and FF were collected from different size (large follicles (diameter ≥ 5 mm), medium follicles (diameter 2-5 mm), and small follicles (diameter ≤ 2 mm)) of antral follicles in sheep ovaries. To assess whether E2 regulates melatonin synthase and its receptors expression in sheep COCs and whether it is mediated through estrogen receptor (ER) pathway. The collected COCs were cultured in vitro for 24 h and then treat with 1 μM E2 and/or 1 μM ICI182780 (non-selective ER antagonist). The expression of AANAT, HIOMT, MT1 and MT2 mRNA and protein were determined by qRT-PCR and western blot. The melatonin level was determined by ELISA.

RESULTS

The expression of AANAT, HIOMT, MT1 and MT2 were significantly higher expression in the COCs of small follicles than in those of large follicles (P < 0.05). However, the melatonin level was significantly higher in large follicle FF than in small follicle FF (P < 0.05). Further, the expression of AANAT, HIOMT, MT1, and MT2 and melatonin production were decreased by E2 treatment (P < 0.05), but when ICI182780 was added, the expression of AANAT, HIOMT, MT1, and MT2 and melatonin production recovered (P < 0.05).

CONCLUSIONS

We suggest that sheep COCs can synthesize melatonin, but this ability is decreased with increasing follicle diameter. Furthermore, E2 play an important role in regulated the expression of MT1 and MT2 as well as melatonin synthesis in sheep COCs through the ER pathway.

Melatonin Enhances the Usefulness of Ionizing Radiation: Involving the Regulation of Different Steps of the Angiogenic Process

Radiotherapy is a part of cancer treatment. To improve its efficacy has been combined with radiosensitizers such as antiangiogenic agents. Among the mechanisms of the antitumor action of melatonin are antiangiogenic effects. Our goal was to investigate whether melatonin may modulate the sensitivity of endothelial cells (HUVECs) to ionizing radiation. Melatonin (1 mM) enhanced the inhibition induced by radiation on different steps of the angiogenic process, cell proliferation, migration, and tubular network formation. In relation with the activity and expression of enzymes implicated in estrogen synthesis, in co-cultures HUVECs/MCF-7, radiation down-regulated aromatase mRNA expression, aromatase endothelial-specific promoter I.7, sulfatase activity and expression and 17β-HSD1 activity and expression and melatonin enhanced these effects. Radiation and melatonin induced a significant decrease in VEGF, ANG-1, and ANG-2 mRNA expression. In ANG-2 and VEGF mRNA expression melatonin potentiated the inhibitory effect induced by radiation. In addition, melatonin counteracted the stimulatory effect of radiation on FGFR3, TGFα, JAG1, IGF-1, and KDR mRNA expression and reduced ANPEP expression. In relation with extracellular matrix molecules, radiation increased MMP14 mRNA expression and melatonin counteracted the stimulatory effect of radiation on MMP14 mRNA expression and increased TIMP1 expression, an angiogenesis inhibitor. Melatonin also counteracted the stimulatory effect of radiation on CXCL6, CCL2, ERK1, ERK2, and AKT1 mRNA expression and increased the inhibitory effect of radiation on NOS3 expression. In CAM assay, melatonin enhanced the reduction of the vascular area induced by radiation. Melatonin potentiated the inhibitory effect on the activation of p-AKT and p-ERK exerted by radiation. Antiangiogenic effect of melatonin could be mediated through AKT and ERK pathways, proteins involved in vascular endothelial (VE) cell growth, cell proliferation, survival, migration, and angiogenesis. In addition, radiation increased endothelial cell permeability and melatonin counteracted it by regulating the internalization of VE-cadherin. Radiation has some side effects on angiogenesis that may reduce its effectiveness against tumor growth and melatonin is able to neutralize these negative actions of radiation. Additionally, melatonin potentiated radiation-induced antiangiogenic actions on several steps of the angiogenic process and enhanced its antitumor action. Our findings point to melatonin as a useful molecule as adjuvant to radiotherapy in cancer treatment.

Sleep duration and the risk of cancer: a systematic review and meta-analysis including dose-response relationship

Background

The effect of sleep duration on cancer risk remains controversial. We aimed to quantify the available evidence on this relationship using categorical and dose–response meta-analyses.

