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

Melatonin in Chemo/Radiation Therapy; Implications for Normal Tissues Sparing and Tumor Suppression: An Updated Review

Resistance to therapy and the toxicity of normal tissue are the major problems for efficacy associated with chemotherapy and radiotherapy. Drug resistance is responsible for most cases of mortality associated with cancer. Furthermore, their side effects can decrease the quality of life for surviving patients. An enhancement in the tumor response to therapy and alleviation of toxic effects remain unsolved challenges. One of the interesting topics is the administration of agents with low toxicity to protect normal tissues and/or sensitize cancers to chemo/radiotherapy. Melatonin is a natural body hormone that is known as a multitasking molecule. Although it has antioxidant properties, a large number of experiments have uncovered interesting effects of melatonin that can increase the therapeutic efficacy of chemo/radiation therapy. Melatonin can enhance anticancer therapy efficacy through various mechanisms, cells such as the immune system, and modulation of cell cycle and death pathways, tumor suppressor genes, and also through suppression of some drug resistance mediators. However, melatonin may protect normal tissues through the suppression of inflammation, fibrosis, and massive oxidative stress in normal cells and tissues. In this review, we will discuss the distinct effects of melatonin on both tumors and normal tissues. We review how melatonin may enhance radio/chemosensitivity of tumors while protecting normal tissues such as the lung, heart, gastrointestinal system, reproductive system, brain, liver, and kidney.

Melatonin and vitamin D as potential synergistic adjuvants for cancer therapy (Review)

Significant advancements have been made in cancer therapy; however, limitations remain with some conventional approaches. Adjuvants are agents used alongside primary treatments to enhance their efficacy and the treatment outcomes of patients. Modern lifestyles contribute to deficiencies in melatonin and vitamin D. Limited sun exposure affects vitamin D synthesis, and artificial light at night suppresses melatonin production. Both melatonin and vitamin D possess anti‑inflammatory, immune‑boosting and anticancer properties, rendering them potential adjuvants of interest. Studies suggest melatonin and vitamin D supplementation may address antioxidant imbalances in lip, oral and pharyngeal cancers. Moreover, promising results from breast, head and neck, brain, and osteosarcoma research indicate potential for tumor growth inhibition, improved survival, and a better quality of life of patients with cancer. The radioprotective properties of melatonin and vitamin D are another exciting area of exploration, potentially enhancing radiotherapy effectiveness while reducing side effects. For its part, the sleep‑promoting effects of melatonin may indirectly benefit patients with cancer by influencing the immune system. Thus, the prevalence of vitamin D and melatonin deficiencies highlights the importance of supplementation, as lower levels can worsen side‑effects from cancer treatments. The present review explores the potential of combining melatonin and vitamin D as synergistic adjuvants for cancer therapy. These agents have shown promise individually in cancer prevention and treatment, and their combined effects warrant investigation. Therefore, large‑scale controlled trials are crucial to definitively determine the optimal dosage, safety and efficacy of this combination in improving the lives of patients with cancer.

Prognostic Evaluation for Hepatocellular Carcinoma with Portal Vein Tumor Thrombus Patients Treated with Transarterial Chemoembolization Plus Molecular Targeted Therapies-Development and Validation of the ABPS Score

RATIONALE AND OBJECTIVES

Transarterial chemoembolization (TACE) plus molecular targeted therapies has emerged as the main approach for treating hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT). A robust model for outcome prediction and risk stratification of recommended TACE plus molecular targeted therapies candidates is lacking. We aimed to develop an easy-to-use tool specifically for these patients.

METHODS

A retrospective analysis was conducted on 384 patients with HCC and PVTT who underwent TACE plus molecular targeted therapies at 16 different institutions. We developed and validated a new prognostic score which called ABPS score. Additionally, an external validation was performed on data from 200 patients enrolled in a prospective cohort study.

RESULTS

The ABPS score (ranging from 0 to 3 scores), which involves only Albumin-bilirubin (ALBI, grade 1: 0 score; grade 2: 1 score), PVTT(I-II type: 0 score; III-IV type: 1 score), and systemic-immune inflammation index (SII,<550 × 1012: 0 score; ≥550 × 1012: 1 score). Patients were categorized into three risk groups based on their ABPS score: ABPS-A, B, and C (scored 0, 1-2, and 3, respectively). The concordance index (C-index) of the ABPS scoring system was calculated to be 0.802, significantly outperforming the HAP score (0.758), 6-12 (0.712), Up to 7 (0.683), and ALBI (0.595) scoring systems (all P < 0.05). These research findings were further validated in the external validation cohorts.

CONCLUSION

The ABPS score demonstrated a strong association with survival outcomes and radiological response in patients undergoing TACE plus molecular targeted therapy for HCC with PVTT. The ABPS scoring system could serve as a valuable tool to guide treatment selection for these patients.

The Relationship Between Melatonin 1-2 Receptor Expression in Patients With Epithelial Ovarian Cancer and Survival

Melatonin has antiproliferative, antiangiogenic, apoptotic, and immunomodulatory properties in ovarian cancer. Considering those, we evaluated the relationship between melatonin 1 (MT1) and melatonin 2 receptor (MT2) expression in tumor tissues of patients with epithelial ovarian cancer, disease-free survival (DFS), and overall survival (OS). Patients who received primary surgical treatment for epithelial ovarian cancer in our clinic between 2000 and 2019 were retrospectively scanned through patient files, electronic databases, and telephone calls. One hundred forty-two eligible patients were included in the study, their tumoral tissues were examined to determine MT1 and MT2 expression by immunohistochemical methods. The percentage of receptor-positive cells and intensity of staining were determined. MT1 receptor expression ( P = 0.002 for DFS and P = 0.002 for OS) showed a significant effect on DFS and OS. MT2 expression had no effect on survival ( P = 0.593 for DFS and P = 0.209 for OS). The results showed that the higher the MT1 receptor expression, the longer the DFS and OS. It is suggested that melatonin should be considered as adjuvant therapy for ovarian cancer patients in addition to standard treatment, and clinical progress should be observed.

