Jiejie Xu

Schwannoma of the gastrointestinal tract: a clinicopathological, immunohistochemical and ultrastructural study of 33 cases

Aims : Thirty‐three cases of gastrointestinal schwannomas were analysed to elucidate their peculiar clinicopathological, immunohistochemical and ultrastructural features.

Ribosomal RACK1 promotes chemoresistance and growth in human hepatocellular carcinoma

Coordinated translation initiation is coupled with cell cycle progression and cell growth, whereas excessive ribosome biogenesis and translation initiation often lead to tumor transformation and survival. Hepatocellular carcinoma (HCC) is among the most common and aggressive cancers worldwide and generally displays inherently high resistance to chemotherapeutic drugs. We found that RACK1, the receptor for activated C-kinase 1, was highly expressed in normal liver and frequently upregulated in HCC. Aberrant expression of RACK1 contributed to in vitro chemoresistance as well as in vivo tumor growth of HCC. These effects depended on ribosome localization of RACK1. Ribosomal RACK1 coupled with PKCβII to promote the phosphorylation of eukaryotic initiation factor 4E (eIF4E), which led to preferential translation of the potent factors involved in growth and survival. Inhibition of PKCβII or depletion of eIF4E abolished RACK1-mediated chemotherapy resistance of HCC in vitro. Our results imply that RACK1 may function as an internal factor involved in the growth and survival of HCC and suggest that targeting RACK1 may be an efficacious strategy for HCC treatment.

Hepatitis B Virus Large Surface Antigen Promotes Liver Carcinogenesis by Activating the Src/PI3K/Akt Pathway

Of the three envelope glycoproteins encoded by hepatitis B virus (HBV) that are collectively referred to as HBV surface antigen (HBsAg), the large HBsAg (LHBs) glycoprotein is expressed preferentially in HBV-associated hepatocellular carcinoma. LHBs can act as an oncogene in transgenic mice, but how it contributes functionally to hepatocarcinogenesis remains unclear. In this study, we determined the molecular and functional roles of LHBs during HBV-associated hepatocarcinogenesis. LHBs increased tumor formation of hepatoma cells. Moreover, expression of LHBs but not other HBV envelope glycoproteins specifically promoted proliferation of hepatoma and hepatic cells in vitro. Mechanistic investigations revealed that these effects were caused by activation of the Src/PI3K/Akt pathway through proximal stimulation of PKCα/Raf1 signaling by LHBs. Proliferation induced by stable LHBs expression was associated with increased G(1)-S cell-cycle progression and apoptosis resistance mediated by Src kinase activation, as established in hepatocellular carcinoma clinical specimens. Importantly, LHBs-induced cellular proliferation and tumor formation were reversed by administration of the Src inhibitor saracatinib. Together, our findings suggest that LHBs promotes tumorigenesis of hepatoma cells by triggering a PKCα/Raf1 to Src/PI3K/Akt signaling pathway, revealing novel insights into the underlying mechanisms of HBV-associated hepatocarcinogenesis.

Hepatitis B Virus X Protein Confers Resistance of Hepatoma Cells to Anoikis by Up-regulating and Activating p21-Activated Kinase 1

BACKGROUND & AIMS Patients with chronic hepatitis B virus (HBV) infection are at risk for metastatic hepatocellular carcinoma (HCC). Metastatic cancer cells develop resistance to anoikis. The serine/threonine p21-activated kinase (PAK) 1 regulates cytoskeletal dynamics and protects cells from anoikis; it also promotes virus replication. We investigated the effects of PAK1 on anoikis resistance in human hepatoma cells and in mice. METHODS We transfected human hepatoma cells with pHBV1.3 (to mimic HBV replication) or plasmids encoding different HBV proteins; we performed colony formation and anoikis assays. We knocked down levels of PAK1 and Bcl2, or inhibited their activity, in hepatoma cells and quantified anoikis and growth of tumor xenografts in nude mice; we also measured anoikis of tumor cells isolated from ascites of the mice. We performed immunohistochemical analysis of PAK1 levels in HCC samples from patients. RESULTS Human hepatoma cells transfected with pHBV1.3 expressing hepatitis B virus X protein (HBx) underwent anchorage-independent proliferation, were resistant to anoikis, and had higher levels of Bcl2 than nontransfected cells. Expression of HBx increased mitochondrial levels of Bcl2 and PAK1, which interacted physically. Anoikis resistance of Huh7 and SK-Hep1 cells required PAK1 activity and Bcl2. Expression of HBx promoted growth of Huh7 xenograft tumors in mice; PAK1 knockdown reduced growth of these tumors in mice and anoikis of cells isolated from these tumors. In human HCC samples, increased levels of PAK1 correlated with poor prognosis, HBV infection, and portal vein tumor thrombosis. CONCLUSIONS The HBV protein HBx up-regulates PAK1, allows hepatoma cells to become resistant to anoikis, and promotes growth of aggressive xenograft tumors in mice. HBx induction of PAK1 might promote progression of HCC in patients with chronic HBV infection.

