title: LINE-1 methylation patterns of different loci in normal and cancerous cells.
abstract: This study evaluated methylation patterns of long interspersed nuclear element-1 (LINE-1) sequences from 17 loci in several cell types, including squamous cell cancer cell lines, normal oral epithelium (NOE), white blood cells and head and neck squamous cell cancers (HNSCC). Although sequences of each LINE-1 are homologous, LINE-1 methylation levels at each locus are different. Moreover, some loci demonstrate the different methylation levels between normal tissue types. Interestingly, in some chromosomal regions, wider ranges of LINE-1 methylation levels were observed. In cancerous cells, the methylation levels of most LINE-1 loci demonstrated a positive correlation with each other and with the genome-wide levels. Therefore, the loss of genome-wide methylation in cancerous cells occurs as a generalized process. However, different LINE-1 loci showed different incidences of HNSCC hypomethylation, which is a lower methylation level than NOE. Additionally, we report a closer direct association between two LINE-1s in different EPHA3 introns. Finally, hypermethylation of some LINE-1s can be found sporadically in cancer. In conclusion, even though the global hypomethylation process that occurs in cancerous cells can generally deplete LINE-1 methylation levels, LINE-1 methylation can be influenced differentially depending on where the particular sequences are located in the genome.
authors.affiliation: Inter-Department Program of BioMedical Sciences, Faculty of Graduate School, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Chureerat
authors.initials: C
authors.lastname: Phokaew
authors.forename: Supakit
authors.initials: S
authors.lastname: Kowudtitham
authors.forename: Keskanya
authors.initials: K
authors.lastname: Subbalekha
authors.forename: Shanop
authors.initials: S
authors.lastname: Shuangshoti
authors.forename: Apiwat
authors.initials: A
authors.lastname: Mutirangura
mesh_terms: D045744:Cell Line, Tumor; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000378:metabolism; D006801:Humans; D020084:Long Interspersed Nucleotide Elements; D009369:Neoplasms / Q000235:genetics*; D016133:Polymerase Chain Reaction
chemical_list: D004273:DNA, Neoplasm
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