Fucoidan/chitosan layered PLGA nanoparticles with melatonin loading for inducing intestinal absorption and addressing triple-negative breast cancer progression

Melatonin and fucoidan are naturally active compounds that have been reported to have therapeutic benefits for patients receiving cancer treatment. However, both compounds face significant challenges, including physical, chemical, and biological metabolisms in the gastrointestinal tract, which limit their ability to achieve therapeutic concentrations at the tumor site. Furthermore, the effectiveness of melatonin and fucoidan as adjuvants in vivo is influenced by the route of administration through the digestive system and their accumulation at the endpoint of the tumor. In this study, we developed an oral administration of nanoparticle, MNPs@C@F, that consisted of PLGA nanoparticles modified with chitosan, to promote intestinal microfold cell transcytosis for the delivery of melatonin and fucoidan into tumors. The experimental results indicated that melatonin and fucoidan in the tumors could regulate the tumor microenvironment by decreasing P-gp, Twist, HIF-1α, and anti-inflammatory immune cell expression, and increasing cytotoxic T cell populations following doxorubicin treatment. This resulted in an increase in chemo-drug sensitivity, inhibition of distant organ metastasis, and promotion of immunogenic cell death. This study demonstrates a favorable co-delivery system of melatonin and fucoidan to directly reduce drug resistance and metastasis in TNBC.

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

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

Comparing the effectiveness and safety of Sorafenib plus TACE with Apatinib plus TACE for treating patients with unresectable hepatocellular carcinoma: a multicentre propensity score matching study

OBJECTIVE

Local combined systemic therapy has been an important method for the treatment of unresectable hepatocellular carcinoma (HCC).The purpose of this study was to compare the effectiveness and safety of transarterial chemoembolization (TACE) plus Sorafenib versus TACE plus Apatinib for treating patients with unresectable HCC.

METHODS

The clinical data of patients with unresectable HCC who were treated with TACE plus Sorafenib or TACE plus Apatinib at 5 Chinese medical centers between January 2016 and December 2020 were retrospectively analyzed. Propensity score matching (PSM) was applied to reduce the bias from confounding factors.

RESULTS

A total of 380 patients were enrolled, of whom 129 cases were treated with TACE plus Sorafenib and 251 cases with TACE plus Apatinib. After the 1:1 PSM, 116 pairs of patients were involved in this study. The results showed that the PFS and OS in the TACE-Sorafenib group were significantly longer than those in the TACE-Apatinib group (PFS: 16.79 ± 6.45 vs. 14.76 ± 6.98 months, P = 0.049; OS: 20.66 ± 6.98 vs. 17.69 ± 6.72 months, P = 0.013). However, the ORR in the TACE-Apatinib group was markedly higher than that in the TACE-Sorafenib group (70.69% vs. 56.03%, P = 0.021). There were more patients with adverse events (AEs) in the TACE-Apatinib group than those in the TACE-Sorafenib group before dose adjustment (87 vs. 63, P = 0.001); however, the number of patients who suffered from AEs was not significantly different between the two groups after the dose adjustment (62 vs. 55, P = 0.148). No treatment-related death was found in the two groups. Subgroup analysis revealed that patients with unresectable HCC could better benefit from regular doses than reduced doses (Sorafenib, 22.59 vs. 18.02, P < 0.001; Apatinib, 19.75 vs. 16.86, P = 0.005).

CONCLUSION

TACE plus either Sorafenib or Apatinib could effectively treat patients with unresectable HCC, the safety of TACE plus Sorafenib was better. and the ORR of TACE plus Apatinib was higher.

Anti-proliferative effect of melatonin in human hepatoma HepG2 cells occurs mainly through cell cycle arrest and inflammation inhibition

Hepatocellular carcinoma (HCC) is the major lethal primary liver malignant worldwide. Although, melatonin has various antitumor bioactivities; there is a requirement for more investigations to elucidate the not discussed effects, and the controversial responses of the treatment with melatonin on targets mediated in HCC. To achieve the aim of the present study, HCC-HepG2 cells were treated with different concentrations of melatonin at various time intervals. The selected minimal proliferation inhibition doses of melatonin were then incubated with cells to examine the arresting effect of melatonin on dividing cells using flow cytometry. Furthermore, the molecular patterns of genes that contributed to apoptosis, drug resistance development, antioxidation, and melatonin crossing were quantified by qRT-PCR. Additionally, the Human inflammation antibody array membrane (40 targets) was used to check the anti-inflammatory effect of melatonin. Our results validated that, melatonin shows anti-proliferative action through preserving cells in G0/G1 phase (P < 0.001) that is associated with a highly significant increase in the expression level of the P53 gene (P < 0.01). On contrary, as a novelty, our data recorded decreases in expression levels of genes involved in the pro-apoptotic pathway; with a significant increase (P < 0.05) in the expression level of an anti-apoptotic gene, Bcl2. Interestingly, we detected observed increases in the expression levels of genes responsible for conferring drug resistance including ABCB1, ABCC1, and ABCC5. Our study proved the anti-inflammatory activity of 1 mM melatonin in HCC-HepG2 cells. Accordingly, we can conclude that melatonin facilitates the anti-proliferation of cells at doses of 1 mM, and 2.5 mM after 24 h. This action is initiated through cell cycle arrest at G0/G1 phase via increasing the expression of P53, but independently on apoptosis. Collectively, melatonin is an effective anti-inflammatory and anti-proliferative promising therapy for the treatment of HCC. However, its consumption should be cautious to avoid the development of drug resistance and provide a better treatment strategy.

