Combined effects of melatonin and all-trans retinoic acid and somatostatin on breast cancer cell proliferation and death: molecular basis for the anticancer effect of these molecules

Postnatal Changes of Somatostatin Expression in Hippocampi of C57BL/6 Mice; Modulation of Neuroblast Differentiation in the Hippocampus

(1) Background: Somatostatin (SST) exhibits expressional changes in the brain during development, but its role is not still clear in brain development. (2) Methods: We investigated postnatal SST expression and its effects on hippocampal neurogenesis via administering SST subcutaneously to P7 mice for 7 days. (3) Results: In the hippocampal CA1 region, SST immunoreactivity reaches peak at P14. However, SST immunoreactivity significantly decreased at P21. In the CA2/3 region, the SST expression pattern was similar to the CA1, and SST-immunoreactive cells were most abundant at P14. In the dentate gyrus, SST-immunoreactive cells were most abundant at P7 and P14 in the polymorphic layer; as in CA1-3 regions, the immunoreactivity decreased at P21. To elucidate the role of SST in postnatal development, we administered SST subcutaneously to P7 mice for 7 days. In the subgranular zone of the hippocampal dentate gyrus, a significant increase was observed in immunoreactivity of doublecortin (DCX)-positive neuroblast after administration of SST.; (4) Conclusions: SST expression in the hippocampal sub-regions is transiently increased during the postnatal formation of the hippocampus and decreases after P21. In addition, SST is involved in neuroblast differentiation in the dentate gyrus of the hippocampus.

Antitumor effect of melatonin on breast cancer in experimental models: A systematic review

Breast cancer is the most frequent malignant neoplasm in females. While conventional treatments such as chemotherapy and radiotherapy are available, they are highly invasive and toxic to oncological patients. Melatonin is a promising molecule for the treatment of breast cancer with antitumor effects on tumorigenesis and tumor progression. The aim of this systematic review was to synthesize knowledge about the antitumor effect of melatonin on breast cancer in experimental models and propose the main mechanisms of action already described in relation to the processes regulated by melatonin. PubMed, Web of Science, and Embase databases were used. The inclusion criteria were in vitro and in vivo experimental studies that used different formulations of melatonin as a treatment for breast cancer, without year or language restrictions. Risk of bias for studies was assessed using the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) tool. Data from selected articles were presented as narrative descriptions and tables. Seventy-five articles on different breast cancer cell lines and experimental models treated with melatonin alone, or in combination with other compounds were included. Melatonin showed antitumor effects on proliferative pathways related to the cell cycle and tumorigenesis, tumor death, angiogenesis, and tumor metastasis, as well as on oxidative stress and immune regulatory pathways. These effects were either dependent or independent of melatonin receptors. Herein, we clarify the antitumor action of melatonin on different tumorigenic processes in breast cancer in experimental models. Systematic review registration: PROSPERO database (CRD42022309822/https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022309822).

Interactions of melatonin with various signaling pathways: implications for cancer therapy

Melatonin is a neuro-hormone with conserved roles in evolution. Initially synthetized as an antioxidant molecule, it has gained prominence as a key molecule in the regulation of the circadian rhythm. Melatonin exerts its effect by binding to cytoplasmic and intra-nuclear receptors, and is able to regulate the expression of key mediators of different signaling pathways. This ability has led scholars to investigate the role of melatonin in reversing the process of carcinogenesis, a process in which many signaling pathways are involved, and regulating these pathways may be of clinical significance. In this review, the role of melatonin in regulating multiple signaling pathways with important roles in cancer progression is discussed, and evidence regarding the beneficence of targeting malignancies with this approach is presented.

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.

Effect of astaxanthin and melatonin on cell viability and DNA damage in human breast cancer cell lines

BACKGROUND

Astaxanthin is a xanthophyll pigment found in algae and marine animals, having strong anti-oxidative, anti-tumoral, and anti-inflammatory effects. Additionally, melatonin has shown inhibitory effects on the growth of human breast cancer cells. The aim of the present study was to evaluate the effect of astaxanthin and the combined effects of astaxanthin and melatonin on breast cancer cells and the non-tumoral breast cell line.

MATERIALS AND METHODS

The human breast cancer cell lines, T47D and MDA-MB-231, and non-tumorigenic cell line MCF 10A were treated and compared to astaxanthin, melatonin, and co-administration of these two compounds. Cell viability, apoptosis induction, Bcl-2 protein expression, and DNA damage were measured by MTT assay, acridine orange/ethidium bromide (AO/EB) staining, immunocytochemistry, and comet assay.

RESULTS

Astaxanthin at lower doses than melatonin reduced cell viability and Bcl2 expression, induced apoptosis and DNA damage in MDA-MB-231 and T47D. Meanwhile, the effects of astaxanthin on cell cytotoxicity, apoptosis, and DNA damage in MCF10A cells are insignificant compared to MDA-MB-231 and T47D. Moreover, the results indicated that astaxanthin in T47D cells caused more cell death compared to MDA-MB-231 cells. Astaxanthin induced cell death on breast cancer cells and without cell cytotoxicity for non-cancerous cells.

CONCLUSION

Furthermore, the presence of astaxanthin increased the function of melatonin-induced cell death in breast cancer cells.

