The response of melanocytes to sunlight

Melanomas are among the most commonly occurring cancers in Australia; each year more than 8000 Australians are diagnosed with melanoma, resulting in approximately 900 deaths annually. Survival rates from melanoma are high if the disease is detected early, however once the disease has progressed to metastatic melanoma, it is usually fatal. Melanocytes are the precursor cells to melanoma and sunlight is the principal environmental causal factor for this group of cancers, although there is increasing evidence that the effect of sunlight on melanocytes is not the same for all people. The objective of this study was to measure the response of melanocytes to solar simulated ultraviolet radi-ation and to test whether these responses are modifi ed by constitutional genotype, host phenotype or sunscreen. We recruited healthy volunteers and exposed several small areas of their lower back to a mildly burning dose of solar simulated ultraviolet radiation. Sunscreen was applied to one site and not the other. Biopsies were taken from these sites at time-points following ultraviolet radiation exposure and immunohistochemistry was used to assess the level of DNA repair, cellular migration and proliferation. This study was designed to improve our understanding of the interplay between sun exposure, genetic susceptibility and mela-noma risk. We will present our preliminary fi ndings and look to shed some light on what happens to melanocytes ‘in vivo’ following exposure to ultraviolet radiation, and address whether phenotypic factors or the use of sunscreen, modify these effects