Search

Summary TSH-regulated activation of cAMP-dependent protein kinase has been demonstrated in calf thyroid slices. Despite the apparently high basal levels of cAMP in the thyroid, small changes in cAMP concentration in response to the phosphodiesterase inhibitor 1-methyl-3-isobutyl xanthine caused a significant activation of the kinase intracellularly. When TSH was added to the incubation medium there was a time-dependent and dose-dependent activation of the kinase which was closely correlated with the concentration of cAMP in the tissue. Homogenization of the tissue in NaCl to prevent re-association of the kinase subunits demonstrated that 16 mU/ml of TSH was sufficient for almost complete activation of kinase intracellularly.

Four-hour inhalation exposure to 1,1-dichloroethylene (1,1-DCE, vinylidene chloride) was more injurious to 18-hr (overnight) fasted rats than to rats fed ad libitum. The estimated 24 hr LC50 for fed rats was 15,000 ppm while the same value for fasted rats was 600 ppm. The minimum lethal concentration was 200 ppm for fasted rats and 10,000 ppm for fed rats. Serum alanine α-ketoglutarate transaminase (AKT) elevation occurred at 150 ppm in fasted rats, but in the fed rats, a significant elevation was only seen at 2000 ppm and higher. Elevated serum AKT preceded hepatic necrosis and death. This fed-fasted difference in serum AKT elevation was also demonstrable in an isolated perfused rat liver system. The AKT elevation in perfusate from livers of fasted rats was consistent with the time course of injury seen in vivo. Increased susceptibility to hepatic injury appeared to be related to decreased hepatic glutathione concentration associated with fasting (18 hour). Diethylmaleate, a material which results in a decreased hepatic glutathione concentration was administered in vivo and in vitro. This treatment potentiated the hepatic injury in fed rats and in livers taken from fed rats and subsequently perfused.

In contrast to other tissues (e.g. brain, heart), no cAMP dependent protein kinase activity and little cAMP-binding activity could be detected in crude homogenates of purified human PMN leucocytes. This was due to the presence of an inhibitor of cAMP binding and protein kinase activity in PMN leucocytes. Since the inhibitor was entirely segregated in PMN lysosomes (rich in β-glucuronidase and acid phosphatase), lysosomefree supernatants yielded cAMP-dependent protein kinase (> 5-fold stimulation with 5 μM cAMP) and considerable cAMP binding activity. The inhibitor was not dialyzable, and unlike the usual protein kinase modulators, was heat-labile. Preparations of beef-heart protein kinase, treated with the PMN inhibitor, lost cAMP-binding and protein kinase activities simultaneously. The presence of this lysosomal inhibitor may invalidate studies of cAMP binding and protein kinase activities in crude homogenates prepared from lysosome-rich tissues.

Purpose Non-steroidal anti-inflammatory drugs (NSAIDs) and statins are potential chemopreventive or chemotherapeutic agents. The mechanism underlying the deregulation of survivin by NSAIDs and statins in human non-small cell lung cancer cells has not been elucidated. In this study, we investigated the synergistic interaction of sulindac and simvastatin in lung cancer A549 cells. Materials and Methods Cell viability was measured by an MTT assay, while the expression of apoptotic markers, AKT, and survivin in response to sulindac and simvastatin was examined by Western blotting. DNA fragmentation by apoptosis was analyzed by flow cytometry in A549 cells. Reactive oxygen species (ROS) generation was measured by flow cytometry using H2DCFDA and MitoSOX Red, and the effects of pretreatment with N-acetylcysteine were tested. The effects of AKT on survivin expression in sulindac- and simvastatin-treated cells were assessed. Survivin was knocked down or overexpressed to determine its role in apoptosis induced by sulindac and simvastatin. Results Sulindac and simvastatin synergistically augmented apoptotic activity and intracellular ROS production in A549 cells. Inhibition of AKT by siRNA or LY294002 inhibited survivin, while AKT overexpression markedly increased survivin expression, even in the presence of sulindac and simvastatin. Moreover, survivin siRNA enhanced sulindac- and simvastatininduced apoptosis. In contrast, survivin upregulation protected against sulindac- and simvastatin-induced apoptosis. Conclusion Combined treatment with sulindac and simvastatin augmented their apoptotic potential in lung cancer cells through AKT signaling-dependent downregulation of survivin. These results indicate that sulindac and simvastatin may be clinically promising therapies for the prevention of lung cancer.

