Time filter

Source Type

Lat Bua Luang, Thailand

Pongrakhananon V.,Chulalongkorn University | Nimmannit U.,National Nanotechnology Center | Luanpitpong S.,Chulalongkorn University | Rojanasakul Y.,West Virginia University | Chanvorachote P.,Chulalongkorn University
Apoptosis | Year: 2010

Anoikis, an apoptosis triggered by loss of cell anchorage, has been shown to be a principal mechanism of inhibition of tumor metastasis. Recently, anti-apoptotic Bcl-2 and Cav-1 proteins have been demonstrated to be highly associated with tumor metastasis and apoptosis resistance. Curcumin, a major active component of turmeric, Curcuma longa, has been shown to inhibit neoplastic evolution and tumor progression; however, the underlying mechanisms are unclear. In this study, we investigated the effect of curcumin on cell anoikis as a possible mechanism of anti-tumorigenic action of curcumin, and evaluated the potential role of Bcl-2 and Cav-1 in this process. Our results showed that ectopic expression of either Bcl-2 or Cav-1 induced anoikis resistance of lung carcinoma H460 cells. Curcumin downregulated Bcl-2 protein during anoikis and sensitized the cells to detachment-induced apoptosis, whereas it had no significant effect on Cav-1 protein expression. Bcl-2 down-regulation as well as anoikis enhancement by curcumin were inhibited by superoxide anion scavenger, Mn(III)tetrakis(4-benzoic acid) porphyrin chloride, but were unaffected by other ROS scavengers including catalase and deferoxamine, suggesting that superoxide anion is a key player in the downregulation of Bcl-2 by curcumin. Furthermore, we provided evidence that curcumin decreased Bcl-2 level through ubiquitin-proteasomal degradation which sensitized cells to detachment-induced apoptosis. These findings indicate a novel pathway for curcumin regulation of Bcl-2 and provide a key mechanism of anoikis regulation that may be exploited for metastatic cancer treatment. © 2010 Springer Science+Business Media, LLC. Source

Luanpitpong S.,Chulalongkorn University | Talbott S.J.,West Virginia University | Rojanasakul Y.,West Virginia University | Nimmannit U.,National Nanotechnology Center | And 3 more authors.
Journal of Biological Chemistry | Year: 2010

The acquired capability of tumor cells to migrate and invade neighboring tissues is associated with high metastatic potential and advanced stage of cancers. Recently, signaling molecules such as reactive oxygen species (ROS) and caveolin-1 (Cav-1) have been implicated in the aggressive behavior of cancer cells. However, the roles of specific ROS in cancer cell migration and Cav-1 regulation are unclear. We demonstrate here that Cav-1 plays an important role in the migration and invasion of human lung carcinoma H460 cells and that these effects are differentially regulated by cellular ROS. Using various known inhibitors and donors of ROS, we found that different ROS have different effects on Cav-1 expression and cell migration and invasion. Superoxide anion and hydrogen peroxide down-regulated Cav-1 expression and inhibited cell migration and invasion, whereas hydroxyl radical up-regulated the Cav-1 expression and promoted cell migration and invasion. The down-regulating effect of superoxide anion and hydrogen peroxide on Cav-1 is mediated through a transcription- independent mechanism that involves protein degradation via the ubiquitin-proteasome pathway. These results indicate the essential role of different ROS in cancer cell motility and through Cav-1 expression, which may provide a key mechanism controlling tumor progression and metastasis. The upregulation of Cav-1 and cell motility by hydroxyl free radical suggests an important role of this ROS as a positive regulator of tumor progression. Source

Sikareepaisan P.,Chulalongkorn University | Ruktanonchai U.,National Nanotechnology Center | Supaphol P.,Chulalongkorn University
Carbohydrate Polymers | Year: 2011

