Human Hepatocellular Carcinoma Cell Line (human + hepatocellular_carcinoma_cell_line)

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Selected Abstracts

Long-term ethanol exposure causes human liver cancer cells to become resistant to mitomycin C treatment through the inactivation of bad-mediated apoptosis,

Ching-Shui Huang
Abstract The aim of this study was to test whether long-term ethanol consumption confers therapeutic resistance to human liver cancer patients infected with hepatitis B virus (HBV). Chronic ethanol-treated cells were established by consecutively culturing a human hepatocellular carcinoma cell line, Hep 3B, which contains integrated HBV sequences, for 20,40 passages with or without 10,mM ethanol (designated as E20,E40 and C20,C40, respectively). Flow cytometry analysis demonstrated that a growth promoting effect of long-term ethanol treatment was induced in the E40 cells through preferential acceleration of S-phase in these cells. Lower protein expression levels of p16, p21/Cip1, and p27/Kip1 were detected in the ethanol-treated E40 cells. We further demonstrated that long-term ethanol-treated E40 cells develop drug resistance in response to mitomycin C (MMC) treatment (>8,M). Immunoblot analysis revealed that caspase-8-mediated mitochondrial apoptotic signals (such as Bad) were inactivated in the MMC-resistant E40 cells. Immunoprecipitation experiments demonstrated that the sequestration of phosphorylated Bad (Ser-112) through its binding with 14-3-3 was detected more profoundly in the MMC-resistant E40 cells. Next, we examined the therapeutic efficacy of MMC (10,mg MMC/kg body weight, three times per week) in severe combined immunodeficient (SCID) mice bearing E40- and C40-xenografted tumors. Significant reductions (>3-fold) in tumor growth were detected in MMC-treated C40-xenografted mice. In vivo and in vitro studies demonstrated that AKT- and extracellular signal-regulated kinase (ERK)-mediated survival factors inhibited the Bad-induced mitochondrial apoptotic signals that were involved in E40 tumor cells and that conferred resistance to MMC. 2010 Wiley-Liss, Inc. [source]

Enhanced transthyretin tetramer stability following expression of an amyloid disease transsuppressor variant in mammalian cells

Masakazu Kamata
Abstract Background The transthyretin (TTR) amyloidosis is an incurable fatal inherited disease that is characterized by progressive peripheral and autonomic neuropathy. It is caused by missense amyloidogenic mutations in the TTR gene that destabilize the native tetrameric state and lead to the cytotoxic misfolded monomeric state. One interesting variant (T119M) stabilizes heterotetramers with amyloidogenic TTR and, in the reported heterozygous individuals, protects the carriers from disease. In the present study, we characterize in vitro and in vivo the ectopic expression of the human T119M mutant, termed a transsuppressor for TTR amyloid disease. Methods Lentiviral vectors encoding wild or mutant forms of human TTR were constructed and transduced to the human hepatocellular carcinoma cell line, HepG2, or mice. Heterooligomerization between T119M TTR and amyloidogenic variants was analysed by immunoprecipitation following western blotting. Results T119M TTR was stably expressed in transduced HepG2 cells and was secreted as an oligomer that can interact with its native partner, retinol-binding protein. Importantly, the T119M TTR formed secreted heterooligomers with amyloidogenic TTR variants, V30M, L55P and V122I, in HepG2 cells that were more stable than the homooligomers of the same amyloidogenic TTR variants. Human T119M TTR also formed heterooligomers with V30M TTR in transduced mice. Conclusions The results obtained in the present study demonstrate the stabilization of heterotetramers by T119M TTR in human cells and suggest that gene transfer of T119M TTR may have potential as a gene therapy for TTR amyloidosis. Copyright 2008 John Wiley & Sons, Ltd. [source]

Acrylate yellow filters in operating lights protect against photosensitization tissue damage

P. Hinnen
Background: Photosensitized patients are exposed to bright lights when undergoing intraoperative photodynamic therapy or fluorescence measurements. Acrylate yellow filters might reduce unwanted tissue damage. Methods: To investigate the protective value of these filters, the spectral power distribution of the operating lights and light energy densities with and without an acrylate yellow filter were measured. Subsequently the effects of light exposure on the survival of a human hepatocellular carcinoma cell line and the photodamage induced in pig tissues after the administration of 5-aminolaevulinic acid were also studied. Results: The light energy density in the ultraviolet and blue region of the light spectrum emitted by the operating light was reduced up to 50 per cent by the acrylate yellow filter. The survival of photosensitized cells was longer and photodamage induced in pig tissues was less when exposed to filtered light. Conclusion: Photodamage induced by operating lights can be reduced by filtering out ultraviolet and blue light by means of acrylate yellow filters. 2000 British Journal of Surgery Society Ltd [source]

Transcriptional and post-transcriptional control of DNA methyltransferase 3B is regulated by phosphatidylinositol 3 kinase/Akt pathway in human hepatocellular carcinoma cell lines

Chuanzhong Mei
Abstract DNA methyltransferases (DNMTs) are essential for maintenance of aberrant methylation in cancer cells and play important roles in the development of cancers. Unregulated activation of PI3K/Akt pathway is a prominent feature of many human cancers including human hepatocellular carcinoma (HCC). In present study, we found that DNMT3B mRNA and protein levels were decreased in a dose- and time-dependent manner in HCC cell lines with LY294002 treatment. However, we detected that LY294002 treatment did not induce increase of the degradation of DNMT3B protein using protein decay assay. Moreover we found that Akt induced alteration of the expression of DNMT3B in cells transfected with myristylated variants of Akt2 or cells transfected with small interfering RNA respectively. Based on DNMT3B promoter dual-luciferase reporter assay, we found PI3K pathway regulates DNMT3B expression at transcriptional level. And DNMT3B mRNA decay analysis suggested that down-regulation of DNMT3B by LY294002 is also post-transcriptional control. Furthermore, we demonstrated that LY294002 down-regulated HuR expression in a time-dependent manner in BEL-7404. In summary, we have, for the first time, demonstrate that PI3K/Akt pathway regulates the expression of DNMT3B at transcriptional and post-transcriptional levels, which is particularly important to understand the effects of PI3K/Akt and DNMT3B on hepatocarcinogenesis. J. Cell. Biochem. 111: 158,167, 2010. 2010 Wiley-Liss, Inc. [source]