Tumorigenicity of Li-7
The identification and development of therapeutic targets in cancer stem cells that lead to tumor development, recurrence, metastasis, and drug resistance is an important goal in cancer research. The hepatocellular carcinoma cell line Li-7 contains functionally different types of cells. Cells with tumor-forming activity are enriched in cancer stem cell-like CD13+CD166- cells and this cell population gradually decreases during culture in conventional culture medium (RPMI1640 containing 10% fetal bovine serum). When Li-7 cells are cultured in mTeSR1, a medium developed for human pluripotent stem cells, CD13+CD166- cells and their tumorigenicity are maintained. We sought to identify the mechanisms of tumorigenicity in this sub-population. After transfer from mTeSR1 to RPMI1640 containing 10% fetal bovine serum, the cells in this population gradually lost tumorigenicity. In contrast, when the genes expressed specifically in CSC-like cells of Li-7 cells were forcibly expressed in cultures using RPMI1640 containing 10% fetal bovine serum, Li-7 cells maintained tumorigenicity. Our analyses here showed potential therapeutic target genes and metabolites for treatment of cancer stem cells in hepatocellular carcinoma.