Hypermethylation of the Keap1 gene in human lung cancer cell lines and lung cancer tissues.
Low expression of the oxidative stress sensor Keap1 is thought to be involved in carcinogenesis. However, the mechanisms responsible for inactivation of the Keap1 gene remain unknown. We investigated Keap1 expression using RT-PCR and found that it was downregulated in lung cancer cell lines and tissues when compared with a normal bronchial epithelial cell line. Treatment with 5-Aza-2'-deoxycytidine restored Keap1 expression in lung cancer cell lines, indicating the silencing mechanism to be promoter methylation. Moreover, we evaluated cytosine methylation in the Keap1 promoter and demonstrated that the P1 region, including 12 CpG sites, was highly methylated in lung cancer cells and tissues, but not in normal cells. Importantly, we found evidence that three specific CpG sites (the 3rd, 6th, and 10th CpGs of P1) might be binding sites for proteins that regulate Keap1 expression. Thus, our results suggest for the first time that Keap1 expression is regulated by an epigenetic mechanism in lung cancer.
Department of Human Anatomy and Histology & Embryology, Capital Medical University, Beijing 100069, China.
Rui
R
Wang
Jing
J
An
Fengqing
F
Ji
Huiqin
H
Jiao
Haimei
H
Sun
Deshan
D
Zhou
D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001665:Binding Sites; D045744:Cell Line, Tumor; D018899:CpG Islands; D019175:DNA Methylation / Q000187:drug effects; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors; D000077209:Decitabine; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D044127:Epigenesis, Genetic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D000072019:Kelch-Like ECH-Associated Protein 1; D008175:Lung Neoplasms / Q000235:genetics*
D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D000077209:Decitabine; D015254:DNA Modification Methylases; D001374:Azacitidine