title: Hypermethylation of the CpG dinucleotide in epidermal growth factor receptor codon 790: implications for a mutational hotspot leading to the T790M mutation in non-small-cell lung cancer.
abstract: Nearly one half of all cases of acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) for non-small-cell lung cancer (NSCLC) are due to the T790M mutation in EGFR exon 20. The T790M mutation is a C→T transition mutation at a CpG dinucleotide. DNA methylation of cytosine (5-methylcytosine (5-mC)) in CpG dinucleotides is a common DNA modification; CpG dinucleotides are considered to be mutational hotspots that cause genetic diseases and cancers through spontaneous deamination of 5-mC, resulting in C→T transition mutations. This study aimed to examine the methylation level of cytosine of EGFR codon 790 and investigate whether DNA methylation was involved in acquiring the T790M mutation. We examined 18 NSCLC tumor tissues, 7 normal lymph node tissues, and 4 NSCLC cell lines (PC9, HCC827, 11-18, and A549). 5-mC was checked by bisulfite sequencing and quantified by pyrosequencing. We found that all tissue samples and cell lines had 5-mC in EGFR codon 790. The 5-mC range was 58.4-90.8%. Our results imply that hypermethylation of the CpG dinucleotide in EGFR codon 790 leads to the C→T transition mutation, causing resistance to EGFR-TKI treatment.
authors: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Akiko
authors: A
authors: Fujii
authors: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. Electronic address: harada-t@kokyu.med.kyushu-u.ac.jp.
authors: Taishi
authors: T
authors: Harada
authors: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Faculty of Medical Sciences, Department of Comprehensive Clinical Oncology, Kyushu University, Fukuoka, Japan.
authors: Eiji
authors: E
authors: Iwama
authors: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Keiichi
authors: K
authors: Ota
authors: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Kazuto
authors: K
authors: Furuyama
authors: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Division of Pathophysiological and Experimental Pathology, Department of Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Kayo
authors: K
authors: Ijichi
authors: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Tatsuro
authors: T
authors: Okamoto
authors: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Center for Clinical and Traditional Research, Kyushu University Hospital, Fukuoka, Japan.
authors: Isamu
authors: I
authors: Okamoto
authors: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Koichi
authors: K
authors: Takayama
authors: Research Institute for Diseases of the Chest, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors: Yoichi
authors: Y
authors: Nakanishi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001483:Base Sequence; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics*; D045744:Cell Line, Tumor; D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics*; D005260:Female; D000077156:Gefitinib; D006801:Humans; D008168:Lung / Q000473:pathology; D008175:Lung Neoplasms / Q000235:genetics*; D061986:MCF-7 Cells; D008297:Male; D008875:Middle Aged; D047428:Protein Kinase Inhibitors / Q000627:therapeutic use; D011799:Quinazolines / Q000627:therapeutic use; D017422:Sequence Analysis, DNA
chemical_list: D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D066246:ErbB Receptors; D000077156:Gefitinib
keywords: EGFR-TKI; T790M; methylation; non–small-cell lung cancer; resistance