Department of Laparoscopic Surgery, Third Affiliated Hospital of Second Military Medical University, Shanghai 200438, China; Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
Department of Pharmacy, Third Affiliated Hospital of Second Military Medical University, 225 Changhai Road, 200438 Shanghai, China.
Exp Cell Res. 2019 May 1;378(1):66-75. doi: 10.1016/j.yexcr.2019.03.007. Epub 2019 Mar 4.
Liver cancer stem cells (CSCs) contribute to tumorigenesis, progression, drug resistance and recurrence of hepatocellular carcinoma (HCC). However, the underlying mechanism for the propagation of liver CSCs remains unclear. Herein, we observed low expression of miR-194 in chemoresistant HCC cells. A remarkable decrease of miR-194 was detected in EpCAM or CD133-positive liver CSCs and CSC-enriched hepatoma spheres. Interference miR-194 facilitated liver CSCs expansion by enhancing the self-renewal of liver CSCs. While up-regulating miR-194 inhibited liver CSCs expansion by suppressing the self-renewal of liver CSCs. Furthermore, hepatoma cells with miR-194 overexpression performed more sensitivity to sorafenib treatment. Mechanistically, functional studies found that Ras-related C3 botulinum toxin substrate 1 (RAC1) was a direct target of miR-194. Overexpression of miR-194 inhibited the expression of RAC1 in liver CSCs. Special RAC1 siRNA diminished the discrepancy in liver CSC proportion and the self-renewal capacity between miR-194 overexpression hepatoma cells and control cells, which further confirmed that RAC1 was required in miR-194-inhibited liver CSCs expansion. More importantly, downregulated expression of miR-194 was a predictor of poor prognosis of HCC patients.
肝癌干细胞(CSCs)促进肝癌的发生、发展、耐药和复发。然而,CSC 增殖的潜在机制尚不清楚。在此,我们观察到耐药 HCC 细胞中 miR-194 的低表达。在 EpCAM 或 CD133 阳性的肝 CSCs 和 CSC 富集的肝癌球体中,检测到 miR-194 的显著减少。干扰 miR-194 通过增强肝 CSCs 的自我更新来促进肝 CSCs 的扩增。上调 miR-194 通过抑制肝 CSCs 的自我更新来抑制肝 CSCs 的扩增。此外,过表达 miR-194 的肝癌细胞对索拉非尼治疗更敏感。机制研究发现,Ras 相关 C3 肉毒杆菌毒素底物 1(RAC1)是 miR-194 的直接靶标。过表达 miR-194 抑制肝 CSCs 中 RAC1 的表达。特殊的 RAC1 siRNA 减少了 miR-194 过表达肝癌细胞与对照细胞之间肝 CSC 比例和自我更新能力的差异,这进一步证实 RAC1 是 miR-194 抑制肝 CSCs 扩增所必需的。更重要的是,miR-194 表达下调是 HCC 患者预后不良的预测因子。