A wound dressing material was successfully prepared from alginate, a natural polymer capable of forming into hydrogels, and asiaticoside (PAC), a substance from the plant Centella asiatica which has commonly been used in traditional medicine to heal wounds. Various amounts of PAC (i.e., at 2.5, 5 and 10%, based on the weight of alginate) were mixed with alginate in distilled water. The mixtures were later cast into films. The formation into solid films was achieved with the two-step cross-linking procedure with Ca 2+. First, a dilute CaCl 2 aqueous solution (at 0.05% (w/v), 200 mL) was added slowly into an alginate aqueous solution (at 2% (w/v), 100 mL). This step imparted the dimensional stability of the obtained "mixed" films. Secondly, the "mixed" films were cross-linked further in either 2.5 or 5% CaCl 2 aqueous solution to obtain "immersed" films. This step caused the "immersed" films to be more stable in environment that requires exposure to a high humidity or contact with an aqueous medium. Due to its insolubility in water, PAC existed in the films as discrete entities. The release of PAC from the PAC-loaded alginate "immersed" films was achieved by both the swelling and the erosion of the alginate matrix in the phosphate buffer solution (PBS) that contained methanol at about 10% (v/v). The potential for use of both the neat and the PAC-loaded alginate "immersed" films as wound dressings was assessed by indirect cytotoxicity evaluation and direct cell culture, using normal human dermal fibroblasts (NHDF). The results showed that these materials were non-toxic to the skin cells. © 2010 Elsevier Ltd. All rights reserved. Source

Maitarad P.,University of Shanghai for Science and Technology | Han J.,University of Shanghai for Science and Technology | Zhang D.,University of Shanghai for Science and Technology | Shi L.,University of Shanghai for Science and Technology | And 2 more authors.
Journal of Physical Chemistry C | Year: 2014

CeO2 nanorods impregnated with 2.5 atom % of NiO (NiO/CeO 2 nanorods) were successfully synthesized and examined as catalysts for the NH3-selective catalytic reduction (NH3-SCR) of nitric oxide (NO). The catalytic activity of NiO/CeO2 nanorods resulted in up to ∼90% NO conversion at 250 °C, which is superior to that of pure CeO2 nanorods or NiO nanoparticles. Subsequently, extensive studies of the NiO/CeO2-catalyzed reduction of NO were conducted using X-ray photoelectron spectroscopy, hydrogen temperature- programmed reduction, temperature-programmed desorption, and density functional theory periodic calculations. Compared to that of the pure CeO2 nanorods, the results demonstrated that the NiO/CeO2 nanorods resulted in (i) a higher concentration of Ce3+ chemical species, (ii) a larger amount of active Oα, (iii) lower temperature reducibility, (iv) a lower amount of energy required for oxygen vacancy distortion, and (v) a significant adsorption of and strong interaction between NO and NH3 molecules. Our findings therefore elucidated considerable details of the structural properties of the NiO/CeO2 nanorods that were decisive for achieving a highly efficient conversion of NO by the NH 3-SCR process at low temperatures. © 2014 American Chemical Society. Source

Dedsuksophon W.,King Mongkuts University of Technology Thonburi | Faungnawakij K.,National Nanotechnology Center | Champreda V.,National Center for Genetic Engineering and Biotechnology | Laosiripojana N.,King Mongkuts University of Technology Thonburi
Bioresource Technology | Year: 2011

Hydrolysis/dehydration/aldol-condensation/hydrogenation of lignocellulosic-biomass (corncobs) and biomass-derived carbohydrates (tapioca flour) to produce water-soluble C5-C15 compounds was developed in a single reactor system. WO3-ZrO2 efficiently catalyzed the hydrolysis/dehydration of these feedstocks to 5-hydroxymethylfurfural and furfural, while the impregnation of WO3-ZrO2 with Pd allowed sequential aldolcondensation/hydrogenation of these furans to C5-C15 compounds. The highest C5-C15 yields of 14.8-20.3% were observed at a hydrolysis/dehydration temperature of 573K for 5min, an aldol-condensation temperature of 353K for 30h, and a hydrogenation temperature of 393K for 6h. The C5-C15 yield from tapioca flour was higher than that from corncobs (20.3% compared to 14.8%). Tapioca flour produced more C6/C9/C15, whereas corncobs generated more C5/C8/C13 compounds due to the presence of hemicellulose in the corncobs. These water-soluble organic compounds can be further converted to liquid alkanes with high cetane numbers for replacing diesel fuel in transportation applications. © 2010 Elsevier Ltd. Source

Discover hidden collaborations