Inhibition of reporter gene expression in mammalian cells. Effects of distinct carcinogen lesions in DNA

The effect of UV photoproducts or benzo[a] pyrene-diolepoxide-1 (BPDE-I) adducts in DNA on the transient expression of a reporter gene was measured in mammalian cells. The plasmid pRSVCAT was UV irradiation or treated with BPDE-I in vitro and co-transfected with undamaged pRSVBGAL into mouse and human fibroblasts. Variations in transfection efficiency among different cell lines were corrected by adjusting the volumes of cell extracts used in the chloramphenicol acetyl transferase (CAT) assays to contain equal β-galactosidase (BGAL) activity. The expression of the CAT gene was found to decrease exponentially after transfection of pRSVCAT containing increasing numbers of DNA lesions per molecule