A Study Of The Relationship Between The N6-methyladenine DNA Modification And The Pathogenesis Of Infantile

Background:The infantile hemangioma(IH)is the most common benign tumor in infants and children,with an incidence of 4%-5%.Although most of IHs can involute spontaneously,it also causes great damage to the child's body due to complications occurred during the course of this disease.At present,the pathogenesis of infantile hemangiomas is still unclear,despite there are many hypotheses,it is confused to fully explain the origin mechanism of IHs.Current studies of transcriptomics of IHs have found that abnormalities in expressions of multiple transcriptome products may be associated with angiogenesis,but it is lack genomic data of IHs' pathogenesis.The N6-methyladenine DNA(6-MA DNA)is a newly discovered DNA modification pattern in eukaryotes in recent years,which plays an important regulatory role in embryonic and stem cell development.The infantile hemangioma is also considered to be a kind of embryonic phenotype,low differentiation,stem cell-derived tumor,so it is worthy of further study for the relationship between the DNA 6-MA modification and pathogenesis of infantile hemangiomas.OBJECTIVE:This study used epigenetic and bioinformatics methods to compare the methylation level of the 6-MA DNA modification in infantile hemangiomas and normal skin tissues adjacent to the tumor,and to analyze the differences in the function of the modified genes to explore the role of 6-MA DNA in the pathogenesis of infantile hemangiomas.METHODS:Three pairs of specimens were obtained from the Department of Burns and Cosmetic Surgery of the Provincial Hospital Affiliated to Shandong University in July 2016.Each pair of specimens includes one tumor tissue as the observation group and a normal skin tissue adjacent to the tumor from the same patient as controls.DNA in tissues was extracted and purified.6-MA methylation immunoprecipitation was used to obtain target DNA fragments to construct the sequencing libraries,using high-throughput sequencing to sequence target fragments.The bioinformatics software was used to analyze the sequencing data,and levels of 6-MA DNA in the tumor and the normal skin adjacent to the tumor was analyzed,the characteristics of 6-MA modification were analyzed,the differentially modified genes were searched by gene annotation,and the biological functions of the differential genes were analyzed by GO analysis.The results were compared with previous studies on the pathogenesis of IHs.RESULTS:The level of DNA 6-MA modification in infantile hemangiomas was higher than that in normal skin tissues;the 6-MA modification of tumor DNA concentrated more on the upstream and downstream 5K regions and intron regions,where regulatory elements are often located;the number of genes modified by 6-MA in tumor tissues is greater than that of normal skin tissues;genes involved in mesoderm development and differentiation,stem cell proliferation and differentiation,mesenchymal cell proliferation and differentiation,and cell cycle regulation in tumor tissues were 6-MA modified,of which the functions are closely related to the occurrence of infantile hemangiomas.Conclusion:This study was the first to detect the modification of 6-MA and to analyze the function of the 6-MA modified genes in infantile hemangiomas.Abnormalities of DNA 6-MA modification in IHs may be one of the pathogenesis of infantile hemangiomas.