The increasing incidence of hepatocellular carcinoma (HCC) is of great concern not only in the United States but throughout the world. Although sorafenib, a multikinase inhibitor with antiangiogenic and antiproliferative effects, currently sets the new standard for advanced HCC, tumor response rates are usually quite low. An understanding of the underlying mechanisms for sorafenib resistance is critical if outcomes are to be improved. In this study we tested the hypothesis that hypoxia caused by the antiangiogenic effects of sustained sorafenib therapy could induce sorafenib resistance as a cytoprotective adaptive response, thereby limiting sorafenib efficiency. We found that HCCs, clinically resistant to sorafenib, exhibit increased intratumor hypoxia compared with HCCs before treatment or HCCs sensitive to sorafenib. Hypoxia protected HCC cells against sorafenib and hypoxia-inducible factor 1 (HIF-1a) was required for the process. HCC cells acquired increased P-gp expression, enhanced glycolytic metabolism, and increased nuclear factor kappa B (NF-jB) activity under hypoxia. EF24, a molecule having structural similarity to curcumin, could synergistically enhance the antitumor effects of sorafenib and overcome sorafenib resistance through inhibiting HIF-1a by sequestering it in cytoplasm and promoting degradation by way of up-regulating Von Hippel-Lindau tumor suppressor (VHL). Furthermore, we found that sustained sorafenib therapy led to increased intratumor hypoxia, which was associated with sorafenib sensitivity in HCC subcutaneous mice tumor models. The combination of EF24 and sorafenib showed synergistically effects against metastasis both in vivo and in vitro. Synergistic tumor growth inhibition effects were also observed in subcutaneous and orthotopic hepatic tumors. Conclusion: Hypoxia induced by sustained sorafenib treatment confers sorafenib resistance to HCC through HIF-1a and NF-jB activation. EF24 overcomes sorafenib resistance through VHL-dependent HIF-1a degradation and NF-jB inactivation. EF24 in combination with sorafenib represents a promising strategy for HCC.

Hepatocellular carcinoma (HCC) is a highly vascularized tumor with frequent extrahepatic metastasis. Active angiogenesis and metastasis are responsible for rapid recurrence and poor survival of HCC. However, the mechanisms that contribute to tumor metastasis remain unclear. Here we evaluate the effects of ATPase inhibitory factor 1 (IF1), an inhibitor of the mitochondrial H(1)-adenosine triphosphate (ATP) synthase, on HCC angiogenesis and metastasis. We found that increased expression of IF1 in human HCC predicts poor survival and disease recurrence after surgery. Patients with HCC who have large tumors, with vascular invasion and metastasis, expressed high levels of IF1. Invasive tumors overexpressing IF1 were featured by active epithelial-mesenchymal transition (EMT) and increased angiogenesis, whereas silencing IF1 expression attenuated EMT and invasion of HCC cells. Mechanistically, IF1 promoted Snai1 and vascular endothelial growth factor (VEGF) expression by way of activating nuclear factor kappa B (NFjB) signaling, which depended on the binding of tumor necrosis factor (TNF) receptorassociated factor 1 (TRAF1) to NF-jB-inducing kinase (NIK) and the disruption of NIK association with the TRAF2-cIAP2 complex. Suppression of the NF-jB pathway interfered with IF1-mediated EMT and invasion. Chromatin immunoprecipitation assay showed that NF-jB can bind to the Snai1 promoter and trigger its transcription. IF1 was directly transcribed by NF-jB, thus forming a positive feedback signaling loop. There was a significant correlation between IF1 expression and pp65 levels in a cohort of HCC biopsies, and the combination of these two parameters was a more powerful predictor of poor prognosis. Conclusion: IF1 promotes HCC angiogenesis and metastasis by up-regulation of Snai1 and VEGF transcription, thereby providing new insight into HCC progression and IF1 function. (HEPATOLOGY 2014;60:1659-1673

BackgroundAbnormal metabolism, including abnormal lipid metabolism, is a hallmark of cancer cells. Some studies have demonstrated that the lipogenic pathway might promote the development of hepatocellular carcinoma (HCC). However, the role of the lipolytic pathway in HCC has not been elucidated.MethodsWe compared levels of adipose triglyceride lipase (ATGL) in human HCC and healthy liver tissues by real time PCR, western blot and immunohistochemistry. We measured diacylglycerol(DAG) and free fatty acid (FFA) levels in HCC cells driven by the NEAT1-ATGL axis and in HCC tissues. We also assessed the effects of ATGL, DAG, FFA, and NEAT1 on HCC cells proliferation in vitro and in an orthotopic xenograft HCC mouse model. We also performed a luciferase reporter assay to investigate the interaction between NEAT1/ATGL and miR-124-3p.ResultsWe found that the lipolytic enzyme, ATGL is highly expressed in human HCC tissues and predicts poor prognosis. We also found that high levels of DAG and FFA are present in HCC tissues. Furthermore, the lncRNA-NEAT1 was found to modulate ATGL expression and disrupt lipolysis in HCC cells via ATGL. Notably, ATGL and its products, DAG and FFA, were shown to be responsible for NEAT1-mediated HCC cell growth. NEAT1 regulated ATGL expression by binding miR-124-3p. Additionally, NEAT1 knockdown attenuated HCC cell growth through miR-124-3p/ATGL/DAG+FFA/PPARα signaling.ConclusionOur results reveal that NEAT1-modulates abnormal lipolysis via ATGL to drive HCC proliferation.Electronic supplementary materialThe online version of this article (10.1186/s12943-018-0838-5) contains supplementary material, which is available to authorized users.

Yes-associated protein (YAP), a transcriptional co-activator, has important regulatory roles in cell signaling and is dysregulated in a number of cancers. However, the role of YAP in cholangiocarcinoma (CCA) progression remains unclear. Here, we demonstrated that YAP was overexpressed in CCA cells and human specimens. High levels of nuclear YAP (nYAP) correlated with histological differentiation, TNM stage, metastasis and poor prognosis in CCA. Silencing YAP increased tumor sensitivity to chemotherapy and inhibited CCA tumorigenesis and metastasis both in vivo and in vitro. YAP overexpression in vivo and in vitro promoted CCA tumorigenesis and metastasis. Additionally, we found that YAP induced epithelial-mesenchymal transition (EMT) and formed a regulatory circuit with miR-29c, IGF1, AKT and gankyrin to promote the progression of CCA. Results of CCA tissue microarray showed positive correlations between nYAP and gankyrin or p-AKT expression. Combination of nYAP and gankyrin or p-AKT exhibited improved prognostic accuracy for CCA patients. In conclusion, YAP promotes carcinogenesis and metastasis by up-regulating gankyrin through activation of the AKT pathway.

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