New Perspectives on Melanoma_ The Role of PAX3

Moreover these melanocytes frequently show expression

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Unformatted text preview: extreme range for much of the year. A recent report from New Zealand [18] shows PAX3 expression in all naevi, melanomas and normal skin samples, confirming our findings. Further studies are required to investigate differences in PAX3 expression in skin samples derived from the Southern vs. the Northern hemisphere. 67 Chapter III – Medic and Ziman, 2010 Normal skin samples used in this study, mainly originating from anatomic locations frequently exposed to the sun (such as limbs and face), were free of any melanocytic lesion having been used for other diagnostic purposes. We have included here two normal skin samples from breast reductions which would have lower sun exposure levels and these samples also show PAX3‐positive melanocytes in the epidermis. We have looked to see if PAX3‐positive melanocytes in our samples were proliferative, by co‐staining with Ki67. In our samples of sun‐ exposed skin, 18.1% of epidermal PAX3‐positive melanocytes were proliferative, but the majority were not. This was in contrast to samples subjected to low levels of sun exposure, where we observed one single PAX3, Ki67‐positive cell. However, to accurately address the question whether the high frequency of PAX3 expression in normal melanocytes observed in this study, relative to previously published papers, is caused in any way by the extent of sun exposure, a more thorough analysis of skin subjected to chronic and/or acute UV exposure relative to sun‐ protected skin, would need to be performed. PAX3 expression in melanocytes of normal adult skin: A role in regulating differentiation? PAX3 and MITF are crucial regulators of melanocyte development and not surprisingly have overlapping expression. To some extent they lie on opposing sides of the differentiation pathway, PAX3 being upstream of MITF and MITF initiating the melanogenic cascade and differentiation. We were interested to see if there is an association between expression of PAX3 and MITF (indicated by their co‐expression) and the stage of melanocyte differentiation (based on the cell location, mainly in the hair follicle), but found no correlation. Studies on m...
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This document was uploaded on 03/06/2014 for the course CHEMISTRY 12 at National University of Singapore.

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