Akt/protein kinase B isoforms are differentially regulated by epidermal growth factor stimulation

Overexpression of epidermal growth factor receptor (EGFR) in certain cancers is well established. There is growing evidence that epidermal growth factor (EGF) activates Akt/protein kinase B (PKB) in a phosphoinositide 3-OH kinase (PI3K)-dependent manner, but it is not yet clear which Akt isoforms are involved in this signal transduction pathway. We investigated the functional regulation of three Akt isoforms, Akt1/PKBalpha, Akt2/PKBbeta, and Akt3/PKBgamma, in esophageal cancer cells where EGFR is frequently overexpressed. Upon EGF simulation, phosphorylation of Akt1 at the Ser-473 residue was remarkably induced. This result was corroborated by in vitro Akt kinase assays using glycogen synthase kinase 3beta as the substrate. PI3K inhibitors, wortmannin or LY294002, significantly blocked the Akt kinase activity induced by EGF. Akt2 activity was evaluated by electrophoretic mobility shift assays. Robust activation of Akt2 by EGF was observed in some cell lines in a PI3K-dependent manner. EGF-induced Akt3 activation was demonstrated by Ser-472 phosphorylation of Akt3 but in a restrictive fashion. In aggregate, EGF-mediated activation of Akt isoforms is overlapping and distinctive. The mechanism by which EGFR recruits the PI3K/Akt pathway was in part differentially regulated at the level of Ras but independent of heterodimerization of EGFR with either ErbB2 or ErbB3 based upon functional dissection of pathways in esophageal cancer cell lines.     

Targeted modification of wheat grain protein to reduce the content of celiac causing epitopes

The prolamin peptides in wheat gluten and in the homologous storage proteins of barley and rye cause painful chronic erasure of microvilli of the small intestine epithelium in celiac patients. If untreated, it can lead to chronic diarrhea, abdominal distension, osteoporosis, weight-loss due to malabsorption of nutrients, and anemia. In addition to congenital cases, life-long exposure to gluten proteins in bread and pasta can also induce development of celiac sprue in adults. To date, the only effective treatment is life-long strict abstinence from the staple food grains. Complete exclusion of dietary gluten is, however, difficult due to use of wheat in many foods, incomplete labeling and social constraints. Thus, finding alternative therapies for this most common foodborne disease remained an active area of research, which has led to many suggestions in last few years. The pros and cons associated with these therapies were reviewed in the present communication. As different celiac patients are immunogenic to different members of the undigestible proline/glutamine rich peptides of ～149 gliadins and low molecular weight glutenin subunits as well as the six high molecular weight glutenin subunits, an exhaustive digestion of the immunogenic peptides in the stomach, duodenum, jejunum, and ileum of celiacs is required. In view of the above, we evaluated the capacity of cereal grains to synthesize and store the enzymes prolyl endopeptidase from Flavobacterium meningosepticum and the barley cysteine endoprotease B2, which in combination are capable of detoxifying immunogenic gluten peptides in a novel treatment of celiac disease.     

Constitutive K-RasG12D activation of ERK2 specifically regulates 3D invasion of human pancreatic cancer cells via MMP-1

Pancreatic ductal adenocarcinomas (PDAC) are highly invasive and metastatic neoplasms commonly unresponsive to current drug therapy. Overwhelmingly, PDAC harbors early constitutive, oncogenic mutations in K-Ras(G12D) that exist prior to invasion. Histologic and genetic analyses of human PDAC biopsies also exhibit increased expression of extracellular signal-regulated kinase (ERK) 1/2 and proinvasive matrix metalloproteinases (MMP), indicators of poor prognosis. However, the distinct molecular mechanisms necessary for K-Ras/ERK1/2 signaling and its influence on MMP-directed stromal invasion in primary human pancreatic ductal epithelial cells (PDEC) have yet to be elucidated in three-dimensions. Expression of oncogenic K-Ras(G12D) alone in genetically defined PDECs reveals increased invadopodia and epithelial-to-mesenchymal transition markers, but only when cultured in a three-dimensional model incorporating a basement membrane analog. Activation of ERK2, but not ERK1, also occurs only in K-Ras(G12D)-mutated PDECs cultured in three-dimensions and is a necessary intracellular signaling event for invasion based upon pharmacologic and short hairpin RNA (shRNA) inhibition. Increased active invasion of K-Ras(G12D) PDECs through the basement membrane model is associated with a specific microarray gene expression signature and induction of MMP endopeptidases. Specifically, MMP-1 RNA, its secreted protein, and its proteolytic cleavage activity are amplified in K-Ras(G12D) PDECs when assayed by real-time quantitative PCR, ELISA, and fluorescence resonance energy transfer (FRET). Importantly, shRNA silencing of MMP-1 mimics ERK2 inhibition and disrupts active, vertical PDEC invasion. ERK2 isoform and MMP-1 targeting are shown to be viable strategies to attenuate invasion of K-Ras(G12D)-mutated human pancreatic cancer cells in a three-dimensional tumor microenvironment.     

