PROTEASE INHIBITORS AND RADIATION TRANSFORMATION

电离辐射是一种普遍的致癌物质，已被认为与 恶性表型在人和动物模型中的发展 系统。一种细胞体外转化系统的研制 人类和上皮来源的将有助于确认和扩展 这一结果已经在啮齿动物成纤维细胞中得到。使用不朽的 人表皮角质形成细胞的体外诱导 通过DNA肿瘤病毒和DNA肿瘤病毒的协同作用 电离辐射。这一过程涉及多个事件。首先，是 由于感染了病毒而获得无限的增长潜力 AD12-SV40杂合病毒。剩下的步骤包括连续曝光。 到电离辐射。这种辐射诱导的转变导致了 形态变化、非锚定生长和形成 无瘤小鼠的低分化鳞状细胞癌。 这些观察表明永生化的人类表皮角质形成细胞 将为研究这两种辐射提供良好的体外模型系统 癌变及其蛋白水解酶抑制剂的抑制作用。因此， 该提案的目标是将该系统作为可重现的 体外模型研究蛋白水解酶抑制剂在血管紧张素转换酶中的作用 抑制人体上皮系统的辐射致癌作用。 此外，使用消减的cdna表达文库，鉴定细胞 已被激活或失活的基因或原癌基因 抑制蛋白水解酶抑制剂处理后的转化。 最后，我们建议通过双向电泳法来鉴定 作为内源性蛋白酶的底物的蛋白质种类， 已经被蛋白酶抑制剂灭活了。 这些研究将为蛋白酶的作用提供分子基础 抑制辐射诱发的恶性转化中的抑制剂 体外培养的人类细胞。此外，它们可能提供了一个分子基础 针对高危人群的化学预防疗法的发展。

Ionizing radiation is a universal carcinogen which has been implicated in the development of malignant phenotypes in both human and animal model systems. The development of an in vitro transformation system using cells of human and epithelial origin would be useful for confirming and extending the results already obtained with rodent fibroblasts. Using immortalized human epidermal keratinocytes in vitro, we have demonstrated the induction of a malignant phenotype by the concerted action of a DNA tumor virus and ionizing radiation. this process involved multiple events. First, was the acquisition of unlimited growth potential as a result of infection with the AD12-SV40 hybrid virus. the remaining steps involved successive exposures to ionizing radiation. This radiation-induces transformation resulted in morphological alterations, anchorage-independent growth and the formation of poorly differentiated squamous cell carcinomas in athymic mice. These observations indicate that immortalized human epidermal keratinocytes will provide a good in vitro model system to study both radiation carcinogenesis and its suppression by protease inhibitors. Accordingly, the goal of this proposal is to evaluate this system as a reproducible in vitro model for the study of the role of protease inhibitors in the suppression of radiation carcinogenesis in a human epithelial system. Further, using subtracted cDNA expressions libraries, identify the cellular genes or proto-oncogenes that have been activated or inactivated during the suppression of transformation following treatment with protease inhibitors. Finally, we propose to identify by 2-dimensional electrophoresis the protein species which are the substrates of the endogenous proteases that have been inactivated by the protease inhibitors. The studies will provide a molecular basis for the role of protease inhibitors in the suppression of radiation-induces malignant transformation of human cells in vitro. further, they may provide a molecular basis for the development of chemo-preventative therapies for human subjects at risk.