BENZO[A]PYRENE-7,8-DIOL-9,10-EPOXIDE DNA-ADDUCTS AND INCREASED P53 PROTEIN IN MOUSE SKIN

p53 protein expression has been shown to increase in response to DNA d amage in cell culture systems. We have studied p53 expression and benz o[a]pyrene (B[a]P)-induced DNA-damage in the form of benzo[a] pyrene-7 ,8-diol-9,10-epoxide (BPDE)-DNA adducts as measured by synchronous flu orescence spectrophotometry (SFS) in B[a]P-treated C57BL/6 mouse skin. Polyclonal murine antibody CM5, which is comparable to human CM1, det ecting both wild-type and mutated protein, was used. BPDE-DNA adducts reached their maximum at 24 h after all dosage regimens, but were very well detectable also at 12 and 48 h after the treatment, while no add ucts were measurable at 1 week and thereafter. p53 expression was seen in 9/17 (53%) skin samples from mouse treated with 500 mu g of B[a]P 12-48 h after the treatment, while all 25 (100%) cases of similarly tr eated mouse skins were negative after 30 weeks of the treatment. Only one positive sample of total 11 was found among mice treated with repe ated 62.5 mu g doses and this was 24 h after the last treatment. After one 62.5 mu g dose all mice were negative. This is the first report o f an association of p53 protein with DNA damage in vivo and gives supp ort for the putative function of p53 in cellular defense machinery tow ards chemical damage.