The overall purpose of the proposed research is to demonstrate the gradual appearance of phenotypically altered cells during in vivo carcinogenesis of xeno-transplanted human respiratory tract epithelium. Using carcinogen- or genetically-altered human cells that repopulate de-epithelialized rat tracheas transplanted s.c. into nude mice, we will monitor their in vivo behavior and sensitivity to exposure or re-exposure to environmentally relevant carcinogens and promoters. The sensitivity of normal and altered cells to chemical agents will be demonstrated by histological detection of metaplastic-dysplastic lesions and histochemical markers of preneoplastic growth. Utilizing an in vivo - in vitro technique, these same tissues will be used to assess increased survival and resistance to terminal differentiation in selective culture media that do not permit growth of normal human tracheobronchial epithelial cells. Immortalized cell lines or cells with increased in vitro survival will be used for further in vivo experiments of xenotransplantation into de-epithelialized tracheas to assess their tumorigenicity and eventual increased sensitivity to chemical agents. Similarly and again to test in an alternative model the hypothesis that a prior history of exposure to chemical or biological carcinogens increases the sensitivity of human cells to promoters or chemical carcinogens, we will determine if immortalized tumorigenic and non-tumorigenic cells of tracheo-bronchial origin produced by viral infection (SV40- adenovirus) transfection (SV40, T antigen gene, B myc, c-Ha-ras, c-Ki-ras) or in vitro exposure to chemicals (TPA, MNNG, cigarette smoke condensate) exhibit progressive changes when exposed in vivo after repopulation in transplanted tracheas. These changes will be evaluated not only in tumorigenesis experiments, but also with histological sequential follow-up studies using histochemical markers and by monitoring the appearance of the late neoplastic or invasive-metastasizing phenotype, i.e., cell surface changes, (such as alterations in binding to laminin, fibronectin and lectins), demonstration of invasive behavior and colonization potential using biological assays.
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