Melatonin inhibits HCC progression through regulating the alternative splicing of NEMO

Hepatocellular carcinoma (HCC) is one of the most common primary cancers with limited therapeutic options. Melatonin, a neuroendocrine hormone produced primarily by the pineal gland, demonstrates an anti-cancer effect on a myriad of cancers including HCC. However, whether melatonin could suppress tumor growth through regulating RNA alternative splicing remains largely unknown. Here we demonstrated that melatonin could inhibit the growth of HCC. Mechanistically, melatonin induced transcriptional alterations of genes, which are involved in DNA replication, DNA metabolic process, DNA repair, response to wounding, steroid metabolic process, and extracellular matrix functions. Importantly, melatonin controlled numerous cancer-related RNA alternative splicing events, regulating mitotic cell cycle, microtubule-based process, kinase activity, DNA metabolic process, GTPase regulator activity functions. The regulatory effect of melatonin on alternative splicing is partially mediated by melatonin receptor MT1. Specifically, melatonin regulates the splicing of IKBKG (NEMO), an essential modulator of NF-κB. In brief, melatonin increased the production of the long isoform of NEMO-L with exon 5 inclusion, thereby inhibiting the growth of HepG2 cells. Collectively, our study provides a novel mechanism of melatonin in regulating RNA alternative splicing, and offers a new perspective for melatonin in the inhibition of cancer progression.

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

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

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.

Melatonin is a potential oncostatic agent to inhibit HepG2 cell proliferation through multiple pathways

CONTEXT

Chemotherapy is a cornerstone in the treatment of hepatocellular carcinoma (HCC). Melatonin is a pineal hormone that targets various cancers, however, its antitumor pathways are still not fully elucidated.

OBJECTIVE

This study investigated melatonin's antitumor molecular mechanisms to inhibit the proliferation of HepG2 cells.

MATERIALS AND METHODS

HepG2 Cells were classified into cells without treatment as a control group and cells treated with melatonin (5.4 mmol/L) for 48 h. Proliferating cell nuclear antigen (PCNA) and marker of proliferation Ki-67 were estimated using immunohistochemical analysis. Apoptosis and cell cycle were evaluated using flow cytometric analysis. Apoptotic markers were detected using RT-qPCR assay. Antioxidants and oxidative stress biomarkers were performed using a colorimetric assay.

RESULTS

Melatonin produced a remarkable steady decrease in the viability of HepG2 cells at a concentration range between 5-20 mmol/L. Melatonin suppressed cell proliferation in the G2/M phase of the cell cycle (34.97 ± 0.92%) and induced apoptosis (12.43 ± 0.73%) through up-regulating p21 and p53 that was confirmed by the reduction of PCNA and Ki-67 expressions. Additionally, melatonin repressed angiogenesis evidenced by the down-regulation of angiopoietin-2, vascular endothelial growth factor receptor-2 expressions (0.42-fold change), and the level of CD133. Moreover, melatonin augmented the oxidative stress manifested by a marked increase of 4-hydroxynonenal levels with a reduction of glutathione content and superoxide dismutase activity.

DISCUSSION AND CONCLUSION

Melatonin inhibits proliferation and angiogenesis and induced apoptosis and oxidative stress in HepG2 cells. These results indicate the oncostatic effectiveness of melatonin on liver cancer.

Modulation of the tumor microenvironment (TME) by melatonin

The tumor microenvironment (TME) includes a number of non-cancerous cells that affect cancer cell survival. Although CD8+ T lymphocytes and natural killer (NK) cells suppress tumor growth through induction of cell death in cancer cells, there are various immunosuppressive cells such as regulatory T cells (Tregs), tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), etc., which drive cancer cell proliferation. These cells may also support tumor growth and metastasis by stimulating angiogenesis, epithelial-mesenchymal transition (EMT), and resistance to apoptosis. Interactions between cancer cells and other cells, as well as molecules released into EMT, play a key role in tumor growth and suppression of antitumoral immunity. Melatonin is a natural hormone that may be found in certain foods and is also available as a drug. Melatonin has been demonstrated to modulate cell activity and the release of cytokines and growth factors in TME. The purpose of this review is to explain the cellular and molecular mechanisms of cancer cell resistance as a result of interactions with TME. Next, we explain how melatonin affects cells and interactions within the TME.

Metabolic Anti-Cancer Effects of Melatonin: Clinically Relevant Prospects

Metabolic reprogramming characterized by alterations in nutrient uptake and critical molecular pathways associated with cancer cell metabolism represents a fundamental process of malignant transformation. Melatonin (N-acetyl-5-methoxytryptamine) is a hormone secreted by the pineal gland. Melatonin primarily regulates circadian rhythms but also exerts anti-inflammatory, anti-depressant, antioxidant and anti-tumor activities. Concerning cancer metabolism, melatonin displays significant anticancer effects via the regulation of key components of aerobic glycolysis, gluconeogenesis, the pentose phosphate pathway (PPP) and lipid metabolism. Melatonin treatment affects glucose transporter (GLUT) expression, glucose-6-phosphate dehydrogenase (G6PDH) activity, lactate production and other metabolic contributors. Moreover, melatonin modulates critical players in cancer development, such as HIF-1 and p53. Taken together, melatonin has notable anti-cancer effects at malignancy initiation, progression and metastasing. Further investigations of melatonin impacts relevant for cancer metabolism are expected to create innovative approaches supportive for the effective prevention and targeted therapy of cancers.

Melatonin in Cancer Treatment: Current Knowledge and Future Opportunities

Melatonin is a pleotropic molecule with numerous biological activities. Epidemiological and experimental studies have documented that melatonin could inhibit different types of cancer in vitro and in vivo. Results showed the involvement of melatonin in different anticancer mechanisms including apoptosis induction, cell proliferation inhibition, reduction in tumor growth and metastases, reduction in the side effects associated with chemotherapy and radiotherapy, decreasing drug resistance in cancer therapy, and augmentation of the therapeutic effects of conventional anticancer therapies. Clinical trials revealed that melatonin is an effective adjuvant drug to all conventional therapies. This review summarized melatonin biosynthesis, availability from natural sources, metabolism, bioavailability, anticancer mechanisms of melatonin, its use in clinical trials, and pharmaceutical formulation. Studies discussed in this review will provide a solid foundation for researchers and physicians to design and develop new therapies to treat and prevent cancer using melatonin.

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

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

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.

