title: Epigenetic silencing of TNFSF7 (CD70) by DNA methylation during progression to breast cancer.
abstract: To escape the immune system, tumor cells may remove surface molecules such as the major histocompatibility complex (MHC) and co-stimulatory molecules, which are essential for recognition by lymphocytes. Down-regulation of the co-stimulatory molecules CD70 (TNFSF7) and CD80 may contribute to tumor cell survival; however, the mechanism of down-regulation of the TNFSF7 gene during tumorigenesis is poorly understood. Here we present evidence indicating that TNFSF7 gene expression is epigenetically down-regulated via DNA hypermethylation within its promoter region during progression in breast cancer cells in the isogenic MCF10 model. Bisulfite sequencing revealed that the CpG pairs at the proximal region of the TNFSF7 promoter are heavily methylated during progression of breast cancer cells but that methylation of the more distal sequences was not changed considerably. Thus, this epigenetic silencing of the TNFSF7 gene via hypermethylation of its proximal region may allow the benign and invasive MCF10 variants to escape immune surveillance.
authors.affiliation: Department of Biology, College of Science, Yonsei University, Seoul, 120-749, Korea.
authors.forename: Seung Eun
authors.initials: SE
authors.lastname: Yu
authors.forename: Su Hyung
authors.initials: SH
authors.lastname: Park
authors.forename: Yeun Kyu
authors.initials: YK
authors.lastname: Jang
mesh_terms: D001374:Azacitidine / Q000494:pharmacology; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D053282:CD27 Ligand / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects / Q000235:genetics*; D018450:Disease Progression; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D053282:CD27 Ligand; C505771:CD70 protein, human; D012333:RNA, Messenger; D001374:Azacitidine