Long non-coding RNAs have previously been demonstrated to play important roles in regulating human diseases, especially cancer. However, the biological functions and molecular mechanisms of long non-coding RNAs in hepatocellular carcinoma have not been extensively studied. The long non-coding RNA CASC2 (cancer susceptibility candidate 2) has been characterised as a tumour suppressor in endometrial cancer and gliomas. However, the role and function of CASC2 in hepatocellular carcinoma remain unknown. In this study, using quantitative real-time polymerase chain reaction, we confirmed that CASC2 expression was downregulated in 50 hepatocellular carcinoma cases (62%) and in hepatocellular carcinoma cell lines compared with the paired adjacent tissues and normal liver cells. In vitro experiments further demonstrated that overexpressed CASC2 decreased hepatocellular carcinoma cell proliferation, migration and invasion as well as promoted apoptosis via inactivating the mitogen-activated protein kinase signalling pathway. Our findings demonstrate that CASC2 could be a useful tumour suppressor factor and a promising therapeutic target for hepatocellular carcinoma.

The aim of this study was to investigate the role of G-protein signaling modulator 2 in the carcinogenesis and progression of hepatocellular carcinoma. We previously showed that G-protein signaling modulator 2 was upregulated in hepatitis B virus-related hepatocellular carcinoma tissues through a hierarchical clustering analysis. With this study, we first assessed the expression pattern of G-protein signaling modulator 2 in hepatocellular carcinoma specimens and adjacent noncancerous tissues; clinical data were analyzed, along survival times, utilizing the Kaplan-Meier method. Moreover, the functions of G-protein signaling modulator 2 were examined using small-interfering RNAs in vitro. The results showed that G-protein signaling modulator 2 was clearly overexpressed in hepatocellular carcinoma tissues and cell lines and that the G-protein signaling modulator 2 expression level was related to tumor size and hepatitis B virus infection. Furthermore, G-protein signaling modulator 2 knockdown studies suggested that G-protein signaling modulator 2 accelerates cell growth, cell cycle, migration, and invasion and inhibits apoptosis, acting as an oncogene in hepatocellular carcinoma. Western blotting indicated that silencing of G-protein signaling modulator 2 in HepG2 and SMMC-7721 cells increased the expression levels of Bax, caspase-3, and E-cadherin, while notably suppressing the cyclin-dependent kinase 4, cyclin-dependent kinase 6, CyclinD1, Snail1, Vimentin, and matrix metallopeptidase 9 expression levels, compared with that in the control groups. In addition, we found that G-protein signaling modulator 2 can affect the expression of key proteins involved in protein kinase B activation. In conclusion, high expression of G-protein signaling modulator 2 was involved in the pathological processes of hepatocellular carcinoma through activation of the phosphatidylinositol 3-kinase/protein kinase B signaling pathway, which may provide an attractive potential diagnostic biomarker and therapeutic target for treatment of hepatocellular carcinoma.

To investigate the expression level of NEK2 in 40 tissue specimens of primary liver cancer and to search for clues whether the effect of NEK2 depletion plays a role on biological behaviors of HepG2 cells and the relevant molecular mechanism are the objectives of this study. Real-time PCR and immunohistochemistry assessed expression level of NEK2 in specimens of cancerous tissues and carcinoma-adjacent tissues. The NEK2 expression level in HepG2, Huh7, SMMC, and 7402 cells was detected by real-time PCR and western blot to screen experimental cell line. To assess the expression levels of NEK2 mRNA and protein, an effective siRNA transfected into the HepG2 cells was designed. CCK8 and colony-forming assays were performed to verify short-term and long-term proliferative activities, respectively. Capacity of apoptosis and cell cycle changes were assessed by flow cytometry. Ability of transference and invasion was measured by Transwell Chambers. Western blot approach was used to determine the protein expression levels. There was significantly high expression level of NEK2 in cancerous tissues compared to adjacent tissues. The expression of NEK2 was higher in HepG2 cells than other cell lines. Real-time PCR and western blot shown there were obviously down-regulated NEK2 expression in the NEK2-siRNA group compared to control groups. The capacity of amplification and invasion was inhibited distinctly, and FCM revealed the apoptosis rate was increased and G1 phase was arrested in NEK2-siRNA group. Western blot indicated that low expression of NEK2 in HepG2 cells could increase the expression levels of Bax, caspase-3, P21, and TIMP-1, but significantly suppressed the c-myc, c-jun, Bcl-2, cyclinD1, CDK4, MMP2, and MMP9 expression levels and the phosphorylation levels of ERK, JNK, and P38 compared with the control groups. Our findings demonstrated that NEK2 could be a valuable carcinogenic factor and a promising therapeutic target for primary liver cancer; NEK2 may regulate proliferation, apoptosis, and other biological behaviors of HepG2 cells via MAPK signal pathway.

Long non-coding RNAs (lncRNAs) have been identified as critical players in multiple cancers and lncRNAs are tightly linked to cancer progression. However, only little amount of lncRNAs have been identified to participate in the molecular mechanisms of the progression of hepatocellular carcinoma. In this study, we found that lncRNA-AK058003 is down-regulated in hepatocellular carcinoma tissues and it is associated with the relapse and metastasis of the cancer. Furthermore, lncRNA-AK058003 acts as a tumor suppressor, suppressing hepatocellular carcinoma cell proliferation and metastasis in vitro and in vivo. lncRNA-AK058003 can reduce mRNA stabilizing protein HuR, which results in the inhibition of the expression of γ-synuclein. In addition, a bioinformatics study indicated that γ-synuclein is a target of miR-15a. To verify whether lncRNA-AK058003 plays a role in miR-15a-mediated inhibition of γ-synuclein, we demonstrated that lncRNA-AK058003 is very likely to be a precursor of miR-15a. Collectively, lncRNA-AK058003 can reduce the expression of mRNA stabilizing protein HuR and act as a precursor of miR-15a to suppress γ-synucleinmediated cell proliferation and the metastasis of hepatocellular carcinoma.

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