Melatonin Lowers HIF-1α Content in Human Proximal Tubular Cells (HK-2) Due to Preventing Its Deacetylation by Sirtuin 1

Although melatonin is widely known for its nephroprotective properties, there are no reports clearly pointing at its impact on the activity of hypoxia-inducible factor-1 (HIF-1), the main mediator of metabolic responses to hypoxia, in kidneys. The aim of the present study was to elucidate how melatonin affects the expression of the regulatory subunit HIF-1α in renal proximal tubules. HK-2 cells, immortalized human proximal tubular cells, were cultured under hypoxic conditions (1% O₂). Melatonin was applied at 100 μM concentration. Protein and mRNA contents were determined by Western blot and RT-qPCR, respectively. HIF-1α acetylation level was established by means of immunoprecipitation followed by Western blot. Melatonin receptors MT1 and MT2 localization in HK-2 cells was visualized using immunofluorescence confocal analysis. It was found that melatonin in HK-2 cells (1) lowered HIF-1α protein, but not mRNA, content; (2) attenuated expression of HIF-1 target genes; (3) increased HIF-1α acetylation level; and (4) diminished sirtuin 1 expression (both protein and mRNA). Sirtuin 1 involvement in the regulation of HIF-1α level was confirmed applying cells with silenced Sirt1 gene. Moreover, the presence of membrane MT1 and MT2 receptors was identified in HK-2 cells and their ligand, ramelteon, turned out to mimic melatonin action on both HIF-1α and sirtuin 1 levels. Thus, it is concluded that the mechanism of melatonin-evoked decline in HIF-1α content in renal proximal tubular cells involves increased acetylation of this subunit which results from the attenuated expression of sirtuin 1, an enzyme reported to deacetylate HIF-1α. This observation provides a new insight to the understanding of melatonin action in kidneys.

Melatonin as an Antitumor Agent against Liver Cancer: An Updated Systematic Review

Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine with antioxidant, chronobiotic and anti-inflammatory properties; reduced levels of this hormone are associated with higher risk of cancer. Several beneficial effects of melatonin have been described in a broad number of tumors, including liver cancers. In this work we systematically reviewed the publications of the last 15 years that assessed the underlying mechanisms of melatonin activities against liver cancers, and its role as coadjuvant in the treatment of these tumors. Literature research was performed employing PubMed, Scopus and Web of Science (WOS) databases and, after screening, 51 articles were included. Results from the selected studies denoted the useful actions of melatonin in preventing carcinogenesis and as a promising treatment option for the primary liver tumors hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), either alone or in combination with other compounds. Different processes were modulated by the indole, such as inhibition of oxidative stress, proliferation, angiogenesis and invasion, promotion of immune system response, cell cycle arrest and apoptosis, as well as recovery of circadian rhythms and autophagy modulation. Taken together, the present systematic review highlights the evidence that document the potential role of melatonin in improving the landscape of liver tumor treatment.

Therapeutic targets of cancer drugs: Modulation by melatonin

The biological functions of melatonin range beyond the regulation of the circadian rhythm. With regard to cancer, melatonin's potential to suppress cancer initiation, progression, angiogenesis and metastasis as well as sensitizing malignant cells to conventional chemo- and radiotherapy are among its most interesting effects. The targets at which melatonin initiates its anti-cancer effects are in common with those of a majority of existing anti-cancer agents, giving rise to the notion that this molecule is a pleiotropic agent sharing many features with other antineoplastic drugs in terms of their mechanisms of action. Among these common mechanisms of action are the regulation of several major intracellular pathways including mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK) and protein kinase B (AKT/PKB) signaling. The important mediators affected by melatonin include cyclins, nuclear factor-κB (NF-κB), heat shock proteins (HSPs) and c-Myc, all of which can serve as potential targets for cancer drugs. Melatonin also exerts some of its anti-cancer effects via inducing epigenetic modifications, DNA damage and mitochondrial disruption in malignant cells. The regulation of these mediators by melatonin mitigates tumor growth and invasiveness via modulating their downstream responsive genes, housekeeping enzymes, telomerase reverse transcriptase, apoptotic gene expression, angiogenic factors and structural proteins involved in metastasis. Increasing our knowledge on how melatonin affects its target sites will help find ways of exploiting the beneficial effects of this ubiquitously-acting molecule in cancer therapy. Acknowledging this, here we reviewed the most studied target pathways attributed to the anti-cancer effects of melatonin, highlighting their therapeutic potential.

Two neuroendocrine G protein-coupled receptor molecules, somatostatin and melatonin: Physiology of signal transduction and therapeutic perspectives

Recent studies have shown that G protein-coupled receptors (GPCRs), the largest signal-conveying receptor family, are targets for mutations occurring frequently in different cancer types. GPCR alterations associated with cancer development represent significant challenges for the discovery and the advancement of targeted therapeutics. Among the different molecules that can activate GPCRs, we focused on two molecules that exert their biological actions regulating many typical features of tumorigenesis such as cellular proliferation, survival, and invasion: somatostatin and melatonin. The modulation of signaling pathways, that involves these two molecules, opens an interesting scenario for cancer therapy, with the opportunity to act at different molecular levels. Therefore, the aim of this review is the analysis of the biological activity and the therapeutic potential of somatostatin and melatonin, displaying a high affinity for GPCRs, that interfere with cancer development and maintenance.

