Department of Life Science, Dongguk University-Seoul, Goyang, Republic of Korea.
Research Institute and Hospital, National Cancer Center, Goyang, Republic of Korea.
Sci Rep. 2017 Mar 21;7(1):272. doi: 10.1038/s41598-017-00424-0.
To identify dysregulated genes by abnormal methylation and expression in breast cancer, we genome-wide analyzed methylation and expression microarray data from the Gene Expression Omnibus and the Cancer Genome Atlas database. One of the genes screened in silico, FLRT2, showed hypermethylation and downregulation in the cancer dataset and the association was verified both in cultured cell lines and cancer patients' tissue. To investigate the role of FLRT2 in breast cancer, its expression was knocked down and upregulated in mammary cell lines, and the effect was examined through three levels of approach: pathway analysis; cell activities such as proliferation, colony formation, migration, and adhesion; target gene expression. The top pathway was "Cellular growth and proliferation", or "Cancer"-related function, with the majority of the genes deregulated in a direction pointing to FLRT2 as a potential tumor suppressor. Concordantly, downregulation of FLRT2 increased cell proliferation and cell migration, while overexpression of FLRT2 had the opposite effect. Notably, cell adhesion was significantly decreased by FLRT2 in the collagen I-coated plate. Taken together, our results provide insights into the role of FLRT2 as a novel tumor suppressor in the breast, which is inactivated by hypermethylation during tumor development.
为了鉴定乳腺癌中异常甲基化和表达失调的基因，我们对来自基因表达综合数据库和癌症基因组图谱数据库的全基因组甲基化和表达微阵列数据进行了分析。通过计算机筛选出的一个基因 FLRT2 在癌症数据集显示出超甲基化和下调，这种关联在培养的细胞系和癌症患者的组织中得到了验证。为了研究 FLRT2 在乳腺癌中的作用，我们在乳腺细胞系中敲低和上调了其表达，并通过三个层面的方法来检测其效果：途径分析、细胞活性（如增殖、集落形成、迁移和黏附）和靶基因表达。最主要的途径是“细胞生长和增殖”或“癌症”相关功能，大多数基因的失调方向指向 FLRT2 作为潜在的肿瘤抑制因子。一致地，下调 FLRT2 增加了细胞增殖和迁移，而上调 FLRT2 则有相反的效果。值得注意的是，FLRT2 在胶原 I 包被的平板上显著降低了细胞黏附。总之，我们的结果提供了关于 FLRT2 作为乳腺癌中新型肿瘤抑制因子的作用的新见解，该基因在肿瘤发展过程中通过超甲基化而失活。
