Abstract 1397: Identification of a hepatocellular carcinoma cell line capable of monitoring the differentiation of CD13(+)CD166(-) cancer stem cells and effects of sorafenib

Background: Recent cancer stem cell (CSC) research has highlighted the necessity to develop drugs targeting CSCs. However, only few in vitro models are available which show CSC hierarchy and allow monitoring of CSC differentiation and screening of drugs targeting CSC. Aim: In the present study, we aimed to identify such hepatocellular carcinoma (HCC) cell line(s). Methods: Based on a hypothesis that the proportion of CSCs would decrease during culture because of their differentiation into progenitors (population switch), we tested the positivity of several markers (CD13, EpCAM, CD133, CD44, CD90, CD24, CD166) in HCC cell lines (HuH-7, Li-7, PLC/PRF/5, HLF, HLE) before and after 2 months culture. Results: Only Li-7 cells showed relevant population switch: the proportion of CD13 decreased, while that of CD166 increased during the culture. High tumorigenicity of Li-7 was lost after the population switch. CD13(+)/CD166(-) cells showed slow growth and reconstructed the bulk Li-7 populations composed of CD13(+)/CD166(-), CD13(-)/CD166(-) and CD13(-)/CD166(+) fractions, while CD13(-)/CD166(+) cells showed rapid growth but could not reproduce any other cell populations. CD13(+)/CD166(-) cells showed high ALDH activity, spheroid forming ability and resistance to 5FU. Microarray analysis demonstrated higher expression of stemness-related genes in CD166(-) than CD166(+) fraction. These results indicated the hierarchy of Li-7 cells, in which CD13(+)/CD166(-) and CD13(-)/CD166(+) cells serve as slow growing CSCs and rapid growing progenitors, respectively. Interestingly, sorafenib selectively targeted CD166(-) fraction including CD13(+) CSCs, which exhibited higher mRNA expression of FGF3 and FGF4, candidate biomarkers for sorafenib. 5-FU followed by sorafenib inhibited the growth of bulk Li-7 cells more effectively than reverse sequence or either alone. Conclusions: We identified an useful cell line Li-7 capable of monitoring the CD13 (+) CSC differentiation and screening the drugs targeting the CSCs of HCC and found that sorafenib preferentially targeted CD13(+) CSCs in vitro. Screening cell lines for “population switch” may be useful to identify novel candidate model systems for screening drugs targeting CSCs. Citation Format: Takeshi Yamada, Masato Abei, Inaho Danjoh, Ryoko Shirota, Taro Yamashita, Shinji Endo, Ichinosuke Hyodo, Yukio Nakamura. Identification of a hepatocellular carcinoma cell line capable of monitoring the differentiation of CD13(+)CD166(-) cancer stem cells and effects of sorafenib. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1397. doi:10.1158/1538-7445.AM2015-1397