Genome-wide screening of m6A-modified transcript in the Wilms’ tumor

Abstract Background Wilms’ tumor, also called nephroblastoma, is the most common pediatric renal malignancy. The pathogenesis of Wilms’ tumor has been attributed to several genetic and epigenetic factors. However, the most pervasive internal mRNA modification that affects almost every process of RNA metabolism, RNA N6-Methyladenosine (m6A) methylation, has not been characterized in Wilms’ tumor. Methods Wilms’ tumor (WT) and adjacent non-cancerous (NC) tissue samples were obtained from 23 children with nephroblastoma, and the global m6A levels were measured by mass spectrometry. Analyses by m6A-mRNA epitranscriptomic microarray and mRNA microarray were performed, and m6A-related mRNAs were validated by quantitative real-time PCR for input and m6A-immunoprecipitated RNA samples from WT and NC tissues. Gene ontology analysis and KEGG pathway analysis were performed for differentially expressed genes, and expression of RNA methylation-related factors was measured by quantitative real-time PCR. Results The total m6A methylation levels in total RNA of WT samples and NC samples were (0.21 ± 0.01)% and (0.22 ± 0.01)%, respectively, with no statistically significant difference. Fifty-nine transcripts were differentially m6A-methylated between the WT and NC groups, which showed distinct m6A modification patterns. Gene ontology analysis indicated that m6A-modified genes were enriched in cancer-associated pathways, including the mTOR pathway, and conjoint analysis of the unique methylation and gene expression patterns in WT samples suggested an association with metabolic pathways.The mRNA levels of the m6A-related “reader” genes, YTHDF1, YTHDF2 and IGF2BP3, were statistically higher in WT samples than in NC samples. Conclusion This is the first study to determine the m6A modification profiles in Wilms’ tumor. Our data provide novel information regarding patterns of m6A modification that correlate with carcinogenesis in Wilms’ tumor.