Advanced glycation end products influence oral cancer cell survival via Bcl-xl and Nrf-2 regulation in vitro.

An irreversible non-enzymatic reaction between carbohydrates and proteins results in the formation of advanced glycation end products (AGEs). AGEs have been demonstrated to be a risk factor of complications in patients with diabetes mellitus (DM). Previous studies have suggested that patients with DM exhibit a higher rate of metastasis of oral cancer and a lower cancer-associated survival rate. The receptor for AGEs (RAGE) has been associated with angiogenesis and an increase in cancer malignancy. Previous studies have suggested that AGE-RAGE regulates cell migration via extracellular signal-regulated kinase (ERK) phosphorylation. Nuclear factor-erythroid 2-related factor 2 (Nrf-2) is associated with the regulation of tumor protein p53 (p53) and the apoptotic response of oral cancer cells. AGEs are associated with oral cancer; however, the mechanism underlying this association remains to be elucidated. The present study hypothesized that AGEs regulate Nrf-2 and downstream pathways through ERK phosphorylation. The results of the current study demonstrated that AGEs inhibit the expression of Nrf-2, p53 and Bcl-2 associated × apoptosis regulator, and increase the expression of apoptosis regulator Bcl-x protein. The effect of AGEs was inhibited through the use of the PD98059. The present study demonstrated that AGEs regulate the downstream pathways Nrf-2 and Bcl-xl via ERK phosphorylation. It is suggested that AGEs regulate the survival of oral cancer cells via Nrf-2 and Bcl-xl through p53 regulation, which explains the poor prognosis of patients with DM who have oral cancer.

Can a 10-Minute Questionnaire Identify Significant Psychological Issues in Patients With Temporomandibular Joint Disease?

PURPOSES: For patients with disc displacement disorders (DDDs), psychiatric illness increases the risk of worsening postsurgical pain, postoperative delirium, postoperative incomplete recovery, and worse postoperative life quality. This study provides a fast and practical protocol to evaluate psychological conditions of patients with DDDs of the temporomandibular joint (TMJ) in clinical care. MATERIALS AND METHODS: The populations under investigation in this cross-sectional study included patients with DDD who received treatment from October 2012 through June 2016. Variables included age, gender, education level, and TMJ (Axis I) and psychological (Axis II) evaluations. The 13-item protocol of Axis II evaluations contained a 5-item Brief Symptom Rating Scale (BSRS-5), a pain visual analog scale (VAS; 1 item), major life events (3 items), suicidal risk (3 items), and substance use (1 item). Analysis of variance, χ2 test, and multivariate logistic regression were used for analyses. RESULTS: Of 177 patients, 75.14% were women (mean age, 37.46 ± 14.06 yr). Pain VAS scores clearly supported the following ranking of psychosocial discomforts: disc displacement without reduction with limited opening (DDWORWLO) > disc displacement without reduction without limited opening > disc displacement with reduction. Pain VAS and BSRS-5 correlated with 5 variables in Axis I (trismus, acute TMJ pain, chronic awake bruxism, chronic sleep bruxism, and deep bite). The DDD study indicated that 9.6% of patients required urgent referrals to mental health resources (MHRs) for their moderate and high suicidal risk DDD and 77% required nonurgent referrals to MHRs for their psychiatric morbidity. CONCLUSIONS: This study found that patients with DDD showed a prevalence of suicidal ideation and mean BSRS scores that were higher for anxiety, hostility, depression, interpersonal hypersensitivity, and insomnia than in the general population. Patients with trismus or acute TMJ pain could have a higher pain VAS score; chronic awake bruxism could involve greater hostility and lower depression; chronic sleep bruxism could increase sensitivity to interpersonal interactions; and deep bite could involve a higher anxiety level. DDWORWLO produced the highest pain VAS score in patients with DDD. The 13-item Axis II evaluations can offer useful clues for oral and maxillofacial surgeons and other specialists to collaborate with MHRs.

The Possible Mechanism of Advanced Glycation End Products (AGEs) for Alzheimer's Disease.

