Epigenetics, Instituto Nacional de Medicina Genomica, Periferico Sur No.4809, Col Arenal Tepepan, Tlalpan, Mexico City 14610, Mexico; Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
Functional Genomics Laboratories, Instituto Nacional de Medicina Genomica, Periferico Sur No.4809, Col Arenal Tepepan, Tlalpan, Mexico City 14610, Mexico.
Biochim Biophys Acta Mol Cell Res. 2019 Apr;1866(4):598-611. doi: 10.1016/j.bbamcr.2019.01.002. Epub 2019 Jan 5.
The Inhibitor of Nuclear Factor Kappa B Kinase Subunit Epsilon (IKKε) is an oncogenic protein that is up-regulated in various types of human cancers, including breast tumors. This kinase regulates diverse processes associated with malignant progression including proliferation, invasion, and metastasis. To delve into the molecular mechanisms regulated by this kinase we performed RNA-seq and network analysis of breast cancer cells overexpressing IKKε. We found that the TNF/NF-κB cascade was clearly enriched, and in accordance, NF-κB pathway inhibition in these cells resulted in a decreased expression of IKKε target genes. Interestingly, we also found an enrichment of a mammary stemness functional pathway. Upregulation of IKKε led to an increase of a stem CD44+/CD24 population accompanied by a high expression of stem markers such as ALDH1A3, NANOG, and KLF4 and with an increased clonogenic ability and mammosphere formation capacity. These results were corroborated with in vivo dilution assays in zebrafish embryos which showed a significant increase in the number of Cancer Stem Cells (CSCs). Finally, we found that Triple-Negative breast tumors, which are enriched in CSCs, display higher levels of IKKε than other breast tumors, supporting the association of this kinase with the stem phenotype. In conclusion, our results highlight the role of IKKε kinase in the regulation of the stem cell phenotype in breast cancer cells, as assessed by expression, functional and in vivo assays. These results add to the potential use of this kinase as a therapeutic target in this neoplasia.
核因子κB 激酶亚单位 ε（IKKε）抑制剂是一种致癌蛋白，在包括乳腺癌在内的多种人类癌症中上调。这种激酶调节与恶性进展相关的多种过程，包括增殖、侵袭和转移。为了深入研究该激酶调节的分子机制，我们对过表达 IKKε 的乳腺癌细胞进行了 RNA-seq 和网络分析。我们发现 TNF/NF-κB 级联明显富集，并且这些细胞中 NF-κB 通路的抑制导致 IKKε 靶基因的表达降低。有趣的是，我们还发现了一个富含乳腺干性功能途径的富集。IKKε 的上调导致干细胞 CD44+/CD24 群体增加，同时高水平表达干细胞标志物，如 ALDH1A3、NANOG 和 KLF4，并具有增强的集落形成能力和乳腺球体形成能力。这些结果与斑马鱼胚胎稀释实验结果一致，该实验显示癌症干细胞（CSCs）的数量显著增加。最后，我们发现富含 CSCs 的三阴性乳腺癌比其他乳腺癌具有更高水平的 IKKε，这支持了该激酶与干细胞表型的关联。总之，我们的结果强调了 IKKε 激酶在乳腺癌细胞中干细胞表型调节中的作用，通过表达、功能和体内实验进行评估。这些结果增加了将该激酶作为该肿瘤的治疗靶点的潜力。
