72 research outputs found
Nicotine Induces Resistance to Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor by Ī±1 Nicotinic Acetylcholine ReceptorāMediated Activation in PC9 Cells
IntroductionNicotine, the major component among the 4000 identified chemicals in cigarette smoke, binds to nicotinic acetylcholine receptors (nAChRs) on nonāsmall-cell lung cancer (NSCLC) cells and regulates cellular proliferation by activating mitogen-activated protein kinases [AQ: MAPK has been expanded to mitogen-activated protein kinases. Please approve.]and PI3K/Akt pathways. In patients with smoking-related lung cancer who continue smoking, the anticancer effect of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) is weaker than that in nonsmokers; however, the precise reason for this difference remains unclear. We investigated the role of Ī±1 nAChR subunit in this phenomenon.MethodsWe screened for Ī±1 nAChR mRNA in three NSCLC cell lines and analyzed the protein in resected primary NSCLC tissues. We used Western blot and RNA interference (siRNA) methodology to confirm the results.ResultsWe determined that Ī±1 nAChR plays an essential role in nicotine-induced cell signaling and nicotine-induced resistance to EGFR-TKI. In addition, we showed that silencing of Ī±1 nAChR subunit in NSCLC may suppress the nicotine-induced resistance to EGFR-TKI.ConclusionsThese results further implicate nicotine in lung carcinogenesis, and suggest that Ī±1 nAChR may be a biomarker for EGFR-TKI treatment and also a personalizing target molecule for patients with smoking-related lung cancer
An efficient synthesis of chiral isoquinuclidines by Diels-Alder reaction using Lewis acid catalyst
The Diels-Alder reaction of 1,2-dihydropyridine derivatives (1-phenoxycarbonyl-1,2-dihydropyridine 1 or 1-methoxycarbonyl-1,2-dihydropyridine 4) with N-acryloyl (1S)-2,10-camphorsultam (1S)-2 (or N-acryloyl (1R)-2,10-camphorsultam (1R)-2) in the presence of Lewisacid such as titanium tetrachloride, zirconium tetrachloride, and hafnium tetrachloride afforded the endo-cycloaddition product, 2-azabicyclo[2.2.2]octane derivatives in good yields with excellent diastereoselectivity. The absolute stereochemistry assignment of the endo-cycloaddition product (1S)-5a starting from N-acryloyl (1S)-2,10-camphorsultam (1S)-2hasbeen established to be (1S, 4R, 7S) and the reaction mechanism was proposed
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Mechanisms With Clinical Implications for Atrial FibrillationāAssociated Remodeling: Cathepsin K Expression, Regulation, and Therapeutic Target and Biomarker
Background: The cysteine protease cathepsin K (CatK) has been implicated in the pathogenesis of cardiovascular disease. We sought to determine the link between atrial fibrillation (AF) and plasma CatK levels and to investigate the expression of and therapeutic target for CatK in vivo and in vitro. Methods and Results: Plasma CatK and extracellular matrix protein peptides (intact procollagen type I of Nāterminal propeptide; carboxylāterminal telopeptide of type I collagen [ICTP]) were measured in 209 consecutive patients with AF (paroxysmal AF, 146; persistent AF, 63) and 112 control subjects. In addition, the regulation of CatK expression was investigated in vivo and vitro. Patients with AF had higher plasma CatK and ICTP levels than did control subjects. Patients with persistent AF had higher levels of plasma CatK and ICTP than did patients with paroxysmal AF. CatK was correlated with ICTP concentration and left atrial diameter in all subjects. In rabbits, superoxide production, CatK activity, fibrosis, and the levels of atrial tissue angiotensin II, angiotensin type 1 receptor, gp91phox, phosphoāp38 mitogenāactivated protein kinase, and CatK were greater in those with tachypacingāinduced AF than in controls, and these changes were reversed with angiotensin type 1 receptor antagonist. Olmesartan and mitogenāactivated protein kinase inhibitor decreased the CatK expression induced by angiotensin II in rat neonatal myocytes. Conclusions: These data indicated that increased plasma CatK levels are linked with the presence of AF. Angiotensin type 1 receptor antagonist appears to be effective in alleviating atrial fibrosis in a rabbit AF model, partly reducing angiotensin type 1 receptorāp38mitogenāactivated protein kinaseādependent and āindependent CatK activation, thus preventing AF
Pharmacokinetics and pharmacodynamics of insulin aspart in patients with Type 2 diabetes: Assessment using a meal tolerance test under clinical conditions
Few studies have evaluated the pharmacokinetics of rapid-acting insulin analogues in patients with Type 2 diabetes, especially under clinical conditions. The aim of the present study was to assess both the pharmacokinetics and pharmacodynamics of insulin aspart in Type 2 diabetic patients who were being treated with the analogue alone. Meal tolerance tests with and without self-injection of a customary dose of insulin aspart (0.05-0.22 U/kg) were conducted in 20 patients in a randomized cross-over study. The dose of insulin aspart (per bodyweight) was significantly correlated with both the maximum concentration (r 2 = 0.59; P < 0.01) and area under the concentration-time curve for insulin aspart (r 2 = 0.53; P < 0.01). However, the time to maximum concentration (T max), which varied widely from < 60 to ā„ 120 min, was not associated with either dosage (r 2 = 0.02; P = 0.51) or body mass index (r 2 = 0.02; P = 0.57). Injection of insulin aspart exacerbated delayed hyperinsulinaemia after meal loading, mainly in patients with T max ā„ 120 min. With regard to pharmacodynamics, insulin aspart had favourable effects on postprandial hyperglycaemia, hyperglucagonaemia and hyperlipidaemia. The T max for this insulin analogue differed greatly between individuals and delayed hyperinsulinaemia was particularly exacerbated in patients with higher T max values. Identification of the factors contributing to interindividual variation in the absorption lag time is essential for improving the efficacy and safety of insulin aspart. Ā© 2012 The Authors. Clinical and Experimental Pharmacology and Physiology Ā© 2012 Blackwell Publishing Asia Pty Ltd