Amyloid precursor protein (APP) has been modified by ß and γ-secretase that cause amyloid deposits (plaques) in neuronal cells. Glyceraldhyde-derived AGEs has been identified as a major source of neurotoxicity in Alzheimer's disease (AD). In a previous study, we demonstrated that glyceraldehyde-derived AGEs increase APP and Aß via ROS. Furthermore, the combination of AGEs and Aß has been shown to enhance neurotoxicity. In mice, APP expression is increased by tail vein injection of AGEs. This evidence suggests a correlation between AGEs and the development of AD. However, the role played by AGEs in the pathogenesis of AD remains unclear. In this report, we demonstrate that AGEs up-regulate APP processing protein (BACE and PS1) and Sirt1 expression via ROS, but do not affect the expression of downstream antioxidant genes HO-1 and NQO-1. Moreover, we found that AGEs increase GRP78 expression and enhance the cell death-related pathway p53, bcl-2/bax ratio, caspase 3. These results indicate that AGEs impair the neuroprotective effects of Sirt1 and lead to neuronal cell death via ER stress. Our findings suggest that AGEs increase ROS production, which stimulates downstream pathways related to APP processing, Aß production, Sirt1, and GRP78, resulting in the up-regulation of cell death related pathway. This in-turn enhances neuronal cell death, which leads to the development of AD.

Caffeic acid phenethyl amide improves glucose homeostasis and attenuates the progression of vascular dysfunction in Streptozotocin-induced diabetic rats.

BACKGROUND: Glucose intolerance and cardiovascular complications are major symptoms in patients with diabetes. Many therapies have proven beneficial in treating diabetes in animals by protecting the cardiovascular system and increasing glucose utilization. In this study, we evaluated the effects of caffeic acid phenethyl amide (CAPA) on glucose homeostasis and vascular function in streptozotocin (STZ)-induced type 1 diabetic rats. METHODS: Diabetes (blood glucose levels > 350 mg/dL), was induced in Wistar rats by a single intravenous injection of 60 mg/kg STZ. Hypoglycemic effects were then assessed in normal and type 1 diabetic rats. In addition, coronary blood flow in Langendorff-perfused hearts was evaluated in the presence or absence of nitric oxide synthase (NOS) inhibitor. The thoracic aorta was used to measure vascular response to phenylephrine. Finally, the effect of chronic treatment of CAPA and insulin on coronary artery flow and vascular response to phenylephrine were analyzed in diabetic rats. RESULTS: Oral administration of 0.1 mg/kg CAPA decreased plasma glucose in normal (32.9 ± 2.3% decrease, P < 0.05) and diabetic rats (11.8 ± 5.5% decrease, P < 0.05). In normal and diabetic rat hearts, 1-10 µM CAPA increased coronary flow rate, and this increase was abolished by 10 µM NOS inhibitor. In the thoracic aorta, the concentration/response curve of phenylephrine was right-shifted by administration of 100 µM CAPA. Coronary flow rate was reduced to 7.2 ± 0.2 mL/min at 8 weeks after STZ-induction. However, 4 weeks of treatment with CAPA (3 mg/kg, intraperitoneal, twice daily) started at 4 weeks after STZ induction increased flow rate to 11.2 ± 0.5 mL/min (P < 0.05). In addition, the contractile response induced by 1 µM phenylephrine increased from 6.8 ± 0.6 mN to 11.4 ± 0.4 mN (P < 0.05) and 14.9 ± 1.4 mN (P < 0.05) by insulin (1 IU/kg, intraperitoneal) or CAPA treatment, respectively. CONCLUSIONS: CAPA induced hypoglycemic activity, increased coronary blood flow and vascular response to phenylephrine in type 1 diabetic rats. The increase in coronary blood flow may result from endothelial NOS activation. However, the detailed cellular mechanisms need to be further evaluated.

Cell hypertrophy and MEK/ERK phosphorylation are regulated by glyceraldehyde-derived AGEs in cardiomyocyte H9c2 cells.

Diabetic cardiomyopathy has been shown to promote hypertrophy, leading to heart failure. Recent studies have reported a correlation between diabetic cardiomyopathy and oxidative stress, suggesting that the accumulation of advanced glycation end products (AGEs) induces the production of reactive oxygen species (ROS). In a clinical setting, AGEs have been shown to increase the risk of cardiovascular disease; however, the relationship between AGEs and cardiac hypertrophy remains unclear. This study sought to identify the role of AGEs in cardiac hypertrophy by treating H9c2 cells with glyceraldehyde-derived AGEs (200 µg/ml) or H2O2 (50 µM) for 96 h. Our results demonstrate that AGEs significantly increased protein levels and cell size. These effects were effectively blocked with PD98059 (10 µM; MEK/ERK inhibitor) pretreatment, suggesting that AGEs caused cell hypertrophy via the MEK/ERK pathway. We then treated cells with AGEs and H2O2 for 0-120 min and employed the Odyssey infrared imaging system to detect MEK/ERK phosphorylation. Our results show that AGEs up-regulated MEK/ERK phosphorylation. However, this effect was blocked by NAC (5 mM; ROS inhibitor), indicating that AGEs regulate MEK/ERK phosphorylation via ROS. Our findings suggest that glyceraldehyde-derived AGEs are closely related to cardiac hypertrophy and further identify a molecular mechanism underlying the promotion of diabetic cardiomyopathy by AGEs.

