López-Álvarez Guadalupe S, Wojdacz Tomasz K, García-Cuellar Claudia M, Monroy-Ramírez Hugo C, Rodríguez-Segura Miguel A, Pacheco-Rivera Ruth A, Valencia-Antúnez Carlos A, Cervantes-Anaya Nancy, Soto-Reyes Ernesto, Vásquez-Garzón Verónica R, Sánchez-Pérez Yesennia, Villa-Treviño Saúl
Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Av. IPN No. 2508 Col. San Pedro Zacatenco, CDMX CP 07360, México.
Aarhus Institute of Advanced Studies and Department of Biomedicine, Bartholins Allé 6 Building, 1242, 8000 Aarhus C, Denmark.
Biol Open. 2017 Jan 15;6(1):59-70. doi: 10.1242/bio.020370.
The association between the downregulation of genes and DNA methylation in their CpG islands has been extensively studied as a mechanism that favors carcinogenesis. The objective of this study was to analyze the methylation of a set of genes selected based on their microarray expression profiles during the process of hepatocarcinogenesis. Rats were euthanized at: 24 h, 7, 11, 16 and 30 days and 5, 9, 12 and 18 months post-treatment. We evaluated the methylation status in the CpG islands of four deregulated genes (Casp3, Cldn1, Pex11a and Nox4) using methylation-sensitive high-resolution melting technology for the samples obtained from different stages of hepatocarcinogenesis. We did not observe methylation in Casp3, Cldn1 or Pex11a. However, Nox4 exhibited altered methylation patterns, reaching a maximum of 10%, even during the early stages of hepatocarcinogenesis. We observed downregulation of mRNA and protein of Nox4 (97.5% and 40%, respectively) after the first carcinogenic stimulus relative to the untreated samples. Our results suggest that Nox4 downregulation is associated with DNA methylation of the CpG island in its promoter. We propose that methylation is a mechanism that can silence the expression of Nox4, which could contribute to the acquisition of neoplastic characteristics during hepatocarcinogenesis in rats.
基因下调与其CpG岛中的DNA甲基化之间的关联已作为一种促进致癌作用的机制被广泛研究。本研究的目的是分析在肝癌发生过程中基于其微阵列表达谱选择的一组基因的甲基化情况。在处理后24小时、7天、11天、16天和30天以及5个月、9个月、12个月和18个月对大鼠实施安乐死。我们使用甲基化敏感的高分辨率熔解技术，对从肝癌发生不同阶段获得的样本，评估了四个失调基因（Casp3、Cldn1、Pex11a和Nox4）的CpG岛中的甲基化状态。我们在Casp3、Cldn1或Pex11a中未观察到甲基化。然而，Nox4呈现出改变的甲基化模式，即使在肝癌发生的早期阶段，其甲基化水平最高达到10%。相对于未处理的样本，在首次致癌刺激后，我们观察到Nox4的mRNA和蛋白质下调（分别为97.5%和40%）。我们的结果表明，Nox4下调与启动子中CpG岛的DNA甲基化相关。我们提出，甲基化是一种可使Nox4表达沉默化的机制，这可能有助于大鼠肝癌发生过程中肿瘤特征的获得。
