Liver sinusoidal endothelial cells (LSECs) critically regulate liver homeostasis and diseases through angiocrine factors. Notch is critical in endothelial cells (ECs). In the current study, Notch ...signaling was activated by inducible EC‐specific expression of the Notch intracellular domain (NIC). We found that endothelial Notch activation damaged liver homeostasis. Notch activation resulted in decreased fenestration and increased basement membrane, and a gene expression profile with decreased LSEC‐associated genes and increased continuous EC‐associated genes, suggesting LSEC dedifferentiation. Consistently, endothelial Notch activation enhanced hepatic fibrosis (HF) induced by CCl4. Notch activation attenuated endothelial nitric oxide synthase (eNOS)/soluble guanylate cyclase (sGC) signaling, and activation of sGC by 3‐(5′‐hydroxymethyl‐2′‐furyl)‐1‐benzylindazole (YC‐1) reversed the dedifferentiation phenotype. In addition, Notch activation subverted the hepatocyte‐supporting angiocrine profile of LSECs by down‐regulating critical hepatocyte mitogens, including Wnt2a, Wnt9b, and hepatocyte growth factor (HGF). This led to compromised hepatocyte proliferation under both quiescent and regenerating conditions. Whereas expression of Wnt2a and Wnt9b was dependent on eNOS‐sGC signaling, HGF expression was not rescued by the sGC activator, suggesting heterogeneous mechanisms of LSECs to maintain hepatocyte homeostasis. Conclusion: Endothelial Notch activation results in LSEC dedifferentiation and accelerated liver fibrogenesis through eNOS‐sGC signaling, and alters the angiocrine profile of LSECs to compromise hepatocyte proliferation and liver regeneration (LR). (Hepatology 2018).
Tumor-associated macrophages (TAM) play pivotal roles in tumor progression and metastasis, but the contribution and regulation of different macrophage populations remain unclear. Here we show that ...Notch signaling plays distinct roles in regulating different TAM subsets in hepatocellular carcinoma (HCC). Myeloid-specific NOTCH blockade by conditional disruption of recombination signal binding protein Jκ (RBPj cKO) significantly delayed the growth of subcutaneously inoculated Lewis lung carcinoma (LLC), but accelerated orthotopically inoculated hepatic Hepa1-6 tumors in mice. In contrast to subcutaneous LLC, RBPj cKO significantly increased the number of TAMs in hepatic Hepa1-6 tumors despite impeded differentiation of monocyte-derived TAMs (moTAM). The dominating TAMs in orthotopic HCC manifested properties of Kupffer cells (KC) and hence are tentatively named KC-like TAMs (kclTAM). The increased proliferation of RBPj cKO kclTAMs was maintained even in
mice, in which moTAMs were genetically blocked. NOTCH signaling blockade accelerated proliferation of kclTAMs via enhanced
-dependent WNT signaling, which also downregulated IL12 and upregulated IL10 expression by kclTAMs likely through c-MYC. In addition, myeloid-specific RBPj cKO facilitated hepatic metastasis of colorectal cancer but suppressed lung metastasis in mice, suggesting that the phenotype of RBPj cKO in promoting tumor growth was liver-specific. In patient-derived HCC biopsies, NOTCH signaling negatively correlated with WNT activation in CD68
macrophages, which positively correlated with advanced HCC stages. Therefore, NOTCH blockade impedes the differentiation of moTAMs, but upregulates Wnt/β-catenin signaling to promote the proliferation and protumor cytokine production of kclTAMs, facilitating HCC progression and hepatic metastasis of colorectal cancer. SIGNIFICANCE: These findings highlight the role of NOTCH and WNT signaling in regulating TAMs in hepatocellular carcinoma.