Melatonin as a potential inhibitor of kidney cancer: A survey of the molecular processes

Studies have shown that despite the decreasing mortality rates of kidney cancer patients, its incidence is increasing. Therefore, a comprehensive re-evaluation of treatment options is necessary to provide appropriate treatments for the increasing number of patients. Moreover, the side effects caused by surgery, which is the main treatment of this disease, may lead to higher morbidity rates. Consequently, new safer approaches must be examined and considered. Major advancements have been made in the field of targeted agents as well as treatments based on immunotherapy since renal cell carcinoma (RCC) does not respond well to chemotherapy. While the therapeutic options for this cancer are increasing, the resulting complexity of selecting the best strategy for treating the patients is daunting. Moreover, each therapeutic option must be evaluated concerning toxicity, cost, and clinical advantages. Several characteristics, which are beneficial for cancer therapies have been attributed to melatonin. For decades, investigations have explored the application of melatonin in the treatment of cancer; insufficient attention has been paid to this molecule at the clinical level. Melatonin plays a role in cancer therapy due to its anti-tumor effects as well as by enhancing the efficacy of other drugs as an adjuvant. In this review, we discuss different roles of melatonin in the treatment of kidney cancer. The studies concerned with the applications of melatonin as an adjuvant in the immunotherapy of patients with kidney cancer are summarized. Also, we highlight the apoptotic and anti-angiogenic effects of melatonin on renal cancer cells which are mediated by different molecules (e.g., HIF-1 and VEGF, ADAMTS1, and MMP-9) and signaling pathways (e.g., P56, P52, and JNK). Furthermore, we take a look into available data on melatonin's ability to reduce the toxicities caused by kidney carcinogens, including ochratoxin A, potassium bromate, and Fe-NTA.

Melatonin and gastrointestinal cancers: Current evidence based on underlying signaling pathways

Gastrointestinal (GI) cancers, leading causes of cancer-related deaths, have been serious challenging human diseases up to now. Because of high rates of mortality, late-stage diagnosis, metastasis to distant locations, and low effectiveness and adverse events of routine standard therapies, the quality of life and survival time are low in patients with GI cancers. Hence, many efforts need to be done to explore and find novel efficient treatments. Beneficial effects of melatonin have been reported in a wide variety of human diseases. Melatonin has antioxidant, anti-inflammatory, antimicrobial, and anticancer effects. Various studies have showed the regulatory effects of melatonin on apoptotsis, autophagy and angiogenesis; these properties result in the inhibition of invasion, migration, and proliferation of GI cancer cells in vivo and in vitro. Together, this review suggests that melatonin in combination with anticancer agents may improve the efficacy of routine medicine and survival rate of patients with cancer.

Regulation of cancer cell glucose metabolism is determinant for cancer cell fate after melatonin administration

Several oncogenic pathways plus local microenvironmental conditions, such as hypoxia, converge on the regulation of cancer cells metabolism. The major metabolic alteration consists of a shift from oxidative phosphorylation as the major glucose consumer to aerobic glycolysis, although most of cancer cells utilize both pathways to a greater or lesser extent. Aerobic glycolysis, together with the directly related metabolic pathways such as the tricarboxylic acid cycle, the pentose phosphate pathway, or gluconeogenesis are currently considered as therapeutic targets in cancer research. Melatonin has been reported to present numerous antitumor effects, which result in a reduced cell growth. This is achieved with both low and high concentrations with no relevant side effects. Indeed, high concentrations of this indolamine reduce proliferation of cancer types resistant to low concentrations and induce cell death in some types of tumors. Previous work suggest that regulation of glucose metabolism and other related pathways play an important role in the antitumoral effects of high concentration of melatonin. In the present review, we analyze recent work on the regulation by such concentrations of this indolamine on aerobic glycolysis, gluconeogenesis, the tricarboxylic acid cycle and the pentose phosphate pathways of cancer cells.

Transcriptomic analysis on the effects of melatonin in gastrointestinal carcinomas

BACKGROUND

Melatonin has been shown with anticancer property and therapeutic potential for tumors. However, there lacks a systematic study on the molecular pathways of melatonin and its antitumor effects in gastrointestinal carcinomas.

METHODS

Using the gene expression profiles of four cancer cell lines from three types of gastrointestinal carcinomas before and after melatonin treatment, including gastric carcinoma (GC), colorectal carcinoma (CRC) and hepatocellular carcinoma (HCC), differentially expressed genes (DEGs) and biological pathways influenced by melatonin were identified. The qRT-PCR analyses were performed to validate the effects of melatonin on 5-FU resistance-related genes in CRC.

RESULTS

There were 17 pathways commonly altered by melatonin in the three cancer types, including FoxO signaling pathways enriched by the upregulated DEGs and cell cycle signaling pathways enriched by the downregulated DEGs, confirmed the dual role of melatonin to tumor growth, pro-apoptosis and anti-proliferation. DEGs upregulated in the three types of cancer tissues but reversely downregulated by melatonin were commonly enriched in RNA transport, spliceosome and cell cycle signaling pathways, which indicate that melatonin might exert antitumor effects through these pathways. Our results further showed that melatonin can downregulate the expression levels of 5-FU resistance-related genes, such as thymidylate synthase in GC and ATR, CHEK1, BAX and MYC in CRC. The qRT-PCR results demonstrated that melatonin enhanced the sensitivity of CRC 5-FU resistant cells by decreasing the expression of ATR.

CONCLUSIONS

Melatonin exerts the effects of pro-apoptosis and anti-proliferation on gastrointestinal carcinomas, and might increase the sensitivity of 5-FU in GC and CRC patients.

Hypoxia, metabolism, and the circadian clock: new links to overcome radiation resistance in high-grade gliomas

Radiotherapy is the cornerstone of treatment of high-grade gliomas (HGGs). It eradicates tumor cells by inducing oxidative stress and subsequent DNA damage. Unfortunately, almost all HGGs recur locally within several months secondary to radioresistance with intricate molecular mechanisms. Therefore, unravelling specific underlying mechanisms of radioresistance is critical to elucidating novel strategies to improve the radiosensitivity of tumor cells, and enhance the efficacy of radiotherapy. This review addresses our current understanding of how hypoxia and the hypoxia-inducible factor 1 (HIF-1) signaling pathway have a profound impact on the response of HGGs to radiotherapy. In addition, intriguing links between hypoxic signaling, circadian rhythms and cell metabolism have been recently discovered, which may provide insights into our fundamental understanding of radioresistance. Cellular pathways involved in the hypoxic response, DNA repair and metabolism can fluctuate over 24-h periods due to circadian regulation. These oscillatory patterns may have consequences for tumor radioresistance. Timing radiotherapy for specific times of the day (chronoradiotherapy) could be beneficial in patients with HGGs and will be discussed.

