BackgroundAberrant expression of A20 has been reported in several human malignancies including hepatocellular carcinoma (HCC). However, its clinical relevance and potential role in HCC remain unknown.MethodsQuantitative PCR, Western blots and immunohistochemistry analyses were used to quantify A20 expression in HCC samples and cell lines. The correlation of A20 expression with clinicopathologic features was analyzed in a cohort containing 143 patients with primary HCC. Kaplan-Meier curves were used to evaluate the association between A20 expression and patient survival. Functional studies were performed to determine the effects of A20 on proliferation and metastasis of HCC cells in vitro and in vivo.ResultsExpression of A20 was increased in HCC tissues and cell lines. Increased expression of A20 was negatively correlated with the tumor size, TNM stage, tumor thrombus formation, capsular invasion and serum AFP levels. Patients with higher A20 expression had a prolonged disease-free survival and overall survival than those with lower A20 expression. Forced expression of A20 significantly inhibited the proliferative and invasive properties of HCC cells both in vitro and in vivo, whereas knockdown of A20 expression showed the opposite effects. Further studies revealed that expression of A20 was inversely correlated with Twist1 levels and NF-κB activity in HCC tissues and cell lines. A20-induced suppression of proliferation and migration of HCC cells were mainly mediated through inhibition of Twist1 expression that was regulated at least partly by A20-induced attenuation of NF-κB activity.ConclusionsOur results demonstrate that A20 plays a negative role in the development and progression of HCC probably through inhibiting Twist1 expression. A20 may serve as a novel prognostic biomarker and potential therapeutic target for HCC patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s12943-015-0454-6) contains supplementary material, which is available to authorized users.

Merlin, which is encoded by the tumour suppressor gene Nf2, plays a crucial role in tumorigenesis and metastasis. However, little is known about the functional importance of Merlin splicing forms. In this study, we show that Merlin is present at low levels in human hepatocellular carcinoma (HCC), particularly in metastatic tumours, where it is associated with a poor prognosis. Surprisingly, a splicing variant of Merlin that lacks exons 2, 3 and 4 (Δ2–4Merlin) is amplified in HCC and portal vein tumour thrombus (PVTT) specimens and in the CSQT2 cell line derived from PVTT. Our studies show that Δ2–4Merlin interferes with the capacity of wild-type Merlin to bind β-catenin and ERM, and it is expressed in the cytoplasm rather than at the cell surface. Furthermore, Δ2–4Merlin overexpression increases the expression levels of β-catenin and stemness-related genes, induces the epithelium–mesenchymal-transition phenotype promoting cell migration in vitro and the formation of lung metastasis in vivo. Our results indicate that the Δ2–4Merlin variant disrupts the normal function of Merlin and promotes tumour metastasis.

Abstract:A high affinity polyclonal antibody-based enzyme linked immunosorbent assay (ELISA) was developed for the quantification of zeranol in bovine urine. On the basis of urine matrix studies, the optimized dilution factors producing insignificant matrix interference were selected as 1:5 in pretreatment. In the improved ELISA, the linear response range was between 0.02 and 1 µg/ml , and the detection limit was 0.02 µg/ml for the assay. The overall recoveries and the coefficients of variation (CVs) were in the range of 82%~127% and 3.5%~8.8%, respectively. Thirty-six bovine urine samples spiked with zeranol (ranging from 0.2 to 10 µg/ml) were detected by the ELISA and liquid chromatography (LC) method, and good correlations were obtained between the two methods (R 2 =0.9643). We conclude that this improved ELISA is suitable tool for a mass zeranol screening and can be an alternative for the conventional LC method for zeranol in bovine urine.

Background and Aims Insulin receptor (IR) transduces cell surface signal through phosphoinositide 3‐kinase (PI3K)–AKT pathways or translocates to the nucleus and binds to the promoters to regulate genes associated with insulin actions, including de novo lipogenesis (DNL). Chronic activation of IR signaling drives malignant transformation, but the underlying mechanisms remain poorly defined. Down‐regulation of fructose‐1,6‐bisphosphate aldolase (ALDO) B in hepatocellular carcinoma (HCC) is correlated with poor prognosis. We aim to study whether and how ALDOB is involved in IR signaling in HCC. Approach and Results Global or liver‐specific ALDOB knockout (L‐ALDOB−/−) mice were used in N‐diethylnitrosamine (DEN)–induced HCC models, whereas restoration of ALDOB expression was achieved in L‐ALDOB−/− mice by adeno‐associated virus (AAV). 13C6‐glucose was employed in metabolic flux analysis to track the de novo fatty acid synthesis from glucose, and nontargeted lipidomics and targeted fatty acid analysis using mass spectrometry were performed. We found that ALDOB physically interacts with IR and attenuates IR signaling through down‐regulating PI3K–AKT pathways and suppressing IR nuclear translocation. ALDOB depletion or disruption of IR/ALDOB interaction in ALDOB mutants promotes DNL and tumorigenesis, which is significantly attenuated with ALDOB restoration in L‐ALDOB−/− mice. Notably, attenuated IR/ALDOB interaction in ALDOB‐R46A mutant exhibits more significant tumorigenesis than releasing ALDOB/AKT interaction in ALDOB‐R43A, whereas knockdown IR sufficiently diminishes tumor‐promoting effects in both mutants. Furthermore, inhibiting phosphorylated AKT or fatty acid synthase significantly attenuates HCC in L‐ALDOB−/− mice. Consistently, ALDOB down‐regulation is correlated with up‐regulation of IR signaling and DNL in human HCC tumor tissues. Conclusions Our study reports a mechanism by which loss of ALDOB activates IR signaling primarily through releasing IR/ALDOB interaction to promote DNL and HCC, highlighting a potential therapeutic strategy in HCC.

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