Project description:Germline mutations in CDKN2A and/or red hair colour variants in MC1R genes are associated with an increased susceptibility to develop cutaneous melanoma. To investigate the impact of germinal p.G101W CDKN2A mutation and MC1R variants on gene expression and transcription profiles associated to skin cancer and melanoma in particular, we set-up primary skin cultures from twins belonging to the melanoma prone-families with and without these genomic features. were analyzed using expression array methodology. Overall, 1535 transcripts were deregulated in CDKN2A mutated cells, finding overexpression of immunity-related genes (HLA-DPB1, CLEC2B, IFI44, IFI44L, IFI27, IFIT1, IFIT2, SP110 and IFNK) and downregulation of genes playing a role in the Notch signaling pathway. 3570 transcripts were deregulated in carriers of MC1R variants. In this case, upregulated genes were involved in oxidative stress and DNA damage pathways as well as in neurodegenerative diseases such as Parkinson’s, Alzheimer and Huntington. In contrast, downregulated genes were associated with pigmentation synthesis/transport and angiogenesis. By using a coculture system, this study identified key molecular functions and/or pathways that are deregulated due to alterations in melanoma susceptibility genes which in turn, could be involved in initiation/progression of the disease. 12 samples total. Several experimental groups: with and without genomic features (CDKN2A, MC1R).
Project description:Germline mutations in CDKN2A and/or red hair colour variants in MC1R genes are associated with an increased susceptibility to develop cutaneous melanoma. To investigate the impact of germinal p.G101W CDKN2A mutation and MC1R variants on gene expression and transcription profiles associated to skin cancer and melanoma in particular, we set-up primary skin cultures from twins belonging to the melanoma prone-families with and without these genomic features. were analyzed using expression array methodology. Overall, 1535 transcripts were deregulated in CDKN2A mutated cells, finding overexpression of immunity-related genes (HLA-DPB1, CLEC2B, IFI44, IFI44L, IFI27, IFIT1, IFIT2, SP110 and IFNK) and downregulation of genes playing a role in the Notch signaling pathway. 3570 transcripts were deregulated in carriers of MC1R variants. In this case, upregulated genes were involved in oxidative stress and DNA damage pathways as well as in neurodegenerative diseases such as Parkinson’s, Alzheimer and Huntington. In contrast, downregulated genes were associated with pigmentation synthesis/transport and angiogenesis. By using a coculture system, this study identified key molecular functions and/or pathways that are deregulated due to alterations in melanoma susceptibility genes which in turn, could be involved in initiation/progression of the disease.
Project description:Melanoma is an aggressive cancer typically arising from transformation of melanocytes residing in the basal layer of the epidermis, where they are in direct contact with surrounding keratinocytes. The role of keratinocytes in shaping the melanoma tumor microenvironment remains understudied. We previously showed that temporary loss of the keratinocyte-specific cadherin, Desmoglein 1 (Dsg1) controls paracrine signaling between normal melanocytes and keratinocytes to stimulate the protective tanning response. Here, we provide evidence that melanoma cells hijack this intercellular communication by secreting factors that keep Dsg1 expression low in surrounding keratinocytes, which in turn generate their own paracrine signals that enhance melanoma spread through CXCL1/CXCR2 signaling. Evidence suggests a model whereby paracrine signaling from melanoma cells increases levels of the transcriptional repressor Slug, and consequently decreases expression of the Dsg1 transcriptional activator Grhl1. Together, these data support the idea that paracrine crosstalk between melanoma cells and keratinocytes resulting in chronic keratinocyte Dsg1 reduction contributes to melanoma cell movement associated with tumor progression.
Project description:It is believed that the inherent differentiation program of melanocytes during embryogenesis predisposes melanoma cells to high frequency of metastasis. Sox10, a transcription factor expressed in neural crest stem cells and a subset of progeny lineages, plays a key role in the development of melanocytes. We show that B16F10 melanoma cells transfected with siRNA specific for Sox10 display reduced migratory activity which in turn indicated that a subset of transcriptional regulatory target genes of Sox10 are likely to be involved in migration and metastasis of melanoma cells. We carried out microarray-based gene expression profiling using Sox10-specific siRNA to identify regulatory targets and found that multiple genes including melanocortin-1 receptor (Mc1R) partake in the regulation of migration. We provide evidences that a significant portion of the effect of Sox10 on migration is mediated by Mitf, a transcription factor downstream to Sox10. The involvement of Mc1R in migration was studied in detail in vivo using a murine metastasis model. Specifically, B16F10 melanoma cells treated with a specific siRNA showed reduced tendency in metastasizing to and colonizing the lung after being injected in the tail vein. These data reveal a cadre of novel regulators and mediators involved in migration and metastasis of melanoma cells that represent potential targets of therapeutic intervention.
Project description:Melanoma arises from transformation of melanocytes in the basal layer of the epidermis where they are surrounded by keratinocytes, with which they interact through cell contact and paracrine communication. Although research focuses on how the accumulation of oncogene and tumor suppressor gene mutations in melanocytes drive melanoma development, how alterations in keratinocytes serve as extrinsic drivers of melanoma initiation and progression is poorly understood. We recently identified keratinocyte desmoglein 1 (Dsg1) as an important mediator of keratinocyte:melanoma crosstalk. Here we address the extent to which Dsg1 loss, which occurs in response to acute environmental stress such as ultraviolet radiation, affects early steps in melanomagenesis. RNA-Seq analysis revealed that paracrine signals from Dsg1-deficient keratinocytes mediate a transcriptional switch from a differentiated to undifferentiated cell state in melanocytes expressing BRAFV600E. Of 221 differentially expressed genes in BRAFV600E cells treated with Dsg1-deficient conditioned media (CM), the laminin superfamily member NTN4/Netrin-4, which inhibits senescence in endothelial cells, stood out. Indeed, while BRAFV600E melanocytes treated with Dsg1-deficient CM showed signs of senescence bypass, knockdown of NTN4 reversed these effects. These results suggest that Dsg1 loss in keratinocytes provides an extrinsic signal to push melanocytes towards oncogenic transformation once an initial mutation has been introduced.