Hepatitis B virus X protein promotes hepatoma cell invasion and metastasis by stabilizing Snail protein

A high incidence of tumor recurrence and metastasis has been reported in hepatocellular carcinoma (HCC) patients with chronic hepatitis B virus (HBV) infection. Although the pathological relevance and significance of hepatitis B virus X protein (HBx) in HBV‐associated hepatocarcinogenesis attracted much attention in recent years, the role and molecular mechanism for HBx in hepatoma invasion and metastasis remains poorly understood. In the present study, we found that HBx expression could induce epithelial–mesenchymal transition in hepatoma and hepatic cells. This effect was shown due to stabilized Snail protein through activating the phosphatidylinositol 3‐kinase/protein kinase B/glycogen synthase kinase‐3β (PI3K/AKT/GSK‐3β) signal pathway by HBx expression. Functional studies revealed that HBx expression could enhance hepatoma cell migration and invasion in vitro. Moreover, stable HBx expression could also facilitate intrahepatic and distant lung metastasis of HCC in a nude mice tumor metastasis model in vivo. The correlation between increased PI3K/AKT/GSK‐3β signaling with elevated Snail protein level was also observed in HCC tumor tissues with intrahepatic metastasis or chronic HBV infection. These results revealed a novel function of HBx in promoting epithelial–mesenchymal transition through Snail protein stabilization by activating PI3K/AKT/GSK‐3β signaling, thus facilitating tumor invasion and metastasis during HCC progression. This could provide a putative molecular mechanism for tumor recurrence and metastasis in HBV‐associated HCC patients.

Klotho suppresses tumor progression via inhibiting PI3K/Akt/GSK3β/Snail signaling in renal cell carcinoma

Klotho is an anti‐aging protein predominantly expressed in renal tubular epithelial cells. Although Klotho was recently identified as a tumor suppressor gene in a variety of cancers, the potential role and molecular events for Klotho in renal cell carcinoma (RCC) remain obscure. In the present study, immunohistochemical staining in tissue microarrays containing 125 RCC samples showed that intratumoral Klotho levels were negatively correlated with tumor size, TNM stage and nuclear grade. The overall survival rate of RCC patients with high Klotho expression was significantly higher than that of patients with low Klotho expression. Functional analysis after gain and loss of Klotho expression revealed that Klotho blunted epithelial‐mesenchymal transition and cellular migration and invasion in RCC. Also, no alteration of α‐2,6‐sialidase activity was found after Klotho overexpression in RCC. The molecular signals for this phenomenon involved the Klotho‐mediated inhibition of PI3K/Akt/GSK3β/Snail pathway. Importantly, compared to localized RCC tissues, advanced RCC tissues exhibited low Klotho expression accompanied with high pAkt and Snail expression. These results indicate Klotho acts as a tumor suppressor by inhibiting PI3K/Akt/GSK3β/Snail signaling, thus suppressing epithelial‐mesenchymal transition and tumor migration and invasion during RCC progression. As a result, Klotho might be used as a potential therapy for advanced RCC.

EZH2-mediated loss of miR-622 determines CXCR4 activation in hepatocellular carcinoma

The CXC chemokine receptor 4 (CXCR4) exerts a variety of functions at different steps of hepatocellular carcinoma (HCC) progression. The molecular mechanisms and therapeutic value of CXCR4 in the development of HCC remain undefined. Here we show that aberrant CXCR4 overexpression is associated with poor prognosis and aggressive characteristics of HCC. Suppression of CXCR4 activity via CXCR4 knockdown, AMD3100 or neutralizing antibody administration inhibits hepatoma cell tumorigenesis in vitro and in vivo. CXCR4 overexpression displays the opposite effects. Using Mir library screening we identify miR-622 as a regulator of CXCR4. Further studies show that miR-622 directly target the 3′ untranslated region of CXCR4 and is transcriptionally repressed by EZH2-induced H3K27 trimethylation and promoter methylation. EZH2/miR-622 promotes tumorigenesis through CXCR4. EZH2-mediated loss of miR-622 is found to correlate with CXCR4 overexpression and unfavourable prognosis in HCC patients. This study establishes EZH2/miR-622/CXCR4 as a potential adverse prognostic factor and therapeutic target for HCC patients.