Empowering Melatonin Therapeutics with Drosophila Models

Melatonin functions as a central regulator of cell and organismal function as well as a neurohormone involved in several processes, e.g., the regulation of the circadian rhythm, sleep, aging, oxidative response, and more. As such, it holds immense pharmacological potential. Receptor-mediated melatonin function mainly occurs through MT1 and MT2, conserved amongst mammals. Other melatonin-binding proteins exist. Non-receptor-mediated activities involve regulating the mitochondrial function and antioxidant cascade, which are frequently affected by normal aging as well as disease. Several pathologies display diseased or dysfunctional mitochondria, suggesting melatonin may be used therapeutically. Drosophila models have extensively been employed to study disease pathogenesis and discover new drugs. Here, we review the multiple functions of melatonin through the lens of functional conservation and model organism research to empower potential melatonin therapeutics to treat neurodegenerative and renal diseases.

Role and Therapeutic Potential of Melatonin in Various Type of Cancers

Cancer is a large group of diseases and the second leading cause of death worldwide. Lung, prostate, colorectal, stomach, and liver cancers are the most common types of cancer in men, whereas breast, colorectal, lung, cervical, and thyroid cancers are the most common among women. Presently, various treatment strategies, including surgical resection combined with chemotherapy, radiotherapy, nanotherapy, and immunotherapy, have been used as conventional treatments for patients with cancer. However, the clinical outcomes of advanced-stage disease remain relatively unfavorable owing to the emergence of chemoresistance, toxicity, and other undesired detrimental side effects. Therefore, new therapies to overcome these limitations are indispensable. Recently, there has been considerable evidence from experimental and clinical studies suggesting that melatonin can be used to prevent and treat cancer. Studies have confirmed that melatonin mitigates the pathogenesis of cancer by directly affecting carcinogenesis and indirectly disrupting the circadian cycle. Melatonin (MLT) is nontoxic and exhibits a range of beneficial effects against cancer via apoptotic, antiangiogenic, antiproliferative, and metastasis-inhibitory pathways. The combination of melatonin with conventional drugs improves the drug sensitivity of cancers, including solid and liquid tumors. In this manuscript, we will comprehensively review some of the cellular, animal, and human studies from the literature that provide evidence that melatonin has oncostatic and anticancer properties. Further, this comprehensive review compiles the available experimental and clinical data analyzing the history, epidemiology, risk factors, therapeutic effect, clinical significance, of melatonin alone or in combination with chemotherapeutic agents or radiotherapy, as well as the underlying molecular mechanisms of its anticancer effect against lung, breast, prostate, colorectal, skin, liver, cervical, and ovarian cancers. Nonetheless, in the interest of readership clarity and ease of reading, we have discussed the overall mechanism of the anticancer activity of melatonin against different types of cancer. We have ended this report with general conclusions and future perspectives.

Cyst Reduction by Melatonin in a Novel Drosophila Model of Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) causes progressive cystic degeneration of the renal tubules, the nephrons, eventually severely compromising kidney function. ADPKD is incurable, with half of the patients eventually needing renal replacement. Treatments for ADPKD patients are limited and new effective therapeutics are needed. Melatonin, a central metabolic regulator conserved across all life kingdoms, exhibits oncostatic and oncoprotective activity and no detected toxicity. Here, we used the Bicaudal C (BicC) Drosophila model of polycystic kidney disease to test the cyst-reducing potential of melatonin. Significant cyst reduction was found in the renal (Malpighian) tubules upon melatonin administration and suggest mechanistic sophistication. Similar to vertebrate PKD, the BicC fly PKD model responds to the antiproliferative drugs rapamycin and mimics of the second mitochondria-derived activator of caspases (Smac). Melatonin appears to be a new cyst-reducing molecule with attractive properties as a potential candidate for PKD treatment.

The potential therapeutic effects of melatonin on breast cancer: An invasion and metastasis inhibitor

Breast cancer is the most common cancer among women and its metastasis which generally observed at the last stage is the major cause of breast cancer-related death. Therefore, the agents that have the potential to prevent metastatic and invasive nature of breast cancer can open up new therapeutic strategies. Melatonin, a major hormone of pineal gland, is a powerful anti-cancer agent. There are growing evidence regarding the protective effect of melatonin against cancer invasion and metastasis. The anti-metastatic feature of melatonin accompanies with suppression of tumor proliferation, induction of tumor apoptosis, regulation of the cell cycle, modulating angiogenesis, impediment of invasion, and induction of cancer cells sensitivity to the chemotherapy agents. More recently, anti-metastatic effect of melatonin through affecting cancer stem cells and vascular mimicry has been identified. Thus, the aim of this review is to discuss the potential therapeutic effect of melatonin on breast cancer via modulating the cells invasion and metastasis.

Melatonin sensitises shikonin-induced cancer cell death mediated by oxidative stress via inhibition of the SIRT3/SOD2-AKT pathway

Recent research suggests that melatonin (Mel), an endogenous hormone and natural supplement, possesses anti-proliferative effects and can sensitise cells to anti-cancer therapies. Although shikonin (SHK) also possesses potential anti-cancer properties, the poor solubility and severe systemic toxicity of this compound hinders its clinical usage. In this study, we combined Mel and SHK, a potentially promising chemotherapeutic drug combination, with the aim of reducing the toxicity of SHK and enhancing the overall anti-cancer effects. We demonstrate for the first time that Mel potentiates the cytotoxic effects of SHK on cancer cells by inducing oxidative stress via inhibition of the SIRT3/SOD2-AKT pathway. Particularly, Mel-SHK treatment induced oxidative stress, increased mitochondrial calcium accumulation and reduced the mitochondrial membrane potential in various cancer cells, leading to apoptosis. This drug combination also promoted endoplasmic reticulum (ER) stress, leading to AKT dephosphorylation. In HeLa cells, Mel-SHK treatment reduced SIRT3/SOD2 expression and SOD2 activity, while SIRT3 overexpression dramatically reduced Mel-SHK-induced oxidative stress, ER stress, mitochondrial dysfunction and apoptosis. Hence, we propose the combination of Mel and SHK as a novel candidate chemotherapeutic regimen that targets the SIRT3/SOD2-AKT pathway in cancer.

