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Hepatocellular carcinoma (HCC) is a highly aggressive liver tumor containing cancer stem cells (CSCs), which participate in tumor invasion, therapeutic resistance, and tumor relapse leading to poor outcome and limited therapeutic options. Histone deacetylatase sirtuin 1 (SIRT1) has been shown to be up-regulated in human cancers; however, its role in liver CSCs is unknown. In this study, we explored the biological functions of SIRT1 in liver CSCs. Our data show that SIRT1 is highly expressed in liver CSCs and decreases during differentiation. In addition, high levels of SIRT1 predict a decreased probability of survival in patients with HCC. SIRT1 is responsible for the maintenance of self-renewal and tumorigenicity of liver CSCs, and overexpression of exogenous SIRT1 can restore self-renewal of non-CSCs. We demonstrated that SOX2 is a main downstream regulator of SIRT1-mediated self-renewal and tumorigenicity potential of liver CSCs. Mechanistically, SIRT1 regulates transcription of the SOX2 gene by way of chromatin-based epigenetic changes, which are dependent on DNA methylation. This effect is achieved by alternation of histone modification and interaction with DNA methyltransferase 3A, resulting in hypermethylation of SOX2 promoter. Furthermore, we demonstrated that insulin growth factor signaling plays an important role in maintaining SIRT1 expression through increased SIRT1 protein stability. Conclusions: These findings highlight the importance of SIRT1 in the biology of liver CSCs and suggest that SIRT1 may serve as a molecular target for HCC therapy. (HEPATOLOGY 2016;64:814-827)

BackgroundPancreatic cancer is generally acknowledged as the most common primary malignant tumor, and it is known to be resistant to conventional chemotherapy. Novel, selective antitumor agents are pressingly needed.MethodsCCK-8 and colony formation assay were used to investigate the cell growth. Flow cytometry analysis was used to evaluate the cell cycle and cell apoptosis. The peroxide-sensitive fluorescent probe DCFH-DA was used to measure the intracellular ROS levels. Western blot assay was used to detect the levels of cell cycle and apoptosis related proteins. Xenografts in nude mice were used to evaluate the effect of Sophoridine on pancreatic cancer cell in vivo.ResultsSophoridine killed cancer cells but had low cytotoxicity to normal cells. Pancreatic cancer cells were particularly sensitive. Sophoridine inhibited the proliferation of pancreatic cancer cells and induced cell cycle arrest at S phase and mitochondrial-related apoptosis. Moreover, Sophoridine induced a sustained activation of the phosphorylation of ERK and JNK. In addition, Sophoridine provoked the generation of reactive oxygen species (ROS) in pancreatic cancer cells. Finally, in vivo, Sophoridine suppressed tumor growth in mouse xenograft models.ConclusionThese findings suggest Sophoridine is promising to be a novel, potent and selective antitumor drug candidate for pancreatic cancer.Electronic supplementary materialThe online version of this article (10.1186/s13046-017-0590-5) contains supplementary material, which is available to authorized users.

Discovery of epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) are two milestones in people exploring the nature of malignant tumor in recent decades. Although some studies have presented the potential connections between them, the link details, underneath their superficial correlation, are largely unknown. In this study, we identified a small subpopulation of NANOG-positive colorectal cancer (CRC) cells, and demonstrated that they exhibited characteristics of CSCs and EMT traits simultaneously. Furthermore, we found that NANOG was a core factor in regulating both of EMT and stemness in CRC cells, NANOG modulate EMT and metastasis by binding to Slug promoter and transcriptionally regulate Slug expression. For the first time, we demonstrated that NANOG was regulated by extracellular IGF signaling pathway via STAT3 phosphorylation in CRC. This coincides with that IGF receptor IGF-1R is often increasing expressed in malignant metastasis colon cancer. Taken together, our data define the crucial functions of IGF/STAT3/NANOG/Slug signaling axis in the progression of CRC by operating EMT and CSCs properties, which make them served as potential therapeutic targets for treatment of CRC. STEM CELLS 2016;34:820-831 SIGNIFICANCE STATEMENTNANOG, a core multipotential transcription factor was described as a stemness maintainer and EMT facilitator, but the knowledge of tumor-environmental triggering signal of NANOG is limited. Here we show that IGF signaling, an important tumor promoting signal and a poor prognosis indicator of CRC, drive the expression of NANOG by cytoplasmic mediator STAT3. Besides the role as a stemness maintainer, NANOG promotes EMT through activating Slug at transcriptional level directly. The evidence of IGF/STAT3/NANOG/Slug axis as a causative mechanism of NANOG-mediated EMT and self-renewal of CSCs contributes to uncover the yet incompletely understood process of tumor initiation and metastasis.