Genome-wide promoter methylation analysis associated with malignant melanoma progression
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ABSTRACT: Epigenetic alterations play significant roles in the melanoma tumorigenesis and malignant progression. We profiled genome-wide promoter DNA methylation patterns of melanoma cells deribed from primary lesions of Radial Growrth phase (RGP) and Vertical Growth Phase (VGP), metastatic lesions, and primary normal melanocytes by interrogating 14,495 genes using Illumina bead chip technology. By comparative analysis of the promoter methylation profiles, we identified epigenetically silenced gene signatures that potentially associated with malignant melanoma progression. Bisulphite converted genomic DNA from a group of melanoma cells representing pathologic stages of melanoma progression (3 cell lines derived from RGP melanoma lesions, 4 cell lines derived from VGP lesions, and 3 melastatic melanomas) and normal human primary melanocytes isolated from lightly pigmented adult skin were hybridized to Illumina's Infinium HumanMethylation27 BeadChips
Project description:Epigenetic alterations play significant roles in the melanoma tumorigenesis and malignant progression. We profiled genome-wide promoter DNA methylation patterns of melanoma cells deribed from primary lesions of Radial Growrth phase (RGP) and Vertical Growth Phase (VGP), metastatic lesions, and primary normal melanocytes by interrogating 14,495 genes using Illumina bead chip technology. By comparative analysis of the promoter methylation profiles, we identified epigenetically silenced gene signatures that potentially associated with malignant melanoma progression.
Project description:Defects in DNA damage responses may underlie genetic instability and malignant progression in melanoma. Cultures of normal human melanocytes (NHMs) and melanoma lines were analyzed to determine whether global patterns of gene expression could predict the efficacy of DNA damage cell cycle checkpoints that arrest growth and suppress genetic instability. NHMs displayed effective G1 and G2 checkpoint responses to ionizing radiation-induced DNA damage. A majority of melanoma cell lines (11/16) displayed significant quantitative defects in one or both checkpoints. Melanomas with B-RAF mutations as a class displayed a significant defect in DNA damage G2 checkpoint function. In contrast the epithelial-like subtype of melanomas with wildtype N-RAS and B-RAF alleles displayed an effective G2 checkpoint but a significant defect in G1 checkpoint function. RNA expression profiling revealed that melanoma lines with defects in the DNA damage G1 checkpoint displayed reduced expression of p53 transcriptional targets, such as CDKN1A and DDB2, and enhanced expression of proliferation-associated genes, such as CDC7 and GEMININ. A Bayesian analysis tool was more accurate than significance analysis of microarrays for predicting checkpoint function using a leave-one-out method. The results suggest that defects in DNA damage checkpoints may be recognized in melanomas through analysis of gene expression. Experiment Overall Design: Normal human melanocyte and melanoma cell lines w/wo mutations in B-raf or N-ras were treated with 1.5 Gy IR irridiartion for G1 and G2 checkpoint determination. RNA was isolated from exponentially growing cultures and applied for microarray hybridizaton with Agilent 44 K (G4112A) array.
Project description:We analysed the whole-genome transcriptional profile of 6 cell lines of dark melanocytes (DM) and 6 of light melanocytes (LM) at basal conditions and after UVB at different time points (6, 12 and 24h) to investigate the mechanisms by which melanocytes protect human skin from the damaging effects of ultraviolet-B radiation (UVB). Further, we assessed the effect of different keratinocyte-conditioned media (KCM+ and KCM-) on melanocytes. We analysed six lines of melanocytes isolated from lightly pigmented neonatal foreskin (LM), and six lines from darkly pigmented neonatal foreskin (DM), at 0, 6, 12 and 24 hours post UV irradiation. We also assessed the effect of different keratinocyte-conditioned media (KCM+ or KCM-)
Project description:Exosomes are small membraneous vesicles secreted into body fluids by tumors. Tumor exosomes contain intact and functional mRNAs, small RNAs (including miRNAs), and proteins that can alter the cellular environment to favor tumor growth. Further exploration into the molecular profiling of exosomes may increase our understanding of their roles in melanoma progression in vivo, and may have potential application in biomarker studies. In the present study, we used mRNA array profiling to identify thousands of exosomal mRNAs associated with melanoma progression and metastasis. Similarly, miRNA array profiling identified specific miRNAs, such as hsa-miR-31, -185, and -34b, involved in melanoma invasion. Our results indicate that melanoma-derived exosomes have unique gene expression signatures and miRNA profiles that may have important functions in melanoma metastasis and progression. Total RNA from cells and exosomes were isolated using mirVana total RNA isolation kit according to the manufacturer’s guidelines. RNA was quantified using Nanodrop ND-1000. The integrity of these total RNAs was assessed using Agilent 2100 Bioanalyzer. Total high-quality RNA was converted to cDNA, transcribed and labelled, and then hybridized to human HG-U133 plus 2 arrays (Affymetrix) then scanned according to the standard protocol recommended by Affymetrix. Two different RNA preparations from two cell lines and their exosomes were used.