Melatonin Induces Apoptosis and Inhibits the Proliferation of Cancer Cells via Reactive Oxygen Species-mediated MAPK and mTOR Pathways

Background:

Recent human and animal studies have demonstrated the oncostatic properties of N-acetyl-5-methoxytryptamine (melatonin) in different types of cancer. However, in few cancer cell lines including colorectal cancer cell line (HT-29), acute T cell leukemia cell line (JURKAT) and cervical cancer cell line (HeLa), precise oncostatic mechanism induced by melatonin is yet to be described.

Objectives:

The aim of this study is to investigate the effects of melatonin in HT-29, JURKAT and HeLa cells and to determine the underlying molecular mechanism.

Methods:

Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay while cell cycle, apoptosis and membrane potential were analysed by flow cytometry. Reactive oxygen species (ROS) was detected by 2',7'.dichlorofluorescein diacetate(DCFH-DA) staining. Protein expressions were determined by Western blot.

Results:

Our results showed that melatonin suppressed cell proliferation, increased the number of sub G1 hypodiploid cells and cell cycle arrest in HT-29, JURKAT and HeLa cells. Besides, melatonin also induced early and late apoptosis, although there were marked variations in responses between different cell lines (sensitivity; HeLa > HT-29 >JURKAT). Apart from that, staining with DCHF-DA demonstrated ROS production that was induced in a dose-dependent manner in HeLa, HT-29 and JURKAT cells. Moreover, the apoptotic process and oncostatic effect of melatonin were seen to be associated with extracellular-signal-regulated kinase (ERK) and stress-activated protein kinase/c-Jun NH (2)-terminal kinase (SAPK-JNK) signalling cascades in HeLa cells. In HT-29 and JURKAT cells, melatonin induced apoptosis via activation of p38 mitogen-activated protein kinases (p38), ERK and SAPK-JNK signalling pathways. In all three cell lines, the apoptotic event was triggered by the mammalian target of rapamycin (mTOR)-mediated activation of the downstream target rapamycininsensitive companion of mTOR (RICTOR) and/or regulatory-associated protein of mTOR (RAPTOR) proteins.

Conclusions:

Our findings confirm that melatonin induces apoptosis through reactive oxygen speciesmediated dysregulated mitogen-activated protein kinase (MAPK) and mTOR signalling pathways in these cancer cell lines.

Mitochondrial functions and melatonin: a tour of the reproductive cancers

Cancers of the reproductive organs have a strong association with mitochondrial defects, and a deeper understanding of the role of this organelle in preneoplastic-neoplastic changes is important to determine the appropriate therapeutic intervention. Mitochondria are involved in events during cancer development, including metabolic and oxidative status, acquisition of metastatic potential, resistance to chemotherapy, apoptosis, and others. Because of their origin from melatonin-producing bacteria, mitochondria are speculated to produce melatonin and its derivatives at high levels; in addition, exogenously administered melatonin accumulates in the mitochondria against a concentration gradient. Melatonin is transported into tumor cell by GLUT/SLC2A and/or by the PEPT1/2 transporters, and plays beneficial roles in mitochondrial homeostasis, such as influencing oxidative phosphorylation and electron flux, ATP synthesis, bioenergetics, calcium influx, and mitochondrial permeability transition pore. Moreover, melatonin promotes mitochondrial homeostasis by regulating nuclear DNA and mtDNA transcriptional activities. This review focuses on the main functions of melatonin on mitochondrial processes, and reviews from a mechanistic standpoint, how mitochondrial crosstalk evolved in ovarian, endometrial, cervical, breast, and prostate cancers relative to melatonin's known actions. We put emphasis on signaling pathways whereby melatonin interferes within cancer-cell mitochondria after its administration. Depending on subtype and intratumor metabolic heterogeneity, melatonin seems to be helpful in promoting apoptosis, anti-proliferation, pro-oxidation, metabolic shifting, inhibiting neovasculogenesis and controlling inflammation, and restoration of chemosensitivity. This results in attenuation of development, progression, and metastatic potential of reproductive cancers, in addition to lowering the risk of recurrence and improving the life quality of patients.

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.

Adjuvant chemotherapy with melatonin for targeting human cancers: A review

Melatonin is a multifunctional hormone that has long been known for its antitumoral effects. An advantage of the application of melatonin in cancer therapy is its ability to differentially influence tumors from normal cells. In this review, the roles of melatonin adjuvant therapy in human cancer are discussed. Combination of melatonin with chemotherapy could provide synergistic antitumoral outcomes and resolve drug resistance in affected patients. This combination reduces the dosage for chemotherapeutic agents with the subsequent attenuation of side effects related to these drugs on normal cells around tumor and on healthy organs. The combination therapy increases the rate of survival and improves the quality of life in affected patients. Cancer cell viability is reduced after application of the combinational melatonin therapy. Melatonin does all these functions by adjusting the signals involved in cancer progression, re-establishing the dark/light circadian rhythm, and disrupting the redox system for cancer cells. To achieve effective therapeutic outcomes, melatonin concentration along with the time of incubation for this indoleamine needs to be adjusted. Importantly, a special focus is required to be made on choosing an appropriate chemotherapy agent for using in combination with melatonin. Because of different sensitivities of cancer cells for melatonin combination therapy, cancer-specific targeted therapy is also needed to be considered. For this review, the PubMed database was searched for relevant articles based on the quality of journals, the novelty of articles published by the journals, and the number of citations per year focusing only on human cancers.