Melatonin: an endogenous miraculous indolamine, fights against cancer progression

PURPOSE

Melatonin is an amphipathic indolamine molecule ubiquitously present in all organisms ranging from cyanobacteria to humans. The pineal gland is the site of melatonin synthesis and secretion under the influence of the retinohypothalamic tract. Some extrapineal tissues (skin, lens, gastrointestinal tract, testis, ovary, lymphocytes, and astrocytes) also enable to produce melatonin. Physiologically, melatonin regulates various functions like circadian rhythm, sleep-wake cycle, gonadal activity, redox homeostasis, neuroprotection, immune-modulation, and anticancer effects in the body. Inappropriate melatonin secretion advances the aging process, tumorigenesis, visceral adiposity, etc. METHODS: For the preparation of this review, I had reviewed the literature on the multidimensional activities of melatonin from the NCBI website database PubMed, Springer Nature, Science Direct (Elsevier), Wiley Online ResearchGate, and Google Scholar databases to search relevant articles. Specifically, I focused on the roles and mechanisms of action of melatonin in cancer prevention.

RESULTS

The actions of melatonin are primarily mediated by G-protein coupled MT1 and MT2 receptors; however, several intracellular protein and nuclear receptors can modulate the activity. Normal levels of the melatonin protect the cells from adverse effects including carcinogenesis. Therapeutically, melatonin has chronomedicinal value; it also shows a remarkable anticancer property. The oncostatic action of melatonin is multidimensional, associated with the advancement of apoptosis, the arrest of the cell cycle, inhibition of metastasis, and antioxidant activity.

CONCLUSION

The present review has emphasized the mechanism of the anti-neoplastic activity of melatonin that increases the possibilities of the new approaches in cancer therapy.

Melatonin regulates the expression of inflammatory cytokines, VEGF and apoptosis in diabetic retinopathy in rats

The present study analyzed whether melatonin could mediate the expression of VEGF, IL-6 and TNF-α, as well as the apoptotic index in rats with diabetic retinopathy. Fifty Wistar albino rats were divided into the following groups: GC: rats without induction of diabetes by streptozotocin; GD: rats induced to diabetes by streptozotocin and treated with placebo; GDM: rats induced to diabetes by streptozotocin and after confirmation treated with melatonin at a dose of 10 mg/kg for 20 days; GDMS: rats induced to diabetes by streptozotocin and treated simultaneously with melatonin at a dosage of 10 mg/kg for 20 days; GDI: rats induced to diabetes by streptozotocin and after confirmation treated with insulin for 20 days. Diabetes was induced by intraperitoneal injections of streptozotocin (60 mg/kg), and insulin (5 U/day) was administered subcutaneously. For apoptosis TUNEL was used, while for the analysis of VEGF, IL-6 and TNF-α. The results showed that the groups that were treated with melatonin decreased the expression of cytokines and VEGF, in addition to apoptosis. Thus, it is concluded that melatonin can regulate the expression of these factors by improving the condition of the retina in diabetic retinopathy.

Melatonin Antagonizes Nickel-Induced Aerobic Glycolysis by Blocking ROS-Mediated HIF-1α/miR210/ISCU Axis Activation

Nickel and its compounds, which are well-documented carcinogens, induce the Warburg effect in normal cells by stabilizing hypoxia-inducible factor 1α (HIF-1α). Melatonin has shown diverse anticancer properties for its reactive oxygen species- (ROS-) scavenging ability. Our aim was to explore how melatonin antagonized a nickel-induced increment in aerobic glycolysis. In the current work, a normal human bronchial epithelium cell line (BEAS-2B) was exposed to a series of nonlethal doses of NiCl₂, with or without 1 mM melatonin. Melatonin attenuated nickel-enhanced aerobic glycolysis. The inhibition effects on aerobic glycolysis were attributed to the capability of melatonin to suppress the regulatory axis comprising HIF-1α, microRNA210 (miR210), and iron-sulfur cluster assembly scaffold protein (ISCU1/2). N-Acetylcysteine (NAC) manifested similar effects as melatonin in scavenging ROS, maintaining prolyl-hydroxylase activity, and mitigating HIF-1α transcriptional activity in nickel-exposed cells. Our results indicated that ROS generation contributed to nickel-caused HIF-1α stabilization and downstream signal activation. Melatonin could antagonize HIF-1α-controlled aerobic glycolysis through ROS scavenging.

Melatonin: An atypical hormone with major functions in the regulation of angiogenesis

Melatonin (N-acetyl-5-methoxytryptamine), a pleotropic molecule with a wide distribution, has received considerable attention in recent years, mostly because of its various major effects on tissues or cells since it has both receptor-dependent and receptor-independent actions over a wide range of concentrations. These biological and physiological functions of melatonin include regulation of circadian rhythms by modulating the expression of core oscillator genes, scavenging the reactive oxygen species and reactive nitrogen species, modulating the immune system and inflammatory response, and exerting cytoprotective and antiapoptotic effects. Given the multiple critical roles of melatonin, dysregulation of its production or any disruption in signaling through its receptors may have contributed in the development of a wide range of disorders including type 2 diabetes, aging, immune-mediated diseases, hypertension, and cancer. Herein, we focus on the modulatory effects of melatonin on angiogenesis and its implications as a therapeutic strategy in cancer and related diseases.

Melatonin and its anti-glioma functions: a comprehensive review

Melatonin (N-acetyl-5-methoxytryptamine) is a naturally synthesized hormone secreted from the pineal gland in a variety of animals and is primarily involved in the regulation of the circadian rhythm, which is the natural cycle controlling sleep in organisms. Melatonin acts on specific receptors and has an important role in overall energy metabolism. This review encompasses several aspects of melatonin activity, such as synthesis, source, structure, distribution, function, signaling and its role in normal physiology. The review highlights the cellular signaling and messenger systems involved in melatonin's action on the body and their wider implications, the distribution and diverse action of different melatonin receptors in specific areas of the brain, and the pharmacological agonists and antagonists that have specific action on these melatonin receptors. This review also incorporates the antitumor effects of melatonin in considerable detail, emphasizing on melatonin's role as an adjuvant therapeutic agent in glioma treatment. We conclude that the diminishing levels of melatonin have significant debilitating effects on normal physiology and can also be associated with malignant conditions such as glioma. Based on the review of the available evidence, our study provides a broad platform for a better understanding of the specific roles of melatonin and serves as a starting point for further investigation into the therapeutic effect of melatonin in glioma as an adjuvant therapeutic agent.

