title: Downregulation of connexin 43 in nasopharyngeal carcinoma cells is related to promoter methylation.
abstract: Down-regulation of Cx43 expression had been shown to occur in nasopharyngeal carcinoma cells. The present study was undertaken to estimate if methylation of the promoter region in Cx43 gene was responsible for the repression of Cx43 expression in the CNE-1 nasopharyngeal carcinoma cells. Calcein transfer and lucifer yellow transfer were detected to evaluate gap junction intercellular communication (GJIC) in CNE-1 cells. It was found that the control CNE-1 cells showed no fluorescent dye transfer. After treatment with DNA methyltransferase inhibitor 5-aza-CdR, fluorescent dye transfer between cells became obvious. RT-PCR and Western blot were performed to determine the expression of Cx43 gene. The control CNE-1 cells showed a low expression level of Cx43, whereas 5-aza-CdR-treated CNE-1 cells showed an enhanced level of Cx43 expression. Methylation-sensitive restriction enzyme and PCR analysis showed that the methylation of the Cx43 gene promoter region occurred in CNE-1 cells. In addition, treatment with 5-aza-CdR inhibited the growth (including anchorage-independent growth) of CNE-1 cells, and resulted in an accumulation of cells in G0/G1 phase. These results indicate the promoter methylation as an important role in inactivation of Cx43 in CNE-1 cells.
authors.affiliation: Department of Biological Engineering, Beijing University of Aeronautics and Astronautics, 37 Xueyuan Road, Beijing 100083, PR China. yizc@buaa.edu.cn
authors.forename: Zong-Chun
authors.initials: ZC
authors.lastname: Yi
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Guang-Yao
authors.initials: GY
authors.lastname: Zhang
authors.forename: Bing
authors.initials: B
authors.lastname: Xia
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002453:Cell Cycle; D045744:Cell Line, Tumor; D018031:Connexin 43 / Q000235:genetics*; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors; D000077209:Decitabine; D015536:Down-Regulation; D005452:Fluoresceins / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007546:Isoquinolines / Q000378:metabolism; D009303:Nasopharyngeal Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic
chemical_list: D018031:Connexin 43; D005452:Fluoresceins; D007546:Isoquinolines; D000077209:Decitabine; C017475:lucifer yellow; D015254:DNA Modification Methylases; D001374:Azacitidine; C007740:fluorexon