Effect of Indolic-Amide Melatonin on Blood Cell Population: A Biophysical Gaussian Statistical Analysis

The problem of the correlation of indolic molecules with special regard to melatonin and immune processes has been widely investigated. However, there are only few studies focusing on circadian variation of peripheral blood leukocytes. The purpose of this study is thus to understand the influence of MLT on leukocyte populations and its correlation with leukocyte distribution. This is accomplished by administrating placebo and melatonin to different groups of individuals and by performing a biophysical Gaussian analysis on the number of leukocytes by means of a comparison of their p.m. vs. a.m. variations under the effect of placebo and of melatonin and via a comparison in the morning between leukocytes population of untreated group and MLT group. It is shown that: (a) melatonin has the effect of narrowing the normal distribution concentrating most of the individuals towards the mean value of the observed variation of leukocytes population and (b) the individuals who have not received either placebo or supplement have a leukocyte population that follows a normal distribution. These results confirm the crucial role played by melatonin, as the most representative of indolic amide in biological systems, in the circadian peripheral variations of leukocyte numbers because counts of white blood cells are essential in medical urgency and differential diagnosis situations. Hence, further studies are suggested to account for these physiological variations and for the evaluation of the full involvement of the action of MLT on leukocytes distribution.

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.

AA-NAT, MT1 and MT2 Correlates with Cancer Stem-Like Cell Markers in Colorectal Cancer: Study of the Influence of Stage and p53 Status of Tumors

The characterization of colon cancer stem cells (CSCs) may help to develop novel diagnostic and therapeutic procedures. p53 loss increases the pool of CSCs in colorectal cancer (CRC). Recent reports suggest that the oncostatic effects of melatonin could be related to its ability to kill CSCs. Although there are no data linking the loss of p53 function and melatonin synthesis or signaling in cancer, melatonin does activate the p53 tumor-suppressor pathway in this disease. In this work, we analyze whether the expression of melatonin synthesis and signaling genes are related to the expression of CSC markers and the implication of p53 status in samples from patients with CRC. Arylalkylamine N-acetyltransferase (AA-NAT), MT1, and MT2 expression decreased in tumor samples versus normal mucosa samples in mutated p53 (mtp53) tumors versus those with wild-type p53 (wtp53). Further, AA-NAT and MT2 expression were lower in advanced stages of the disease in wtp53 tumors. On the contrary, CD44 and CD66c expression was higher in tumor versus normal mucosa in wtp53 tumors. Additionally, CD44 expression was higher in advanced stages of the disease regardless of the p53 status. Patients with CD44_highCD66c_high and wtp53 tumors in advanced stages showed low expression of AA-NAT and MT2 in wtp53 tumors. These results could indicate a possible interaction of these pathways in CRC.

Melatonin, a Full Service Anti-Cancer Agent: Inhibition of Initiation, Progression and Metastasis

There is highly credible evidence that melatonin mitigates cancer at the initiation, progression and metastasis phases. In many cases, the molecular mechanisms underpinning these inhibitory actions have been proposed. What is rather perplexing, however, is the large number of processes by which melatonin reportedly restrains cancer development and growth. These diverse actions suggest that what is being observed are merely epiphenomena of an underlying more fundamental action of melatonin that remains to be disclosed. Some of the arresting actions of melatonin on cancer are clearly membrane receptor-mediated while others are membrane receptor-independent and involve direct intracellular actions of this ubiquitously-distributed molecule. While the emphasis of melatonin/cancer research has been on the role of the indoleamine in restraining breast cancer, this is changing quickly with many cancer types having been shown to be susceptible to inhibition by melatonin. There are several facets of this research which could have immediate applications at the clinical level. Many studies have shown that melatonin's co-administration improves the sensitivity of cancers to inhibition by conventional drugs. Even more important are the findings that melatonin renders cancers previously totally resistant to treatment sensitive to these same therapies. Melatonin also inhibits molecular processes associated with metastasis by limiting the entrance of cancer cells into the vascular system and preventing them from establishing secondary growths at distant sites. This is of particular importance since cancer metastasis often significantly contributes to death of the patient. Another area that deserves additional consideration is related to the capacity of melatonin in reducing the toxic consequences of anti-cancer drugs while increasing their efficacy. Although this information has been available for more than a decade, it has not been adequately exploited at the clinical level. Even if the only beneficial actions of melatonin in cancer patients are its ability to attenuate acute and long-term drug toxicity, melatonin should be used to improve the physical wellbeing of the patients. The experimental findings, however, suggest that the advantages of using melatonin as a co-treatment with conventional cancer therapies would far exceed improvements in the wellbeing of the patients.