Metformin Prevents and Reverses Inflammation in a Non-Diabetic Mouse Model of Nonalcoholic Steatohepatitis
Background: Optimal treatment for nonalcoholic steatohepatitis (NASH) has not yet been established, particularly for individuals without diabetes. We examined the effects of metformin, commonly used to treat patients with type 2 diabetes, on liver pathology in a non-diabetic NASH mouse model. Methodology/Principal Findings: Eight-week-old C57BL/6 mice were fed a methionine- and choline-deficient plus high fat (MCD+HF) diet with or without 0.1% metformin for 8 weeks. Co-administration of metformin significantly decreased fasting plasma glucose levels, but did not affect glucose tolerance or peripheral insulin sensitivity. Metformin ameliorated MCD+HF diet-induced hepatic steatosis, inflammation, and fibrosis. Furthermore, metformin significantly reversed hepatic steatosis and inflammation when administered after the development of experimental NASH. Conclusions/Significance: These histological changes were accompanied by reduced hepatic triglyceride content, suppressed hepatic stellate cell activation, and the downregulation of genes involved in fatty acid metabolism, inflammation, and fibrogenesis. Metformin prevented and reversed steatosis and inflammation of NASH in an experimental non-diabetic model without affecting peripheral insulin resistance. Ā© 2012 Kita et al
Selenoprotein P as a diabetes-associated hepatokine that impairs angiogenesis by inducing VEGF resistance in vascular endothelial cells
Aims/hypothesis Impaired angiogenesis induced by vascular endothelial growth factor (VEGF) resistance is a hallmark of vascular complications in type 2 diabetes; however, its molecular mechanism is not fully understood. We have previously identified selenoprotein P (SeP, encoded by the SEPP1 gene in humans) as a liver-derived secretory protein that induces insulin resistance. Levels of serum SeP and hepatic expression of SEPP1 are elevated in type 2 diabetes. Here, we investigated the effects of SeP on VEGF signalling and angiogenesis. Methods We assessed the action of glucose on Sepp1 expression in cultured hepatocytes. We examined the actions of SeP on VEGF signalling and VEGF-induced angiogenesis in HUVECs. We assessed wound healing in mice with hepatic SeP overexpression or SeP deletion. The blood flow recovery after ischaemia was also examined by using hindlimb ischaemia model with Sepp1-heterozygous-knockout mice. Results Treatment with glucose increased gene expression and transcriptional activity for Sepp1 in H4IIEC hepatocytes. Physiological concentrations of SeP inhibited VEGF-stimulated cell proliferation, tubule formation and migration in HUVECs. SeP suppressed VEGF-induced reactive oxygen species (ROS) generation and phosphorylation of VEGF receptor 2 (VEGFR2) and extracellular signal-regulated kinase 1/2 (ERK1/2) in HUVECs. Wound closure was impaired in the mice overexpressing Sepp1, whereas it was improved in SeP-/-mice. SeP+/-mice showed an increase in blood flow recovery and vascular endothelial cells after hindlimb ischaemia. Conclusions/interpretation The hepatokine SeP may be a novel therapeutic target for impaired angiogenesis in type 2 diabetes. Ā© 2014 Springer-Verlag Berlin Heidelberg
Ī²-Catenin asymmetry is regulated by PLA1 and retrograde traffic in C. elegans stem cell divisions
Asymmetric division is an important property of stem cells. In Caenorhabditis elegans, the Wnt/Ī²-catenin asymmetry pathway determines the polarity of most asymmetric divisions. The Wnt signalling components such as Ī²-catenin localize asymmetrically to the cortex of mother cells to produce two distinct daughter cells. However, the molecular mechanism to polarize them remains to be elucidated. Here, we demonstrate that intracellular phospholipase A1 (PLA1), a poorly characterized lipid-metabolizing enzyme, controls the subcellular localizations of Ī²-catenin in the terminal asymmetric divisions of epithelial stem cells (seam cells). In mutants of ipla-1, a single C. elegans PLA1 gene, cortical Ī²-catenin is delocalized and the asymmetry of cell-fate specification is disrupted in the asymmetric divisions. ipla-1 mutant phenotypes are rescued by expression of ipla-1 in seam cells in a catalytic activity-dependent manner. Furthermore, our genetic screen utilizing ipla-1 mutants reveals that reduction of endosome-to-Golgi retrograde transport in seam cells restores normal subcellular localization of Ī²-catenin to ipla-1 mutants. We propose that membrane trafficking regulated by ipla-1 provides a mechanism to control the cortical asymmetry of Ī²-catenin
Olmesartan ameliorates a dietary rat model of non-alcoholic steatohepatitis through its pleiotropic effects
Selenoprotein P as a diabetes-associated hepatokine that impairs angiogenesis by inducing VEGF resistance in vascular endothelial cells
Systemic steroid therapy for pneumonic chronic obstructive pulmonary disease exacerbation: A retrospective cohort study
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