Project description:It is believed that the inherent differentiation program of melanocytes during embryogenesis predisposes melanoma cells to high frequency of metastasis. Sox10, a transcription factor expressed in neural crest stem cells and a subset of progeny lineages, plays a key role in the development of melanocytes. We show that B16F10 melanoma cells transfected with siRNA specific for Sox10 display reduced migratory activity which in turn indicated that a subset of transcriptional regulatory target genes of Sox10 are likely to be involved in migration and metastasis of melanoma cells. We carried out microarray-based gene expression profiling using Sox10-specific siRNA to identify regulatory targets and found that multiple genes including melanocortin-1 receptor (Mc1R) partake in the regulation of migration. We provide evidences that a significant portion of the effect of Sox10 on migration is mediated by Mitf, a transcription factor downstream to Sox10. The involvement of Mc1R in migration was studied in detail in vivo using a murine metastasis model. Specifically, B16F10 melanoma cells treated with a specific siRNA showed reduced tendency in metastasizing to and colonizing the lung after being injected in the tail vein. These data reveal a cadre of novel regulators and mediators involved in migration and metastasis of melanoma cells that represent potential targets of therapeutic intervention. Chemically synthesized siRNA duplex (WT1-Sox10) was used to knock-down the transcription factor Sox10 in murine melanoma cell line B16F10. For the control, siRNA containing 5 nucleotide alterations (MT1-Sox10) were used. Total RNA was subsequently prepared to synthesize probes for microarray screening. A total of three pairs of replicate samples were generated each from separate transfection followed by RNA preparation. Expression values were determined and compared within each pair of WT1-Sox10 and MT1-Sox10 transfections. Genes showing over 2 fold changes in all three replicate pairs were subjected to subsequent analyses.
Project description:We used single-cell RNA-sequencing (scRNA-seq) of melanocytes isolated from two distict red hair color (RHC) mouse models for comparison with and black hair color, functional MC1R signaling, to reveal a Pheomelanin Gene Signature (PGS) of differentially expressed genes in RHC melanocytes.
Project description:Mounting evidence suggests that copy number variations (CNVs) can contribute to cancer susceptibility. The main goal of this study was to evaluate the role of germline CNVs in melanoma predisposition in high-risk melanoma families. We used genome-wide tiling comparative genomic hybridization and SNP arrays to characterize CNVs in 335 individuals (240 melanoma cases) from American melanoma-prone families (22 with germline CDKN2A or CDK4 mutations). We found that the global burden of overall CNVs (or deletions or duplications separately) was not significantly associated with case-control or CDKN2A/CDK4 mutation status after accounting for the familial dependence. However, we identified several rare CNVs that either involved known melanoma genes (e.g. PARP1, CDKN2A) or co-segregated with melanoma (duplication on 10q23.23, 3p12.2 and deletions on 8q424.3, 2q22.1) in families without mutations in known melanoma high-risk genes. Some of these CNVs were correlated with expression changes in disrupted genes based on RNASeq data from a subset of melanoma cases included in the CNV study. These results suggest that rare co-segregating CNVs may influence melanoma susceptibility in some melanoma-prone families and genes found in our study warrant further evaluation in future genetic analyses of melanoma.
Project description:Oncogenes can only initiate tumors in certain cellular contexts, which is referred to as oncogenic competence. In melanoma, whether cells in the microenvironment can endow such competence remains unclear. Using a combination of zebrafish transgenesis coupled with human tissues, we demonstrate that GABAergic signaling between keratinocytes and melanocytes promotes melanoma initiation by BRAFV600E. GABA is synthesized in melanoma cells, which then acts on GABA-A receptors on keratinocytes. Electron microscopy demonstrates specialized cell-cell junctions between keratinocytes and melanoma cells, and multi-electrode array analysis shows that GABA acts to inhibit electrical activity in melanoma/keratinocyte co-cultures. Genetic and pharmacologic perturbation of GABA synthesis abrogates melanoma initiation in vivo. These data suggest that GABAergic signaling across the skin microenvironment regulates the ability of oncogenes to initiate melanoma.
Project description:Aberrant DNA methylation and histone modifications both contribute to carcinogenesis, but how these two epigenetic factors interact to impact gene expression remain unclear. To address this issue, we studied gene expression profiles, DNA methylation and two key histone modifications (H3K4me3 and H3K27me3), in two types of normal melanocytes (HEMn and HEMa) and two melanoma cell lines SK-MEL-28 and LOXIMVI. Using these data, we analyzed the relationship between epigenetic factors and gene expression status in both normal and melanoma cells, and the impact of epigenetic switches on gene expression during melanomagenesis. ChIP-seq analysis of H3K4me3 and H3K27me3 in two types of normal melanocytes (HEMn and HEMa) and two melanoma cell lines (SK-MEL-28 and LOXIMVI).