[Show abstract][Hide abstract] ABSTRACT: To investigate the effect of glyceraldehyde-derived advanced glycation end-products (Glycer-AGEs) on hepatocellular carcinoma (HCC) cells.
Two HCC cell lines (Hep3B and HepG2 cells) and human umbilical vein endothelial cells (HUVEC) were used. Cell viability was determined using the WST-8 assay. Western blotting, enzyme linked immunosorbent assay, and real-time reverse transcription-polymerase chain reactions were used to detect protein and mRNA. Angiogenesis was evaluated by assessing the proliferation, migration, and tube formation of HUVEC.
The receptor for AGEs (RAGE) protein was detected in Hep3B and HepG2 cells. HepG2 cells were not affected by the addition of Glycer-AGEs. Glycer-AGEs markedly increased vascular endothelial growth factor (VEGF) mRNA and protein expression, which is one of the most potent angiogenic factors. Compared with the control unglycated bovine serum albumin (BSA) treatment, VEGF mRNA expression levels induced by the Glycer-AGEs treatment were 1.00 ± 0.10 vs 1.92 ± 0.09 (P < 0.01). Similarly, protein expression levels induced by the Glycer-AGEs treatment were 1.63 ± 0.04 ng/mL vs 2.28 ± 0.17 ng/mL for the 24 h treatment and 3.36 ± 0.10 ng/mL vs 4.79 ± 0.31 ng/mL for the 48 h treatment, respectively (P < 0.01). Furthermore, compared with the effect of the control unglycated BSA-treated conditioned medium, the Glycer-AGEs-treated conditioned medium significantly increased the proliferation, migration, and tube formation of HUVEC, with values of 122.4% ± 9.0% vs 144.5% ± 11.3% for cell viability, 4.29 ± 1.53 vs 6.78 ± 1.84 for migration indices, and 71.0 ± 7.5 vs 112.4 ± 8.0 for the number of branching points, respectively (P < 0.01).
These results suggest that Glycer-AGEs-RAGE signaling enhances the angiogenic potential of HCC cells by upregulating VEGF expression.
World Journal of Gastroenterology 04/2012; 18(15):1781-8. · 2.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A dysfunctional ubiquitin-proteasome system recently has been proposed to play a role in the pathogenesis of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). We have shown previously that spinal motor neurons are more vulnerable to proteasome inhibition-induced neurotoxicity, using a dissociated culture system. To confirm this toxicity, we used organotypic slice cultures from rat neonatal spinal cords, which conserve the structure of the spinal cord in a horizontal plane, enabling us to identify motor neurons more accurately than in dissociated cultures. Furthermore, such easy identifications make it possible to follow up the course of the degeneration of motor neurons. When a specific proteasome inhibitor, lactacystin (5 microM), was applied to slice cultures, proteasome activity of a whole slice was suppressed below 30% of control. Motor neurons were selectively damaged, especially in neurites, with the increase of phosphorylated neurofilaments. They were eventually lost in a dose-dependent manner (1 microM, P < 0.05; 5 microM, P < 0.01). The low capacity of Ca(2+) buffering is believed to be one of the factors of selectivity for damaged motor neurons in ALS. In our system, negative staining of Ca(2+)-binding proteins supported this notion. An intracellular Ca(2+) chelator, BAPTA-AM (10 microM), exerted a significant protective effect when it was applied with lactacystin simultaneously (P < 0.01). We postulate that proteasome inhibition is an excellent model for studying the mechanisms underlying selective motor neuron death and searching for new therapeutic strategies in the treatment of ALS.
