Effects of N-acetyltransferase activity and gene expression involved in berberine-induced N-acetylation of 2-aminofluorene in human breast cell line (MCF-7)

• Main Author: 陳豐仁
• Other Authors: 鍾景光
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/95991545891601749307

碩士 === 中國醫藥大學 === 醫學研究所 === 92 === N-Acetyltransferase（NAT） has been shown to be a major enzyme that catalyzes the heterocyclic aromatic amines to form the active carcinogens. 2-Aminofluorene（2-AF） is a synthetic arylamine which can be converted by N-acetyltransferase to a well-known animal carcinogen, called 2-acetylaminofluorene（2-AAF）. Berberine is an alkaloid present in a number of clinically important medicinal plants, including Hydrastis canadensis (goldenseal), Coptis chinensis (coptis or goldenthread), Berberis aquifolium (Oregon grape), and Berberis vulgaris (barberry). Many papers have shown that berberine can inhibit the activity of N-acetyltransferase but there are no available information addressing berberine effects on the NAT activity of human breast cancer cell. Thus, we used berberine to test its inhibition of NAT activity in human breast cancer cell line (MCF-7). The NAT activity was measured by a high performance liquid chromatography assaying for the amounts of 2-AAF and the remaining 2-AF. The protein of NAT and NAT mRNA gene expression were evaluated by Western blotting and RT-PCR methods separately. Our results demonstrated that (1) Berberine can inhibit the activity and protein level of NAT in a dose-dependent and time-dependent manner. (2) Berberine is an uncompetitive inhibitor of NAT that berberine can decrease the value of Km and Vmax. (3) Berberine can decrease NAT mRNA gene expression.