Analysis of intracellular distribution and binding of benzo[alpha]pyrene in human diploid fibroblasts

Previous work with low passage synchronized human foreskin fibroblast cell populations has indicated that benzo[alpha]pyrene (BP) can induce a carcinogenic event [3]. BP additionally has shown to damage DNA in log-arithmically growing low passage cultures [9]. High passage cells, on the other hand, seem to be refractory to transformation by BP, even though this agent can induce DNA damage, similar to that seen in low passage cells. When low passage cells were treated with BP, the initial binding of the hydrocarbon was primarily to a cytoplasmic protein complex of molecular weight 12,500 while in high passage cells, a major portion of BP was bound to protein complex of molecular weight 200,000. High-pressure liquid chromatography (HPLC) profiles of ethyl acetate extractable fractions from the BP-cytoplasmic protein complexes of low and high passage cells demonstrated that the majority of the BP remained unmetabolized. When nuclei were isolated from low and high passage cells prior to the HPLC analysis, the major component (90%) was again unmetabolized BP. The results suggest selective attachment of BP to different cytoplasmic protein complexes of logarithmically growing human diploid fibroblast cells dependent on the passage level of the cells.