Comparison of melatonin with growth factors in promoting precursor cells proliferation in adult mouse subventricular zone

Melatonin, secreted mainly by the pineal gland, plays roles in various physiological functions including protecting cell death. We showed in previous study that the proliferation and differentiation of precursor cells from the adult mouse subventricular zone (SVZ) can be modulated by melatonin via the MT1 melatonin receptor. Since melatonin and epidermal growth factor receptor (EGFR) share some signaling pathway components, we investigated whether melatonin can promote the proliferation of precursor cells from the adult mouse SVZ via the extracellular signal-regulated protein kinase /mitogen-activated protein kinase (ERK/MAPK) pathways in comparison with epidermal growth factor (EGF). Melatonin-induced ERK/MAPK pathways compared with EGF were measured by using in vitro and vivo models. We used neurosphere proliferation assay, immunocytochemistry, and immuno-blotting to analyze significant differences between melatonin and growth factor treatment. We also used specific antagonist and inhibitors to confirm the exactly signaling pathway including luzindole and U0126. We found that significant increase in proliferation was observed when two growth factors (EGF+bFGF) and melatonin were used simultaneously compared with EGF + bFGF or compared with melatonin alone. In addition, the present result suggested the synergistic effect occurred of melatonin and growth factors on the activating the ERK/MAPK pathway. This study exhibited that melatonin could act as a trophic factor, increasing proliferation in precursor cells mediated through the melatonin receptor coupled to ERK/MAPK signaling pathways. Understanding the mechanism by which melatonin regulates precursor cells may conduct to the development of novel strategies for neurodegenerative disease therapy.

Effects of melatonin on HIF-1α and VEGF expression and on the invasive properties of hepatocarcinoma cells

Liver cancer is the sixth most commonly occurring cancer globally, and the main histological type is hepatocellular carcinoma. This type of neoplasia has a poor prognosis due to a high rate of recurrence and intrahepatic metastasis, which are closely are closely associated with the angiogenic process. Vascular endothelial growth factor (VEGF), which is under the control of hypoxia inducible factor-1α (HIF-1α), stimulates the proliferation of endothelial cells and increases cell permeability, promoting the growth, spread and metastasis of tumors. Melatonin, the main hormone secreted by the pineal gland, may have a significant role in tumor suppression and has demonstrated antiangiogenic and antimetastatic effects. The aim of the present study was to analyze the cell viability, migration and invasion, as well as the expression of proangiogenic proteins VEGF and HIF-1α, in HepG2 hepatocarcinoma cells, following treatment with melatonin. Cells were cultured and cell viability was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The expression of proangiogenic proteins VEGF and HIF-1α, under conditions of normoxia and hypoxia, was verified using immunocytochemistry and quantified by densitometry. The analysis of the processes of cell migration and invasion was performed in a Boyden chamber. The MTT assay revealed a reduction in cell viability (P=0.018) following treatment with 1 mM melatonin for 24 h. The expression of proangiogenic proteins VEGF and HIF-1α was reduced in cells treated with 1 mM melatonin for 24 h in normoxic (P<0.001) and hypoxic (P<0.001) conditions, compared with the control group and with induced hypoxia alone. The rate of cell migration and invasion was additionally reduced in cells treated with 1 mM melatonin for 48 h when compared with the control group (P=0.496). The results of the present study suggest that melatonin may have an antiproliferative, antiangiogenic and antimetastatic role in hepatocarcinoma cells and may present a novel therapeutic option for the treatment of liver cancer.

Oncostatic-Cytoprotective Effect of Melatonin and Other Bioactive Molecules: A Common Target in Mitochondrial Respiration

For several years, oncostatic and antiproliferative properties, as well as thoses of cell death induction through 5-methoxy-N-acetiltryptamine or melatonin treatment, have been known. Paradoxically, its remarkable scavenger, cytoprotective and anti-apoptotic characteristics in neurodegeneration models, such as Alzheimer’s disease and Parkinson’s disease are known too. Analogous results have been confirmed by a large literature to be associated to the use of many other bioactive molecules such as resveratrol, tocopherol derivatives or vitamin E and others. It is interesting to note that the two opposite situations, namely the neoplastic pathology and the neurodegeneration, are characterized by deep alterations of the metabolome, of mitochondrial function and of oxygen consumption, so that the oncostatic and cytoprotective action can find a potential rationalization because of the different metabolic and mitochondrial situations, and in the effect that these molecules exercise on the mitochondrial function. In this review we discuss historical and general aspects of melatonin, relations between cancers and the metabolome and between neurodegeneration and the metabolome, and the possible effects of melatonin and of other bioactive molecules on metabolic and mitochondrial dynamics. Finally, we suggest a common general mechanism as responsible for the oncostatic/cytoprotective effect of melatonin and of other molecules examined.

Metabolomics of papillary thyroid carcinoma tissues: potential biomarkers for diagnosis and promising targets for therapy

Papillary thyroid carcinoma (PTC) is the most common pathological type of thyroid cancer. Our study was to construct a tissue-targeted metabolomics analysis method based on untargeted and targeted metabolic multi-platforms to identify a comprehensive PTC metabolic network in clinical samples. We applied untargeted gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS) for preliminary screening of potential biomarkers. With diagnostic models constructed using principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and orthogonal partial least squares discriminant analysis (OPLS-DA), 45 differentially abundant metabolites with a variable importance in the projection (VIP) value greater than 1 and a P value less than 0.05 were identified, and we show that our approach was able to discriminate PTC tissues from healthy tissues. We then performed validation experiments based on targeted GC-TOF-MS combined with ultra-high-performance liquid chromatography-triple-quadrupole mass spectrometry (UHPLC-QqQ-MS) through constructing linear standard curves of analytes. Ultimately, galactinol, melibiose, and melatonin were validated as significantly altered metabolites (p < 0.05). These three metabolites were defined as a combinatorial biomarker to assist needle biopsy for PTC diagnosis as demonstrated by receiver operating characteristic (ROC) curve analysis, which revealed an area under the ROC curve (AUC) value of 0.96. Based on the metabolite enrichment analysis results, the galactose metabolism pathway was regarded as an important factor influencing PTC development by affecting energy metabolism. Alpha-galactosidase (GLA) was considered to be a potential target for PTC therapy.

