CELL-PROLIFERATION AND DNA-ADDUCTS IN HAMSTER TRACHEAL EPITHELIUM EXPOSED TO BENZO[ALPHA]PYRENE IN ORGAN-CULTURE

The effect of benzo[a]pyrene (B[a]P) on cell proliferation in cultured hamster tracheal epithelium was studied in relation to the formation of B[a]P-DNA adducts. To this end, tracheae were isolated from Syrian golden hamsters, cut into rings and cultured in Ham's F12 medium. Then , the tracheal rings were exposed to 2 or 20 mu M B[a]P, either contin uously for 7 days or for 2 days followed by a 5-day recovery period wi thout B[a]P. At intervals rings were sampled for determination of cell proliferation (by means of the labelling index). In addition, B[a]P-D NA adduct levels were determined in the continuous exposure experiment by means of in situ detection by immunofluorescence microscopy. After 2 days of exposure to 2 or 20 mu M B[a]P, there was a significant inc rease in B[a]P-DNA adduct level. A further, linear increase in B[a]P-D NA adduct level, however, was only observed after continuous exposure to 20 mu M B[a]P, whereas the adduct level in the 2 mu M continuous ex posure group remained virtually the same. In unexposed tracheal epithe lium an initial peak of cell proliferation was observed. This initial proliferation was significantly lower in the exposed samples. Only con tinuous exposure to 20 mu M B[a]P steadily decreased the labelling ind ex from day 2 to 7. It is concluded that the increase in B[a]P-DNA add uct level is correlated with the reduction of cell proliferation in ha mster tracheal epithelium exposed to B[a]P in Ham's F12 medium. Copyri ght (C) 1996 Elsevier Science Ltd