[Show abstract][Hide abstract] ABSTRACT: Metastasis contributes to the poor prognosis of hepatocellular carcinoma (HCC). Anoikis resistance and orientation chemotaxis are two important and sequential events in tumor cell metastasis. The process of tumor metastasis is known to be regulated by AEG-1, an important oncogene that plays a critical role in tumor metastasis, though the effects of this oncogene on anoikis resistance and orientation chemotaxis in HCC cells are currently unknown. To directly assess the role of AEG-1 in these processes, we up-regulated AEG-1 expression via exogenous transfection in SMMC-7721 cells, which express low endogenous levels of AEG-1; and down-regulated AEG-1 expression via siRNA-mediated knockdown in MHCC-97H and HCC-LM3 cells, which express high endogenous levels of AEG-1. Our data directly demonstrate that AEG-1 promotes cell growth as assessed by cell proliferation/viability and cell cycle analysis. Furthermore, the prevention of anoikis by AEG-1 correlates with decreased activation of caspase-3. AEG-1-dependent anoikis resistance is activated via the PI3K/Akt pathway and is characterized by the regulation of Bcl-2 and Bad. The PI3K inhibitor LY294002 reverses the AEG-1 dependent effects on Akt phosphorylation, Bcl-2 expression and anoikis resistance. AEG-1 also promotes orientation chemotaxis of suspension-cultured cells towards supernatant from Human Pulmonary Microvascular Endothelial Cells (HPMECs). Our results show that AEG-1 activates the expression of the metastasis-associated chemokine receptor CXCR4, and that its ligand, CXCL12, is secreted by HPMECs. Furthermore, the CXCR4 antoagonist AMD3100 decreases AEG-1-induced orientation chemotaxis. These results define a pathway by which AEG-1 regulates anoikis resistance and orientation chemotaxis during HCC cell metastasis.
PLoS ONE 01/2014; 9(6):e100372. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Astrocyte-elevated gene-1 (AEG-1) has been reported to be associated with cancer progression in various types of human cancers, including liver cancer. However, to date, the molecular mechanism of AEG-1 action on the growth of liver cancer cells has been poorly elucidated. The present study aimed to investigate the effect of AEG-1 on the proliferation and apoptosis of liver cancer cells and the role of IL-6 in this process using the HepG2 human hepatoma cell line. shRNAs targeting AEG-1 were used to silence the expression of AEG-1. The effects on cell growth were detected by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, colony formation and cell cycle assays. Apoptosis was analyzed by flow cytometry. The expression of IL-6 was examined by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, and the phosphorylation of Stat3 was detected by western blotting. AEG-1 knockdown was observed to induce cell proliferation inhibition and apoptosis through the suppression of IL-6 secretion. Stat3, a downstream target of IL-6 signaling, was suppressed in the AEG-1-silenced cells and target genes, including Bcl-2 and crystalin, αB, which are associated with cell survival, were downregulated. Overall, the findings suggest that aberrant AEG-1 expression promotes the growth of HepG2 liver cancer cells, contributing to the progression of liver cancer, which may partly be mediated by IL-6 signaling.
[Show abstract][Hide abstract] ABSTRACT: Metastasis contributes to the poor prognosis of hepatocellular carcinoma (HCC). However, the mechanism through which a primary HCC cell develops into a metastatic phenotype is not well understood. The purpose of this study was to examine the correlation between metadherin (MTDH)/astrocyte elevated gene-1 (AEG-1) expression in HCC cell lines of different metastatic potentials and such metastatic phenotypes as orientation chemotaxis and adhesion. MTDH/AEG-1 expression was detected by RT-PCR and western blotting in HCC cell lines (HepG2, Huh7, Sk-HEP-1, MHCC-97H). Distribution of MTDH/AEG-1 was observed by immunofluorescence staining and confocal laser scanning microscopy. The abilities of orientation chemotaxis and adhesion and the index of interaction between HCC cell lines and microvascular endothelial cell lines (MVECs, including HUVECs and HPMECs) were measured by chemotaxis assay and adhesion assay, respectively. The results showed that MTDH/AEG-1 protein expression was significantly higher in high metastatic potential cancer cell lines (Sk-HEP-1, MHCC-97H) than in low metastatic potential cell lines (HepG2, Huh7) (P<0.05). The MTDH/AEG-1 protein was localized in the perinuclear region of HCC cells. Furthermore, the abilities of orientation chemotaxis and adhesion of HCC cells to HPMECs were increased as compared with those of HCC cells to HUVECs (P<0.05). The abilities of orientation chemotaxis and adhesion were much stronger in Sk-HEP-1 and MHCC-97H cells with MTDH/AEG-1 highly expressed than in HepG2 and Huh7 cells with MTDH/AEG-1 lowly expressed (P<0.05). These results suggested that the expression of MTDH/AEG-1 gene in HCC cell lines of different metastatic potentials was closely positively related to the abilities of orientation chemotaxis and adhesion of HCC cells. It was deduced that MTDH/AEG-1 might play a pivotal role in the lung-specific metastasis of HCC, which may be mediated through orientation chemotaxis and adhesion abilities of HCC cells. MTDH/AEG-1 may serve as a potential therapeutic target for HCC.