Methods

Population-based cohort studies and case-control studies with at least three categories of sleep duration were identified by searching PubMed, EMBASE, and the Cochrane Library database up to July 2017.

Results

Sixty-five studies from 25 articles were included, involving 1,550,524 participants and 86,201 cancer cases. The categorical meta-analysis revealed that neither short nor long sleep duration was associated with increased cancer risk (short: odds ratio [OR] = 1.01, 95% confidence intervals [CI] = 0.97–1.05; long: OR = 1.02, 95% CI = 0.97–1.07). Subgroup analysis revealed that short sleep duration was associated with cancer risk among Asians (OR = 1.36; 95% CI: 1.02–1.80) and long sleep duration significantly increased the risk of colorectal cancer (OR = 1.21; 95% CI: 1.08–1.34). The dose–response meta-analysis showed no significant relationship between sleep duration and cancer risk. When treated as two linear piecewise functions with a cut point of 7 h, similar nonsignificant associations were found (per 1-h reduction: OR = 1.02, 95% CI = 0.98–1.07; per 1-h increment: OR = 1.003, 95% CI = 0.97–1.03).

Conclusion

Categorical meta-analysis indicated that short sleep duration increased cancer risk in Asians and long sleep duration increased the risk of colorectal cancer, but these findings were not consistent in the dose–response meta-analysis. Long-term randomized controlled trials and well-designed prospective studies are needed to establish causality and to elucidate the mechanism underlying the association between sleep duration and cancer risk.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5025-y) contains supplementary material, which is available to authorized users.

Therapeutic potential of melatonin for breast cancer radiation therapy patients

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

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

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

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

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

Melatonin inhibits angiogenesis in SH-SY5Y human neuroblastoma cells by downregulation of VEGF

Vascular endothelial growth factor (VEGF) produced from tumor cells plays a crucial role in the pathogenesis and neovascularization of neuroblastoma. Inhibition of VEGF secretion by tumor cells, as well as VEGF-regulated signaling in endothelial cells, are important to reduce the angiogenesis and growth of neuroblastoma. Since melatonin has anti-angiogenic effects in tumor cell lines, the aim of the present study was to study melatonin modulation of the pro-angiogenic effects of VEGF in neuroblastoma cells (SH-SY5Y). We used co-cultures of SH-SY5Y and endothelial cells. VEGF expression and protein levels were analyzed by quantitative RT-PCR and ELISA, respectively. Endothelial cell migration was assessed by wound-healing assay and endothelial angiogenesis by a tube formation assay. Melatonin inhibited the pro-angiogenic effects of SH-SY5Y cells. The conditioned medium collected from the neuroblastoma cells was angiogenically active and stimulated proliferation, migration and tube formation in endothelial cells. This effect was significantly counteracted by the addition of either anti-VEGF or melatonin. Melatonin inhibited VEGF expression and secretion in SH-SY5Y cells, decreasing the levels of VEGF available for endothelial cells. Melatonin has anti-angiogenic effects at different steps of the angiogenic process in SH-SY5Y neuroblastoma cells, through the downregulation of VEGF.

What is known about melatonin, chemotherapy and altered gene expression in breast cancer

Melatonin, synthesized in and released from the pineal gland, has been demonstrated by multiple in vivo and in vitro studies to have an oncostatic role in hormone-dependent tumors. Furthermore, several clinical trials point to melatonin as a promising adjuvant molecule to be considered for cancer treatment. In the past few years, evidence of a broader spectrum of action of melatonin as an antitumor agent has arisen; thus, melatonin appears to also have therapeutic effects in several types of hormone-independent cancer, including ovarian, leukemic, pancreatic, gastric and non-small cell lung carcinoma. In the present study, the latest findings regarding melatonin molecular actions when concomitantly administered with either radiotherapy or chemotherapy in cancer were reviewed, with a particular focus on hormone-dependent breast cancer. Finally, the present study discusses which direction should be followed in the next years to definitely clarify whether or not melatonin administration could protect against non-desirable effects (such as altered gene expression and post-translational protein modifications) caused by chemotherapy or radiotherapy treatments. As treatments move towards personalized medicine, comparative gene expression profiling with and without melatonin may be a powerful tool to better understand the antitumor effects of melatonin, the pineal gland hormone.