The MYC oncogene is overexpressed in hepatocellular carcinoma (HCC) and has been associated with widespread microRNA (miRNA) repression; however, the underlying mechanisms are largely unknown. Here, ...we report that the c‐Myc oncogenic transcription factor physically interacts with enhancer of zeste homolog 2 (EZH2), a core enzymatic unit of polycomb repressive complex 2 (PRC2). Furthermore, miR‐101, an important tumor‐suppressive miRNA in human hepatocarcinomas, is epigenetically repressed by PRC2 complex in a c‐Myc‐mediated manner. miR‐101, in turn, inhibits the expression of two subunits of PRC2 (EZH2 and EED), thus creating a double‐negative feedback loop that regulates the process of hepatocarcinogenesis. Restoration of miR‐101 expression suppresses multiple malignant phenotypes of HCC cells by coordinate repression of a cohort of oncogenes, including STMN1, JUNB, and CXCR7, and further increases expression of endogenous miR‐101 by inhibition of PRC2 activation. In addition, co‐overexpression of c‐Myc and EZH2 in HCC samples was closely associated with lower expression of miR‐101 (P < 0.0001) and poorer prognosis of HCC patients (P < 0.01). Conclusions: c‐Myc collaborates with EZH2‐containing PRC2 complex in silencing tumor‐suppressive miRNAs during hepatocarcinogenesis and provides promising therapeutic candidates for human HCC. (Hepatology 2014;59:1850–1863)
Hepatic ischemia/reperfusion (I/R) injury is initiated by reactive oxygen species (ROS) accumulated during the early reperfusion phase after ischemia, but cellular mechanisms controlling ROS ...production and scavenging have not been fully understood. In this study, we show that blocking Notch signal by knockout of the transcription factor RBP‐J or a pharmacological inhibitor led to aggravated hepatic I/R injury, as manifested by deteriorated liver function and increased apoptosis, necrosis, and inflammation, both in vitro and in vivo. Interruption of Notch signaling resulted in increased intracellular ROS in hepatocytes, and a ROS scavenger cured exacerbated hepatic I/R injury after Notch signaling blockade, suggesting that Notch signal deficiency aggravated I/R injury through increased ROS levels. Notch signal blockade resulted in down‐regulation of Hes5, leading to reduced formation of the Hes5‐STAT3 complex and hypophosphorylation of STAT3, which further attenuated manganese superoxide dismutase (MnSOD) expression and increased ROS and apoptosis. Indeed, overexpression of a constitutively active STAT3 rescued MnSOD expression and I/R injury–induced apoptosis in the absence of Notch signaling. Finally, forced Notch activation by ligand stimulation or Hes5 overexpression reduced intracellular ROS and protected hepatocytes from apoptosis after I/R injury through the activation of STAT3 and MnSOD expression.
Conclusion:
Notch signal protects hepatocytes from I/R injury by Hes5‐dependent activation of STAT3, which activates the expression of MnSOD, leading to the scavenging of ROS. (HEPATOLOGY 2011;).
MiR-34a, a direct target of p53, has been shown to target several molecules associated with the cell cycle and cell survival pathways, and its dysregulation is implicated in cancer drug resistance or ...sensitivity in several human cancers. However, the correlation between miR-34a expression and chemoresistance has not been explored in HCC. In this study, we confirmed that miR-34a was significantly down-regulated in HCC tissues and HCC cell lines by qRT-PCR. HCC tissues with lower miR-34a expression displayed higher expression of Bcl-2 protein than those with high expression of miR-34a; therefore, an inverse correlation is evident between the miR-34a level and Bcl-2 expression. Moreover, patients with lower miR-34a expression had significantly poorer overall survival. Bioinformatics and luciferase reporter assays revealed that miR-34a binds the 3'-UTR of the Bcl-2 mRNA and represses its translation. Western blotting analysis and qRT-PCR confirmed that Bcl-2 is inhibited by miR-34a overexpression. Functional analyses indicated that the restoration of miR-34a reduced cell viability, promoted cell apoptosis and potentiated sorafenib-induced apoptosis and toxicity in HCC cell lines by inhibiting Bcl-2 expression. This study is the first to demonstrate that miR-34a induces sensitivity to the anti-tumor effect of sorafenib in human HCC cells, suggesting a potential role of miR-34a in the treatment of HCC.
AIM： To compare the influence of different transplant sites in bone marrow mesenchymal stem cell （MSC）-based therapy for liver fibrosis. METHODS： MSCs isolated from Sprague Dawley （SD） rats were ...induced into hepatocyte-like cells. Liver fibrosis in SD rats was induced with carbon tetrachloride. Following hepatocyte induction in vitro, 4＇,6-diamidino- 2-phenylindole （DAPI）-labeled MSCs were transplanted by intravenous, intrahepatic, and intraperitoneal injection. Histopathological staining, immunohistochemistry, and biochemical analysis were used to compare the morphological and functional liver regeneration among different MSC injection modalities. The expression differences of interleukins, growth factor, extracellular matrix, matrix metalloproteinases, and tissue inhibitor of metalloproteinase were examined by real-time reverse transcription-polymerase chain reaction （RT-PCR） andenzyme linked immunosorbent assay （ELISA）. RESULTS： Four days after exposure to hepatocyte differentiation medium, MSCs that did not express hepatocyte markers could express α-fetoprotein, albumin, and cytokeratin 18. The results of histopathological staining, immunohistochemistry, and biochemical analysis indicated that intravenous injection is more effective at rescuing liver failure than other injection modalities. DAPI-labeled cells were found around liver lobules in all three injection site groups, but the intravenous group had the highest number of cells. PCR and ELISA analysis indicated that interleukin-10 （IL-10） was highest in the intravenous group, whereas il1β, il6, tnfα and tgfβ, which can be regulated by IL10 and are promoters of liver fibrosis, were significantly lower than in the other groups. CONCLUSION： MSC administration is able to protect against liver fibrosis. Intravenous injection is the most favorable treatment modality through promotion of IL10 expression.
Dendritic cells (DCs) release bioactive exosomes that play an important role in immune regulation. Because they express low levels of class I major histocompatibility complex (MHC) and co-stimulatory ...molecules, exosomes derived from donor immature DCs (imDex) prolong allograft survival by inhibiting T-cell activation. However, this effect is limited and does not induce immunological tolerance when imDex are administered alone. Thus, we tested the effect of combined treatment with donor imDex and low-dose rapamycin on inducing tolerance in a mouse cardiac transplantation model.
