DIOXIN-EPITHELIAL CELL INTERACTIONS: MECHANISM & ASSAY

虽然许多涉及动物和分子生物学技术的研究 生物学已经定义了一些与二恶英中毒有关的参数， 这种毒性的机制和靶器官仍然未知。 电流 政府致力减轻二恶英对公众健康可能造成的影响 暴露涉及通过昂贵高分辨率检测这些化合物 化学分析 然而，这种技术虽然精确且 决定性的，昂贵的，可能无法处理大量的 样品需要在环境监测项目中进行测试。 我们最近已经证明，2，3，7，8-TCDD是非常有效的， 诱导融合后细胞增殖的可逆体外变化 和细胞系的形态，命名为XBF，来源于角化 从小鼠畸胎瘤克隆的细胞系（XB）。 浓度的 2，3，7，8-TCDD在低至10-11 M时就能引起“平细胞效应”。 初步的实验表明，平板电池效应将是有用的 作为一种新的工具，用于研究与 暴露于二恶英类化合物。 本实验室开展的其他工作 表明这种影响是特定的毒性更大的多氯化物， 二恶英和二苯并呋喃，这一系统有可能用作 用于检测该活性的相对简单和便宜的测定 在各种环境样品中，包括空气、土壤、沉积物、鱼、煤烟， 表面和水。 我们建议研究二恶英类活性的机制， 使用2，3，7，8-TCDD的扁平细胞效应的各个方面， 作为一个原型。 这些研究将侧重于 XBF细胞系的特异性、饲养细胞和细胞-细胞的功能 相互作用，这种影响的关系，分化和 这种效应可能与Ah基因座的基因产物有关。 我们 还建议确定使用诱导的可行性， 用平板细胞效应半定量筛选类二恶英 环境样品中的化合物的验证研究，使用纯 化合物、实际样品和样品构建体以及它们的混合物， 化学物质，以确定化学相互作用的程度。 这样的测定 将允许阳性样本的优先级排序，用于随后的高 分离化学分析和阴性样品的消除 进一步测试。 这将允许更合理地使用更精确的 但分析技术有限。

While numerous investigations involving animals and techniques of molecular biology have defined some parameters relating to dioxin intoxication, the mechanism of this toxicity and the target organ remain unknown. Current efforts to alleviate the possible public health consequence of dioxin exposure involve detection of these compounds by costly high resolution chemical analysis. However, such techniques, while both precise and definitive, are expensive and may not be able to handle the vast number of samples needed to be tested in an environmental monitoring program. We have recently demonstrated that 2,3,7,8-TCDD is extremely potent in inducing a reversible in vitro change in post confluent cell proliferation and morphology of a cell line, designated XBF, derived frm a keratinizing cell line (XB) cloned from a mouse teratoma. Concentrations of 2,3,7,8-TCDD as low as 10-11 M will induce the "flat-cell effect". Preliminary experiments indicate that the flat-cell effect will be useful as a novel tool for the study of the mechanism of toxicity associated with exposure to dioxinlike compounds. Other work performed in this laboratory indicates that this effect is specific for the more toxic polychlorinated dioxins and dibenzofurans, and that this system has potential for use as a relatively simple and inexpensive assay for the detection of this activity in various environmental samples including air, soil, sediment, fish, soot, surfaces, and water. We propose to investigate the mechanism of dioxinlike activity by studying various aspects of the flat-cell effect using 2,3,7,8-TCDD, the most potent member of this group, as a prototype. These studies will focus on the specificity of the XBF line, the function of the feeder cells and cell-cell interactions, the relation of this effect to differentiation and the possible association of this effect with gene products of the Ah locus. We also propose to determine the feasibility of using the induction of the flat-cell effect as a semiquantitative screening assay for dioxinlike compounds in environmental samples by validation studies using pure compounds, actual samples, and sample constructs as well as mixtures of chemicals to determine the extent of chemical interactions. Such an assay would allow priority ranking of positive samples for subsequent high resolution chemical analysis and the elimination of negative samples from further testing. This would allow more rational use of the more precise but limited analytical techniques.