Di Cheng

Epigenetic regulation of miR-124 by hepatitis C virus core protein promotes migration and invasion of intrahepatic cholangiocarcinoma cells by targeting SMYD3

Hepatitis C Virus core protein (HCVc) plays important roles in the development of intrahepatic cholangiocarcinoma (ICC). MicroRNAs (miRNAs) contribute to tumor progression by interacting with downstream target genes. However, the regulation and role of miRNAs in HCV‐related intrahepatic cholangiocarcinoma (HCV‐ICC) is poorly understood. In this study, we found that miR‐124 was down‐regulated in HCV‐ICC and the induction of DNMT1 by HCVc mediated the suppression of miR‐124. Over‐expression of miR‐124 suppressed cell migration and invasion in vitro, and reduced the protein levels of SMYD3 and downstream target genes (c‐Myc and MMP9). Knockdown of SMYD3 inhibited cell migration and invasion resembling that of miR‐124 over‐expression. In conclusion, our studies indicate that low miR‐124 levels mediated by HCVc via DNMT1 promote ICC cell migration and invasion by targeting SMYD3.

Hepatitis C virus core upregulates the methylation status of the RASSF1A promoter through regulation of SMYD3 in hilar cholangiocarcinoma cells

Increasing evidence has been accumulated indicating the important role of epigenetic regulation in tumor genesis. Previously, we observed that the transfection of hepatitis C virus core (HCVc) protein led to malignant transformation in normal biliary cells, and that tumor suppressor gene RASSF1A was downregulated in many hilar cholangiocarcinoma patients by hypermethylation in the promoter region. In the present study, we found SET and MYND domain-containing protein 3 (SMYD3), a novel histone methyltransferase, was overexpressed in cholangiocarcinoma patients especially in those with HCV infection. Transfection of HCVc into hilar cholangiocarcinoma cell lines QBC939 and FRH0201 could upregulate the expression of SMYD3 and promote cell growth, which was consistent with the results of our clinical research. This phenomenon indicated that SMYD3 was related to the epigenetic regulation of cholangiocarcinoma genesis with HCV infection. Overexpression of SMYD3 could inhibit RASSF1A expression, whereas inhibition of SMYD3 by siRNA improved its expression. Methylation-specific polymerase chain reaction (MS-PCR) results showed the methylation status of RASSF1A promoter was regulated by SMYD3. In conclusion, HCVc could upregulate the methylation status of the RASSF1A promoter through regulation of SMYD3, and histone methylation may affect the DNA methylation of downstream gene by an unknown mechanism.

Hepatitis C virus core protein regulates NANOG expression via the stat3 pathway

HCV Core plays a role in the development of hepatocellular carcinoma. Aberrant expression of NANOG has been observed in many types of human malignancies. However, relationship between Core and NANOG has not been clarified. In this study, we found that Core is capable of up‐regulating NANOG expression. Core‐induced NANOG expression was accompanied by enforced expression of phosphorylated stat3 protein and was attenuated by inhibition of stat3 phosphorylation. ChIP showed that phosphorylated stat3 directly binds to the NANOG promoter. Core‐induced NANOG expression resulted in enhanced cell growth and cell cycle progression. Knockdown of NANOG blocked the cell cycle at the G0/G1 phases and inhibited the cyclin D1 expression. Our findings provide a new insight into the mechanism of hepatocarcinogenesis by HCV infection.

LncRNA TUG1 sponges miR-145 to promote cancer progression and regulate glutamine metabolism via Sirt3/GDH axis

Long noncoding RNAs (lncRNAs) are important regulators in cancer progression. Deregulation of the lncRNA taurine upregulated gene 1 (TUG1) predicts poor prognosis and is implicated in the development of several cancers. In this study, we investigated the role of TUG1 in the pathogenesis of intrahepatic cholangiocarcinoma (ICC). We found that TUG1 is upregulated in ICC samples, which correlates with poor prognosis and adverse clinical pathological characteristics. Knockdown of TUG1 inhibited the proliferation, motility, and invasiveness of cultured ICC cells, and decreased tumor burden in a xenograft mouse model. When we explored the mechanisms underlying these effects, we found that TUG1 acts as an endogenous competing RNA (ceRNA) that ‘sponges’ miR-145, thereby preventing the degradation of Sirt3 mRNA and increasing expression of Sirt3 and GDH proteins. Accordingly, glutamine consumption, α-KG production, and ATP levels were dramatically decreased by TUG1 knockdown in ICC cells, and this effect was reversed by miR-145 inhibition. These findings indicate that the TUG1/miR-145/Sirt3/GDH regulatory network may provide a novel therapeutic strategy for treatment of ICC.

Knockdown of long non‑coding RNA HOTAIR sensitizes hepatocellular carcinoma cell to cisplatin by suppressing the STAT3/ABCB1 signaling pathway

Long non-coding RNA HOX transcript antisense RNA (HOTAIR) has been demonstrated to exhibit oncogenic activity in several types of cancer, including hepatocellular carcinoma (HCC). However, the association between HOTAIR and HCC multidrug resistance remains uncertain. The present study aimed to investigate the role of HOTAIR in HCC chemoresistance; it was found that knockdown of HOTAIR expression in HCC Huh7 cells resulted in decreased cell proliferation and increased chemosensitivity to cisplatin. Furthermore, expression levels of ATP binding cassette subfamily B member 1 (ABCB1) mRNA and protein were decreased in Huh7 cells upon HOTAIR-knockdown. In addition, HOTAIR-knockdown reduced the levels of phosphorylated signal transducer and activator of transcription 3 (STAT3), and inhibition of STAT3 phosphorylation reduced HOTAIR-mediated ABCB1 expression. Together, these findings indicated that knockdown of HOTAIR in Huh7 cells decreased STAT3 activity and ABCB1 expression, and increased chemosensitivity to cisplatin. Thus HOTAIR could serve as a novel potential therapeutic target to reverse multidrug resistance in HCC.