Journal of Huazhong University of Science and Technology 06/2012; 32(3):353-7. · 0.58 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Special AT-rich binding protein-1 (SATB1) reprograms chromatin organization and transcription profiles to promote tumour growth and metastasis.
This study aimed to confirm the effects of SATB1 on the growth and metastasis of liver cancer and its specific regulation mechanism.
SATB1 expression was evaluated in human hepatoma tissue, adjacent noncancerous tissue and seven kinds of liver cancer cell lines. Cell cycle, cell proliferation, apoptosis and epithelial-mesenchymal transition (EMT) was investigated after enhanced or silenced expression of SATB1. The regulatory action of SATB1 on the expression of genes that are known to regulate cell cycle progression, apoptosis and EMT and the specific apoptotic pathway on which it acts were further analysed. Nude mice that received subcutaneous implantation were used to study the effects of SATB1 on tumour growth in vivo.
Our data show that the high expression of SATB1 was observed in the human hepatocellular carcinoma tissue (26/45) and liver cancer cell lines with high metastatic potential. SATB1 upregulated CDK4 and downregulated p16 (INK) (4A) to promote cell cycle progression and cell proliferation and prevented apoptosis by inhibiting the FADD-caspase-8-caspase-3 death receptor-mediated apoptosis pathway. SATB1 also induced EMT concomitant with increased expression of Snail1, Slug, Twist and vimentin and decreased expression of E-cadherin, tight junction protein ZO-1 and desmoplakin. SATB1 promoted the growth of tumour in vivo.
These data suggest that the SATB1 gene may play an important role in the development and progression of liver cancer by regulation of genes related to cell cycle progression, apoptosis and EMT.
Liver international: official journal of the International Association for the Study of the Liver 05/2012; 32(7):1064-78. · 3.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to investigate the effect of HBV-induced Mig and role of autophagy in the process.
Adxsi-1.3 x HBV plasmid was constructed and identified. The three cell lines (L02, HepG2, SMMC-7721) were infected with adenovirus-HBV. HBsAg and HBeAg were assessed by electrochemiluminescence immunoassay. HBV DNA, HBx, Beclin 1 and Mig expression were detected by quantitative real-Time PCR, western blotting and ELISA. The level of autophagy was evaluated by transmission electron microscope.
Human fetal liver cells and hepatocellular carcinoma cells were successfully transfected with overlength HBV genome using an adenovirus vector (Ad-HBV). Ad-HBV induced Mig production and cell autophagy through up-regulation of Beclin 1 expression. We further demonstrated that the increased autophagy extent was in association with HBV-induced Mig expression.
Autophagy may be a crucial intracellular mechanism of Mig induction in response to HBV infection. The results provide new insights into the pathogenesis of HBV.
[Show abstract][Hide abstract] ABSTRACT: Objective
The aim of this study was to investigate whether astrocyte elevated gene 1 (AEG1) regulates COX-2 expression in human hepatoma HepG2 cells and related pathways involved in this process.
Human hepatoma HepG2 cells were transfected with pcDNA3.1(-)-AEG1 plasmid or psilencer2.0-AEG1-shRNA1 plasmid to up/down-regulate AEG1 expression, pcDNA3.1(-) and psilencer 2.0 empty vector plasmids were transfected respectively as control. Real-time RT-PCR was carried out to measure the expression levels of AEG1 and COX-2 mRNA. The expression levels of AEG1 and COX-2 protein were detected by Western blot. NF-κB signaling was blocked by PDTC, and AP-1 signaling was blocked by curcumin.
AEG1 mRNA and protein levels were increased after pcDNA3.1(-)-AEG1 transfection, and decreased after psilencer2.0-AEG1-shRNAs transfection. COX-2 mRNA and protein levels were increased in AEG1-overexpressing cells and decreased in AEG1-knockdown cells. Phosphorylations of p65 and c-jun were up-regulated in AEG1-overexpressing cells. Both PDTC and curcumin reduced COX-2 expression in HepG2 cells with AEG1 overexpression.
AEG1-overexpressing and -knockdown HepG2 cells are established successfully. AEG1 could induce COX-2 expression though activating NF-κB and AP-1 in human hepatoma HepG2 cells.
The Chinese-German Journal of Clinical Oncology 12(6).