Melatonin enhancement of the radiosensitivity of human breast cancer cells is associated with the modulation of proteins involved in estrogen biosynthesis

Enhancing the radiosensitivity of cancer cells is one of the most important tasks in clinical radiobiology. Endocrine therapy and radiotherapy are two cancer treatment modalities which are often given together in patients with locally-advanced breast cancer and positive hormone-receptor status. Oncostatic actions of melatonin are relevant on estrogen-dependent mammary tumors. In the present study, we wanted to evaluate the effects of the combination of ionizing radiation and melatonin on proteins involved in estrogen biosynthesis in breast cancer cells. We demonstrated a role of melatonin in mediating the sensitization of human breast cancer cells to the ionizing radiation by decreasing around 50% the activity and expression of proteins involved in the synthesis of estrogens in these cells. Thus, melatonin pretreatment before radiation reduces the amount of active estrogens at cancer cell level. Melatonin 1 nM induced a 2-fold change in p53 expression as compared to radiation alone. The regulatory action of melatonin on p53 could be a link between melatonin and its modulatory action on the sensitivity of breast cancer cells to ionizing radiation. These findings may have implications for designing clinical trials using melatonin and radiotherapy.

Estrogenic endocrine disruptors: Molecular mechanisms of action

A comprehensive summary of more than 450 estrogenic chemicals including estrogenic endocrine disruptors is provided here to understand the complex and profound impact of estrogen action. First, estrogenic chemicals are categorized by structure as well as their applications, usage and effects. Second, estrogenic signaling is examined by the molecular mechanism based on the receptors, signaling pathways, crosstalk/bypassing and autocrine/paracrine/homeostatic networks involved in the signaling. Third, evaluation of estrogen action is discussed by focusing on the technologies and protocols of the assays for assessing estrogenicity. Understanding the molecular mechanisms of estrogen action is important to assess the action of endocrine disruptors and will be used for risk management based on pathway-based toxicity testing.

Gender and age influence in daytime and nighttime seizure occurrence in epilepsy associated with mesial temporal sclerosis

OBJECTIVES

The aim of this study was to analyze the daytime and nighttime seizure distribution during video-EEG monitoring in patients with epilepsy associated with unilateral mesial temporal sclerosis (MTS) and the role of gender, age, and lesion side on 24-hour seizure distribution.

METHODS

We studied 167 consecutive adult (age≥16years) patients with epilepsy associated with unilateral mesial temporal sclerosis that had three or more recorded seizures during continuous video-EEG monitoring with a minimum recording time period of 24h. Seizure onset time was classified according to occurrence in six 4-hour periods.

RESULTS

Seven hundred thirty-five seizures were evaluated. We observed two higher seizure occurrence periods: 08:01-12:00 (p=0.001) and 16:01-20:00 (p=0.03). Significantly fewer seizures were observed between 0:01 and 4:00 (p=0.01). Nonuniform seizure distribution was noted in women (p<0.0001), in young patients (less than 45years of age) (p<0.0001), and in both patients with left (p=0.03) and patients with right mesial temporal sclerosis (p=0.008). Men presented uniform seizure occurrence distribution (p=0.15). Women had fewer seizures than expected and fewer seizures than men between 0:01-04:00 (p<0.0001 and p=0.0015, respectively) and 04:01-08:00 (p=0.01 and p=0.03, respectively). Young patients (age<45years) had two seizure occurrence peaks, 08:01-12:00 (p=0.016) and 16:01-20:00 (p=0.004). Middle-aged/old patients (≥45years) had only one seizure occurrence peak, 08:01-12:00 (p=0.012). Young patients had more seizures than middle-aged/old patients between 16:01-20:00 (p=0.04). No differences were noted between left and right MTS.

SIGNIFICANCE

We observed two seizure occurrence peaks: morning and late afternoon/evening. We encountered variations in daytime and nighttime seizure distribution according to gender and age, but not according to side of MTS. Future studies are needed to confirm these findings and to unravel the neurobiological substrate underlying daytime and nighttime variations of seizure occurrence in different age groups and between genders.

