Cancer Systems Biology Laboratory, Graduate School of Informatics, ODTU, Ankara, Turkey.
Department of Molecular Biology and Genetics, Bilkent University, Ankara, Turkey.
Mol Cancer Ther. 2019 Nov;18(11):2146-2157. doi: 10.1158/1535-7163.MCT-19-0004. Epub 2019 Aug 22.
Activation of the PI3K/Akt/mTOR pathway is an important signaling mechanism involved in the development and the progression of liver cancer stem cell (LCSC) population during acquired Sorafenib resistance in advanced hepatocellular carcinoma (HCC). Therefore, identification of novel therapeutic targets involving this pathway and acting on LCSCs is highly essential. Here, we analyzed the bioactivities and the molecular pathways involved in the action of small-molecule PI3K/Akt/mTOR pathway inhibitors in comparison with Sorafenib, DNA intercalators, and DAPT (CSC inhibitor) on CD133/EpCAM-positive LCSCs. Sorafenib and DNA intercalators lead to the enrichment of LCSCs, whereas Rapamycin and DAPT significantly reduced CD133/EpCAM positivity. Sequential treatment with Rapamycin followed by Sorafenib decreased the ratio of LCSCs as well as their sphere formation capacity, as opposed to Sorafenib alone. Under the stress of the inhibitors, differential expression analysis of 770 cancer pathway genes using network-based systems biology approach singled out expression association with LCSCs. Furthermore, IL8 secretion and LCSC enrichment ratio was also positively correlated. Following IL8 inhibition with its receptor inhibitor Reparixin or siRNA knockdown, LCSC features of HCC cells were repressed, and sensitivity of cells to Sorafenib increased significantly. Furthermore, inflammatory cytokines (IL8, IL1β, and IL11) were also upregulated upon treatment with HCC-approved kinase inhibitors Sorafenib and Regorafenib. Hence, chemotherapeutic stress alters inflammatory cytokine gene expression in favor of hepatic CSC population survival. Autocrine IL8 signaling is identified as a critical event, and its inhibition provides a promising complimentary therapeutic approach for the prevention of LCSC population enrichment.
PI3K/Akt/mTOR 通路的激活是肝癌干细胞（LCSC）群体在获得索拉非尼耐药的晚期肝癌（HCC）中发展和进展的重要信号机制。因此，鉴定涉及该通路并作用于 LCSC 的新治疗靶点是非常必要的。在这里，我们分析了小分子 PI3K/Akt/mTOR 通路抑制剂与索拉非尼、DNA 嵌入剂和 DAPT（CSC 抑制剂）在 CD133/EpCAM 阳性 LCSC 上的生物活性和分子途径，索拉非尼和 DNA 嵌入剂导致 LCSC 富集，而雷帕霉素和 DAPT 则显著降低 CD133/EpCAM 阳性率。雷帕霉素序贯治疗后再用索拉非尼治疗，可降低 LCSC 的比例及其球体形成能力，而单用索拉非尼则不然。在抑制剂的压力下，使用基于网络的系统生物学方法对 770 种癌症途径基因进行差异表达分析，挑出与 LCSC 表达相关的基因。此外，IL8 分泌和 LCSC 富集率也呈正相关。用其受体抑制剂 Reparixin 或 siRNA 敲低抑制 IL8 后，HCC 细胞的 LCSC 特征受到抑制，细胞对索拉非尼的敏感性显著增加。此外，炎症细胞因子（IL8、IL1β 和 IL11）在接受 HCC 批准的激酶抑制剂索拉非尼和 Regorafenib 治疗后也上调。因此，化疗应激改变了有利于肝 CSC 群体存活的炎症细胞因子基因表达。自分泌 IL8 信号被确定为一个关键事件，其抑制为预防 LCSC 群体富集提供了一种有前途的补充治疗方法。
