Pleiotropic Effects of Linagliptin Monotherapy on Levels of Nitric Oxide, Nitric Oxide Synthase, and Superoxide Dismutase in Hemodialysis Patients with Diabetes

Linagliptin is an anti-diabetic drug and the only bile-excreted dipeptidyl peptidase-4 inhibitor. Malnutrition-inflammation-atherosclerosis syndrome is an important prognostic factor for hemodialysis patients, and we previously reported anti-inflammatory effects of linagliptin in hemodialysis patients with diabetes. Inflammation can accelerate oxidative stress, vasoconstriction, and platelet aggregation. However, few studies have investigated the pleiotropic effects of linagliptin treatment on inflammation in hemodialysis patients. In this study, we have extended our previous investigations of these effects in a longer and more thorough follow-up of hemodialysis patients with diabetes. We examined 20 hemodialysis patients with diabetes who were not receiving oral diabetes drugs or insulin therapy and who exhibited inadequate glycemic control (glycated albumin levels＞20%). Linagliptin (5mg) was administered daily, and we evaluated the patients’ superoxide dismutase, 8-hydroxydeoxyguanosine, nitric oxide, nitric oxide synthase, and asymmetric dimethylarginine levels in serum at baseline and after 1, 3, and 6 months of treatment. After 6 months of treatment, superoxide dismutase levels had significantly decreased from 8.8±0.5U/ml to 7.0±0.5U/ml. Nitric oxide synthase levels were significantly increased at 3 and 6 months (maximum, 94.2±13.2µg/ml; baseline, 31.6±5.5µg/ml). After 3 months of treatment, nitric oxide levels had significantly increased from 64.5±6.6µmol/l to 104±15.4µmol/l, and remained significantly elevated at 6 months. Asymmetric dimethylarginine and 8-hydroxydeoxyguanosine levels did not change during the 6-month treatment course, and no patients exhibited hypoglycemia or other significant adverse effects. Linagliptin treatment significantly changed various markers of inflammation relevant to the atherosclerosis in malnutrition-inflammation-atherosclerosis syndrome. Therefore, linagliptin monotherapy has pleiotropic effects on inflammation in hemodialysis patients with diabetes, and may improve their prognosis

Ethanol Increases NADPH Oxidase-derived Oxidative Stress and Induces Apoptosis in Human Liver Adenocarcinoma Cells (SK-HEP-1)

Alcohol-induced liver injury is linked to oxidative stress and increased production of reactive oxygen species (ROS). Oxidative stress is an early event in the process of apoptosis. However, it is not completely understood how ethanol-induced oxidative stress induces apoptosis. In contrast, nicotinamide adenine dinucleotide phosphate oxidase (NOX) is known to generate ROS in hepatocytes. The purpose of the present study was to determine whether or not ethanol-induced ROS generation stimulates the death receptor or mitochondrial pathways of apoptosis in alcohol dehydrogenase containing human liver adenocarcinoma (SK-HEP-1) cells. Treatment with ethanol increased the generation of ROS and expression of NOX4 mRNA, and also induced mitochondrial dysfunction in SK-HEP-1 cells. Moreover, ethanol induced the activation of caspase-8 and -3 in hepatocytes. These activities were suppressed by pretreatment with N-acetyl-cysteine, an antioxidant, or apocynin, an inhibitor of NOX activity. These results suggested that ethanol induces an increase in NOX-derived ROS generation upstream of caspase-8 activation and in the mitochondria in SK-HEP-1 cells. In conclusion, this study demonstrated that ethanol increases the generation of ROS and subsequently induces apoptosis using a mechanism involving mitochondrial dysfunction and caspase activation in SK-HEP-1 cells

Quantification of (-)-epigallocatechin-3-gallate Inhibition of Migration and Invasion of Oral Squamous Cell Carcinoma Cell Lines Using Real-time Cell Analysis

Catechins found in green tea, in particular (−)-epigallocatechin-3-gallate (EGCG), have antitumor activity. The primary antitumor actions of catechins are anti-oxidative, anti-angiogenic, and anti-metastatic effects. Cell migration and invasion contribute to the metastatic potential of tumors. Real-time cell analysis (RTCA) measures cell migration and invasion in vitro. In the present study, using RTCA, we investigated whether the cell migration and invasion of oral squamous cell carcinomas (OSCCs) of the tongue and floor of the mouth were inhibited by EGCG. Studies were performed using the human SCC-4 and SAS cell lines, which are poorly differentiated OSCCs of the tongue, and the HO-1-u-1 cell line, an OSCC of the floor of the mouth. SCC-4 cells exhibited high cell migration and invasion compared with the SAS and HO-1-u-1 cells. EGCG was most effective in inhibiting the migration and invasion of SCC-4 cells, and inhibited OSCC cell invasion more strongly than it inhibited cell migration. EGCG inhibited the expression of matrix metalloproteinase (MMP)-2, MMP-9, and integrin α1 and β1 mRNA in the OSCC cell lines, particularly SCC-4 cells. The findings of the present study suggest that EGCG inhibits OSCC cell migration and invasion by inhibiting MMP-2, MMP-9, and integrin α1and β1 expression. Thus, EGCG may be a suitable agent or lead compound for the inhibition of OSCC metastasis

