Project description:The selection of specific miRNAs by exosomes and their release from cultured melanocytes after exposure to solar UVR (UVA+UVB) have activities in inducing these cells into a premature senescence.
Project description:The selection of specific miRNAs by exosomes and their release from cultured melanocytes after exposure to solar UVR (UVA+UVB) have activities in inducing these cells into a premature senescence. In this analysis, human TaqMan microRNA array cards A+B were used to measure the relative expression of miRNAs in exosomes isolated from the irradiated and un-irradiated melanocytes.
Project description:Carbaryl (1-naphthyl-methylcarbamate), a broad-spectrum insecticide, has recently been associated with the development of cutaneous melanoma in an epidemiological cohort study with U.S. farm workers also exposed to ultraviolet radiation, which is known to be the main etiologic factor for skin carcinogenesis. Although comprehensive and well designed, the agricultural epidemiological study was not sufficient to characterize the direct contribution of the insecticide and solar radiation in melanomagenesis. Several studies have explored the synergistic effect of certain chemicals with UV radiation, increasing its deleterious effects on the skin. We hypothesized that carbaryl exposure associated with UV solar radiation may induce melanocyte transformation. This study aimed to characterize human melanocytes after individual or combined exposure to carbaryl (100 μM) and solar radiation (375 mJ/cm2). In a microarray analysis, carbaryl, but not solar radiation, induced an important oxidative stress response, evidenced by the upregulation of antioxidant genes, such as Hemeoxygenase-1 (HMOX1), and downregulation of Microphtalmia-associated Transcription Factor (MITF), the main regulator of melanocytic activity; results were confirmed by qRT-PCR. Carbaryl and solar radiation induced a gene response suggestive of DNA damage and cell cycle alteration. The expression of genes in these categories was notably more intense in the combined treatment group, in a synergistic manner, for CDKN1A, BRCA1/2 and MDM2 genes. Likewise, flow cytometry assays demonstrated S-phase cell cycle arrest, reduced apoptosis levels and faster induction of cyclobutane pyrimidine dimers (CPD) lesions in carbaryl treated groups. Our data suggests that carbaryl is genotoxic to human melanocytes, especially when associated with solar radiation.
Project description:The response of microRNAs (miRNAs) to solar ultraviolet radiation (UVR) in human melanocytes while in their natural environment, and in particular, melanocytes from persons with a history of melanoma versus those from healthy persons, have yet to be described. Here, we used laser capture microdissection (LCM) to isolate and subsequently profile the expression of miRNAs in a pure population of melanocytes from human volunteers exposed to physiological doses of simulated sunlight (ssUVR). The majority of the UV-responsive miRNAs in the melanocytes of melanoma patients were down-regulated in expression when compared to those in the melanocytes of healthy individuals. De-repressed genes associated with these down-regulated UV-miRNAs belonged to regulatory modules involved in controlling the epithelial-to-mesenchymal transition (EMT), apoptosis, and immune-evasion, processes reputedly linked to melanoma.
Project description:Ultraviolet radiation (UVR) is the greatest risk factor for melanoma development. While the role of UVR in DNA mutagenesis is generally accepted, the role of UVR-induced mutations in melanomagenesis remains controversial. To understand better how UVR is contributing to melanoma development, we investigated the non-mutational effect of UVR on the epigenome, specifically DNA methylation. Aberrant DNA methylation changes are a hallmark in melanoma and there are few reports on the effects of UVR on DNA methylation. We exposed melanocytes to UVR and cultured them for one-month to detect heritable and stable changes in DNA methylation. We found both hyper and hypo methylated sites after UVR exposure. While many of these changes occurred outside of promoters and areas of active gene expression, there were changes in promoter DNA methylation changes that correlated with changes in gene expression. These changes also correlated with those found in melanoma and UVR sensitive sites were prognostic of patient overall survival. Our work shows UVR-induced DNA methylation changes in melanocytes and may be a novel non-mutational mechanism in which UVR contributes to melanoma development.