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 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 change during melanomagenesis. Each of the two normal melanocytes (HEMn and HEMa) and the two melanoma cell lines SK-MEL-28 and LOXIMVI was cultured in triplicate. For each cell line, the same culture conditions and cell density were applied to the triplicates. Total RNA was extracted and microarray analysis was performed for genome-wide gene expression profiling. Using the Sentrix Human-HT12 v4 Beadchip, all four cell samples, each in triplicate, were examined in 12 individual arrays on a same beadchip. Thus, together with the data on DNA methylation and histone modifications, we could not only analyze the epigenetic regulation of gene expression in each cell sample, but also investigate the expression change associated with epigenetic changes in melanoma when compared to normal melanocytes.
Project description:Here we report a novel role for H2A.Z.2 (H2AFV) as a mediator of cell proliferation and sensitivity to targeted therapies in malignant melanoma. While both H2A.Z.1 and H2A.Z.2 are highly expressed in metastatic melanoma and correlate with decreased patient survival, only H2A.Z.2 deficiency results in impaired cellular proliferation of melanoma cells, which occurs via a G1/S arrest. Integrated gene expression and ChIP-seq analyses revealed that H2A.Z.2 positively regulates E2F target genes, and that such genes acquire a distinct H2A.Z occupancy signature over the promoter and gene body in metastatic melanoma cells. We further identified the BET family member BRD2 as an H2A.Z-interacting protein in melanoma cells, and demonstrate that H2A.Z.2 silencing cooperates with BET inhibition to induce cell death. Expression levels for non tumorigenic (Melanocytes) and human melanoma cell line SKmel147, before and after JQ1 treatement
Project description:Exosomes are small membraneous vesicles secreted into body fluids by tumors. Tumor exosomes contain intact and functional mRNAs, small RNAs (including miRNAs), and proteins that can alter the cellular environment to favor tumor growth. Further exploration into the molecular profiling of exosomes may increase our understanding of their roles in melanoma progression in vivo, and may have potential application in biomarker studies. In the present study, we used mRNA array profiling to identify thousands of exosomal mRNAs associated with melanoma progression and metastasis. Similarly, miRNA array profiling identified specific miRNAs, such as hsa-miR-31, -185, and -34b, involved in melanoma invasion. Our results indicate that melanoma-derived exosomes have unique gene expression signatures and miRNA profiles that may have important functions in melanoma metastasis and progression. Total RNA from cells and exosomes were isolated using mirVana total RNA isolation kit according to the manufacturer’s guidelines. RNA was quantified using Nanodrop ND-1000. The integrity of these total RNAs was assessed using Agilent 2100 Bioanalyzer. Total high-quality RNA was labelled. The miRNA array profiling was performed by using the Affymetrix GeneChip miRNA Array 1.0. Two different RNA preparations from two cell lines and their exosomes were used, except that only one RNA preparation was used for HEMa-LP exosome miRNA array. Due to the limited number of passages (approximately 10), adequate exosomal RNA and proteins from HEMa-LP cells for multiple analyses was not available.
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).
Project description:DNA methylation profiling of human melanocytes and melanoma cell lines. Goal was to identify hypermethylated gene promoters in melanoma Genomic DNA from 4 human melanoma cell lines and normal human epidermal melanocytes was subjected to methylated DNA immunoprecipitation (MeDIP) and hybridized to Agilent's G4489A Human Promoter ChIP-on-Chip Set 244K
Project description:Here we report a novel role for H2A.Z.2 (H2AFV) as a mediator of cell proliferation and sensitivity to targeted therapies in malignant melanoma. While both H2A.Z.1 and H2A.Z.2 are highly expressed in metastatic melanoma and correlate with decreased patient survival, only H2A.Z.2 deficiency results in impaired cellular proliferation of melanoma cells, which occurs via a G1/S arrest. Integrated gene expression and ChIP-seq analyses revealed that H2A.Z.2 positively regulates E2F target genes, and that such genes acquire a distinct H2A.Z occupancy signature over the promoter and gene body in metastatic melanoma cells. We further identified the BET family member BRD2 as an H2A.Z-interacting protein in melanoma cells, and demonstrate that H2A.Z.2 silencing cooperates with BET inhibition to induce cell death. Total RNA samples from SKmel147 melanoma cell line. Transcript levels were analyzed after control or H2AZ variant RNA interference.