A Novel mTOR Inhibitor; Anthracimycin for the Treatment of Human Hepatocellular Carcinoma

BACKGROUND/AIM: Anthracimycin, a secondary metabolite of Streptomyces, has been shown to inhibit the invasion of certain cancer cell lines. MATERIALS AND METHODS: In this study we evaluated the effect of anthracimycin on cell growth and signaling pathways in hepatocellular carcinoma (HCC). RESULTS: Anthracimycin suppressed cell proliferation and motility and induced apoptosis in human HCC cell lines. Furthermore, anthracimycin had no effect on the enrichment of EpCAM-high liver cancer stem cells (CSCs), while fluorouracil dramatically enriched the CSCs with activation of the stemness-related genes EPCAM and SOX9 in HuH7 cells. Mechanistically, anthracimycin suppressed mammalian target of rapamycin (mTOR) signaling, and was most effective at inhibiting HCC cell proliferation with mTOR activation. CONCLUSION: Anthracimycin is a novel mTOR inhibitor capable of suppressing the proliferation of CSCs and non-CSCs equally well in HCC, and it is suggested that anthracimycin could be effective in the eradication of HCC associated with mTOR-signaling activation.