title: Axin gene methylation status correlates with radiosensitivity of lung cancer cells.
abstract: BACKGROUND
  We previously reported that Axin1 (Axin) is down-regulated in many cases of lung cancer, and X-ray irradiation increased Axin expression and inhibited lung cancer cells. The mechanisms, however, were not clear.
  
  
  METHODS
  Four lung cancer cell lines were used to detect the methylation status of Axin with or without X-ray treatment. Real-time PCR was used to quantify the expression of Axin, and western blot analysis was applied to measure protein levels of Axin, β-catenin, Cyclin D1, MMP-7, DNMTS, MeCP2 and acetylated histones. Flow cytometric analysis, colony formation assay, transwell assay and xenograft growth experiment were used to study the biological behavior of the cells with hypermethylated or unmethylated Axin gene after X-ray treatment.
  
  
  RESULTS
  Hypermethylated Axin gene was detected in 2 of 4 cell lines, and it correlated inversely with Axin expression. X-ray treatment significantly up-regulated Axin expression in H446 and H157 cells, which possess intrinsic hypermethylation of the Axin gene (P<0.01), but did not show up-regulation in LTE and H460 cells, which have unmethylated Axin gene. 2Gy X-ray significantly reduced colony formation (from 71% to 10.5%) in H157 cells, while the reduction was lower in LTE cells (from 71% to 20%). After X-ray irradiation, xenograft growth was significantly decreased in H157 cells (from 1.15 g to 0.28 g) in comparison with LTE cells (from 1.06 g to 0.65 g). Significantly decreased cell invasiveness and increased apoptosis were also observed in H157 cells treated with X-ray irradiation (P<0.01). Down-regulation of DNMTs and MeCP2 and up-regulation of acetylated histones could be detected in lung cancer cells.
  
  
  CONCLUSIONS
  X-ray-induced inhibition of lung cancer cells may be mediated by enhanced expression of Axin via genomic DNA demethylation and histone acetylation. Lung cancer cells with a different methylation status of the Axin gene showed different radiosensitivity, suggesting that the methylation status of the Axin gene may be one important factor to predict radiosensitivity of the tumor.
authors.affiliation: Department of Pathology, First Affiliated Hospital and College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, China.
authors.forename: Lian-He
authors.initials: LH
authors.lastname: Yang
authors.forename: Yang
authors.initials: Y
authors.lastname: Han
authors.forename: Guang
authors.initials: G
authors.lastname: Li
authors.forename: Hong-Tao
authors.initials: HT
authors.lastname: Xu
authors.forename: Gui-Yang
authors.initials: GY
authors.lastname: Jiang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Miao
authors.forename: Xiu-Peng
authors.initials: XP
authors.lastname: Zhang
authors.forename: Huan-Yu
authors.initials: HY
authors.lastname: Zhao
authors.forename: Zheng-Fan
authors.initials: ZF
authors.lastname: Xu
authors.forename: Maggie
authors.initials: M
authors.lastname: Stoecker
authors.forename: Endi
authors.initials: E
authors.lastname: Wang
authors.forename: Ke
authors.initials: K
authors.lastname: Xu
authors.forename: En-Hua
authors.initials: EH
authors.lastname: Wang
mesh_terms: D000818:Animals; D060466:Axin Protein / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D045744:Cell Line, Tumor; D019175:DNA Methylation / Q000235:genetics*; D005434:Flow Cytometry; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008819:Mice, Nude; D011836:Radiation Tolerance / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014183:Transplantation, Heterologous
chemical_list: D060466:Axin Protein
references.citation: Oncogene. 2007 Feb 1;26(5):774-80
references.pmid: 16964294
references.citation: J Gene Med. 2010 Jul;12(7):561-3
references.pmid: 20607692
references.citation: Int J Radiat Oncol Biol Phys. 2009 Oct 1;75(2):518-26
references.pmid: 19735876
references.citation: Genes Chromosomes Cancer. 2002 May;34(1):9-16
references.pmid: 11921277
references.citation: Oncol Rep. 2004 Jun;11(6):1201-7
references.pmid: 15138556
references.citation: J Clin Pathol. 2005 Mar;58(3):225-36
references.pmid: 15735151
references.citation: J Biol Chem. 2010 Aug 20;285(34):26058-65
references.pmid: 20566634
references.citation: Genes Chromosomes Cancer. 2000 Aug;28(4):443-53
references.pmid: 10862053
references.citation: Mol Cancer Res. 2004 Oct;2(10):567-73
references.pmid: 15498931
references.citation: Int J Radiat Oncol Biol Phys. 2006 Oct 1;66(2):327-30
references.pmid: 16965987
references.citation: Am J Clin Pathol. 2006 Apr;125(4):534-41
references.pmid: 16627264
references.citation: Tumour Biol. 2013 Apr;34(2):749-57
references.pmid: 23192643
references.citation: Oncogene. 2002 Jul 18;21(31):4863-71
references.pmid: 12101426
references.citation: J Radiat Res. 1998 Dec;39(4):271-8
references.pmid: 10196782
references.citation: J Cancer Res Clin Oncol. 2003 Apr;129(4):199-221
references.pmid: 12707770
references.citation: Biochem Biophys Res Commun. 2005 Nov 18;337(2):526-33
references.pmid: 16202973
references.citation: J Pathol. 2005 Jan;205(2):172-80
references.pmid: 15643671
references.citation: Int J Cancer. 2003 Dec 10;107(5):696-9
references.pmid: 14566817
references.citation: Oncogene. 2006 Jul 20;25(31):4267-75
references.pmid: 16532033
references.citation: Radiat Res. 1989 Feb;117(2):185-97
references.pmid: 2922465
references.citation: Hepatol Res. 2003 Feb;25(2):174-179
references.pmid: 12644054
references.citation: Biochem Biophys Res Commun. 2004 Dec 3;325(1):39-47
references.pmid: 15522198
references.citation: Biochem Biophys Res Commun. 2004 Aug 6;320(4):1253-61
references.pmid: 15249225
references.citation: Mol Cancer Res. 2005 Oct;3(10):553-61
references.pmid: 16254189
references.citation: Mutat Res. 2004 Apr 14;548(1-2):75-84
references.pmid: 15063138
references.citation: Genes Chromosomes Cancer. 2002 Jan;33(1):73-81
references.pmid: 11746989
references.citation: Br J Cancer. 2003 Jun 2;88(11):1734-9
references.pmid: 12771989
references.citation: Mol Cancer. 2010 Feb 02;9:25
references.pmid: 20122174
references.citation: Environ Mol Mutagen. 2008 Jan;49(1):16-25
references.pmid: 18172877