Background/Aims: Melatonin, synthesized by the pineal gland and released into the blood, appears to have antitumour properties; however, the mechanisms of its anti-cancer effects are largely unknown, especially in stomach cancer. Here, we explore the antitumour activity of melatonin in a gastric cancer cell line (AGS) and analyse its molecular mechanisms. Methods: AGS cells were treated with melatonin, and cell viability was assessed using a CCK-8 assay. Flow cytometry was performed to evaluate apoptosis, and protein expression was examined by Western blotting. Results: Melatonin significantly inhibited cell viability, clone formation, and cell migration and invasion and induced apoptosis in AGS cells. Moreover, MAPK pathways (p38, JNK and ERK) were activated by melatonin treatment, which also significantly increased caspase-3 cleavage and Bax protein expression and decreased Bcl-2 protein expression in a time-dependent manner. Our results demonstrate that p38 and JNK inhibitors (SB203580 and SP600125, respectively) prevented melatonin-induced apoptosis; thus, the propensity of p38 MAPK and JNK to promote apoptosis could be at least partly due to the inhibition of NF-κB p65 activation by p38 and JNK. Finally, melatonin was able to strengthen cisplatin-mediated antitumour effects in human gastric carcinoma cells by up-regulating the expression of Bax, down-regulating the expression of Bcl-2 and activating the caspase-dependent apoptotic pathway. Conclusion: Melatonin induced apoptosis in AGS cells by activating the caspase-dependent apoptotic pathway and by inhibiting the nuclear translocation of NF-κB p65, two processes that are regulated by p38 and JNK. Furthermore, melatonin significantly enhanced the anti-tumour effects of cisplatin, with low systemic toxicity. These new findings suggest that melatonin may act as a potent anti-tumour agent and may have great potential as an adjuvant therapy in the future.

Background/Aims: Melatonin, which is mainly secreted by the pineal gland and released into blood, has anti-inflammatory properties in acute pancreatitis. Many studies show that melatonin can relieve inflammation in taurocholate-induced acute pancreatitis. However, the mechanisms of its anti-inflammatory effects are still undefined, especially the relationship between melatonin and endoplasmic reticulum stress. We explored the anti-inflammatory activity of melatonin in AR42J and rat models. Methods: The CCK-8 assay was used to assess effects of melatonin on AR42J cell viability. Inflammatory degree and the expressions of endoplasmic reticulum stress related molecules were examined by quantitative RT-PCR and western blotting. The degree of inflammation in the tissue was also accessed by pathological grading. Finally, we used the western blotting method to verify apoptosis and autophagy. Results: Endoplasmic reticulum stress was obviously activated in early stage inflammation in AR42J and rat models. Melatonin could induce anti-inflammatory effects via endoplasmic reticulum stress. Melatonin significantly inhibited inflammatory cytokines and the expression of ERS-related molecules. Finally, it played a protective role by promoting apoptosis and autophagy of the cells, which were damaged in the process of inflammatory reaction. Conclusion: Melatonin induces anti-inflammatory effects via endoplasmic reticulum stress in acute pancreatitis to play a protective role.

Abstract. Melatonin, which is synthesized by the pineal gland and released into the blood, exhibits antitumor properties. However, the mechanisms underlying these effects, particularly in stomach cancer, remain unknown. In the present study, the effect of melatonin on the nuclear factor (NF)-κB signaling pathway and the mitogen-activated protein kinase signaling pathway, involving p38 and c-Jun-N-terminal kinase (JNK), were investigated in SGC7901 gastric cancer cells. In addition, the effect of melatonin on the survival, migration and apoptosis of these cells was investigated in vitro in order to evaluate the use of melatonin for the treatment of gastric cancer. The results of the present study revealed that melatonin decreased the viability and migration of SGC7901 cells. Furthermore, melatonin induced apoptosis. Melatonin was identified to elevate the expression levels of phosphorylated (p)-p38 and p-JNK protein, and decrease the expression level of nucleic p-p65. These results suggest that the protein levels of p65, p38 and JNK are associated with the survival of SGC7901 cells following treatment with melatonin. The optimal concentration of melatonin was demonstrated to be 2 mM, which significantly induced apoptosis following a 24 h treatment period. These findings suggest that conflicting growth signals in cells may inhibit the efficacy of melatonin in the treatment of gastric cancer. Therefore, adjunct therapy would be required to improve the efficacy of melatonin in the treatment of cancer. IntroductionGastric carcinoma is one of the most common types of malignancy, worldwide (1). In Asia, patients tend to be diagnosed at an average age of 66.8 years, and exhibit poor rates of survival (1). Gastric cancer is a refractory cancer and the third-leading cause of cancer-associated mortality in China (2). Gastric adenocarcinoma is the predominant type of gastric cancer and has limited treatment options (3). The typical treatments for gastric cancer, surgery and chemotherapy, only partially improve the overall survival of patients with this disease (4,5). Therefore, more effective drugs or comprehensive therapies are required (6).Melatonin is an indole hormone secreted by the pineal gland and was first identified in 1958 (7). Melatonin serves a significant role in a wide variety of biological processes, including sleep, immunomodulation, anti-inflammation and antioxidative stress (8-11). In addition, melatonin is an anticancer hormone and a potential target for cancer treatments (12). Several studies have revealed that melatonin is useful for the prevention of cancer (13,14). The antitumor ability of melatonin may be mediated by numerous mechanisms, including the activation of antioxidative stress, inhibition of migration and induction of apoptosis (15)(16)(17). Melatonin has also been demonstrated to suppress the growth, migration and invasion of SGC7901 gastric cancer cells in vitro (18), and to exert an apoptotic effect in the hepatocellular carcinoma HepG2 cell line (19). Additionally, the use of melatonin h...