Membrane receptor-dependent Notch1/Hes1 activation by melatonin protects against myocardial ischemia-reperfusion injury: in vivo and in vitro studies

Melatonin confers profound protective effect against myocardial ischemia-reperfusion injury (MI/RI). Activation of Notch1/Hairy and enhancer of split 1 (Hes1) signaling also ameliorates MI/RI. We hypothesize that melatonin attenuates MI/RI-induced oxidative damage by activating Notch1/Hes1 signaling pathway with phosphatase and tensin homolog deleted on chromosome 10 (Pten)/Akt acting as the downstream signaling pathway in a melatonin membrane receptor-dependent manner. Male Sprague Dawley rats were treated with melatonin (10 mg/kg/day) for 4 wk and then subjected to MI/R surgery. Melatonin significantly improved cardiac function and decreased myocardial apoptosis and oxidative damage. Furthermore, in cultured H9C2 cardiomyocytes, melatonin (100 μmol/L) attenuated simulated ischemia-reperfusion (SIR)-induced myocardial apoptosis and oxidative damage. Both in vivo and in vitro study demonstrated that melatonin treatment increased Notch1, Notch1 intracellular domain (NICD), Hes1, Bcl-2 expressions, and p-Akt/Akt ratio and decreased Pten, Bax, and caspase-3 expressions. However, these protective effects conferred by melatonin were blocked by DAPT (the specific inhibitor of Notch1 signaling), luzindole (the antagonist of melatonin membrane receptors), Notch1 siRNA, or Hes1 siRNA administration. In summary, our study demonstrates that melatonin treatment protects against MI/RI by modulating Notch1/Hes1 signaling in a receptor-dependent manner and Pten/Akt signaling pathways are key downstream mediators.

Melatonin affects voltage-dependent calcium and potassium currents in MCF-7 cell line cultured either in growth or differentiation medium

Big efforts have been dedicated up to now to identify novel targets for cancer treatment. The peculiar biophysical profile and the atypical ionic channels activity shown by diverse types of human cancers suggest that ion channels may be possible targets in cancer therapy. Earlier studies have shown that melatonin exerts an oncostatic action on different tumors. In particular, it was shown that melatonin was able to inhibit growth/viability and proliferation, to reduce the invasiveness and metastatic properties of human estrogen-sensitive breast adenocarcinoma MCF-7 cell line cultured in growth medium, with substantial impairments of epidermal growth factor (EGF) and Notch-1-mediated signaling. The purpose of this work was to evaluate on MCF-7 cells the possible effects of melatonin on the biophysical features known to have a role in proliferation and differentiation, by using the patch-clamp technique. Our results show that in cells cultured in growth as well as in differentiation medium melatonin caused a hyperpolarization of resting membrane potential paralleled by significant changes of the inward Ca(2+) currents (T- and L-type), outward delayed rectifier K(+) currents and cell capacitance. All these effects are involved in MCF-7 growth and differentiation. These findings strongly suggest that melatonin, acting as a modulator of different voltage-dependent ion channels, might be considered a new promising tool for specifically disrupting cell viability and differentiation pathways in tumour cells with possible beneficial effects on cancer therapy.

mRNA expression of somatostatin receptor subtypes SSTR-2, SSTR-3, and SSTR-5 and its significance in pancreatic cancer

Background

The aim of this study is to investigate the expressions of somatostatin receptor (SSTR), SSTR-2, SSTR-3, and SSTR-5, in pancreatic tissue and non-cancerous tissue and elucidate their clinical significance.

Methods

The expression of somatostatin receptor subtypes SSTR-2, SSTR-3, and SSTR-5 messenger RNA (mRNA) in 108 cases of cancer tissue and adjacent tissue in patients with pancreatic cancer was detected by reverse transcriptase polymerase chain reaction (RT-PCR). Expression of SSTR-2, SSTR-3, and SSTR-5 mRNA was evaluated after specimens were taken from selected patients who underwent surgical resection by Whipple’s operation. We speculated the clinical significance of the expression of somatostatin receptor (SSTR) subtype genes SSTR-2, SSTR-3, and SSTR-5 in pancreatic tissue and non-cancerous tissue and further elucidated their clinical significance.

Results

The expression rates of SSTR-2 mRNA in cancer and adjacent tissue of 108 patients with pancreatic cancer were 81.5% (88/108) and 97.2% (105/108), respectively; SSTR-3 mRNA expression rates were 69.4% (75/108) and 55.6% (60/108). SSTR-5 mRNA expression rates were 13.0% (14/108) and 18.5% (20/108).

Conclusion

We propose that SSTR-2 plays an important role in clinical implications for patients with pancreatic cancer undergoing somatostatin or its analog therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12957-015-0467-z) contains supplementary material, which is available to authorized users.