Caffeic Acid Phenylethyl Amide Protects against the Metabolic Consequences in Diabetes Mellitus Induced by Diet and Streptozocin.

Caffeic acid phenyl ester is distributed wildly in nature and has antidiabetic and cardiovascular protective effects. However, rapid decomposition by esterase leads to its low bioavailability in vivo. In this study, chronic metabolic and cardiovascular effects of oral caffeic acid phenylethyl amide, whose structure is similar to caffeic acid phenyl ester and resveratrol, were investigated in ICR mice. We found that caffeic acid phenylethyl amide protected against diet or streptozocin-induced metabolic changes increased coronary flow and decreased infarct size after global ischemia-reperfusion in Langendorff perfused heart. Further study indicated that at least two pathways might be involved in such beneficial effects: the induction of the antioxidant protein MnSOD and the decrease of the proinflammatory cytokine TNFα and NFκB in the liver. However, the detailed mechanisms of caffeic acid phenylethyl amide need further studies. In summary, this study demonstrated the protective potential of chronic treatment of caffeic acid phenylethyl amide against the metabolic consequences in diabetes mellitus.

Borapetoside C from Tinospora crispa improves insulin sensitivity in diabetic mice.

Diabetes mellitus (DM) often leads to disability from vascular complications and neurological complications. Tinospora crispa has been widely used in Asia and Africa as a remedy for diabetes and other diseases. In this study, we investigated the hypoglycemic actions of borapetoside C isolated from T. crispa, and the mechanisms underlying its actions. Acute treatment with borapetoside C (5mg/kg, i.p.) attenuated the elevated plasma glucose induced by oral glucose in normal and type 2 DM (T2DM) mice. Compared to the effect of injected insulin (0.5 IU/kg), borapetoside C caused a more prominent increase of glycogen content in skeletal muscle of T2DM mice, but a less increase in type 1 DM (T1DM) mice. Combined treatment of a low dose borapetoside C (0.1mg/kg, i.p.) plus insulin enhanced insulin-induced lowering of the plasma glucose level and insulin-induced increase of muscle glycogen content. Continuous treatment with 5mg/kg borapetoside C (twice daily) for 7 days increased phosphorylation of insulin receptor (IR) and protein kinase B (Akt) as well as the expression of glucose transporter-2 (GLUT2) in T1DM mice. Combined treatment of a low dose borapetoside C (0.1mg/kg, twice daily) plus insulin for 7 days enhanced insulin-induced IR and Akt phosphorylation and GLUT2 expression in the liver of T1DM mice. This study proved that borapetoside C can increase glucose utilization, delayed the development of insulin resistance and enhanced insulin sensitivity. The activation of IR-Akt-GLUT2 expression and the enhancement of insulin sensitivity may contribute to the hypoglycemic action of borapetoside C in diabetic mice.

Effects of metformin on rosiglitazone-induced cardiac hypertrophy in mice.

Thiazolidinediones (TZD) can cause adipose tissue accumulation and myocardial hypertrophy. This study aimed to determine if combined Metformin (Glucophage) and Rosiglitazone (Avandia) could reduce the risk of heart failure caused by Rosiglitazone in BALB/c mice. BALB/c mice were treated with oral Rosiglitazone/Metformin twice daily for four weeks. Metformin or Rosiglitazone alone and non-treated mice acted as double control. Myocardial hypertrophy and associated side effects of the combined therapy were determined through isolated heart and body weights. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were applied to evaluate expression of sulfonylurea receptor 2A (SUR2A) and Kir 6.2. The activities of peroxisome proliferator activated receptor alpha (PPARalpha) in the myocardium were also observed. Rosiglitazone/Metformin decreased body weight gain and food intake, and inhibited an increasing adipose ratio but did not reduce myocardial hypertrophy. Rosiglitazone increased Kir6.2/SUR2A, Kir6.2/SUR2B, and PPARalpha gene expression. The Rosiglitazone/Metformin combination further increased these gene expressions, especially PPARalpha. Metformin inhibits obesity but has no effect in reducing myocardial hypertrophy caused by Rosiglitazone. Whether Metformin can reduce side effects of TZDs in humans warrants further study.

