Date

2017-10-26

Author

Kahraman, Deniz Cansen
Atalay, Rengül

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Liver cancer stem cells (LCSCs) are derived from damaged and transformed Hepatic progenitor cells (HPCs) during precancerous cirrhosis stage. Ras/Raf/MAPK and PI3K/Akt/mTOR signaling pathways are significantly deregulated during this process. The activation of PI3K/Akt/mTOR pathway in LCSC population is one of the reasons for acquired resistance to Sorafenib in advanced Hepatocellular carcinoma (HCC). Therefore, identifying novel inhibitors against LCSCs is highly essential. We elucidated the bioactivities of 10 different kinase inhibitors acting through PI3K/Akt/mTOR pathway on HCC cells and identified their potential for an inhibitory action on the LCSC population. We compared the LCSC inhibitory bioactivities of the inhibitors to that of DAPT (CSC inhibitor), DNA intercalators and Sorafenib. For this purpose, CD133+/EpCAM+ cells originated from HCC cells were analyzed by flow cytometry and effective inhibitors on LCSCs were further tested for their use in combination with Sorafenib. Treatment of cells with Sorafenib, and DNA intercalators resulted in enrichment of CD133+/EpCAM+ cells and sphere formation. Yet, Rapamycin, LY294002 and DAPT significantly reduced CD133/EpCAM positivity and dramatically decreased the number of LCSC spheres. Combination studies revealed that sequential treatment strategy decreased the ratio of LCSCs as opposed to Sorafenib treatment alone (Table). Additionally, a large panel of genes involved in cancer pathways were analyzed using Nanostring® nCounter® Technology to identify the differentially expressed genes in Rapamycin, Sorafenib, their combination or DAPT treated cells. Genes involved in stemness were down-regulated in cells treated with Rapamycin or DAPT, whereas JAG1 gene was found to be up-regulated in Sorafenib treated cells. Interleukin 8 (IL-8) was down-regulated upon treatment with DAPT, yet up-regulated upon Sorafenib treatment (Table). Following IL-8 inhibition with Reparixin, the ratio of CD133+/EpCAM+ cells and the LCSC sphere size and count decreased significantly, indicating that IL-8 signaling is crucial for the conservation of stemness features of liver cancer cells. In this study we demonstrated that PI3K/Akt/mTOR pathway inhibitors alter hepatic CSC composition and gene expression in favor or to the detriment of cancer stem cell survival. IL-8 signaling can be promising therapeutic target for LCSC.

URI

https://hdl.handle.net/11511/72304
https://mct.aacrjournals.org/content/17/1_Supplement/LB-A08

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Graduate School of Informatics, Conference / Seminar