Journal of Neuroscience Research 11/2005; 82(4):443-51. · 2.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Glycation, one of the post-translational modifications of proteins, is a nonenzymatic reaction initiated by the primary addition of a sugar aldehyde or ketone to the amino groups of proteins. In the early stage of glycation, the synthesis of intermediates leading to the formation of Amadori compounds occurs. In the late stage, advanced glycation end products (AGE) are irreversibly formed after a complex cascade of reactions. Several AGEs have been characterized chemically, while other new compounds remain to be identified. To date, studies of the contribution of glycation to diseases have been primarily focused on its relationship to diabetes and diabetes-related complications. However, glucose-induced damage is not limited to diabetic patients. Although it does not cause rapid or remarkable cell damage, glycation advances slowly and accompanies every fundamental process of cellular metabolism. It has recently become clear that glycation also affects physiological aging and neurodegenerative diseases such as Alzheimer's disease and amyotrophic lateral sclerosis. Glycation alters the biological activity of proteins and their degradation processes. Protein cross-linking by AGE results in the formation of detergent-insoluble and protease-resistant aggregates. Such aggregates may interfere with both axonal transport and intracellular protein traffic in neurons. In addition, glycation reactions lead to the production of reactive oxygen species. Conversely, glycation is promoted by oxidative stress. We speculate on the presence of synergism between glycation and oxidative stress. In this review, we provide an outline of glycation and propose some possible mechanisms of its cytotoxicity and defense systems against it.
Brain Research Reviews 04/2003; 41(2-3):306-23. · 7.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Proteasomal dysfunction has been implicated in the pathogenesis of Parkinson's disease (PD). We examined the effect of a selective proteasomal inhibitor, epoxomicin, on primary cultured mesencephalic neurons. Exposing rat cultured mesencephalic neurons to epoxomicin for 24 h resulted in neurotoxicity in a dose-dependent manner. Epoxomicin caused mitochondrial dysfunction, reduction in reduced glutathione (GSH), and increased generation of free radicals. Neuronal damage was significantly blocked by antioxidative/GSH-augmenting agents. Epoxomicin also increased the expression of Bax and decreased that of Bcl-2, which may cause mitochondrial dysfunction and release of free radicals. Dopaminergic neurons were preferentially resistant to the toxicity of epoxomicin. Inhibiting the synthesis of tetrahydrobiopterin (BH(4)), which has been reported to have antioxidative function, increased the susceptibility of dopaminergic neurons, whereas increasing BH(4) levels protected non-dopaminergic neurons. These findings suggest that BH(4) is at least in part a contributing factor to grand the resistance to dopaminergic neurons against epoxomicin neurotoxicity. Our results suggest that proteasome inhibition causes the neurotoxicity in mesencephalic neurons, but that is not sufficient to reproduce the selective damage to dopaminergic neurons, such as that seen in PD.
Brain Research 03/2003; 964(2):228-36. · 2.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Vascular complications arising from multiple environmental and genetic factors are responsible for many of the disabilities and short life expectancy associated with diabetes mellitus. Here we provide the first direct in vivo evidence that interactions between advanced glycation end products (AGEs; nonenzymatically glycosylated protein derivatives formed during prolonged hyperglycemic exposure) and their receptor, RAGE, lead to diabetic vascular derangement. We created transgenic mice that overexpress human RAGE in vascular cells and crossbred them with another transgenic line that develops insulin-dependent diabetes shortly after birth. The resultant double transgenic mice exhibited increased hemoglobin A1c and serum AGE levels, as did the diabetic controls. The double transgenic mice demonstrated enlargement of the kidney, glomerular hypertrophy, increased albuminuria, mesangial expansion, advanced glomerulosclerosis, and increased serum creatinine compared with diabetic littermates lacking the RAGE transgene. To our knowledge, the development of this double transgenic mouse provides the first animal model that exhibits the renal changes seen in humans. Furthermore, the phenotypes of advanced diabetic nephropathy were prevented by administering an AGE inhibitor, (±)-2-isopropylidenehydrazono-4-oxo-thiazolidin-5-ylacetanilide (OPB-9195), thus establishing the AGE-RAGE system as a promising target for overcoming this aspect of diabetic pathogenesis.
Journal of Clinical Investigation 08/2001; · 12.81 Impact Factor