B[A]P-DNA ADDUCT FORMATION AND INDUCTION OF HUMAN EPITHELIAL LUNG-CELL TRANSFORMATION

In this study we tested the suitability of the human epithelial lung c ell line BEAS-2B for in vitro studies of lung carcinogenesis. The huma n bronchial epithelial lung cell line BEAS-2B, immortalized with an SV -40/Ad-12 hybrid virus construct, was treated for 24 hours with five d ifferent concentrations of the lung carcinogen benzo(a)pyrene (B[a]P) to assess the relationship between DNA adduct levels, cell cycle distr ibution, micronuclei formation (MN), colony forming efficiency (CFE), and anchorage independent growth (AIG). There appeared to be a strong linear correlation between B[a]P concentration and DNA adduct formatio n, but no difference in cell cycle distribution was observed after inc ubation with various concentrations of B[a]P. In the incubation range of 4 to 100 nM B[a]P, the number of DNA adducts was linearly correlate d with colony formation in AIG and with the number of cells within ind ividual colonies but not the number of colonies in the CFE test. At hi gher B[a]P concentrations, the clonal expansion of cells in the CFE an d the number of colonies in the AIG declined. Also, the number of micr onuclei increased with the formation of DNA adducts. It is concluded t hai after 24 hours of incubation with 100 nM B[a]P, the formation of B PDE-DNA adducts in the human epithelial lung cells BEAS-2B results in maximal induction of cell transformation. Because of this correlation between DNA adduct formation and lung epithelial cell transformation, the BEAS-2B cells seem suitable for in vitro studies on lung carcinoge ns. (C) 1997 Wiley-Liss, Inc.