Authors' Affiliations: Department of Medicine A, Hematology, Hemostaseology, Oncology and Pneumology; Institute of Medical Informatics; Genetic Epidemiology of Vascular Disorders, Leibniz-Institute for Arteriosclerosis Research, University of Münster, Münster; University of Applied Science Hamm-Lippstadt, Hamm; Division of Tumor Biochemistry and Epigenetics, German Cancer Research Center, Heidelberg, Germany; and Department of Hematology and Oncology Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Clin Cancer Res. 2014 Feb 15;20(4):814-26. doi: 10.1158/1078-0432.CCR-13-1483. Epub 2013 Dec 13.
Cancer cell phenotypes are partially determined by epigenetic specifications, such as DNA methylation. Metastasis development is a late event in cancerogenesis and might be associated with epigenetic alterations.
An in vivo selection approach was used to generate highly aggressive non-small cell lung cancer (NSCLC) cell lines (A549 and HTB56) followed by genome-wide DNA methylation analysis. Furthermore, the therapeutic effects of the epigenetic agent azacytidine on DNA methylation patterns and the in vivo phenotypes were explored.
Widespread changes of DNA methylation were observed during development of highly aggressive cell lines. Up to 2.5% of the CpG-rich region was differentially methylated as identified by reduced representation bisulfite sequencing compared with the less aggressive parental cell lines. DNA methyltransferase inhibition by azacytidine reversed the prometastatic phenotype; this was highly associated with the preferential loss of DNA methylation at sites that were hypermethylated during the in vivo selection. Of note, polycomb (PRC2) binding sites were particularly affected by DNA methylation changes after azacytidine exposure that persisted over time.
We could show that metastatic capability of NSCLC is closely associated with DNA methylome alterations. Because inhibition of DNA methyltransferase reversed metastasis-prone phenotype, epigenetic modulation seems to be a potential therapeutic approach to prevent metastasis formation.
癌细胞表型部分由表观遗传规范决定，如 DNA 甲基化。转移的发展是癌症发生的晚期事件，可能与表观遗传改变有关。
采用体内选择方法生成高度侵袭性的非小细胞肺癌（NSCLC）细胞系（A549 和 HTB56），然后进行全基因组 DNA 甲基化分析。此外，还探索了表观遗传药物阿扎胞苷对 DNA 甲基化模式和体内表型的治疗效果。
在高度侵袭性细胞系的发展过程中观察到广泛的 DNA 甲基化变化。与侵袭性较低的亲本细胞系相比，通过减少代表性亚硫酸氢盐测序鉴定出高达 2.5%的 CpG 丰富区域存在差异甲基化。阿扎胞苷抑制 DNA 甲基转移酶逆转了促转移表型；这与在体内选择过程中高度甲基化的位点优先丢失 DNA 甲基化密切相关。值得注意的是，多梳（PRC2）结合位点在阿扎胞苷暴露后特别受到 DNA 甲基化变化的影响，这种变化会持续很长时间。
我们可以证明 NSCLC 的转移能力与 DNA 甲基组改变密切相关。由于 DNA 甲基转移酶抑制剂可逆转易转移的表型，因此表观遗传调节似乎是预防转移形成的一种潜在治疗方法。
