Side population purified from hepatocellular carcinoma cells harbors cancer stem cell–like properties

Authors

  • Tetsuhiro Chiba,

    1. Department of Regenerative Medicine, Graduate School of Medical Science, Yokohama City University, Yokohama, Japan
    2. Department of Cellular and Molecular Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
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  • Kaoru Kita,

    1. Department of Regenerative Medicine, Graduate School of Medical Science, Yokohama City University, Yokohama, Japan
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  • Yun-Wen Zheng,

    1. Department of Regenerative Medicine, Graduate School of Medical Science, Yokohama City University, Yokohama, Japan
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  • Osamu Yokosuka,

    1. Department of Medicine and Clinical Oncology, Graduate School of Medicine, Chiba University, Chiba, Japan
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  • Hiromitsu Saisho,

    1. Department of Medicine and Clinical Oncology, Graduate School of Medicine, Chiba University, Chiba, Japan
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  • Atsushi Iwama,

    1. Department of Cellular and Molecular Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan
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  • Hiromitsu Nakauchi,

    1. Laboratory of Stem Cell Therapy, Center for Experimental Medicine, Institute of Medical Science, University of Tokyo, Tokyo, Japan
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  • Hideki Taniguchi

    Corresponding author
    1. Department of Regenerative Medicine, Graduate School of Medical Science, Yokohama City University, Yokohama, Japan
    2. Research Unit for Organ Regeneration, Center for Developmental Biology, RIKEN, Kobe, Japan
    3. Biomaterials Center, National Institute for Materials Science, Tsukuba, Japan
    • Department of Regenerative Medicine, Graduate School of Medical Science, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan
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    • fax: (81) 45-7878963


  • See Editorial on Page 23

  • Potential conflict of interest: Nothing to report.

Abstract

Recent advances in stem cell biology enable us to identify cancer stem cells in solid tumors as well as putative stem cells in normal solid organs. In this study, we applied side population (SP) cell analysis and sorting to established hepatocellular carcinoma (HCC) cell lines to detect subpopulations that function as cancer stem cells and to elucidate their roles in tumorigenesis. Among four cell lines analyzed, SP cells were detected in Huh7 (0.25%) and PLC/PRF/5 cells (0.80%), but not in HepG2 and Huh6 cells. SP cells demonstrated high proliferative potential and anti-apoptotic properties compared with those of non-SP cells. Immunocytochemistry examination showed that SP fractions contain a large number of cells presenting characteristics of both hepatocyte and cholangiocyte lineages. Non-obese diabetic/severe combined immunodeficiency (NOD/SCID) xenograft transplant experiments showed that only 1 × 103 SP cells were sufficient for tumor formation, whereas an injection of 1 × 106 non-SP cells did not initiate tumors. Re-analysis of SP cell–derived tumors showed that SP cells generated both SP and non-SP cells and tumor-initiating potential was maintained only in SP cells in serial transplantation. Microarray analysis discriminated a differential gene expression profile between SP and non-SP cells, and several so-called “stemness genes” were upregulated in SP cells in HCC cells. In conclusion, we propose that a minority population, detected as SP cells in HCC cells, possess extreme tumorigenic potential and provide heterogeneity to the cancer stem cell system characterized by distinct hierarchy. (HEPATOLOGY 2006;44:240–251.)

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