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Hepatocellular carcinoma (HCC) is a highly vascularized tumor with frequent intrahepatic metastasis. Active angiogenesis and metastasis are responsible for rapid recurrence and poor survival of HCC. We previously found that microRNA-29b (miR-29b) downregulation was significantly associated with poor recurrence-free survival of HCC patients. Therefore, the role of miR-29b in tumor angiogenesis, invasion, and metastasis was further investigated in this study using in vitro capillary tube formation and transwell assays, in vivo subcutaneous and orthotopic xenograft mouse models, and Matrigel plug assay, and human HCC samples. Both gain-and loss-of-function studies showed that miR-29b dramatically suppressed the ability of HCC cells to promote capillary tube formation of endothelial cells and to invade extracellular matrix gel in vitro. Using mouse models, we revealed that tumors derived from miR-29b-expressed HCC cells displayed significant reduction in microvessel density and in intrahepatic metastatic capacity compared with those from the control group. Subsequent investigations revealed that matrix metalloproteinase-2 (MMP-2) was a direct target of miR-29b. The blocking of MMP-2 by neutralizing antibody or RNA interference phenocopied the antiangiogenesis and antiinvasion effects of miR-29b, whereas introduction of MMP-2 antagonized the function of miR29b. We further disclosed that miR-29b exerted its antiangiogenesis function, at least partly, by suppressing MMP-2 expression in tumor cells and, in turn, impairing vascular endothelial growth factor receptor 2-signaling in endothelial cells. Consistently, in human HCC tissues and mouse xenograft tumors miR-29b level was inversely correlated with MMP-2 expression, as well as tumor angiogenesis, venous invasion, and metastasis. Conclusion: miR-29b deregulation contributes to angiogenesis, invasion, and metastasis of HCC. Restoration of miR-29b represents a promising new strategy in anti-HCC therapy.

ObjectiveHepatocellular carcinoma (HCC) is a heterogeneous tumour displaying a complex variety of genetic and epigenetic changes. In human cancers, aberrant post-transcriptional modifications, such as alternative splicing and RNA editing, may lead to tumour specific transcriptome diversity.DesignBy utilising large scale transcriptome sequencing of three paired HCC clinical specimens and their adjacent non-tumour (NT) tissue counterparts at depth, we discovered an average of 20 007 inferred A to I (adenosine to inosine) RNA editing events in transcripts. The roles of the double stranded RNA specific ADAR (Adenosine DeAminase that act on RNA) family members (ADARs) and the altered gene specific editing patterns were investigated in clinical specimens, cell models and mice.ResultsHCC displays a severely disrupted A to I RNA editing balance. ADAR1 and ADAR2 manipulate the A to I imbalance of HCC via their differential expression in HCC compared with NT liver tissues. Patients with ADAR1 overexpression and ADAR2 downregulation in tumours demonstrated an increased risk of liver cirrhosis and postoperative recurrence and had poor prognoses. Due to the differentially expressed ADAR1 and ADAR2 in tumours, the altered gene specific editing activities, which was reflected by the hyper-editing of FLNB (filamin B, β) and the hypo-editing of COPA (coatomer protein complex, subunit α), are closely associated with HCC pathogenesis. In vitro and in vivo functional assays prove that ADAR1 functions as an oncogene while ADAR2 has tumour suppressive ability in HCC.ConclusionsThese findings highlight the fact that the differentially expressed ADARs in tumours, which are responsible for an A to I editing imbalance, has great prognostic value and diagnostic potential for HCC.