Hepatitis C virus core protein regulates OCT4 expression and promotes cell cycle progression in hepatocellular carcinoma

Hepatitis C virus (HCV) core protein plays an important role in the development of hepatocellular carcinoma. octamer-binding protein 4 (OCT4) is critically essential for the pluripotency and self-renewal of embryonic stem cells. Abnormal expression of OCT4 has been detected in several human solid tumors. However, the relationship between HCV core and OCT4 remains uncertain. In the present study, we found that HCV core is capable of upregulating OCT4 expression. The effect of HCV core-induced OCT4 overexpression was abolished by RNAi-mediated scilencing of HCV core. In addition, HCV core-induced OCT4 overexpression resulted in enhanced cell proliferation and cell cycle progression. Inhibition of OCT4 reduced the CCND1 expression and induced G0/G1 cell cycle arrest. Furthermore, OCT4 protein directly binds to CCND1 promoter and transactivates CCND1. These findings suggest that HCV core protein regulates OCT4 expression and promotes cell cycle progression in hepatocellular carcinoma providing new insight into the mechanism of hepatocarcinogenesis by HCV infection.

Upregulation of LncDQ is Associated with Poor Prognosis and Promotes Tumor Progression via Epigenetic Regulation of the EMT Pathway in HCC

Background/Aims: Long noncoding RNAs (lncRNAs) are key regulators of cancer initiation and progression. In this study, we investigated the clinical value and functional role of LncRNA DQ786243 (LncDQ) in the pathogenesis of hepatocellular carcinoma (HCC). Methods: To investigate the expression level of LncDQ in HCC, we performed quantitative real-time PCR using total RNA extracted from HCC tumor tissues and their matched non-neoplastic counterparts, as well as from the serum of HCC patients and healthy volunteers. The correlation of LncDQ expression with clinicopathologic features and prognosis was analyzed. The functional role of LncDQ in cell proliferation, migration, and invasion were evaluated by MTT cell viability, wound healing, and transwell assays in vitro and in vivo. RNA immunoprecipitation and chromatin immunoprecipitation assays were performed to analyze the potential mechanism of LncDQ in HCC cells. Results: LncDQ was upregulated in both HCC tissue samples and serum and was correlated with low survival rate and adverse clinical pathological characteristics. Multivariate analysis demonstrated that LncDQ expression was an independent prognostic factor for HCC. The area under the receiver operating characteristic curve was 0.804 with a sensitivity of 0.72 and a specificity of 0.8. Knockdown of LncDQ induced inhibition of cell proliferation, migration, and invasion in vitro and in vivo. Mechanistically, LncDQ regulated the epithelial–mesenchymal transition pathway by interacting with EZH2, to epigenetically repress the expression of E-cadherin in HCC cells. Conclusions: Taken together, the results of our study indicate that LncDQ plays a critical role in HCC progression, and may serve as a potential diagnostic and prognostic biomarker for HCC.

Transfection of HCVc improves hTERT expression through STAT3 pathway by epigenetic regulation in Huh7 cells.

Previous studies showed that transient transfection of HCVc improved hTERT expression in hepatoma cell lines and it was noteworthy that phosphorylated signal transducer and activator of transcription 3 (pSTAT3) and DNA methyltransferases (DNMTs) were up regulated simultaneously. This study was designed to investigate the role of epigenetic regulation in the process of hTERT up regulation after HCVc transfection. Q‐PCR and Western blot were used to analyze the expression of pSTAT3, DNMT1, and hTERT after the transfection of HCVc in hepatoma cell line Huh7. Proliferation and hTERT activity of Huh7 after HCVc transfection were examined by CCK8 and ELISA, respectively. Then, we blocked the JAK/STAT3 pathway or inhibited DNMT1 expression to investigate the regulation of pSTAT3, DNMT1, and hTERT. Methylation status of the promoter of hTERT gene was monitored by MS‐PCR. Cell proliferation, hTERT expression level and activity of hTERT were promoted after HCVc transfection. The expression of pSTAT3 and DNMT1 were up‐regulated simultaneously. DNMT1 and hTERT were down‐regulated after blocking JAK/STAT3 pathway and the expression of hTERT weakened with DNMT1 inhibition. MS‐PCR showed HCVc transfection increased the methylation level of hTERT promoter, and this effect was weakened after blocking the JAK/STAT3 pathway or with the treatment with DNMT1 inhibitor. HCVc transfection improved hTERT expression via epigenetic regulation. JAK/STAT3 pathway could be one of the essential factors in regulating DNMT1 expression during this process. J. Cell. Biochem. 113: 3419–3426, 2012.

Hepatitis C virus core protein increases Snail expression and induces epithelial-mesenchymal transition through the signal transducer and activator of transcription 3 pathway in hepatoma cells: HCV core regulates Snail and EMT in HCC

Aberrant expression of Snail, a mediator of epithelial–mesenchymal transition (EMT), is crucial for cancer invasiveness and metastasis. Although hepatitis C virus (HCV) core protein has been implicated in hepatocarcinogenesis, the relationship between HCV core and Snail expression has not been clarified.

Hepatitis C virus core protein increases Snail expression and induces epithelial–mesenchymal transition through the signal transducer and activator of transcription 3 pathway in hepatoma cells

Aberrant expression of Snail, a mediator of epithelial–mesenchymal transition (EMT), is crucial for cancer invasiveness and metastasis. Although hepatitis C virus (HCV) core protein has been implicated in hepatocarcinogenesis, the relationship between HCV core and Snail expression has not been clarified.