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Carcinogenesis studies in human epithelial tissues and cells in vitro: emphasis on serum-free culture conditions and transformation studies.

Serum-free techniques are now available for maintenance of normal non-tumorous human tissues for periods ranging from days to months, and for the selective culture of normal replicative epithelial cells from common sites of human cancer. These model systems are particularly useful in mechanistic studies of molecular and cellular events related to multistep carcinogenesis, including studies of carcinogen metabolism, related DNA damage and repair, toxicity, growth and differentiation, and, moreover, transformation of the cells to immortal and malignant phenotypes. Studies with cultured human epithelial tissues and cells allow comparisons among individuals on both a tissue and cellular level, and link clinical and epidemiologic studies with laboratory animal studies in efforts to determine the influence of predisposing factors and environment in the development of human cancers.