The proliferative response of melanocytes to sunlight

Over 434 000 non melanoma and 10 000 melanoma skin cancers are removed in Australia each year. That is approximately 1200 people every day having a skin cancer removed. This costs the Australian health system $300 million 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 radiation and to test whether these responses are modified by constitutional genotype, host phenotype or sunscreen. We recruited 57 healthy volunteers and exposed several small areas of their lower back to a mildly burning dose of solar simulated ultraviolet radiation with sunscreen applied to one site for comparison. Biopsies were taken from these sites at time-points following ultraviolet radiation exposure and immunohistochemistry was used to assess the level of melanocyte proliferation and cellular migration. This study was designed to improve our understanding of the interplay between sun exposure, genetic susceptibility and melanoma risk. We will present our preliminary findings 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.