Molecular analysis of the chemoprotective effects of topical sunscreen and vitamin C in preventing UV-induced and reactive oxygen species-induced DNA damage, respectively, using the PCR inhibition methodology.
BACKGROUND
We have developed a PCR-based technique which has previously been shown to be capable of detecting DNA damage (Adducts, strand breaks) induced by carcinogens. We wanted to explore the possibility of detecting anti-carcinogens with this methodology through a corresponding reduction in DNA damage induction.


METHODS
We have used a PCR-based system which relies on the fact that Taq polymerase cannot amplify damaged DNA efficiently. We immobilised DNA in microtitre plates and exposed them to UV-B light and hydrogen peroxide. In addition, we tested the capacity of sunscreens and ascorbate (vitamin C) to ameliorate the DNA damage caused by UV-B and hydrogen peroxide, respectively.


RESULTS
We have shown that in the case of UV-B, sunscreens can effectively reduce the amount of DNA damage induced. This appears to be dependent upon the Sun Protection Factor of the sunscreen, with SPF 35 sunscreens protecting DNA particularly well. We found that both hydrogen peroxide and ascorbate were capable, at high doses, of inducing DNA damage. When mixed, ascorbate effectively increased the DNA damaging effect of hydrogen peroxide.


CONCLUSIONS
We have shown that the PCR inhibition method may be suitable for untangling the complex carcinogenic/anticarcinogenic aspects of factors in the diet and environment. However, the DNA damaging effect of ascorbate must be viewed in the context of the high concentrations used here.
Jenkins
G J S
GJ
School of Biological Sciences, University of Wales Swansea, Swansea SA28PP, U.K. g.j.Jenkins@swansea.ac.uk
Stephens
L A
LA
Masnavi
N
N
Parry
J M
JM
D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000009:adverse effects / Q000494:pharmacology; D001205:Ascorbic Acid / Q000009:adverse effects / Q000494:pharmacology*; D004247:DNA / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D004249:DNA Damage / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000633:toxicity; D051379:Mice; D016133:Polymerase Chain Reaction / Q000379:methods; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000633:toxicity*; D013473:Sunscreening Agents / Q000494:pharmacology*; D014466:Ultraviolet Rays / Q000009:adverse effects*
D016588:Anticarcinogenic Agents; D000975:Antioxidants; D017382:Reactive Oxygen Species; D013473:Sunscreening Agents; D004247:DNA; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid