Murakami Shigekazu, Ninomiya Wataru, Sakamoto Erina, Shibata Tatsuhiro, Akiyama Hirotada, Tashiro Fumio
Department of Biological Sciences and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, Niijuku, Katsushika-ku, Tokyo, Japan.
Division of Cancer Genomics, National Cancer Center Research Institute, Tsukiji, Chuo-ku, Tokyo Japan.
Stem Cells. 2015 Sep;33(9):2652-63. doi: 10.1002/stem.2059. Epub 2015 Jun 23.
The acquisition of stemness is a hallmark of aggressive human hepatocellular carcinoma (hHCC). The stem cell marker OCT4 is frequently expressed in HCCs, and its expression correlates with those of putative cancer stem cell (CSC) markers and CSC properties. Here, we describe a novel mechanism of CSC maintenance by SRY through OCT4. We previously reported that Sry is involved in tumor malignancy in rodent HCCs. However, the oncogenic function of SRY in hHCCs is poorly understood. Ectopic expression of SRY increased multiple stem cell factors, including OCT4 and CD13. The OCT4 promoter contained SRY-binding sites that were directly activated by SRY. In HCC-derived cells, SRY knockdown decreased OCT4 expression and cancer stem-like phenotypes such as self-renewal, chemoresistance, and tumorigenicity. Conversely, OCT4 and SRY overexpression promoted cancer stem-like phenotypes. OCT4 knockdown in SRY clones downregulated the self-renewal capacity and chemoresistance. These data suggest that SRY is involved in the maintenance of cancer stem-like characteristics through OCT4. Moreover, CSCs of HCC-derived cells differentiated into Tuj1-positive neuron-like cells by retinoic acid. Noteworthily, SRY was highly expressed in some hHCC patients. Taken together, our findings imply a novel therapeutic strategy against CSCs of hHCCs.
干性的获得是侵袭性人类肝细胞癌(hHCC)的一个标志。干细胞标志物OCT4在肝癌中经常表达,其表达与假定的癌症干细胞(CSC)标志物及CSC特性相关。在此,我们描述了SRY通过OCT4维持CSC的一种新机制。我们之前报道过Sry参与啮齿动物肝癌的肿瘤恶性进展。然而,SRY在hHCC中的致癌功能尚不清楚。SRY的异位表达增加了多种干细胞因子,包括OCT4和CD13。OCT4启动子含有可被SRY直接激活的SRY结合位点。在肝癌衍生细胞中,敲低SRY会降低OCT4表达以及癌症干细胞样表型,如自我更新、化疗耐药性和致瘤性。相反,OCT4和SRY过表达会促进癌症干细胞样表型。在SRY克隆中敲低OCT4会下调自我更新能力和化疗耐药性。这些数据表明SRY通过OCT4参与维持癌症干细胞样特征。此外,肝癌衍生细胞的CSC通过视黄酸分化为Tuj1阳性神经元样细胞。值得注意的是,SRY在一些hHCC患者中高表达。综上所述,我们的研究结果暗示了一种针对hHCC中CSC的新治疗策略。