4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone induces retinoic acid receptor β hypermethylation through DNA methyltransferase 1 accumulation in esophageal squamous epithelial cells.
Overexpression of DNA methyltransferase 1 (DNMT1) has been detected in many cancers. Tobacco exposure is known to induce genetic and epigenetic changes in the pathogenesis of malignancy. 4-(Methylnitrosamino)- 1-(3-pyridyl)-1-butanone (NNK) is an important carcinogen present in tobacco smoke; however the detailed molecular mechanism of how NNK induces esophageal carcinogenesis is still unclear. We found that DNMT1 was overexpressed in ESCC tissues compared with paired non-cancerous tissues, the overexpression being correlated with smoking status and low expression of RARβ. The latter could be upregulated by NNK treatment in Het-1A cells, and the increased DNMT1 expression level reflected promoter hypermethylation and downregulation of retinoic acid receptor β (RARβ). RNA interference mediated knockdown of DNMT1 resulted in promoter demethylation and upregulation of RARβ in KYSE30 and TE-1 cells. 3-(4,5-Dimethyl-thiazol-2yl)- 2,5-diphenyltetrazolium bromide (MTT) and flow cytometric analysis demonstrated that NNK treatment in Het- 1A cells could enhance cell proliferation and inhibit cell apoptosis in a dose-dependent manner. In conclusion, DNMT1 overexpression is correlated with smoking status and low expression of RARβ in esophageal SCC patients. NNK could induce RARβ promoter hypermethylation through upregulation of DNMT1 in esophageal squamous epithelial cells, finally leading to enhancement of cell proliferation and inhibition of apoptosis.
Department of Gastroenterology, Provincial Hospital Affiliated to Shandong University, Jinan, China.
Jing
J
Wang
Shu-Lei
SL
Zhao
Yan
Y
Li
Mei
M
Meng
Cheng-Yong
CY
Qin
D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002273:Carcinogens / Q000494:pharmacology*; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D019175:DNA Methylation / Q000187:drug effects*; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D009602:Nitrosamines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D018168:Receptors, Retinoic Acid / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured
D002273:Carcinogens; D009602:Nitrosamines; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; C082925:retinoic acid receptor beta; C016583:4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human