Increased and mistimed sex hormone production in night shift workers

BACKGROUND

Night shift work has been associated with an increased risk for breast and prostate cancer. The effect of circadian disruption on sex steroid production is a possible underlying mechanism, underinvestigated in humans. We have assessed daily rhythms of sex hormones and melatonin in night and day shift workers of both sexes.

METHODS

We recruited 75 night and 42 day workers, ages 22 to 64 years, in different working settings. Participants collected urine samples from all voids over 24 hours on a working day. Urinary concentrations of 16 sex steroid hormones and metabolites (estrogens, progestagens, and androgens) and 6-sulfatoxymelatonin were measured in all samples. Mean levels and peak time of total and individual metabolite production were compared between night and day workers.

RESULTS

Night workers had higher levels of total progestagens [geometric mean ratio (GMR) 1.65; 95% confidence intervals (CI), 1.17-2.32] and androgens (GMR: 1.44; 95% CI, 1.03-2.00), compared with day workers, after adjusting for potential confounders. The increased sex hormone levels among night shift workers were not related to the observed suppression of 6-sulfatoxymelatonin. Peak time of androgens was significantly later among night workers, compared with day workers (testosterone: 12:14 hours; 10:06-14:48 vs. 08:35 hours; 06:52-10:46).

CONCLUSIONS

We found increased levels of progestagens and androgens as well as delayed peak androgen production in night shift workers compared with day workers.

IMPACT

The increase and mistiming of sex hormone production may explain part of the increased risk for hormone-related cancers observed in night shift workers.

Melatonin sensitizes human breast cancer cells to ionizing radiation by downregulating proteins involved in double-strand DNA break repair

Radiation and adjuvant endocrine therapy are nowadays considered a standard treatment option after surgery in breast cancer. Melatonin exerts oncostatic actions on human breast cancer cells. In the current study, we investigated the effects of a combination of radiotherapy and melatonin on human breast cancer cells. Melatonin (1 mm, 10 μm and 1 nm) significantly inhibited the proliferation of MCF-7 cells. Radiation alone inhibited the MCF-7 cell proliferation in a dose-dependent manner. Pretreatment of breast cancer cells with melatonin 1 wk before radiation led to a significantly greater decrease of MCF-7 cell proliferation compared with radiation alone. Melatonin pretreatment before radiation also decreased G2 -M phase arrest compared with irradiation alone, with a higher percentage of cells in the G0 -G1 phase and a lower percentage of cells in S phase. Radiation alone diminished RAD51 and DNA-protein kinase (PKcs) mRNA expression, two main proteins involved in double-strand DNA break repair. Treatment with melatonin for 7 days before radiation led to a significantly greater decrease in RAD51 and DNA-PKcs mRNA expression compared with radiation alone. Our findings suggest that melatonin pretreatment before radiation sensitizes breast cancer cells to the ionizing effects of radiation by decreasing cell proliferation, inducing cell cycle arrest and downregulating proteins involved in double-strand DNA break repair. These findings may have implications for designing clinical trials using melatonin and radiotherapy.

Melatonin in perimenopausal and postmenopausal women: associations with mood, sleep, climacteric symptoms, and quality of life

OBJECTIVE

Melatonin synthesis and secretion are partly modulated by estrogen and progesterone. Changes in melatonin concentrations, possibly related to the menopausal transition, may be associated with climacteric mood, sleep, and vasomotor symptoms. The aims of this study were to compare the serum concentrations of melatonin in perimenopausal and postmenopausal women and to evaluate melatonin's influence on mood, sleep, vasomotor symptoms, and quality of life.

METHODS

We analyzed the data of 17 healthy perimenopausal women (aged 43-51 y) and 18 healthy postmenopausal women (aged 58-71 y) who participated in a prospective study. On study night (9:00 pm-9:00 am), serum melatonin was sampled at 20-minute (9:00 pm-12:00 midnight; 6:00-9:00 am) and 1-hour (12:00 midnight-6:00 am) intervals. Questionnaires were used to assess depression (Beck Depression Inventory), anxiety (State-Trait Anxiety Inventory), insomnia and sleepiness (Basic Nordic Sleep Questionnaire [BNSQ]), subjective sleep quality, vasomotor symptoms, and quality of life (EuroQoL).

