Effects of Lactobacillus spp. Exopolysaccharides on the Anticytotoxicity of Human Intestine Cell Line Int-407 and Inhibition of Colon Cancer Cell Line HT-29 Proliferation

• Main Authors: Sue-Xia Low, 劉素霞
• Other Authors: 游若篍
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/19698874893450882192

碩士 === 國立臺灣大學 === 食品科技研究所 === 100 === Colorectal cancer commonly known as bowel cancer, is one of the leading causes of cancer. About 70% of colorectal cancer is related to dietary habits. Probiotics and prebiotics have received an increasing amount of attention in recent years mainly because of their positive health effects such as maintenance of human intestinal microflora, reduction of lactose intolerance, cholesterol-lowering activities, immunomodulating, antitumor and antimutagenic activity. Studies had shown that the beneficial effects could be attributable to positive physiological effect of exopolysaccharides (EPS). In this study, we employed EPS produced by five Lactobacillus spp. as materials. At first, we investigated the prebiotic effects of EPS on the growth of bifidobacteria. Then EPS were studied for their anticytotoxicity and antigenotoxicity activities against 4-nitroquinoline-1-oxide (4NQO) induced human intestine cell line Int 407. In addition, MTT assay and flow cytometry were used to explore the antiproliferation and cell cycle arrest of human colon cancer cell, HT-29. The results showed that EPS had the prebiotic effects on the growth of bifidobacteria, especially EPS produced by L. acidophilus BCRC 14079. Besides that, EPS could reduce cytotoxicity of Int-407 induced by 4NQO. The possible anticytotoxic mechanisms of EPS were blocking effects and bioanticytotoxic effects. From the results of comet assay, we observed that the DNA tails significantly reduced in the EPS groups, showed the antigenotoxicity effects of EPS. Furthermore, MTT assay showed that the proliferation of HT-29 cells was inhibited after treatment with EPS, and in a time- and dose-dependent manner. At 200 ug/mL, EPS produced by L. casei 01 strongly inhibited the proliferation of HT-29 cells, with a sustained diminution of the number of viable cells throughout the 48 h treatment period. The results of flow cytometry analysis showed that EPS treatment enabled the HT-29 cell cycle arrest at G0/G1 phase, and a significant increase in the sub-G1 phase which induced cell apoptosis. Conclusively, all of EPS produced by Lactobacillus spp. in this study had the prebiotic effects, and protect the intestinal cells from damage effect, antiproliferation of cancer cells and reducing the possibility of suffering from colorectal cancer.