Effect of budesonide on the methylation and mRNA expression of the insulin-like growth factor 2 and c-myc genes in mouse lung tumors.
Effect of budesonide on the methylation and mRNA expression of the insulin-like growth factor 2 and c-myc genes in mouse lung tumors.
复制标题
布地奈德对小鼠肺肿瘤中胰岛素样生长因子2和c-myc基因甲基化和mRNA表达的影响。
DOI：
10.1002/mc.10078
复制
发表时间：
2002
影响因子：
4.6
通讯作者：
Pereira,MichaelA
中科院分区：
文献类型：
--
作者：
Tao,Lianhui;Li,Yingzhe;Wang,Wei;Kramer,PaulaM;Gunning,WilliamT;Lubet,RonaldA;Steele,VernonE;Pereira,MichaelA
使用替代终点生物标志物可以帮助开发化学预防药物。为了确定潜在的替代终点生物标志物，研究了布地奈德在肺肿瘤中降低胰岛素样生长因子- 2 （Igf - II）和c - mycgenes mRNA表达并引起基因再甲基化的能力。用16 mg/kg氨基甲酸乙烯酯连续2周或100 mg/kg苯并[A]芘（B[A]P）单次给药诱导雌性A系小鼠肺肿瘤。34周后，给予氨基甲酸乙酯的小鼠给予布地奈德（0.6或2.4 mg/kg日粮）7 d，然后处死。给药24周后处死小鼠。igf - ii和c - mycgenes的mRNA表达在肺肿瘤中相对于正常肺组织升高。布地奈德降低肿瘤中这两个基因的mRNA表达。用亚硫酸氢盐处理的DNA测序方法测定了igf - IIgene差异甲基化区2中27个CpG位点的甲基化状态。正常肺CpG甲基化位点为17 ~ 21个（70.4±2.6%）；氨基甲酸乙酯和B[a]P诱导的肺肿瘤中，0-2、1-2分别为4.9±1.2%和4.6±1.2%；0.6或2.4 mg/kg布地奈德治疗后肿瘤发生率分别为16.0±1.2%和46.2±5.1%，分别为4-5和7-16例。因此，肺肿瘤的CpG位点甲基化程度明显低于正常肺组织，而即使使用布地奈德进行有限治疗，也会导致肿瘤中CpG位点的再甲基化。通过hpai消化和Southern blot分析，发现c - mycgene中CCGG位点的内胞嘧啶在正常肺组织中甲基化，而在肺肿瘤中一些位点未甲基化。布地奈德治疗7 d导致这些位点的再甲基化。总之，小鼠肺肿瘤显示igf - ii和c - mycgenes甲基化降低，这与这些基因的表达增加有关。布地奈德治疗引起再甲基化和两个基因的表达降低。研究结果支持将igf - ii和c - mycgenes的mRNA表达减少和再甲基化作为布地奈德疗效的生物标志物的可能性。©2002 Wiley‐Liss, Inc。
The use of surrogate end‐point biomarkers could help in the development of chemopreventive agents. To define potential surrogate end‐point biomarkers, the ability of budesonide to decrease mRNA expression of the insulin‐like growth factor‐2 (Igf‐II) and c‐mycgenes and to cause the remethylation of the genes was investigated in lung tumors. Lung tumors were induced in female strain A mice by administering i.p. 16 mg/kg vinyl carbamate for 2 consecutive wk or by a single dose of 100 mg/kg benzo[a]pyrene (B[a]P). Thirty‐four weeks later, the mice given vinyl carbamate received budesonide (0.6 or 2.4 mg/kg diet) for 7 d and then were killed. Mice were killed 24 wk after administration of B[a]P. The mRNA expression of theIgf‐IIand c‐mycgenes was increased in lung tumors relative to normal lung tissue. Budesonide decreased mRNA expression of both genes in tumors. The methylation status of 27 CpG sites in the differentially methylated region 2 in theIgf‐IIgene was determined with the bisulfite‐treated DNA‐sequencing procedure. The numbers of methylated CpG sites were 17–21 in normal lung (70.4 ± 2.6%); 0–2, and 1–2 in lung tumors induced by vinyl carbamate and B[a]P (4.9 ± 1.2% and 4.6 ± 1.2%, respectively); and 4–5 or 7–16 in tumors after treatment with 0.6 or 2.4 mg/kg budesonide (16.0 ± 1.2% and 46.2 ± 5.1%, respectively). Thus, lung tumors had strikingly less methylated CpG sites than normal lung tissue, while even limited treatment with budesonide resulted in remethylation of the CpG sites in tumors. With HpaII digestion followed by Southern blot analysis, the internal cytosine of CCGG sites in the c‐mycgene was found to be methylated in normal lung tissue, whereas some of the sites were unmethylated in lung tumors. Treatment for 7 d with budesonide resulted in the remethylation of these sites. In conclusion, mouse lung tumors showed decreased methylation of theIgf‐IIand c‐mycgenes that was associated with increased expression of these genes. Budesonide treatment caused remethylation and decreased expression of both genes. The results support the possibility of using decreased mRNA expression and remethylation of theIgf‐IIand c‐mycgenes as biomarkers for the efficacy of budesonide. © 2002 Wiley‐Liss, Inc.