ImDex were obtained from the culture supernatant of immature DCs derived from donor mouse (C57BL/6) bone marrow and were injected with suboptimal doses of rapamycin into recipient mouse (BALB/c) before and after transplantation. The capacity of this treatment to induce immune tolerance was analyzed in vitro and in vivo using the mouse cardiac transplantation model.
Donor imDex expressed moderate levels of MHC class II and low levels of MHC class I and co-stimulatory molecules, but neither imDex nor subtherapeutic rapamycin dose alone induced cardiac allograft tolerance. Combined treatment with imDex and rapamycin, however, led to donor specific cardiac allograft tolerance. This effect was accompanied by decreased anti-donor antigen cellular response and an increased percentage of spleen CD4(+)CD25(+) T cells in recipients. Furthermore, this donor specific tolerance could be further transferred to naïve allograft recipients through injection of splenocytes, but not serum, from tolerant recipients.
Combined with immunosuppressive treatment, donor imDex can prolong cardiac allograft survival and induce donor specific allograft tolerance.
Macrophages play multidimensional roles in hepatic fibrosis, but their control has not been fully understood. The Notch pathway mediated by recombination signal binding protein Jκ (RBP‐J), the ...transcription factor transactivated by signals from four mammalian Notch receptors, is implicated in macrophage activation and plasticity. In this study, by using mouse hepatic fibrosis models, we show that myeloid‐specific disruption of RBP‐J resulted in attenuated fibrosis. The activation of hepatic stellate cells and production of profibrotic factors including platelet‐derived growth factor (PDGF)‐B and transforming growth factor beta1 (TGF‐β1) reduced significantly in myeloid‐specific RBP‐J deficient mice. The infiltration of inflammatory cells and production of proinflammatory factors were reduced in liver of myeloid‐specific RBP‐J‐deficient mice during fibrosis. In RBP‐J‐deficient macrophages, the nuclear factor kappa B (NF‐κB) activation was remarkably attenuated as compared with the control. This could be attributed to the up‐regulation of cylindromatosis (CYLD), a negative regulator of NF‐κB, in Notch signal‐compromised macrophages, because the knockdown of CYLD in RBP‐J‐deficient macrophages or overexpression of p65 in RBP‐J knockdown cells both restored NF‐κB activation and the production of proinflammatory and/or profibrotic factors by macrophages. In human hepatic fibrosis biopsies, stronger Notch activation is correlated with more severe fibrosis, which is accompanied by a lower level of CYLD but irrespective of etiological reasons. Conclusion: RBP‐J‐mediated Notch signaling is required for macrophages to promote hepatic fibrosis by up‐regulation of NF‐κB activation through CYLD. (Hepatology 2015;61:303–314)
It has been reported that Annexin A2 (ANXA2) is up-regulated in hepatocellular carcinoma (HCC), but the roles of ANXA2 in the migration and invasion of HCC cells have not been determined. In this ...study, we found that ANXA2-specific siRNA (si-ANXA2) significantly inhibited the migration and invasion of HCC cells co-cultured with fibroblasts in vitro. In addition, the production of MMP-2 by fibroblasts cultured in supernatant collected from si-ANXA2-transfected HCC cells was notably down-regulated. ANXA2 was also found to be co-localized and co-immunoprecipitated with CD147. Further investigation revealed that the expression of ANXA2 in HCC cells affected the shedding of CD147-harboring membrane microvesicles, acting as a vehicle for CD147 in tumor-stromal interactions and thereby regulating the production of MMP-2 by fibroblasts. Together, these results suggest that ANXA2 enhances the migration and invasion potential of HCC cells in vitro by regulating the trafficking of CD147-harboring membrane microvesicles.
MicroRNA-10b (miR-10b) was recently reported to be dysregulated in some types of cancer and to play a role in invasion and metastasis. However, effects and potential mechanisms of action of miR-10b ...in the metastasis of hepatocellular carcinoma (HCC) have not been explored. In this study, we confirmed that miR-10b is highly expressed in metastatic HCC tissues and in metastatic HCC cell lines by qRT-PCR. Moreover, patients with higher miR-10b expression had significantly poorer overall survival, and high miR-10b expression was an independent predictor of poor prognosis. Inhibition of miR-10b reduced cell migration and invasion in MHCC97H cells, whereas over-expression of miR-10b in HepG2 cells increased cell migration and invasion. Bioinformatics and luciferase reporter assays revealed that miR-10b binds the 3′-UTR of CADM1 mRNA and represses its translation. Western blot and qRT-PCR showed that CADM1 is inhibited by miR-10b over-expression. Silencing of CADM1 resulted in substantially increased cell motility and invasion similar to that observed with over-expression of miR-10b in HepG2 cells. These results suggest that miR-10b may positively regulate the invasion and metastasis of HCC through targeting CADM1.
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