Screening of DNA methylation sites associated with melanoma and construction of an aberrant methylation profile: a preliminary study / 中华皮肤科杂志

ABSTRACT

Objective:To screen aberrant DNA methylation sites associated with melanoma using gene chip technology, and to preliminarily construct a melanoma-specific methylation profile.Methods:The Illumina Human Methylation 450K whole-genome methylation chip was used to detect the whole-genome DNA in 6 melanoma tissues and their paralesional skin tissues, and DNA differentially methylated sites were obtained. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) -based pathway analysis were carried out to investigate gene functions.Results:Gene chip testing showed that there were 27 779 differentially methylated sites between melanoma tissues and paralesional tissues, of which 16 673 were hypermethylated sites and 11 106 were hypomethylated sites in melanoma tissues. According to more stringent screening criteria " P < 0.01 and |&Delta;β| > 0.2", a total of 4 883 differentially methylated sites were screened out after filtering out all single nucleotide polymorphism-related probes, probes located on the XY chromosomes and cross-reactive probes, 1 459 (30%) of which were located in the promoter region including TSS1500, TSS200, 5′UTR and 1st Exon. GO enrichment analysis showed that differentially methylated genes were involved in many biological processes, including cell growth, differentiation, adhesion, movement and migration, signal transduction, transcriptional regulation, etc. KEGG-based pathway analysis showed that differentially methylated genes were mainly involved in signaling pathways, such as focal adhesion pathway, cancer pathways, transforming growth factor-β signaling pathway, phosphatidylinositol signaling pathway, melanogenesis pathway, chemokine signaling pathway, adhesion junction pathway, calcium signaling pathway, cell adhesion molecule pathway, mitogen-activated protein kinase signaling pathway, Wnt signaling pathway, Janus kinase-signal transducer and activator of transcription signaling pathway. Based on the criteira "the top 16 most differentially methylated genes related to hypermethylated sites in the promoter region, the genes with the highest methylation frequency (CpG sites ≥ 7) , the genes with certain functions or involved in a certain signaling pathway", 8 genes (KAAG1, DGKE, SOCS2, TFAP2A, GNMT, GALNT3, ANK2 and HOXA9) were selected as candidate biomarkers for melanoma. Conclusion:There are many hypermethylated genes in melanoma tissues, and 8 differentially methylated genes may serve as biomarkers for melanoma.