Study on Inhibitory Effects of Curcumin at Different Concentrations in a Rat Hepatic Stellate Cell Line (HSC-T6)

• Main Authors: Chia-Yu Lin, 林佳瑜
• Other Authors: Yi-Tsau Huang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/23362174436538548708

碩士 === 國立陽明大學 === 傳統醫藥學研究所 === 95 === Hepatic fibrosis is a wound-healing response to repeated liver injuries and is characterized by the activation of hepatic stellate cells (HSCs) and excess accumulation of extracellular matrix (ECM) proteins. Activation and fibrogenesis of HSCs have been implicated in the pathogenesis of liver fibrosis. Therefore, suppression of activation and fibrogenesis of HSCs, as well as induction of apoptosis have been proposed as therapeutic strategies against liver fibrosis. Curcumin, a yellow curry pigment from turmeric (Curcuma longa Linn), has been shown to possess anti-inflammatory and antioxidant properties. Transforming growth factor-beta1 (TGF-β1) is a multifunctional growth factor and is the most potent cytokine for enhancing hepatic fibrogenesis. In this study, we investigated the in vitro effects of curcumin on hepatic fibrosis at the concentration range of (1~40 μM). A cell line of rat HSC-T6 was stimulated with 1 ng/ml TGF-β1 in the presence or absence of curcumin. The inhibitory effects of curcumin (1.25~10 μM) on fibrosis markers including α-smooth muscle actin (α-SMA), collagen and the mRNA expression of α-SMA were assessed by immunoblotting, Sircol collagen assay and reverse transcription-polymerase chain reaction (RT-PCR), respectively. The cell viability affected by curcumin was measured by MTT assay. In addition, the induction effects of curcumin (20~40 μM) on apoptosis in HSC-T6 cells were also determinated by Hoechst stains and flow cytometry analysis. Then we also investigated the release of cytochrome c from the mitochondria to the cytoplasm by using immunoblotting. Our results revealed that TGF-β1 at 1 ng/ml induced collagen deposition of HSC-T6 cells (145 ± 5 % of controls), and pre-exposure of cells to curcumin (1.25~10 μM) inhibited the stimulatory effect of TGF-β1 in a concentration-dependent manner. Curcumin (10 μM) significantly reduced the TGF-β1-induced collagen deposition (97 ± 7 % of controls) without cytotoxicity in the MTT assay . In addition, TGF-β1 at 1 ng/ml also increased mRNA and protein expressions of α-SMA and pretreatment of curcumin (1.25~10 μM) concentration-dependently attenuated the up-regulating effect by TGF-β1. On the other hand, curcumin (20~40 μM) alone significantly and concentration- dependently enhanced apoptosis of HSC-T6 cells and this effect was accompanied by the induction of cytochrome c release from the mitochondria to the cytoplasm in a concentration-dependent manner. We suggested that curcumin exerted anti-fibrotic effects, possibly through two different strategies depending on its concentrations. At lower concentrations (1.25~10 μM), curcumin exerted anti-fibrogenetic effect without causing significant cytotoxicity to HSC-T6 cells and at higher concentrations (20~40 μM), curcumin exerted induction of apoptosis in HSC-T6 cells. These findings indicated that curcumin might be a potential anti-fibrotic herb for treatment and prevention of hepatic fibrosis through its anti-fibrogenetic and pro-apoptotic effects.