RESULTS

Postmenopausal women had lower nighttime serum melatonin concentrations than perimenopausal women. The duration of melatonin secretion tended to be shorter in postmenopause, whereas melatonin peak time did not differ. Mean melatonin concentrations and exposure levels did not correlate with follicle-stimulating hormone level, estradiol level, body mass index, Beck Depression Inventory score, State-Trait Anxiety Inventory score, BNSQ insomnia score, BNSQ sleepiness score, subjective sleep score, climacteric vasomotor score, or quality of life. In perimenopause, the later is the melatonin peak, the higher is the level of anxiety (P = 0.022), and the longer is the melatonin secretion, the better is the quality of life (P < 0.001).

CONCLUSIONS

Longitudinal research is needed to better understand the possible contributory role of menopause in lower melatonin levels.

Melatonin attenuates the TLR4-mediated inflammatory response through MyD88- and TRIF-dependent signaling pathways in an in vivo model of ovarian cancer

Background

Toll-like receptors (TLRs) are effector molecules expressed on the surface of ovarian cancer (OC) cells, but the functions of the TLR2/TLR4 signaling pathways in these cells remain unclear. Melatonin (mel) acts as an anti-inflammatory factor and has been reported to modulate TLRs in some aggressive tumor cell types. Therefore, we investigated OC and the effect of long-term mel therapy on the signaling pathways mediated by TLR2 and TLR4 via myeloid differentiation factor 88 (MyD88) and toll-like receptor-associated activator of interferon (TRIF) in an ethanol-preferring rat model.

Methods

To induce OC, the left ovary of animals either consuming 10% (v/v) ethanol or not was injected directly under the bursa with a single dose of 100 μg of 7,12-dimethylbenz(a)anthracene (DMBA) dissolved in 10 μL of sesame oil. The right ovaries were used as sham-surgery controls. After developing OC, half of the animals received i.p. injections of mel (200 μg/100 g b.w./day) for 60 days.

Results

Although mel therapy was unable to reduce TLR2 levels, it was able to suppress the OC-associated increase in the levels of the following proteins: TLR4, MyD88, nuclear factor kappa B (NFkB p65), inhibitor of NFkB alpha (IkBα), IkB kinase alpha (IKK-α), TNF receptor-associated factor 6 (TRAF6), TRIF, interferon regulatory factor 3 (IRF3), interferon β (IFN-β), tumor necrosis factor alpha (TNF-α), and interleukin (IL)-6. In addition, mel significantly attenuated the expression of IkBα, NFkB p65, TRIF and IRF-3, which are involved in TLR4-mediated signaling in OC during ethanol intake.

Conclusion

Collectively, our results suggest that mel attenuates the TLR4-induced MyD88- and TRIF-dependent signaling pathways in ethanol-preferring rats with OC.

Melatonin: a "Higgs boson" in human reproduction

As the Higgs boson could be a key to unlocking mysteries regarding our Universe, melatonin, a somewhat mysterious substance secreted by the pineal gland primarily at night, might be a crucial factor in regulating numerous processes in human reproduction. Melatonin is a powerful antioxidant which has an essential role in controlling several physiological reactions, as well as biological rhythms throughout human reproductive life. Melatonin, which is referred to as a hormone, but also as an autocoid, a chronobiotic, a hypnotic, an immunomodulator and a biological modifier, plays a crucial part in establishing homeostatic, neurohumoral balance and circadian rhythm in the body through synergic actions with other hormones and neuropeptides. This paper aims to analyze the effects of melatonin on the reproductive function, as well as to shed light on immunological and oncostatic properties of one of the most powerful hormones.