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

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

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Effectiveness and Safety of Combination Therapy of Transarterial Chemoembolization and Apatinib for Unresectable Hepatocellular Carcinoma in the Chinese Population: A Meta-Analysis

BACKGROUND

The combination of transarterial chemoembolization (TACE) and apatinib has been used in the treatment of intermediate or advanced hepatocellular carcinoma (HCC). However, its effectiveness and safety are also argued.

METHODS

Eligible studies were collected from a computer search of literatures published from the database establishment to May 2019 in PubMed, Web of Science, EMBASE, Ovid, the Cochrane Library, Wanfang Database, China National Knowledge Infrastructure, and China Biology Medicine Disc. The objective response rate (ORR), the disease control rate (DCR), survival rate (SR), and the incidences of treatment-related adverse effects (AEs) were collected as the relevant outcomes. Data were analyzed through fixed/random effects of meta-analysis models with RevMan 5.3 software.

RESULTS

Eight randomized controlled clinical trials comprising 528 patients and 4 cohort studies comprising 226 patients were eventually included. Compared to the control group treated with TACE solely, combination therapy group, in which intermediate or advanced HCC patients were treated with TACE and apatinib, significantly enhanced ORR (relative risk [RR] 2.06, 95% CI 1.63-2.61, p < 0.001), DCR (RR 1.65, 95% CI 1.24-2.20, p < 0.001), and whole SRs of 6-month (RR 1.52, 95% CI 1.08-2.14, p = 0.02), 1-year (RR 1.52, 95% CI 1.25-1.84, p < 0.001), and 2-year (RR 1.84, 95% CI 1.34-2.54, p < 0.001). The incidence of hand foot syndrome, proteinuria, hypertension, and diarrhea was significantly increased in the combination therapy group compared with the control group (p < 0.05), and the incidence of nausea and vomiting, fever, and myelosuppression, respectively, was similar in 2 groups (p > 0.05).

CONCLUSIONS

The combination therapy of TACE and apatinib can enhance the clinical effectiveness better than TACE solely in patients with intermediate or advanced HCC, while increase in the AEs is usually tolerable.

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.

Melatonin: An important anticancer agent in colorectal cancer

Colorectal cancer is one of the most common cancers among the elderly, which is also seen in the forms of hereditary syndromes occurring in younger individuals. Numerous studies have been conducted to understand the molecular and cellular pathobiology underlying colorectal cancer. These studies have found that cellular signaling pathways are at the core of colorectal cancer pathology. Because of this, new agents have been proposed as possible candidates to accompany routine therapy regimens. One of these agents is melatonin, a neuro-hormone known best for its essential role in upholding the circadian rhythm and orchestrating the many physiologic changes it accompanies. Melatonin is shown to be able to modulate many signaling pathways involved in many essential cell functions, which if deregulated cause an accelerated pace towards cancer. More so, melatonin is involved in the regulation of immune function, tumor microenvironment, and acts as an antioxidant agent. Many studies have focused on the beneficial effects of melatonin in colorectal cancers, such as induction of apoptosis, increased sensitivity to chemotherapy agents and radiotherapy, limiting cellular proliferation, migration, and invasion. The present review aims to illustrate the known significance of melatonin in colorectal cancer and to address possible clinical use.

Melatonin is a potential inhibitor of ovarian cancer: molecular aspects

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

Melatonin restricts the viability and angiogenesis of vascular endothelial cells by suppressing HIF-1α/ROS/VEGF

Angiogenesis is an essential process involved in various physiological, including placentation, and pathological, including cancer and endometriosis, processes. Melatonin (MLT), a well-known natural hormone secreted primarily in the pineal gland, is involved in regulating neoangiogenesis and inhibiting the development of a variety of cancer types, including lung and breast cancer. However, the specific mechanism of its anti-angiogenesis activity has not been systematically elucidated. In the present study, the effect of MLT on viability and angiogenesis of human umbilical vein endothelial cells (HUVECs), and the production of vascular endothelial growth factor (VEGF) and reactive oxygen species (ROS), under normoxia or hypoxia was analyzed using Cell Counting kit 8, tube formation, flow cytometry, ELISA and western blot assays. It was determined that the secretion of VEGF by HUVECs was significantly increased under hypoxia, while MLT selectively obstructed VEGF release as well as the production of ROS under hypoxia. Furthermore, MLT inhibited the viability of HUVECs in a dose-dependent manner and reversed the increase in cell viability and tube formation that was induced by hypoxia/VEGF/H₂O₂. Additionally, treatment with an inhibitor of hypoxia inducible factor (HIF)-1α (KC7F2) and MLT synergistically reduced the release of ROS and VEGF, and inhibited cell viability and tube formation of HUVECs. These observations demonstrate that MLT may serve dual roles in the inhibition of angiogenesis, as an antioxidant and a free radical scavenging agent. MLT suppresses the viability and angiogenesis of HUVECs through the downregulation of HIF-1α/ROS/VEGF. In summary, the present data indicate that MLT may be a potential anticancer agent in solid tumors with abundant blood vessels, particularly combined with KC7F2.

3D MR Elastography of Hepatocellular Carcinomas as a Potential Biomarker for Predicting Tumor Recurrence

BACKGROUND

Preoperative prediction of tumor recurrence is important in the management of patients with hepatocellular carcinoma (HCC).

PURPOSE

To investigate whether tumor stiffness derived by magnetic resonance elastography (MRE) could predict early recurrence of HCC after hepatic resection.