Esophageal squamous cell carcinoma (ESCC), the major histologic form of esophageal cancer, is a heterogeneous tumor displaying a complex variety of genetic and epigenetic changes. Aberrant RNA editing of adenosine-to-inosine (A-to-I), as it is catalyzed by adenosine deaminases acting on RNA (ADAR), represents a common posttranscriptional modification in certain human diseases. In this study, we investigated the status and role of ADARs and altered A-to-I RNA editing in ESCC tumorigenesis. Among the three ADAR enzymes expressed in human cells, only ADAR1 was overexpressed in primary ESCC tumors. ADAR1 overexpression was due to gene amplification. Patients with ESCC with tumoral overexpression of ADAR1 displayed a poor prognosis. In vitro and in vivo functional assays established that ADAR1 functions as an oncogene during ESCC progression. Differential expression of ADAR1 resulted in altered gene-specific editing activities, as reflected by hyperediting of FLNB and AZIN1 messages in primary ESCC. Notably, the edited form of AZIN1 conferred a gain-of-function phenotype associated with aggressive tumor behavior. Our findings reveal that altered gene-specific A-to-I editing events mediated by ADAR1 drive the development of ESCC, with potential implications in diagnosis, prognosis, and treatment of this disease. Cancer Res; 74(3); 840-51. Ó2013 AACR.

TGF-β is known to influence tumour progression. Here we report an additional role of Smad3 in the tumour microenvironment regulating cancer progression. Deletion or inhibition of Smad3 in the tumour microenvironment suppresses tumour growth, invasion and metastasis in two syngeneic mouse tumour models. Smad3−/− bone marrow gives rise to an expanded NK cell population with enhanced tumour-suppressive activities in vivo, and promotes differentiation of NK cells ex vivo. We identify E4BP4/NFIL3 as a direct Smad3 target gene critical for NK cell differentiation. Smad3 suppresses transcription of IFN-γ via E4BP4 in a T-bet independent manner. Therefore disruption of Smad3 enhances both the E4BP4-mediated NK cell differentiation and anti-cancer effector functions in vivo and in vitro. Furthermore, systemic treatment with a Smad3 inhibitor SIS3 effectively suppresses cancer progression. In summary, suppression of NK cell-mediated immunosurveillance via the Smad3-E4BP4 axis contributes to cancer progression. We propose targeting Smad3-dependent tumour microenvironment may represent an effective anti-cancer strategy.

BACKGROUND: Epstein-Barr virus (EBV) microRNAs are abundant in nasopharyngeal carcinoma (NPC) tumors. With recent advances in serum microRNA detection, the distinct presence of EBV microRNAs in serum could aid in screening endemic regions for NPC. A proposed network of genes targeted by these microRNAs could also shed light on EBV-associated tumorigenesis. METHODS: MicroRNA microarray profiling of 5 paired NPC biopsies was followed by validation of 12 up-regulated EBV microRNAs (BART1-3p, 2-5p, 5, 6-5p, 6-3p, 7, 8, 9, 14, 17-5p, 18-5p, 19-3p) in 15 additional cases by real-time polymerase chain reaction. Tumor (cellular) and serum microRNA copy numbers from the same 15 patients were correlated. Expression of the same microRNAs were also examined in EBV-positive cell lines C666 and NP460hTERTþEBV. Bioinformatic tools helped predict cellular target genes, which were later confirmed by gene expression analysis. RESULTS: The authors' high-throughput approach shows that EBV microRNAs are generally more up-regulated than microRNAs of human origin. Twenty-nine of 39 EBV microRNAs were significantly up-regulated in tumor versus their nontumor biopsies (P < .05). Upon successfully validating 12 selected EBV microRNAs in 15 additional paired NPC cases, the authors found that their distinct presence in the serum of NPC patients positively correlated with cellular copy numbers of EBV microRNAs. Further investigation of potential EBV microRNA target genes revealed inhibition of tumor suppressor genes (eg, PTEN) and extensive deregulation of several pathways frequently involved in NPC (eg, Wnt signaling). CONCLUSIONS: Increasing knowledge of host-virus interaction via microRNAs may provide feasible explanations underlying NPC tumorigenesis along with the development of biomarkers for screening high-risk populations. Cancer 2012;118:698-

These findings uncover the noncanonical regulation of Wnt/β-catenin in liver CSCs by the Oct4/miR-1246 signaling axis, and also provide a novel diagnostic marker as well as therapeutic intervention for HCC. (Hepatology 2016;64:2062-2076).