Capsaicin inhibits proliferation of human colon cancer Colo 205 cells via inducing cell cycle arrest and apoptosis
| Autor: | Jia-you Liu, 劉嘉又 |
|---|---|
| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 In Taiwan, Colorectal cancer is the third most common cancer in men and women. The spicy ingredient in hot pepper was isolated by Thresh, and was named it capsaicin .According to some studies, Capsaicin is an effective component of nature Chinese herb medicine and with a powerful anti-tumor, against mutation and chemoprotective activity. Capsaicin is capable of inducing apoptosis of cancer cells, including gastric cancer, prostate cancer and breast cancer etc. In addition, Capsaicin also inhibits human angiogenesis.Several studies have already shown that Capsaicin could produce a large number of intracellular reactive oxygen species (ROS) and promote that calcium release from endoplasmic reticulum (ER) to damage cancer cells and then cause the activation of apoptosis mechanism in cancer cells. However, there are few studies of the effect of Capsaicin on Colorectal cancer. Because Capsaicin could induce a large of intracellular reactive oxygen species in cancer cells, we will detect the drug-induced DNA damage and the influence on cell cycle process which promotes the proliferation effect on cancer cells. Finally, we will examine the other apoptosis mechanism- endoplasmic reticulum stress (ER stress) associated with the release of intracellular calcium, and then evaluate the inhibition effect of Capsaicin on human Colo 205 cells. The assays methods are using : 1) flow cytometry for examining the cell cycle arrest and apoptosis; inclusive of cell viability, the levels of ROS, Ca2+, and mitochondrial membrane potential in human Colo 205 cells. 2) Real-Time PCR and flow cytometry to detect mRNA expression. 3)Western blotting methods for examining the apoptosis associated proteins to find out the mechanism of apoptosis. The approach taken in this experiment is to demonstrate that p53 level elevates obviously and causes p21 to inhibit the activity of protein kinase complex, that decreased the percentage of the Colo 205 cells in the S- and G2/M- phases, and increased the percentage in G0/G1- phase (G0/G1 arrest). Based on the result of this study, the extrinsic and Intrinsic pathways of apoptosis were induced. The caspase-3, -8 and -9 mRNA levels increased after treatment with 150μM Capsaicin. The protein of caspase caspase-3, -8 and -9 also be activated after treatment with 150μM Capsaicin. The extrinsic apoptosis pathway is triggered by Fas ligand (FasL) on account of the amount of Fas and FADD protein elevation. These proteins results in the formation of caspase-8 and caspase-3, which trigger the execution of apoptosis. The percentage of ROS and Ca2+ levels are significantly different between Capsaicin treated group and control. We also found the expression of anti-apoptosis Bcl-2 family lower down. Due to anti-apoptosis Bcl-2 not able to inhibit apoptosis in these examined cells, mitochondria membrane release cytochrome c to cause the activations of Caspase-9、-3 which result in apoptosis. On account of the elevation of AIF protein, we suggest that both Caspase-Dependent and independent pathways of apoptosis were activated. So far as we know, a group of inhibitor of apoptosis protein (IAPs) can bind to caspase and block apoptosis. In this study, the decrease of xIAPs lead to apoptosis due to no inhibition of caspase activity. From the above cited, Capsaicin induced cell cycle arrest of Colo 205 cells in G0/G1- phase and caused apoptosis via extrinsic and Intrinsic pathways. Capsaicin is a strong potential agent for the treatment of Colorectal cancer since it induced apoptosis through the activation of caspase activity in Colo 205 cells. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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