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ABSTRACT: Signal transducer and activator of transcription 1 (STAT1) regulates cell proliferation and survival. The present study aimed to investigate the role of STAT1 in the development and progression of human hepatocellular carcinoma (HCC). The levels of STAT1 expression in 36 HCC and 12 non-HCC liver tissues were examined by immunohistochemistry. The effect of STAT1 overexpression or silencing on the proliferation and apoptosis of HCC cells was determined by MTT and flow cytometric assays. The effect of STAT1 overexpression or silencing on the levels of p53 and cyclin E expression was determined by quantitative PCR and western blot assays. The level of STAT1 expression in the HCC tissues was significantly lower compared to the level in the non-HCC liver tissues and was negatively associated with the histological grade of HCC and serum HBsAg, anti-HCV and α-fetoprotein positivity in HCC patients. Induction of STAT1 overexpression significantly inhibited HepG2 cell proliferation and enhanced HCC cell apoptosis, accompanied by upregulation of p53 expression and STAT1 phosphorylation, but a reduction in cyclin E expression in HepG2 cells. In contrast, knockdown of STAT1 by introduction of STAT1-specific siRNA promoted HepG2 cell proliferation, but inhibited HCC cell apoptosis, accompanied by significant downregulation of p53 expression, but enhancement of cyclin E expression in vitro. Our data suggest that STAT1 may inhibit HCC growth by regulating p53-related cell cycling and apoptosis.
Oncology Reports 04/2013; · 1.84 Impact Factor
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ABSTRACT: Ras homologous C (RhoC) is expressed in various cancers, including hepatocellular carcinoma (HCC). In this study, we first analyzed RhoC expression in 46 HCC tissue specimens and found that RhoC expression was significantly increased in HCC tissues compared to the adjacent normal liver tissues. Next, we investigated the role of RhoC in malignant transformation of normal hepatocytes. The HL7702 cell line was stably transfected with a RhoC expression vector and then subjected to cell proliferation, differentiation, colony formation, migration and invasion assays, as well as nude mouse xenograft assays. Gene expressions in these cells were determined using RT-PCR and Western blot. Overexpression of RhoC significantly promoted proliferation and anchorage-independent growth of HL7702 cells, but suppressed cell differentiation, as compared with the parental cells and the empty vector-transfected control cells. Moreover, RhoC overexpression induced migration and invasion of HL7702 cells in vitro. Molecularly, RhoC increased the expression of cell cycle-related genes, matrix metalloprotease 2 (MMP2), MMP9 and vascular endothelial growth factor (VEGF). In addition, RhoC-transfected cells formed tumors in nude mice, whereas vector-transfected HL7702 cells did not form any tumors in nude mice. This study demonstrated the role of RhoC overexpression in malignant transformation of normal human hepatocytes, suggesting that RhoC may function as an oncogene in hepatocytes.
PLoS ONE 01/2013; 8(1):e54493. · 4.09 Impact Factor
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ABSTRACT: In this study, we examined the effects of RhoC expression on the growth and apoptosis of human hepatocellular carcinoma cells (HCCs) in vitro in order to gain more understanding of its potential as a therapeutic target gene. We knocked down the endogenous expression levels of RhoC in human HCCs, BEL-7402, using siRNA and ectopically expressed RhoC in untransformed hepatocytes, HL7702. Stable cell lines were established, and cell growth was examined by MTT and colony formation assays, cell proliferation examined by silver nitrate staining of AgNORs, and cell cycle distribution examined by flow cytometry. RT-PCR analysis was performed to determine the mRNA expression levels of RhoC and cell cycle-related genes. Finally, the effect of RhoC expression on apoptosis was also examined by flow cytometry, agarose gel electrophoresis of fragmented DNA, Wright staining, and RT-PCR analysis for genes regulating apoptosis. Compared to the parental and control siRNA (siCtrl)-transfected BEL-7402 cells, the siRhoC-transfected cells exhibited significantly reduced cell growth, cell proliferation, percentage of cells in the S-G2/M phase, and expression of Cyclin D1, CDK4, and Bcl2. Knockdown of RhoC expression in BEL-7402 cells also significantly increased the percentage of cells in the G0/G1 phase, cellular apoptosis, and expression of p21, p16, and Bax. Furthermore, ectopic expression of RhoC in HL7702 cells led to a significant increase in cell growth compared to parental or siCtrl-transfected cells. These data suggest that RhoC is a key regulator of cell growth and apoptosis in HCC cells, making it a potential target for gene therapy.
Medical Oncology 06/2011; 29(3):1802-9. · 2.14 Impact Factor