Decreased Expression of Hepatocyte Nuclear Factor 4α (Hnf4α)/MicroRNA-122 (miR-122) Axis in Hepatitis B Virus-associated Hepatocellular Carcinoma Enhances Potential Oncogenic GALNT10 Protein Activity

Background: GALNT, the initial enzyme in mucin-type O-glycosylation, plays critical roles in cancer etiology. Results: GALNT10-induced cellular proliferation was associated with EGFR activation mediated by down-regulation of miR-122 in HBV-associated HCC. Conclusion: A regulatory pathway of Hnf4α/miR-122/GALNT10/EGFR may represent a possible mechanism underlying HBV-associated hepatocarcinogenesis. Significance: This finding provides a novel role for O-glycosylation in HCC pathogenesis. MicroRNA-122 (miR-122), a mammalian liver-specific miRNA, has been reported to play crucial roles in the control of diverse aspects of hepatic function and dysfunction, including viral infection and hepatocarcinogenesis. In this study, we explored the clinical significance, transcriptional regulation, and direct target of miR-122 in hepatitis B virus (HBV)-associated hepatocellular carcinoma. Reduced expression of miR-122 in patients with HBV-associated hepatocellular carcinoma was correlated with venous invasion and poor prognosis. Furthermore, UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferase-10 (GALNT10) was identified as a bona fide target of miR-122 in hepatoma cells. Ectopic expression and knockdown studies showed that GALNT10 indeed promotes proliferation and apoptosis resistance of hepatoma cells in a glycosyltransferase-dependent manner. Critically, adverse correlation between miR-122 and GALNT10, a poor prognosticator of clinical outcome, was demonstrated in hepatoma patients. Hepatocyte nuclear factor 4α (Hnf4α), a liver-enriched transcription factor that activates miR-122 gene transcription, was suppressed in HBV-infected hepatoma cells. Chromatin immunoprecipitation assay showed significantly reduced association of Hnf4α with the miR-122 promoter in HBV-infected hepatoma cells. Moreover, GALNT10 was found to intensify O-glycosylation following signal activation of the epidermal growth factor receptor. In addition, in a therapeutic perspective, we proved that GALNT10 silencing increases sensitivity to sorafenib and doxorubicin challenge. In summary, our results reveal a novel Hnf4α/miR-122/GALNT10 regulatory pathway that facilitates EGF miR-122 activation and hepatoma growth in HBV-associated hepatocarcinogenesis.

Association between indel polymorphism in the promoter region of lncRNA GAS5 and the risk of hepatocellular carcinoma.

The growth arrest special 5 (GAS5) is known to be involved in various cancers. However, its expression regulation remains unclear. Polymorphisms in the promoter region of GAS5 may affect its expression and be associated with cancer susceptibility. In this research, we first evaluated the association of a 5-base pair indel polymorphism (rs145204276) in the promoter region of GAS5 with hepatocelluar carcinoma (HCC) susceptibility in Chinese populations. Logistic regression analysis showed that the deletion allele of rs145204276 significantly increased the risk of HCC in two independent case control sets (1034 HCC and 1054 controls). Further genotype-phenotype association analysis revealed that the deletion allele was markedly correlated with higher expression of GAS5 in HCC tissues. The luciferase activity analysis in an in vitro reporter gene system suggested that the deletion allele improved an increased expression of GAS5 in three hepatoma cell lines. Intriguingly, overexpression of GAS5 displayed an anti-apoptosis effect in HCC cell lines, GAS5 knockdown could partially revert this anti-apoptosis effect, suggesting that GAS5 may act as a proto-oncogene in HCC, in contrast with its inhibitory role in other cancers. Further pyrosequencing revealed that the genotypes of rs145204276 were associated with methylation status of GAS5 promoter region. Taken together, our findings provided evidence that rs145204276 may contribute to hepatocarcinogenesis by affecting methylation status of the GAS5 promoter and subsequently its transcriptional activity thus serving as a potential therapy target for HCC.

Systemic inflammation score predicts postoperative prognosis of patients with clear-cell renal cell carcinoma

Background:Growing evidence indicates that inflammation has a crucial role in the development and progression of cancer. We developed a novel systemic inflammation score (SIS) based on preoperative serum albumin and lymphocyte-to-monocyte ratio (LMR), and examined its prognostic value for patients with clear-cell renal cell carcinoma (ccRCC) after surgery.Methods:The study comprised 441 ccRCC patients undergoing nephrectomy between 2008 and 2009 in a single centre. The SIS was developed and its associations with clinicopathological features and overall survival (OS) were evaluated.Results:The SIS consisted of serum albumin and LMR that were both retained as independent indicators adjusting for other haematological and laboratory markers of systemic inflammation responses and traditional clinicopathological features. A high SIS was significantly associated with aggressive tumour behaviours and served as an independent prognostic factor of reduced OS. Furthermore, the SIS could significantly stratify patient prognosis in different tumour stages and Mayo Clinic stage, size, grade and necrosis scores. Incorporation of the SIS into a prognostic model including TNM stage, Fuhrman grade and lymphovascular invasion generated a nomogram, which predicted accurately 3- and 5-year survival for ccRCC patients.Conclusions:The SIS as a potentially powerful prognostic biomarker might improve traditional clinicopathological analysis to refine clinical outcome prediction for ccRCC patients after surgery.