Buying time: a rationale for examining the use of circadian rhythm and sleep interventions to delay progression of mild cognitive impairment to Alzheimer's disease

As of 2010, the worldwide economic impact of dementia was estimated at $604 billion USD; and without discovery of a cure or effective interventions to delay disease progression, dementia's annual global economic impact is expected to surpass $1 trillion USD as early as 2030. Alzheimer's disease (AD) is the leading cause of dementia accounting for over 75% of all cases. Toxic accumulation of amyloid beta (Aβ), either by overproduction or some clearance failure, is thought to be an underlying mechanism of the neuronal cell death characteristic of AD-though this amyloid hypothesis has been increasingly challenged in recent years. A compelling alternative hypothesis points to chronic neuroinflammation as a common root in late-life degenerative diseases including AD. Apolipoprotein-E (APOE) genotype is the strongest genetic risk factor for AD: APOE-ε4 is proinflammatory and individuals with this genotype accumulate more Aβ, are at high risk of developing AD, and almost half of all AD patients have at least one ε4 allele. Recent studies suggest a bidirectional relationship exists between sleep and AD pathology. Sleep may play an important role in Aβ clearance, and getting good quality sleep vs. poor quality sleep might reduce the AD risk associated with neuroinflammation and the ε4 allele. Taken together, these findings are particularly important given the sleep disruptions commonly associated with AD and the increased burden disrupted sleep poses for AD caregivers. The current review aims to: (1) identify individuals at high risk for dementia who may benefit most from sleep interventions; (2) explore the role poor sleep quality plays in exacerbating AD type dementia; (3) examine the science of sleep interventions to date; and (4) provide a road map in pursuit of comprehensive sleep interventions, specifically targeted to promote cognitive function and delay progression of dementia.

Effect of melatonin on tumor growth and angiogenesis in xenograft model of breast cancer

As neovascularization is essential for tumor growth and metastasis, controlling angiogenesis is a promising tactic in limiting cancer progression. Melatonin has been studied for their inhibitory properties on angiogenesis in cancer. We performed an in vivo study to evaluate the effects of melatonin treatment on angiogenesis in breast cancer. Cell viability was measured by MTT assay after melatonin treatment in triple-negative breast cancer cells (MDA-MB-231). After, cells were implanted in athymic nude mice and treated with melatonin or vehicle daily, administered intraperitoneally 1 hour before turning the room light off. Volume of the tumors was measured weekly with a digital caliper and at the end of treatments animals underwent single photon emission computed tomography (SPECT) with Technetium-99m tagged vascular endothelial growth factor (VEGF) C to detect in vivo angiogenesis. In addition, expression of pro-angiogenic/growth factors in the tumor extracts was evaluated by membrane antibody array and collected tumor tissues were analyzed with histochemical staining. Melatonin in vitro treatment (1 mM) decreased cell viability (p<0.05). The breast cancer xenografts nude mice treated with melatonin showed reduced tumor size and cell proliferation (Ki-67) compared to control animals after 21 days of treatment (p<0.05). Expression of VEGF receptor 2 decreased significantly in the treated animals compared to that of control when determined by immunohistochemistry (p<0.05) but the changes were not significant on SPECT (p>0.05) images. In addition, there was a decrease of micro-vessel density (Von Willebrand Factor) in melatonin treated mice (p<0.05). However, semiquantitative densitometry analysis of membrane array indicated increased expression of epidermal growth factor receptor and insulin-like growth factor 1 in treated tumors compared to vehicle treated tumors (p<0.05). In conclusion, melatonin treatment showed effectiveness in reducing tumor growth and cell proliferation, as well as in the inhibition of angiogenesis.

Melatonin potentiates the antiproliferative and pro-apoptotic effects of ursolic acid in colon cancer cells by modulating multiple signaling pathways

Ursolic acid (UA), a natural pentacyclic triterpenoid carboxylic acid, is largely distributed in medical herbs and edible plants. Melatonin is an indoleamine compound produced in the pineal gland and also a plant-derived product. Both UA and melatonin have been shown to inhibit cancer cell growth in numerous studies, but they have never been combined altogether as an anticolon cancer treatment. In this study, we investigated whether the association between UA and melatonin leads to an enhanced antiproliferative and pro-apoptotic activities in colon cancer SW480 and LoVo cells. We found that combined treatment with UA and melatonin significantly enhanced inhibition of cell viability and migration, promoted changes in cell morphology and spreading, and increased induction of apoptosis, thereby potentiating the effects of UA alone in colon cancer cells. Moreover, we found that the enhanced effects of UA and melatonin combination are mediated through simultaneous modulation of cytochrome c/caspase, MMP9/COX-2, and p300/NF-κB signaling pathways. Combined treatment with UA and melatonin triggered the release of cytochrome c from the mitochondrial intermembrane space into the cytosol, induced cleavage of caspase and PARP proteins, enhanced inhibition of MMP9 and COX-2 expression, promoted p300 and NF-κB translocation from cell nuclei to cytoplasm, and abrogated NF-κB binding and p300 recruitment to COX-2 promoter in colon cancer cells. These results, therefore, demonstrated that melatonin potentiated the antiproliferative and pro-apoptotic effects of UA in colon cancer cells by modulating multiple signaling pathways and suggest that such a combinational treatment might potentially become an effective way in colon cancer therapy.