The Role of a Brain-specific Splice Variant of Ryanodine Receptor Type 1

The ryanodine receptor type 1 (RyR1) is capable of homotetrameric assembly to form a Ca2+ release channel at intracellular Ca2+ storage sites such as endoplasmic reticulum (ER). The mRNA transcript encoding full-length RyR1 is approximately 16kb and is mainly distributed in excitable cells. A 2.4-kb mRNA splice variant from the 3\u27-terminal region of the RyR1 gene coexists specifically in brain together with the full-length form, although the functions of this brain-specific splice variant remain unclear. To investigate the short form of RyR1 in intracellular Ca2+ signaling in brain at the cellular level, we established an experimental system whereby the green fluorescent protein (GFP) -tagged brain-specific variant of RyR1 is coexpressed with the full-length protein in the same cell. Both forms of RyR1 were localized in the ER. Caffeine-induced Ca2+-release activities in cells expressing both the brain-specific and full-length RyR1 were reduced compared to cells expressing only the full-length form of RyR1. These results suggested that coexpression of the brain-specific splice variant of RyR1 with its full-length counterpart modulates intracellular Ca2+ signaling by acting as a dominant-negative subunit of the Ca2+ release channel in a tissue-specific fashion

Role of Gremlins in the Aortic Arch of Spontaneously Hypertensive and Hyperlipidemic Rats

Atherosclerosis is a lifestyle-related disease that plays a major role in cardiovascular disease. Recently, we found that gene expression of Gremlin 2, an antagonist of bone morphogenetic protein (BMP), was significantly increased in the aorta of spontaneously hypertensive and hyperlipidemic rats (SHHRs) fed a high-fat, 30% sucrose solution diet (HFDS). However, the role of Gremlin 1 (Grem1) and Gremlin 2 (Grem2) in the aortic arch of rats under hypertensive, hyperlipidemic, and hyperglycemic conditions remains unclear. Therefore, in the present study we investigated the molecular role of Gremlins in the aorta of SHHRs. Four-month-old male Sprague-Dawley rats and SHHRs were fed a normal diet or the HFDS ad libitum for 4 months. Then, gene and protein expression was analyzed using quantitative polymerase chain reaction and western blotting, respectively. Grem1 and Grem2 protein expression was increased, whereas phosphorylated Smad1/5 protein expression was low, in the aorta of SHHRs fed the HFDS. In addition, the expression of the downstream gene targets of BMP, namely inhibitor of DNA binding 1 (Id1) and atonal homolog 8 (Atoh8), was decreased in aortas of SHHRs fed the HFDS. Furthermore, mRNA expression of Snail, α-smooth muscle actin (αSMA), and Fibronectin was increased in SHHRs fed the HFDS. These findings suggest that upregulation of Gremlins attenuates the activation of BMP signaling, which contributes to fibrogenesis of the aorta

Investigation of Cell Migration and Invasion Using Real-time Cell Analysis, as well as the Association with Matrix Metalloproteinase-9 in Oral Squamous Cell Carcinomas

The recently developed technology of real-time cell analysis (RTCA) was designed to analyze cell migration and invasion in vitro. In this study, we investigated these cellular factors in oral squamous cell carcinomas (OSCCs) of the tongue and floor of the mouth with RTCA. We also examined the associated matrix metalloproteinases (MMPs) and integrins. We used the cell lines SCC-4 and SAS, which are human poorly differentiated OSCCs from the tongue, and HO-1-u-1, which are human poorly differentiated OSCCs from the floor of the mouth. Using RTCA, cell migration was assessed on fibronectin–coated CIM-Plates, and invasion was assessed on fibronectin- and matrigel-coated CIM-Plates. SCC-4 cells demonstrated a high ability for cell migration and invasion compared with SAS and HO-1-u-1 cells. The SCC-4 cells also expressed high levels of MMP-9 and integrin α1 mRNA compared with SAS and HO-1-u-1 cells. The MMP inhibitor Marimastat blocked migration and invasion of all OSCCs. The findings suggest that MMP-9 is associated with cell migration and invasion in OSCCs, and indicate that RTCA will be useful for analyzing the metastatic capability of OSCCs and developing more effective new drugs for this disease

Ethanol-induced Stress Leads to Apoptosls Via Endoplasmic Reticulum Stress in SK-Hepl Cells

Alcoholic liver disease causes oxidative stress and induces apoptosis during alcohol metabolism. Ethanol causes endoplasmic reticulum (ER) stress in hepatocytes, stimulating the unfolded protein response (UPR) pathway and/or Ca2+-dependent calpain and caspase-4 activities. However, it is poorly understood whether ethanol-induced oxidative stress directly leads to apoptosis promoted by ER stress-associated pathways. This study investigated this question in human liver adenocarcinoma (SK-Hep1) cells, which were treated with 200 mM ethanol for 5 hours in the presence or absence of the antioxidant N-acetyl-cysteine (NAC). We found that treatment with ethanol significantly increased ROS production and cellular apoptosis in the SK-Hep1 cells, and that this response was significantly suppressed by pretreatment with NAC. Furthermore, pretreatment with NAC significantly reduced the observed increases in the mRNA expressions of Bip, Chop, and sXbp-1, and the activity of caspase-3 in ethanol-induced apoptotic cells. However, pretreatment with NAC did not attenuate the transient rise in cytosolic Ca2+ nor the activities of caspase-4 and calpain induced by ethanol. Together, these results revealed that ethanol-induced stress promotes apoptosis not only through mitochondria-mediated pathways, but also via ER stress. The findings further suggested that ethanol-induced oxidative stress and non-oxidative stress both stimulate the pathway regulating ER stress-mediated apoptosis