Expression of MT2 receptor in patients with gastric adenocarcinoma and its relationship with clinicopathological features

BACKGROUND

Gastric cancer accounts 8% of the total cancer cases and 10% of total cancer deaths worldwide. The indoleamine N-acetyl-5-methoxytryptamine, better known as melatonin, is the principal hormone produced by the pineal gland. Recently, it has shown some anticancer role in some malignancies such as breast and colon cancer; also, some of its protective roles in the GI tract are as free radical scavenger and as antimitogenic and apoptotic agents. Based on the anticancer effects of melatonin and wide distribution of this neurohormone in the GI tract and some proposed physiologic and pharmacologic roles for this neurohormone, this study is initially scheduled to determine the expression of melatonin receptor MT2 in tissue samples of adenocarcinoma cancer patients.

METHODS

For this aim, a total of 30 gastric adenocarcinoma patients and 30 normal individuals were selected and examined for MT2 gene expression by real-time PCR.

RESULTS

Our results have shown interestingly high expression for MT2 receptor in cancer and marginal cancer tissues compared with normal people.

CONCLUSIONS

According to our results, it is concluded that for the first time, the expression of MT2 receptor in gastric adenocarcinoma tissues which was in parallel with breast and colon cancer studies and high expression of this receptor in the marginal tissues indicate refractory mechanism which shows the defending role of melatonin in the GI system. Our experiments has not shown any relationship between MT2 receptor expression and grade and clinicopathological features of gastric tumor, so we cannot conclude any relationship between this receptor expression and progression of the tumor, although this expression can be considered as an etiology.

First-morning urinary melatonin and breast cancer risk in the Guernsey Study

It has been hypothesized that suppressed nocturnal melatonin production is associated with an increased risk of breast cancer, but results from several small prospective studies of the association have been inconclusive. We examined the association between nocturnal melatonin and breast cancer risk in a case-control study nested within the Guernsey III Study, a British prospective cohort study (1977-2009). Concentrations of 6-sulfatoxymelatonin were measured in prediagnostic first-morning urine samples from 251 breast cancer cases and 727 matched controls. Conditional logistic regression models were used to calculate odds ratios for breast cancer in relation to 6-sulfatoxymelatonin level. No significant association was found between 6-sulfatoxymelatonin level and breast cancer risk, either overall (for highest third vs. lowest, multivariable-adjusted odds ratio = 0.90, 95% confidence interval: 0.61, 1.33) or by menopausal status. However, in a meta-analysis of all published prospective data, including 1,113 cases from 5 studies, higher 6-sulfatoxymelatonin levels were associated with lower breast cancer risk (for highest fourth vs. lowest, odds ratio = 0.81, 95% confidence interval: 0.66, 0.99). In summary, we found no evidence that 6-sulfatoxymelatonin level in a first-morning urine sample was associated with breast cancer risk among British women. However, overall the published data suggest a modest inverse association between melatonin levels and breast cancer risk. Further data are needed to confirm this association.

Seasonal variation in children with developmental dysplasia of the hip

BACKGROUND

It has been postulated that developmental dysplasia of the hip (DDH) is more frequent in infants born in the winter months. It was the purpose of this study to ascertain if there was any seasonal variation in DDH at the author's institution and compare/contrast our results with those in the literature using rigorous mathematical fitting.

METHODS

All children with DDH treated at the author's institution from 1993 to 2012 were identified. The month of birth was recorded and temporal variation was analyzed using cosinor analysis. Similar data from the literature was analyzed.

RESULTS

There were 424 children (363 girls, 61 boys). An additional 22,936 children were added from the literature for a total of 23,360. Pearson's Chi-square test demonstrated a non-uniform distribution in the month of birth for both our 424 children as well as the combined literature series in both the Northern and Southern hemispheres. Cosinor analysis of the 424 children demonstrated double peaks in mid-March and mid-October. For the entire 23,360 children, no seasonal variation was observed in 2,205 (9.4 %), a single winter peak in 16,425 (70.3 %), a single summer peak in 1,280 (5.5 %), and double peaks in the spring and autumn in 3,450 (14.8 %).

CONCLUSIONS

This study partly supports the hypothesis of tight clothing/cold temperature as one factor in the etiology of DDH with the tighter clothing/swaddling increasing the risk of DDH. However ~20 % of the DDH births demonstrated a non-winter peak. The single summer and double spring/autumn peaks, as well as in those series where no seasonal variation was noted, refutes the cold winter clothing hypothesis. Perhaps these different patterns in seasonal variation represent the heterogeneity of the genetic factors in DDH interacting with external factors (temperature and clothing) and internal factors (metabolic). Further study will be required to understand these different patterns in DDH seasonal variation.