A Comparison of B16 Melanoma Cells and 3T3 Fibroblasts Concerning Cell Viability and ROS Production in the Presence of Melatonin, Tested Over a Wide Range of Concentrations

Melatonin is a pleiotropic molecule with many cellular and systemic actions, including chronobiotic effects. Beneficial effects are widely documented concerning the treatment of neoplastic diseases in vivo as well as reductions in viability of cultured cells from melanoma, one of the most aggressive cancers in humans. However, studies of its effects on non-tumor cells in vitro have not focused on viability, except for experiments aiming to protect against oxidotoxicity or other toxicological insults. Furthermore, there is no agreement on the range of effective melatonin concentrations in vitro, and the mechanisms that reduce cell viability have remained unclear. Tumor cell-specific increases in the production of reactive oxygen and nitrogen species (ROS/RNS) may provide a possible explanation. Our aim was to analyze the potential inhibition of tumor (B16 melanoma 4A5) and non-tumor cell (3T3 Swiss albino) viability using a wide range of melatonin concentrations (10⁻¹¹–10⁻² M), and to determine whether intracellular ROS enhancement was involved in this process. In the absence of fetal bovine serum (FBS), low melatonin concentrations (10⁻⁹–10⁻⁵ M) reduced the proliferation of melanoma cells with no effect in fibroblasts, whereas, in the presence of FBS, they had no effect or even increased the proliferation of both fibroblast and melanoma cells. Melatonin concentrations in the upper millimolar range increased ROS levels and reduced the viability of both cell types, but more markedly so in non-tumor cells. Thus, low melatonin concentrations reduce proliferation in this specific melanoma cell line, whereas high concentrations affect the viability of both tumor (B16 4A5 melanoma) and non-tumor (3T3 fibroblasts) cells. Increased ROS levels in both lines indicate a role for ROS production in the reduction of cell viability at high—but not low—melatonin concentrations, although the mechanism of action still remains to be elucidated.

Insulin resistance and cancer: the role of insulin and IGFs

Insulin, IGF1, and IGF2 are the most studied insulin-like peptides (ILPs). These are evolutionary conserved factors well known as key regulators of energy metabolism and growth, with crucial roles in insulin resistance-related metabolic disorders such as obesity, diseases like type 2 diabetes mellitus, as well as associated immune deregulations. A growing body of evidence suggests that insulin and IGF1 receptors mediate their effects on regulating cell proliferation, differentiation, apoptosis, glucose transport, and energy metabolism by signaling downstream through insulin receptor substrate molecules and thus play a pivotal role in cell fate determination. Despite the emerging evidence from epidemiological studies on the possible relationship between insulin resistance and cancer, our understanding on the cellular and molecular mechanisms that might account for this relationship remains incompletely understood. The involvement of IGFs in carcinogenesis is attributed to their role in linking high energy intake, increased cell proliferation, and suppression of apoptosis to cancer risks, which has been proposed as the key mechanism bridging insulin resistance and cancer. The present review summarizes and discusses evidence highlighting recent advances in our understanding on the role of ILPs as the link between insulin resistance and cancer and between immune deregulation and cancer in obesity, as well as those areas where there remains a paucity of data. It is anticipated that issues discussed in this paper will also recover new therapeutic targets that can assist in diagnostic screening and novel approaches to controlling tumor development.

Melatonin anticancer effects: review

Melatonin (N-acetyl-5-methoxytryptamine, MLT), the main hormone produced by the pineal gland, not only regulates circadian rhythm, but also has antioxidant, anti-ageing and immunomodulatory properties. MLT plays an important role in blood composition, medullary dynamics, platelet genesis, vessel endothelia, and in platelet aggregation, leukocyte formula regulation and hemoglobin synthesis. Its significant atoxic, apoptotic, oncostatic, angiogenetic, differentiating and antiproliferative properties against all solid and liquid tumors have also been documented. Thanks, in fact, to its considerable functional versatility, MLT can exert both direct and indirect anticancer effects in factorial synergy with other differentiating, antiproliferative, immunomodulating and trophic molecules that form part of the anticancer treatment formulated by Luigi Di Bella (Di Bella Method, DBM: somatostatin, retinoids, ascorbic acid, vitamin D3, prolactin inhibitors, chondroitin-sulfate). The interaction between MLT and the DBM molecules counters the multiple processes that characterize the neoplastic phenotype (induction, promotion, progression and/or dissemination, tumoral mutation). All these particular characteristics suggest the use of MLT in oncological diseases.

Photoactivation of bone marrow mesenchymal stromal cells with diode laser: effects and mechanisms of action

Mesenchymal stromal cells (MSCs) are a promising cell candidate in tissue engineering and regenerative medicine. Their proliferative potential can be increased by low-level laser irradiation (LLLI), but the mechanisms involved remain to be clarified. With the aim of expanding the therapeutic application of LLLI to MSC therapy, in the present study we investigated the effects of 635 nm diode laser on mouse MSC proliferation and investigated the underlying cellular and molecular mechanisms, focusing the attention on the effects of laser irradiation on Notch-1 signal activation and membrane ion channel modulation. It was found that MSC proliferation was significantly enhanced after laser irradiation, as judged by time lapse videomicroscopy and EdU incorporation. This phenomenon was associated with the up-regulation and activation of Notch-1 pathway, and with increased membrane conductance through voltage-gated K(+) , BK and Kir, channels and T- and L-type Ca(2+) channels. We also showed that MSC proliferation was mainly dependent on Kir channel activity, on the basis that the cell growth and Notch-1 up-regulation were severely decreased by the pre-treatment with the channel inhibitor Ba(2+) (0.5 mM). Interestingly, the channel inhibition was also able to attenuate the stimulatory effects of diode laser on MSCs, thus providing novel evidence to expand our knowledge on the mechanisms of biostimulation after LLLI. In conclusions, our findings suggest that diode laser may be a valid approach for the preconditioning of MSCs in vitro prior cell transplantation.