Self-assembly of phenylalanine creates Phe fibers which is the characteristic fiber model found in amyloid fibrils linked with various neurodegenerative diseases. L-Isoleucyl-L-Phenylalanine (Ile-Phe) dipeptide is composed of isoleucine and phenylalanine amino acids, having fibrillary structure similar to nanotube forms of the core recognition motif of Alzheimer's β-amyloid polypeptide. The integrated coordination of neuronal responses via the PI3-K / Akt pathway has a significant functional impact on Alzheimer's disease. Exposure to Aβ in neuronal cultures leads to deterioration of PI3-K, Akt and mTOR signaling, which may cause cognitive loss during disease. Modulation of PI3-K, Akt and mTOR signal activity need aim to reduce or eliminate the accumulation of potential neurotoxins. The therapeutic approaches aimed to normalize neuronal responses on these pathways or activation of PI3-kinase have a protective effect against cognitive decline in animal models of Alzheimer disease. This study aims to determine the interaction of PI3-kinase with Ile-Phe dipeptide having amyloid fibril structure by three-dimensional simulation techniques such as molecular dynamics (with the GROMACS program) and molecular docking techniques (Schrodinger Software program).

Objective: To investigate the effects of different concentrations of isorhamnetin on C6 rat glioma cells in vitro from January 2015 to June 2015. Methods: The blank control group, blank solvent control group and four concentration groups were used to observe the cell growth status under a microscope. MTT colorimetric assay was used to detect the effect of isorhamnetin on C6 glioma cells in vitro and the cell inhibition rate And survival rate were measured. The apoptotic and apoptotic rates were measured by flow cytometry in the treatment group and the control group. The relationship between the different concentrations of isorhamnetin and C6 glioma cell apoptosis was analyzed the total protein was extracted and the total AKT protein and Ser473 AKT protein content were detected by Western blotting. The rat model of glioma was constructed by SD rats.Five days of isorhamnetin was continuously fed and the plasma was detected by high-performance liquid chromatography,liver, brain tissue isorhamnetin content.Â

Purpose: Head and neck cancer (HNC) is the sixth most common cancer worldwide with a 5-year survival rate of less than 50%. The PI3K/AKT/mTOR signaling pathway is frequently implicated in HNC. Recently, IQ motif–containing GTPase-activating protein 1 (IQGAP1) was discovered to scaffold the PI3K/AKT signaling pathway. IQGAP1 gene expression is increased in HNC, raising the hypothesis that IQGAP1 contributes to HNC. Experimental Design: We performed a combination of in vitro studies using human cancer cell lines treated with a cell-permeable peptide that interferes with IQGAP1′s ability to bind to PI3K, and in vivo studies utilizing mice genetically knocked out for the Iqgap1 (Iqgap1−/−). In vivo EGF stimulation assays were used to evaluate PI3K signaling. To study the role of IQGAP1 in HNC, we used a well-validated mouse model that drives HNC via a synthetic oral carcinogen, 4-nitroquinoline 1-oxide (4NQO). Results: IQGAP1 is necessary for efficient PI3K signaling in vitro and in vivo. Disruption of IQGAP1-scaffolded PI3K/AKT signaling reduced HNC cell survival. Iqgap1−/− mice had significantly lower cancer incidences, lesser disease severity, and fewer cancer foci. IQGAP1 protein levels were increased in HNC arising in Iqgap1+/+ mice. The level of PI3K signaling in 4NQO-induced HNC arising in Iqgap1−/− mice was significantly reduced, consistent with the hypothesis that IQGAP1 contributes to HNC at least partly through PI3K signaling. High IQGAP1 expression correlated with reduced survival, and high pS6 levels correlated with high IQGAP1 levels in patients with HNC. Conclusions: These data demonstrate that IQGAP1 contributes to head and neck carcinogenesis.

The splicing factor SF2/ASF is an oncoprotein that is up-regulated in many cancers and can transform immortal rodent fibroblasts when slightly overexpressed. The mTOR signaling pathway is activated in many cancers, and pharmacological blockers of this pathway are in clinical trials as anticancer drugs. We examined the activity of the mTOR pathway in cells transformed by SF2/ASF and found that this splicing factor activates the mTORC1 branch of the pathway, as measured by S6K and eIF4EBP1 phosphorylation. This activation is specific to mTORC1 because no activation of Akt, an mTORC2 substrate, was detected. mTORC1 activation by SF2/ASF bypasses upstream PI3K/Akt signaling and is essential for SF2/ASF-mediated transformation, as inhibition of mTOR by rapamycin blocked transformation by SF2/ASF in vitro and in vivo. Moreover, shRNA-mediated knockdown of mTOR, or of the specific mTORC1 and mTORC2 components Raptor and Rictor, abolished the tumorigenic potential of cells overexpressing SF2/ASF. These results suggest that clinical tumors with SF2/ASF up-regulation could be especially sensitive to mTOR inhibitors.

n/a