To cite this version:Agnieszka Szuster-Ciesielska, Krzysztof Plewka, Jadwiga Daniluk, Martyna Kandefer-Szerszeń. Zinc supplementation attenuates ethanol-and acetaldehyde-induced liver stellate cell activation by inhibiting reactive oxygen species (ROS) production and by influencing intracellular signaling. Biochemical Pharmacology, Elsevier, 2009, 78 (3) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Liver fibrosis has been reported to be inhibited in vivo by oleanolic and ursolic acids; however, the activity of other triterpenes like betulin and betulinic acid has not been examined. Butein has also been reported to prevent and partly reverse liver fibrosis in vivo, although its mechanism of action is poorly understood. Therefore, the aim of this study was to determine the antifibrotic potential of butein, betulin, and betulinic acid and examine their mechanisms of action in vitro. This study was conducted in rat stellate cells (HSCs) that were treated with acetaldehyde, which is the most reactive product of ethanol metabolism. Butein, betulin, and betulinic acid were preincubated with rat HSCs at non-toxic concentrations. Treatment effects were measured in regard to acetaldehyde-induced toxicity and cell migration, and several markers of HSC activation were evaluated, including smooth muscle α-actin (α-SMA) and procollagen I expression. In addition, changes in the release of reactive oxygen species (ROS) and cytokines such as tumor necrosis factor-α (TNF-α) and tumor growth factor-β1 (TGF-β1) and changes in the production of metalloproteinase-2 (MMP-2) and tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) were determined. In vitro, HSCs were protected against acetaldehyde-induced toxicity by betulin but not by betulinic acid and butein. However, butein, betulin, and betulinic acid inhibited the production of ROS by HSCs treated with acetaldehyde and inhibited their migration. Butein also inhibited acetaldehyde-induced TGF-β1 production. Butein, betulin, and betulinic acid down-regulated acetaldehyde-induced production of TIMP-1 and TIMP-2. Betulin decreased the acetaldehyde-induced activity of MMP-2, but butein and betulinic acid did not. The results indicated that butein, betulin, and betulinic acid inhibited the acetaldehyde-induced activation of HSCs. Each drug functioned in a different manner, whereby some were acting as either antioxidants or inhibitors of TIMPs expression and butein additionally acted as an inhibitor of TGF-β production.
Colon carcinoma invasiveness is a process involving cell-cell and cell-matrix alterations, local proteolysis of the ECM (extracellular matrix) or changes in cytokine and growth factor levels. In order to evaluate the role of TGF-beta1 (transforming growth factor-beta1) and small G protein RhoA in tumour progression, the influence of TGF-beta1 treatment or RhoA-associated kinase inhibitor on the production of NO (nitric oxide) and MMP-2 and MMP-9 (metalloproteinases-2 and -9) was analysed in three human colon adenocarcinoma cell lines (HT29, LS180, SW948) representing different stages of tumour development. All the tested cell lines produced low amounts of MMP-2 and MMP-9. rhTGF-beta1 and the synthetic Rho kinase inhibitor (Y-27632) decreased MMP-2 secretion by colon cancer cells, especially in the most advanced stage of colon cancer. rhTGF-beta1 decreased NO secretion by cells, while Y-27632 had no effect on it. Immunoblotting with anti-RhoA antibodies followed by densitometry revealed that RhoA levels were slightly increased after incubation of colon carcinoma cells (SW948) with rhTGF-beta1. rhTGF-beta1 induced alpha-smooth muscle actin (alpha-SMA) expression, especially in high Duke's grade of colon cancer, while Y-27632 blocked it. Summing up, in colon carcinoma cells, TGF-beta1 and RhoA protein may regulate tumour invasiveness measured as MMP, NO and alpha-SMA expression or assayed using motility data and may be a good target for cancer therapy.
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