LEVEL OF EVIDENCE

IV-case series.

Action of melatonin on squamous cell carcinoma and other tumors of the oral cavity (Review)

Melatonin (MLT; N-acetyl-5-metoxy-tryptamine) is a hormone that is principally synthesized in the pineal gland. MLT has been shown to exhibit a variety of functions. The hormone, which is a free radical scavenger, plays an immunomodulatory role, stimulates the proliferation and synthesis of type I collagen and promotes bone formation. Moreover, MLT exerts oncostatic activity through several biological mechanisms, including antiproliferative functions, stimulation of anticancer immunity, modulation of oncogene expression and anti-inflammatory, antioxidant and antiangiogenic effects. In addition, MLT inhibits human cancer cell growth in culture, and previous clinical studies have also confirmed its anticancer properties in vivo. With regard to the underlying mechanisms of MLT in tumor processes, including oral cavity tumors such as epidermoid carcinoma, knowledge of the role played by the MT1 and 2 membrane receptors, MT3 and the calmodulin cytosolic binding sites, as well as the nuclear receptors of the RZR/ROR family, is increasing. It has been hypothesized that exogenous restoration of MT1 (MTNR1A) expression inhibits the growth of oral squamous cell carcinoma cells lacking the expression of the receptor. The tumor suppressing functions of MLT and the presence of the MT1 receptor in various tumors indicate that the receptor may play a pivotal role in oral carcinogenesis. The current review discusses the clinical significance of MLT in oral cancer.

Characterization of chemically induced ovarian carcinomas in an ethanol-preferring rat model: influence of long-term melatonin treatment

Ovarian cancer is the fourth most common cause of cancer deaths among women, and chronic alcoholism may exert co-carcinogenic effects. Because melatonin (mel) has oncostatic properties, we aimed to investigate and characterize the chemical induction of ovarian tumors in a model of ethanol-preferring rats and to verify the influence of mel treatment on the overall features of these tumors. After rats were selected to receive ethanol (EtOH), they were surgically injected with 100 µg of 7,12-dimethyl-benz[a]anthracene (DMBA) plus sesame oil directly under the left ovarian bursa. At 260 days old, half of the animals received i.p. injections of 200 µg mel/100 g b.w. for 60 days. Four experimental groups were established: Group C, rats bearing ovarian carcinomas (OC); Group C+EtOH, rats voluntarily consuming 10% (v/v) EtOH and bearing OC; Group C+M, rats bearing OC and receiving mel; and Group C+EtOH+M, rats with OC consuming EtOH and receiving mel. Estrous cycle and nutritional parameters were evaluated, and anatomopathological analyses of the ovarian tumors were conducted. The incidence of ovarian tumors was higher in EtOH drinking animals 120 days post-DMBA administration, and mel efficiently reduced the prevalence of some aggressive tumors. Although mel promoted high EtOH consumption, it was effective in synchronizing the estrous cycle and reducing ovarian tumor mass by 20%. While rats in the C group displayed cysts containing serous fluid, C+EtOH rats showed solid tumor masses. After mel treatment, the ovaries of these rats presented as soft and mobile tissues. EtOH consumption increased the incidence of serous papillary carcinomas and sarcomas but not clear cell carcinomas. In contrast, mel reduced the incidence of sarcomas, endometrioid carcinomas and cystic teratomas. Combination of DMBA with EtOH intake potentiated the incidence of OC with malignant histologic subtypes. We concluded that mel reduces ovarian masses and the incidence of adenocarcinomas in ethanol-deprived rats.

