Epigenetic Responses to Solar UVR in Melanocytes

皮肤黑色素瘤是美国最致命的人类皮肤癌，其发病率在年轻人中

Cutaneous melanoma is the most lethal of human skin cancers in the United States, and its incidence in young adults as well as in persons over the age of 65 has been steadily increasing over the last 50 years. A large body of evidence supports the role of solar ultra-violet radiation (UVR) in being a major factor in the rise of this disease. However, it is still unclear how UVR, particularly recreational or intermittent exposure to such, causes melanoma, especially since none of the mutated genes (e.g., N-RAS, BRAF, PTEN, and CDKN2A) that are frequently found in melanoma typify UV-induced mutations. This incongruity, therefore, raises the possibility that these genes associated with melanoma could in fact be collaborating with UV-induced epigenetic changes as imposed by DNA hypo- or hyper-methylation and/or covalent modifications of core histones. Thus, our main hypothesis is that UVR induces epigenetic alterations in the melanocytes of human skin and that this in turn leads to the activation of oncogenes and/or the silencing of tumor suppressor genes, ultimately resulting in the development of melanoma. A corollary of this hypothesis is that these types of alterations might also arise from indirect UVR-induced changes to the surrounding microenvironment. To establish proof of our hypotheses, however, we first need to generate data as a point of reference for our future studies. Therefore, the following specific aims are proposed: SPECIFIC AIM 1: Evaluating the profiles of gene expression in melanocytes after exposure to UVR in vivo. 1a. Human volunteers, light source, spectral measurements, and UVR exposure. 1b. Sample processing, staining and capture by LCM. 1c. The isolation of RNA from captured melanocytes and/or keratinocytes. 1d. GeneChip Probe Array and Data Analysis. SPECIFIC AIM 2: Constructing a 3-dimensional human-skin model 2a. The Isolation of keratinocytes and melanocytes from human tissue. 2b. Reconstructing 3-dimensional human-skin. SPECIFIC AIM 3: Characterizing gene expression patterns in melanocytes of 3-D culture after UVR. 3a. Light source and spectral measurements. 3b. Irradiation procedure and microarray analysis.