L. Marrot et al., AN IN-VITRO STRATEGY TO EVALUATE THE PHOTOTOXICITY OF SOLAR UV AT THEMOLECULAR AND CELLULAR-LEVEL - APPLICATION TO PHOTOPROTECTION ASSESSMENT, EJD. European journal of dermatology, 8(6), 1998, pp. 403-412
Skin cancers are among the most common human cancers and have an incre
asing incidence. The ultraviolet radiation components of sunlight play
a major role in skin tumor induction and development. Cellular DNA ha
s been identified as a target for most of the biological effects of UV
, and the induction of photodamage is considered as the initiating ste
p of photocarcinogenesis. Thus, effective photoprotection of DNA again
st harmful overexposure to solar UV is a critical issue. The efficienc
y of a sunscreen is usually tested with respect to its ability to prev
ent skin erythema, but conceivably, more data are required at the mole
cular and cellular level in order to ascertain protection against phot
ocarcinogenic risk. In the present study, we define a strategy based o
n the use of various in vitro models and solar-simulated light to eval
uate photodamage and photoprotection: Supercoiled circular plasmid DNA
for detection of structural alterations. The yeast Saccharomyces cere
visiae to evaluate cytotoxicity and genotoxicity. The single-cell gel
electrophoresis or comet assay to determine DNA damage and DNA repair
in human keratinocytes. p53 expression as a hallmark for genotoxic str
ess. Induction of pigmentation in human melanocytes. In conditions whe
re light source, spectrum and control of radiation delivery were preci
sely defined, we have demonstrated that the wide spectrum WA sunscreen
Mexoryl(R) SX protects from the cytotoxicity and genotoxicity of sola
r UV.