Antihyperglycemic effect of a caffeamide derivative, KS370G, in normal and diabetic mice.

The antihyperglycemic actions of caffeamide derivatives, especially KS370G, in normal ICR, streptozotocin-induced diabetic (T1DM) and diet-induced diabetic (T2DM) mice were investigated in this study. Oral administration of the compound decreased the plasma glucose levels in both normal and diabetic mice, and appeared to be in a dose-dependent manner in normal and diet-induced type 2 diabetic mice. It was found that KS370G could stimulate the release of insulin in both normal and T2DM mice, and a dose of 1 mg per kg KS370G could significantly attenuate the increase of plasma glucose induced by an intraperitoneal glucose challenge test in normal and diabetic mice. Similar treatment with KS370G significantly increased glycogen content in both liver and skeletal muscle. Hence, the hypoglycemic effect of KS370G in normal and diabetic mice could be attributed to the stimulation of insulin release and the increase of glucose utilization.

Resveratrol enhances insulin secretion by blocking K(ATP) and K(V) channels of beta cells.

The present study investigated the effect of resveratrol on the electrophysiology and insulin secretion of pancreatic beta cells, and examined resveratrol-induced alterations in insulin levels and plasma glucose of normal and streptozotocin-induced diabetic rats. Whole-cell voltage clamp study in the MIN6 cell, a mouse beta cell line, revealed that resveratrol significantly inhibited ATP-sensitive K(+) current at 3 micromol/l, and voltage-gated K(+) currents at 30 micromol/l. Ca(2+)-activated K(+) current was activated by resveratrol at 100 micromol/l. In MIN6 cells stained with membrane potential dye DiBAC(4)(5), resveratrol markedly depolarized membrane potential at the concentrations of 3-100 micromol/l. Insulin secretion was increased in the presence of resveratrol in MIN6, Hit-T15, and RIN-m5F cells. Resveratrol (3 mg/kg, i.p.) increased insulin secretion associated with a lowering in plasma glucose in normal rats, but not in streptozotocin-diabetic rats within the initial 60 min. In conclusion, resveratrol can act as an insulin-secretagogue through I(KATP) and I(KV) inhibition which can contribute to plasma glucose lowering effect in normal rats.

Serotonin enhances beta-endorphin secretion to lower plasma glucose in streptozotocin-induced diabetic rats.

Although serotonin, serotonin uptake inhibitors and serotonin precursors (including tryptophan or 5-hydroxytryptophan) are known to have hypoglycemic action in rodents or human, it is not clear whether serotonin has hypoglycemic effect in streptozotocin-induced diabetic rats (STZ-diabetic rats). The aim of this study was to investigate the action of serotonin in regulating the plasma glucose STZ-diabetic rats. Plasma glucose, insulin, beta-endorphin and adrenaline were assessed after intraperitoneal administration of serotonin. Serotonin produced hypoglycemic effects without altering plasma insulin and adrenaline levels but increasing beta-endorphin level in STZ-diabetic rats. The glycogen content in soleus muscle was increased at 90 min after application of serotonin (0.3 mg/kg) in STZ-diabetic rats. Dihydroergotamine (non-selective 5-HT receptor blocker) and pimozide (5-HT(7) receptor blocker) abolished the hypoglycemic effect of serotonin in STZ-diabetic rats. Serotonin-induced hypoglycemic effect in association with the increase of beta-endorphin release was abolished in bilaterally adrenalectomized STZ-diabetic rats. In isolated adrenal gland of STZ-diabetic rats, the increase of beta-endorphin secretion in response to serotonin was reduced by either dihydroergotamine or pimozide. Pretreatment with naloxone (1.0 mg/kg, i.p.) prevented serotonin-induced plasma glucose lowering effect in STZ-diabetic rats. The results demonstrated that serotonin may activate 5-HT(7) receptor on rat adrenal gland to enhance of beta-endorphin secretion, which then stimulates the opioid receptor to increase peripheral glucose utilization, resulting in decreased plasma glucose levels in STZ-diabetic rats.

