BACKGROUND & AIMS:
:We have examined the cytotoxicity and cellular incorporation of aflatoxin B1 (AFB1) in several types of established and primary cultured cells. The inhibition of DNA synthesis by AFB1 at 1 microgram/ml was about 0-30% in the established cell lines, including human hepatic cells. In chicken primary hepatocytes, however, DNA synthesis as well as RNA and protein syntheses were strongly inhibited by much lower concentrations of AFB1, e.g., 0.1 microgram/ml. In contrast, chicken primary fibroblasts showed almost no significant response to the toxin. Microsomal cytochrome P-450 activities in hepatic tissues were 10-20-fold higher than those in fibroblastic tissues. The amount of [3H]AFB1 incorporated into acid-insoluble materials in the primary hepatocytes was also 10-100-fold more than that in the primary fibroblasts. However, a significant amount of AFB1, which was enough to induce cytotoxic effects on the primary hepatocytes, could be incorporated into the primary fibroblasts when the concentrations of AFB1 were increased. Characterization of the AFB1-associated cellular components showed that most of them were DNA, RNA, and proteins in the primary hepatocytes, while in the primary fibroblasts a large portion of the incorporated AFB1 was recovered from lipid fractions. In addition, the selective binding of [3H]AFB1 to several proteins was observed only in the primary hepatocytes. The possible role of the AFB1-binding proteins are also discussed.
背景与目标:
:我们已经研究了黄曲霉毒素B1(AFB1)在几种类型的已建立和原代培养细胞中的细胞毒性和细胞掺入。在已建立的细胞系(包括人肝细胞)中,AFB1对DNA合成的抑制作用为1微克/毫升,约为0-30%。但是,在鸡原代肝细胞中,DNA的合成以及RNA和蛋白质的合成受到浓度低得多的AFB1(例如0.1微克/毫升)的强烈抑制。相反,鸡原代成纤维细胞对毒素几乎没有明显反应。肝组织中的微粒体细胞色素P-450活性比成纤维细胞组织中的微粒体细胞色素P-450活性高10-20倍。在原代肝细胞中掺入酸不溶性物质中的[3H] AFB1的量也比原代成纤维细胞高10-100倍。但是,当AFB1浓度增加时,足以诱导对原代肝细胞的细胞毒性作用的大量AFB1可以掺入原代成纤维细胞中。与AFB1相关的细胞成分的表征表明,它们中的大多数是原代肝细胞中的DNA,RNA和蛋白质,而在原代成纤维细胞中,大部分掺入的AFB1是从脂质组分中回收的。此外,仅在原代肝细胞中观察到[3H] AFB1与几种蛋白质的选择性结合。还讨论了AFB1结合蛋白的可能作用。