The Notch Pathway Regulates The Cancer Stem Cell Characteristics Of CD90~+Cells In Hepatocellular Carcinoma

Background&Aims:Hepatic cancer stem cells (CSCs) represent a small population of hepatic cancer cells that have the capacity to initiate and propagate tumor formation. CD90+cancer stem cells isolated from hepatocellular cancer (HCC) tissues or HCC cell lines could initiate tumors. Notch pathway could always contribute to the maintance of properties of CSCs. We hypothesize that Notch pathway is involved in stem cell properties of CD90+cancer stem cells in HCC.Methods:We retrospectively analysed the potential relationship between CD90expression in HCC and non-HCC tissues measured by IHC and clinico-pathologic features of HCC patients. Then we characterized CD90+cells isolated from HCC cell lines using microbeads sorting by tumor formation in NOD/SCID mice, plate clone assay, transwell invasion and migration, chemoresistant assay, qRT-PCR and WB. Human recombinant Jaggedl was used to activate Notch pathway and lentivirus-based siRNA knock-down systems was conducted to inhibit Notch pathway. The cell cycle phase and apoptosis analysis were measured by flow cytometry.Results:Retrospective analysis indicated that high expression of CD90in HCC tissues correlates with poor prognosis of HCC patients. CD90+cells exhibited enhanced ability of tumor formation in vivo, clonogenicity in vitro, chemoresistance, tumor invasion and migration and could differentiate into CD90" cells and not vice versa. Furthermore, we found the elevated expression of Notch signaling (Notch1, Hes1, Hey1, NICD) and stem-cell-related genes (Nanog, Sox2, Oct4) in CD90+cells, compared with CD90cells. Knock-down expression of NICD in CD90+CSCs could decrease self-renewal, invasion and migration accompanied with decreased expression of stem-cell-related genes, inhibit G1-S transition in the cell cycle phase and induce apoptosis. Overexpression of NICD in CD90-cells could increase self-renewal, invasion and migration and promote G1-S transition.Conclusion:Our results suggested CD90could be used to identify potential biomarker for liver CSCs and in CD90+CSCs the cancer stem cell characteristics were elevated through regulating Notch pathway.