title: [Regulation of α-tocopherol on NFκB and Nrf2 signaling pathway at early stage of N-nitrosomethylbenzylamine⁃induced human esophageal cell carcinogenesis].
abstract: OBJECTIVE
  To investigate the regulation of α-Tocopherol on NFκB and Nrf2 signaling pathway at early stage of N-nitrosomethylbenzylamine (NMBzA)-induced human esophageal carcinogenesis.
  
  
  METHODS
  Human normal esophageal HET-1A cells were treated with NMBzA at 50 µmol/L, 100 µmol/L for 24 h to intimate the initiation of esophageal carcinogenesis. For intervention groups, HET-1A cells were pre-treated with α-T at 25, 50, 100 µmol/L for 3 h and then co-treated with NMBzA (100 µmol/L) for 24 h. In comparison with HET-1A cells, human esophageal cancer EC109 cells were treated with α-T at corresponding concentrations. Cells treated with 0.1% DMSO were used as negative control. Immunofluorence staining was used for the determination of distribution and activation of NFκB p65 and Nrf2 in the cell. Real time PCR and Western blot were used to determine the expression levels of target genes including cyclinD1, KI67, proliferating cell nuclear antigen (PCNA), cyclo-oxygen-ase 2 (COX2), 5LOX, HO-1, NQO1 and GCLC. Flow cytometry was utilized to analyze the reactive oxygen species contents in the cells.
  
  
  RESULTS
  As compared to the control group (1.00 ± 0.08), the expression of CyclinD1 (2.99 ± 0.15), KI67 (2.35 ± 0.38) and PCNA (2.46 ± 0.25) in HET-1A were all markedly increased by NMBzA treatment (F values were 97.23, 65.28, 34.62, P < 0.001). Also, the proportion of cells with nucleus translocation of NFκB p65 (71.0%, 98/138) or Nrf2 (36.3%, 49/135) were significantly increased (χ² values were 194.71, 133.72, P < 0.001), and the expression of COX2 (3.22 ± 0.17), 5LOX (2.87 ± 0.12) as well as HO-1 (1.87 ± 0.22), NQO1 (2.14 ± 0.08), GCLC (2.63 ± 0.41) at protein levels were elevated (F values were 72.35, 43.87, 69.23, 71.34, 85.79, P values were 0.013, 0.015, 0.010, 0.011, 0.002). Under the treatment with 50 µmol/L α-T, comparing with the control group(59.1%,65/110),the nuclear translocation of NFκB p65 (77.7%, 8/104) was clearly inhibited (χ² = 148.1, P < 0.001), and protein expression levels of COX2 (0.74 ± 0.19) and 5LOX (0.42 ± 0.13) were decreased (F values were 56.31, 73.25, P values were 0.003, 0.001). However, no changes on Nrf2 signaling pathway were observed; α-T showed little impact on NFκB or Nrf2 pathway in EC109 cells.
  
  
  CONCLUSIONS
  At the early stage of NMBz-induced esophageal cancer, α-T could block the initiation of carcinogenesis through suppressing the activation of NFκB signaling pathway. It might be the major mechanism by which α-T is potentially chemopreventive to esophageal cancer. During the progression of esophageal cancer, the cells may acquire the adaptive functions to accommodate oxidative stress via activating Nrf2 pathway.
authors: China National Center for Food Safety Risk Assessment, Key Laboratory of Food Safety Risk Assessment of Ministry of Health, Beijing 100021, China.
authors: Hui
authors: H
authors: Yang
authors: China National Center for Food Safety Risk Assessment, Key Laboratory of Food Safety Risk Assessment of Ministry of Health, Beijing 100021, China.
authors: Nana
authors: N
authors: Sun
authors: China National Center for Food Safety Risk Assessment, Key Laboratory of Food Safety Risk Assessment of Ministry of Health, Beijing 100021, China.
authors: Yongning
authors: Y
authors: Li
authors: China National Center for Food Safety Risk Assessment, Key Laboratory of Food Safety Risk Assessment of Ministry of Health, Beijing 100021, China.
authors: Chunlai
authors: C
authors: Liang
authors: China National Center for Food Safety Risk Assessment, Key Laboratory of Food Safety Risk Assessment of Ministry of Health, Beijing 100021, China; Email: jiaxudong@cfsa.net.cn.
authors: Xudong
authors: X
authors: Jia
mesh_terms: D063646:Carcinogenesis; D051546:Cyclooxygenase 2; D004128:Dimethylnitrosamine / Q000031:analogs & derivatives; D004938:Esophageal Neoplasms; D051547:Heme Oxygenase-1; D006801:Humans; D016660:NAD(P)H Dehydrogenase (Quinone); D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; D018384:Oxidative Stress; D017382:Reactive Oxygen Species; D015398:Signal Transduction; D024502:alpha-Tocopherol
chemical_list: D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; C495635:NFE2L2 protein, human; D017382:Reactive Oxygen Species; C014707:nitrosobenzylmethylamine; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; D024502:alpha-Tocopherol; D004128:Dimethylnitrosamine