Data on vildagliptin and vildagliptin plus metformin combination in type-2 diabetes mellitus management

It is of interest to evaluate the clinical effectiveness and safety of vildagliptin as monotherapy and combination therapy of vildagliptin and metformin for the management of type 2 diabetes mellitus (T2DM) patients in Indian settings. The study included patients with T2DM (aged >18 years) receiving vildagliptin monotherapy and vildagliptin in combination with metformin therapy of various strengths. Data related to demographics, risk factors, medical history, glycated hemoglobin (HbA1c) levels, and medical therapies were retrieved from medical records. Out of 9678 patients (median age, 52.0 years), 59.1% were men. A combination of vildagliptin and metformin (50/500 mg) was the most commonly used therapy (54.8%), and the median duration of therapy was 24.0 months. The predominant reason for selecting vildagliptin therapy was to improve HbA1c levels (87.8%). A total of 87.5% of patients required dosage up-titration. Vildagliptin therapy was used in patients with T2DM and associated complications (peripheral neuropathy, CAD, nephropathy, retinopathy, autonomous neuropathy, stroke/TIA, and peripheral artery disease). Among 5175 patients who experienced body weight changes, a majority of patients showed a loss of weight (68.6%). The target glycemic control was achieved in 95.3% of patients. The mean HbA1c levels were significantly decreased post-treatment (mean change: 1.34%; p<0.001). Adverse events were reported in 0.4% of patients. Physicians rated the majority of patients as good to excellent on the global evaluation of efficacy and tolerability scale (98.9%, each). Vildagliptin as monotherapy and combination therapy of vildagliptin and metformin was an effective therapy in reducing HbA1c helps in achieving target glycemic control, and was well tolerated in Indian patients with T2DM continuum.     

ACUTE EFFECTS OF MOVEMENT VELOCITY ON BLOOD LACTATE AND GROWTH HORMONE RESPONSES AFTER ECCENTRIC BENCH PRESS EXERCISE IN RESISTANCE-TRAINED MEN

This study aimed to compare the effects of different velocities of eccentric muscle actions on acute blood lactate and serum growth hormone (GH) concentrations following free weight bench press exercises performed by resistance-trained men. Sixteen healthy men were divided into two groups: slow eccentric velocity (SEV; n = 8) and fast eccentric velocity (FEV; n = 8). Both groups performed four sets of eight eccentric repetitions at an intensity of 70% of their one repetition maximum eccentric (1RMecc) test, with 2-minute rest intervals between sets. The eccentric velocity was controlled to 3 seconds per range of motion for SEV and 0.5 seconds for the FEV group. There was a significant difference (P < 0.001) in the kinetics of blood lactate removal (at 3, 6, 9, 15, and 20 min) and higher mean values for peak blood lactate (P = 0.001) for the SEV group (9.1 ± 0.5 mM) compared to the FEV group (6.1 ± 0.4 mM). Additionally, serum GH concentrations were significantly higher (P < 0.001) at 15 minutes after bench press exercise in the SEV group (1.7 ± 0.6 ng · mL⁻¹) relative to the FEV group (0.1 ± 0.0 ng · mL⁻¹). In conclusion, the velocity of eccentric muscle action influences acute responses following bench press exercises performed by resistance-trained men using a slow velocity resulting in a greater metabolic stress and hormone response.