Marquardt Jens U, Gomez-Quiroz Luis, Arreguin Camacho Lucrecia O, Pinna Federico, Lee Yun-Han, Kitade Mitsuteru, Domínguez Mayrel Palestino, Castven Darko, Breuhahn Kai, Conner Elizabeth A, Galle Peter R, Andersen Jesper B, Factor Valentina M, Thorgeirsson Snorri S
Laboratory of Experimental Carcinogenesis, National Cancer Institute, NIH, Bethesda, USA; Department of Medicine I, Johannes Gutenberg University, Mainz, Germany.
Departamento de Ciencias de la Salud, División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana-Iztapalapa, Mexico.
J Hepatol. 2015 Sep;63(3):661-9. doi: 10.1016/j.jhep.2015.04.018. Epub 2015 May 1.
BACKGROUND & AIMS: The cancer stem cells (CSCs) have important therapeutic implications for multi-resistant cancers including hepatocellular carcinoma (HCC). Among the key pathways frequently activated in liver CSCs is NF-κB signaling.
We evaluated the CSCs-depleting potential of NF-κB inhibition in liver cancer achieved by the IKK inhibitor curcumin, RNAi and specific peptide SN50. The effects on CSCs were assessed by analysis of side population (SP), sphere formation and tumorigenicity. Molecular changes were determined by RT-qPCR, global gene expression microarray, EMSA, and Western blotting.
HCC cell lines exposed to curcumin exhibited differential responses to curcumin and were classified as sensitive and resistant. In sensitive lines, curcumin-mediated induction of cell death was directly related to the extent of NF-κB inhibition. The treatment also led to a selective CSC-depletion as evidenced by a reduced SP size, decreased sphere formation, down-regulation of CSC markers and suppressed tumorigenicity. Similarly, NF-κB inhibition by SN50 and siRNA against p65 suppressed tumor cell growth. In contrast, curcumin-resistant cells displayed a paradoxical increase in proliferation and expression of CSC markers. Mechanistically, an important component of the CSC-depleting activity of curcumin could be attributed to a NF-κB-mediated HDAC inhibition. Co-administration of the class I/II HDAC inhibitor trichostatine sensitized resistant cells to curcumin. Further, integration of a predictive signature of curcumin sensitivity with human HCC database indicated that HCCs with poor prognosis and progenitor features are most likely to benefit from NF-κB inhibition.
These results demonstrate that blocking NF-κB can specifically target CSC populations and suggest a potential for combined inhibition of NF-κB and HDAC signaling for treatment of liver cancer patients with poor prognosis.
癌症干细胞（CSCs）对包括肝细胞癌（HCC）在内的多药耐药癌症具有重要的治疗意义。肝CSCs中频繁激活的关键信号通路之一是NF-κB信号通路。
我们评估了通过IKK抑制剂姜黄素、RNA干扰（RNAi）和特异性肽SN50抑制NF-κB对肝癌中CSCs的清除潜力。通过分析侧群细胞（SP）、成球能力和致瘤性来评估对CSCs的影响。通过逆转录定量聚合酶链反应（RT-qPCR）、全基因表达微阵列、电泳迁移率变动分析（EMSA）和蛋白质免疫印迹法确定分子变化。
暴露于姜黄素的肝癌细胞系对姜黄素表现出不同反应，并被分为敏感型和耐药型。在敏感细胞系中，姜黄素介导的细胞死亡诱导与NF-κB抑制程度直接相关。该处理还导致CSCs选择性清除，表现为SP细胞群减少、成球能力下降、CSC标志物下调以及致瘤性受抑制。同样，SN50和针对p65的小干扰RNA（siRNA）抑制NF-κB可抑制肿瘤细胞生长。相反，姜黄素耐药细胞的增殖和CSC标志物表达出现反常增加。从机制上讲，姜黄素清除CSC活性的一个重要组成部分可能归因于NF-κB介导的组蛋白去乙酰化酶（HDAC）抑制。I/II类HDAC抑制剂曲古抑菌素的联合使用使耐药细胞对姜黄素敏感。此外，将姜黄素敏感性的预测特征与人类HCC数据库相结合表明，预后不良且具有祖细胞特征的HCC最有可能从NF-κB抑制中获益。
这些结果表明，阻断NF-κB可特异性靶向CSC群体，并提示联合抑制NF-κB和HDAC信号通路治疗预后不良的肝癌患者具有潜力。