Exposure to road traffic and railway noise and postmenopausal breast cancer: A cohort study

Exposure to traffic noise may result in stress and sleep disturbances. Studies on self-reported sleep duration and breast cancer risk have found inconsistent results. In a population-based Danish cohort of 29,875 women aged 50-64 years at enrolment in 1993-1997, we identified 1219 incident, postmenopausal breast cancer cases during follow-up through 2010. Mean follow-up time was 12.3 years. Road traffic and railway noise was calculated for all present and historical residential addresses from 1987 to 2010. We used Cox proportional hazard model for analyses and adjusted for hormone replacement therapy use, parity, alcohol consumption and other potential confounders. We found no overall association between residential road traffic or railway noise and breast cancer risk. Among women with estrogen receptor negative breast cancer, a 10-dB higher level of road traffic noise (continuous scale) during the previous 1, 5 and 10 years were associated with 28% (95% CI: 1.04-1.56), 23% (95% CI: 1.00-1.51) and 20% (95% CI: 0.97-1.48) higher risks of estrogen receptor negative breast cancer, respectively, in fully adjusted models. Similarly, a 10-dB increase in railway noise (1-year mean at diagnosis address) increased risk for estrogen receptor negative breast cancer by 38% (95% CI: 1.01-1.89). There was no association between road traffic or railway noise and estrogen receptor positive breast cancer. In conclusion, these results suggest that residential road traffic and railway noise may increase risk of estrogen receptor negative breast cancer. As the first study on traffic noise and breast cancer results should be treated with caution.

Regulation of vascular endothelial growth factor by melatonin in human breast cancer cells

Melatonin exerts oncostatic effects on breast cancer by interfering with the estrogen-signaling pathways. Melatonin reduces estrogen biosynthesis in human breast cancer cells, surrounding fibroblasts and peritumoral endothelial cells by regulating cytokines that influence tumor microenvironment. This hormone also exerts antiangiogenic activity in tumoral tissue. In this work, our objective was to study the role of melatonin on the regulation of the vascular endothelial growth factor (VEGF) in breast cancer cells. To accomplish this, we cocultured human breast cancer cells (MCF-7) with human umbilical vein endothelial cells (HUVECs). VEGF added to the cultures stimulated the proliferation of HUVECs and melatonin (1 mM) counteracted this effect. Melatonin reduced VEGF production and VEGF mRNA expression in MCF-7 cells. MCF-7 cells cocultured with HUVECs stimulated the endothelial cells proliferation and increased VEGF levels in the culture media. Melatonin counteracted both stimulatory effects on HUVECs proliferation and on VEGF protein levels in the coculture media. Conditioned media from MCF-7 cells increased HUVECs proliferation, and this effect was significantly counteracted by anti-VEGF and 1 mM melatonin. All these findings suggest that melatonin may play a role in the paracrine interactions between malignant epithelial cells and proximal endothelial cells through a downregulatory action on VEGF expression in human breast cancer cells, which decrease the levels of VEGF around endothelial cells. Lower levels of VEGF could be important in reducing the number of estrogen-producing cells proximal to malignant cells as well as decreasing tumoral angiogenesis.

Expression of melatonin receptor MT1 in cells of human invasive ductal breast carcinoma

In humans, two main types of membrane melatonin receptors have been identified, MT1 and MT2. Expression of MT1 in neoplastic cells seems to increase the efficacy of melatonin's oncostatic activity. The purpose of this study was to determine the distribution and the intensity of MT1 expression in breast cancer cells and to correlate it with clinicopathological factors. Immunohistochemical studies (IHC) were conducted on 190 cases of invasive ductal breast carcinomas (IDC) and molecular studies were performed on 29 cases of frozen tumor fragments and selected breast cancer cell lines. Most of the studied tumors manifested a membranous/cytoplasmic IHC expression of MT1. In IDC, the MT1 expression was higher than in fibrocystic breast disease. MT1 expression was higher in estrogen receptor positive (ER+) and HER2 positive (HER2+) tumors. Triple negative tumors (TN) manifested the lowest MT1 expression level. The lowest MT1 protein expression level was noted in the TN breast cancer cell line MDA-MB-231 compared with ER+ cell lines MCF-7 and SK-BR-3. MT1 mRNA expression was negatively correlated with the malignancy grade of the studied IDC cases. Moreover, higher MT1 expression was associated with patients' longer overall survival (OS) in the group of ER+ breast cancers and treated with tamoxifen. Multivariate analysis indicated that MT1 was an independent prognostic factor in the ER+ tumors for OS and event-free survival in the ER+ tumors. The results of this study may point to a potential prognostic and therapeutic significance of MT1 in IDC.