STUDY TYPE

Retrospective.

POPULATION

In all, 99 patients with pathologically confirmed HCCs after surgical resection.

FIELD STRENGTH/SEQUENCE

3.0T; preoperative MRE with 60-Hz mechanical vibrations using an active acoustic driver.

ASSESSMENT

Regions of interest (ROIs) were manually drawn in the tumors to measure mean tumor stiffness. Surgical specimens were reviewed for histological grade, capsule, vascular invasion, and surgical margins. The early recurrence of HCC was defined as that occurring within 2 years after resection.

STATISTICAL TESTS

Cox proportional hazard models were used to evaluate risk factors associated with the time to early recurrence.

RESULTS

HCCs with recurrence had higher tumor stiffness, higher rate of advanced T stage, vascular invasion, lower rate of capsule formation, larger tumor size, higher aspartate aminotransferase (AST), and hepatitis B virus (HBV)-DNA level and aspartate aminotransferase / alanine aminotransferase ratio (P = 0.031, 0.007, 0.01, <0.001, 0.015, 0.034, 0.01, and 0.014, respectively) than HCCs without recurrence. Vascular invasion (hazard ratio [HR] = 2.922; 95% confidence interval [CI]: [1.079, 7.914], P = 0.035) and mean tumor stiffness (HR = 1.163; 95% CI: [1.055, 1.282], P = 0.002) were risk factors associated with early recurrence. Each 1-kPa increase in tumor stiffness was associated with a 16.3% increase in the risk for tumor recurrence.

DATA CONCLUSION

The mean stiffness of HCCs may be a useful, noninvasive, quantitative biomarker for the prediction of early HCC recurrence after hepatic resection.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;49:719-730.

Idiopathic pulmonary fibrosis (IPF) signaling pathways and protective roles of melatonin

Idiopathic pulmonary fibrosis (IPF) is characterized by the progressive loss of lung function due to tissue scarring. A variety of pro-inflammatory and pro-fibrogenic factors including interleukin‑17A, transforming growth factor β, Wnt/β‑catenin, vascular endothelial growth factor, platelet-derived growth factor, fibroblast growth factors, endotelin‑1, renin angiotensin system and impaired caveolin‑1 function are involved in the IPF pathogenesis. Current therapies for IPF have some limitations and this highlights the need for effective therapeutic agents to treat this fatal disease. Melatonin and its metabolites are broad-spectrum antioxidants that not only remove reactive oxygen and nitrogen species by radical scavenging but also up-regulate the expression and activity of endogenous antioxidants. Via these actions, melatonin and its metabolites modulate a variety of molecular pathways in different pathophysiological conditions. Herein, we review the signaling pathways involved in the pathophysiology of IPF and the potentially protective effects of melatonin on these pathways.

Down regulation of RNA binding motif, single-stranded interacting protein 3, along with up regulation of nuclear HIF1A correlates with poor prognosis in patients with gastric cancer

Frequent loss of multiple regions in short arm of chromosome 3 is found in various tumors including gastric cancer (GC). RNA binding motif, single-stranded interacting protein 3 (RBMS3) is a tumor suppressor gene located in this region and mediates cancer angiogenesis. However, the role of RBMS3 in GC remains unclear.

To evaluate whether RBMS3, together with HIF1A, another key regulator of angiogenesis, predicts GC prognosis, the levels of RBMS3 and HIF1A were first examined by quantitative PCR (qPCR) and western blot from 27 fresh frozen GC and paired normal gastric tissues and then tested by immunohistochemistry (IHC) from 191 GC and 46 normal controls. Moreover, uni- and multivariate analysis were employed to assess the correlations between their levels and microvessel density (MVD) and clinical prognosis. To further identify RBMS3 function in vitro, cell proliferation assay, clonogenic assay, flow cytometry analysis and endothelial cell tube formation assay were employed.

We found that RBMS3 level was decreased, whereas HIF1A was elevated in GC. Furthermore, we demonstrated that RBMS3 was an independent prognostic factor and the levels of RBMS3 and HIF1A were associated with GC angiogenesis and histopathological differentiation: patients with lower RBMS3 level and higher nuclear HIF1A expression had poorer prognosis. Besides, gain- and loss-of-function study revealed RBMS3 regulation on G1/S progression, cell proliferation and the tube formation of human umbilical vein endothelial cells (HUVECs) in vitro. These findings implicated that RBMS3 and nuclear HIF1A could act as prognostic biomarkers and therapeutic targets for GC.

Melatonin and Cancer Hallmarks

Melatonin is a natural indoleamine produced by the pineal gland that has many functions, including regulation of the circadian rhythm. Many studies have reported the anticancer effect of melatonin against a myriad of cancer types. Cancer hallmarks include sustained proliferation, evading growth suppressors, metastasis, replicative immortality, angiogenesis, resisting cell death, altered cellular energetics, and immune evasion. Melatonin anticancer activity is mediated by interfering with various cancer hallmarks. This review summarizes the anticancer role of melatonin in each cancer hallmark. The studies discussed in this review should serve as a solid foundation for researchers and physicians to support basic and clinical studies on melatonin as a promising anticancer agent.

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

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

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

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

Melatonin as a potential inhibitory agent in head and neck cancer

Melatonin is a molecule secreted by the pineal gland; it is an important regulator of sleep and circadian rhythms. Through multiple interrelated mechanisms, melatonin exhibits various inhibitory properties at different stages of tumor progression. Many studies have explored the oncostatic effects of melatonin on hormone-dependent tumors. In this review, we highlight recent advances in understanding the effects of melatonin on the development of head and neck cancers, including molecular mechanisms identified through experimental and clinical observations. Because melatonin exerts a wide range of effects, melatonin may influence many mechanisms that influence the development of cancer. These include cell proliferation, apoptosis, angiogenesis, extracellular matrix remodeling through matrix metalloproteinases, and genetic polymorphism. Thus, the evidence discussed in this article will serve as a basis for basic and clinical research to promote the use of melatonin for understanding and controlling the development of head and neck cancers.