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Melatonin, which is predominantly secreted by the pineal gland and is released into the blood, appears to have anti‑inflammatory properties. Several studies have shown that melatonin can relieve lipopolysaccharide-induced inflammatory responses of RAW264.7 cells. However, the mechanisms underlying this anti‑inflammatory effect remain to be fully elucidated, particularly the association between melatonin and endoplasmic reticulum (ER) stress (ERS). Therefore, the present study examined the anti‑inflammatory activity of melatonin in RAW264.7 cells and analyzed its molecular mechanisms in ERS. The RAW264.7 cells were stimulated by lipopolysaccharide and treated with melatonin. A Cell Counting Kit‑8 assay was used to assess the toxicity of melatonin. The degree of inflammation was evaluated using ELISA. The expression levels of ERS‑associated protein molecules were examined using reverse transcription‑quantitative polymerase chain reaction and western blot analyses. The results revealed that melatonin had no toxic effect on the RAW264.7 cells at the range of concentrations used in the experiment. Lipo-polysaccharide stimulated the cells to produce inflammatory molecules; in the early stage, proteins associated with ERS increased, and then apoptosis occurred. The cells treated with melatonin exhibited attenuated inflammation, decreased expression of ERS‑associated proteins and inhibition of apoptosis. Taken together, the results of the present study showed that melatonin may attenuate the inflammatory response by inhibiting the activation of ERS in RAW264.7 macrophages.

BackgroundThe aim of this study was to investigate and interpret the expression level and potential function of TCEA3 in gastric cancer.Material/MethodsqRT-PCR was used to determine the expression level of TCEA3 in gastric cancer tissues. Pearson χ2 test was performed to clarify the correlation between TCEA3 expression and patients’ clinicopathologic characteristics. Biological function of TCEA3 was tested by proliferation assay and colony formation assay. Flow cytometry was used to study the potential function of TCEA3 in apoptosis induction.ResultsTCEA3 expression was significantly downregulated in gastric cancer tissues compared with paired normal tissues. Poor prognoses were observed in the low TCEA3 expression group of patients in contrast to the high TCEA3 expression group. Functionally, upregulation of TCEA3 inhibited gastric cancer cell proliferation and colony formation. We also found that TCEA3 may attenuate cell growth through apoptosis induction.ConclusionsOur findings suggest that TCEA3 attenuates the proliferation and induces apoptosis of gastric cancer cells.

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(1) Background: The association between metabolic obesity phenotypes and incident lung cancer (LC) remains unclear. (2) Methods: Based on the combination of baseline BMI categories and metabolic health status, participants were categorized into eight groups: metabolically healthy underweight (MHUW), metabolically unhealthy underweight (MUUW), metabolically healthy normal (MHN), metabolically unhealthy normal (MUN), metabolically healthy overweight (MHOW), metabolically unhealthy overweight (MUOW), metabolically healthy obesity (MHO), and metabolically unhealthy obesity (MUO). The Cox proportional hazards model and Mendelian randomization (MR) were applied to assess the association between metabolic obesity phenotypes with LC risk. (3) Results: During a median follow-up of 9.1 years, 3654 incident LC patients were confirmed among 450,482 individuals. Compared with participants with MHN, those with MUUW had higher rates of incident LC (hazard ratio (HR) = 3.24, 95% confidence interval (CI) = 1.33–7.87, p = 0.009). MHO and MHOW individuals had a 24% and 18% lower risk of developing LC, respectively (MHO: HR = 0.76, 95% CI = 0.61–0.95, p = 0.02; MHO: HR = 0.82, 95% CI = 0.70–0.96, p = 0.02). No genetic association of metabolic obesity phenotypes and LC risk was observed in MR analysis. (4) Conclusions: In this prospective cohort study, individuals with MHOW and MHO phenotypes were at a lower risk and MUUW were at a higher risk of LC. However, MR failed to reveal any evidence that metabolic obesity phenotypes would be associated with a higher risk of LC.