Phosphatidylinositol-3-kinase is involved in the antihyperglycemic effect induced by resveratrol in streptozotocin-induced diabetic rats.

Resveratrol, a polyphenolic substance found in grape skin, is proposed to account in part for the protective effect of red wine in the cardiovascular system. The aim of the present study is to investigate the action and possible mechanisms of resveratrol-produced regulation of plasma glucose in normal and diabetic rats including the animal model of streptozotocin (STZ)-induced and nicotinamide-STZ-induced (NA-STZ), and insulin-resistant diabetic rats. Resveratrol (p.o.) produced a hypoglycemic effect in a dose-dependent manner in normal and diabetic rats, and the insulin level was increased following resveratrol treatment in normal and NA-STZ diabetic rats. In insulin-deficient STZ-diabetic rats, resveratrol significantly lowered the plasma glucose 90 min after oral treatment, and the hypoglycemic effect was abolished by phosphatidyl-3-kinase (PI3K) inhibitors (LY294002 and wortmannin) which also inhibited resveratrol-induced Akt phosphorylation in soleus muscle of STZ-diabetic rats. The change in the protein expression level of glucose transporter subtype 4 (GLUT4) in the soleus muscle and phosphoenolpyruvate carboxykinase (PEPCK) in the liver of STZ-diabetic rats treated with resveratrol (3 mg/kg, p.o.) for 7 days was examined. Resveratrol normalized hepatic PEPCK expression and increased GLUT4 expression in the soleus muscle of STZ-diabetic rats. The results indicate that the mechanisms contributing to the hypoglycemic effect of resveratrol include insulin-dependent and insulin-independent pathway, and PI3K-Akt-signaling was involved in the latter mechanism to enhance glucose uptake in skeletal muscle.

Antihyperglycemic effect of aporphines and their derivatives in normal and diabetic rats.

The antihyperglycemic actions of some aporphines and their derivatives in normal Wistar, streptozotocin (STZ)-induced diabetic (IDDM) and nicotinamide-STZ induced diabetic (NIDDM) rats were investigated in this study. These compounds included thaliporphine, glaucine, boldine, N-methyllaurotetanine, and predicentrine and the derivatives, N-[2-(2-methoxyphenoxy)ethyl]norglaucine and diacetyl- N-allylsecoboldine. Bolus intravenous injection of these compounds decreased the plasma glucose levels in a dose-dependent manner in both normal and diabetic rats. Among them, thaliporphine was found to have the most potent antihyperglycemic effect in both NIDDM and IDDM diabetic rats. It was found that thaliporphine could stimulate the release of insulin in both normal and diabetic rats, and a dose of 1 mg per kg thaliporphine could significantly attenuate the increase of plasma glucose induced by an intravenous glucose challenge test in normal rats. Similar treatment with thaliporphine significantly increased the skeletal muscle glycogen synthesis in both normal and diabetic rats. Hence, the hypoglycemic effect of thaliporphine in diabetic rats could be attributed to the stimulation of insulin release and the increase of glucose utilization.

Microbial transformations of isosteviol.

Microbial transformations of the tetracyclic diterpenoid isosteviol (ent-16-ketobeyeran-19-oic acid) (2) have revealed that isosteviol is metabolized by Cunninghamella bainieri, Actinoplanes sp., Mucor recurvatus, and Cunninghamella blakesleeana to yield five new metabolites, ent-11alpha,12alpha-dihydroxy-16-ketobeyeran-19-oic acid (5), ent-11alpha,12alpha,17-trihydroxy-16-ketobeyeran-19-oic acid (6), ent-12alpha,15alpha-dihydroxy-16-ketobeyeran-19-oic acid (7), ent-7alpha,15alpha-dihydroxy-16- ketobeyeran-19-oic acid (8), and ent-9alpha-hydroxy-16-ketobeyeran-19-oic acid (9), together with three known metabolites, ent-7alpha-hydroxy-16-ketobeyeran-19-oic acid (3), ent-7beta-hydroxy-16-ketobeyeran-19-oic acid (4), and ent-12alpha-hydroxy-16-ketobeyeran-19-oic acid (10). The structures of these metabolites were established on the basis of HRFABMS and 1D and 2D NMR spectral data. In addition, metabolites 3-10 were tested for antihypertensive activity and were found to be less active than the parent compound 2.