cyclin-d1 and sodium-arsenite

Objective To investigate the effect of rat serum containing oxymatrine (OM) on the activation of LX2 human hepatic stellate cells induced by sodium arsenite and its mechanism. Methods SD rats were gavaged with 100 mg/kg OM or equal volume of normal saline to prepare OM-containing serum and blank serum. LO2 human embryonic liver cell line was treated with 100 μmol/L sodium arsenite for 24 hours, and then the supernatant was collected. LX2 cells were incubated with the mixture of the supernatant and normal medium at the ratio of 1:4 for 24 hours to establish the cell model of indirect arsenic exposure. Blank serum group (160 mL/L blank serum), indirect arsenic exposure group (160 mL/L blank serum with arsenic exposure), low-dose OM-containing serum group (80 mL/L blank serum and 80 mL/L OM-containing serum with arsenic exposure), high-dose OM-containing serum group (160 mL/L medicated serum with arsenic exposure) were set up. MTT assay and flow cytometry were used to detect cell proliferation and cell cycle, respectively. Western blot analysis was performed to detect the protein expressions of α-SMA, Bcl2, BAX, cyclin D1, PI3K, and phospho-AKT (p-AKT) in LX2 cells. Results After indirect arsenic treatment, the proliferation rate of LX2 cells increased, the proportion of G1 phase decreased, the proportion of apoptosis decreased, the expression of α-SMA, PI3K, p-AKT, cyclin D1, Bcl2 were significantly up-regulated, and the expression of BAX decreased. After OM-containing serum treatment, the proportion of cells in G1 phase increased, the proportion of apoptosis increased, the expression of BAX protein increased significantly, and the expression of other proteins were significantly down-regulated, especially in the high-dose group. Conclusion OM-containing serum can effectively inhibit the proliferation of LX2 hepatic stellate cells induced by arsenite and promote their apoptosis, which may be related to the blocking of PI3K/AKT signaling pathway.

Topics: Alkaloids; Animals; Arsenic; Arsenites; bcl-2-Associated X Protein; Cell Proliferation; Cyclin D1; Hepatic Stellate Cells; Humans; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Quinolizines; Rats; Rats, Sprague-Dawley; Sodium Compounds

To investigate the effect of chronic exposure to sodium arsenite at a dose of 1. 0 μmol / L on proliferation of human bronchial epithelial cells( HBE) and human keratinocytes( HaCaT) and discuss the mechanism of arsenic carcinogenesis.. Malignant transformation model of HBE and HaCaT cells cultured in vitro were used in this study. MTT assay was used to detect the capacity of proliferation. Flow cytometry was used to detect cell cycle. The expression of cell cycle related protein like cyclin E, cyclin D1 and cyclin A protein were inspected by Western blot.. The treated cells, including passage 36 and 43 of HBE cells and passage 28 and 35 of HaCaT cells grow faster than the control group( P < 0. 01 and P < 0. 05). The treated cells in the G1 phase were decreased( P < 0. 05), however cells in the S phase were increased( P <0. 05). In addition, the expression of cyclin E displayed a trend of up-regulation( P <0. 05), and it was maintained at a high level in advanced period.. By increasing the expression of cyclin E in HBE and HaCaT cells, low dose of sodium arsenite made cells escaping from the G1 phase to S phase, accelerating cell cycle progression and proliferation, a way that may lead to malignant transformation.

Topics: Arsenic; Arsenites; Cell Cycle; Cell Line; Cell Proliferation; Cell Transformation, Neoplastic; Cyclin D1; Epithelial Cells; Humans; Keratinocytes; Sodium Compounds; Up-Regulation

Inorganic arsenic, a ubiquitous environmental contaminant, is associated with an increased risk of cancer. There are several hypotheses regarding arsenic-induced carcinogenesis. The mechanism of action remains obscure, although hyper-proliferation of cells is involved. In the present study, the molecular mechanisms underlying the proliferation and malignant transformation of human embryo lung fibroblast (HELF) cells induced by a low concentration of arsenite were investigated. The results reveal that a low concentration of arsenite induces cell proliferation and promotes cell cycle transition from the G(1) to the S phase. Moreover, arsenite activates the JNK1/c-Jun signal pathway, but not JNK2, which up-regulates the expression of cyclin D1/CDK4 and phosphorylates the retinoblastoma (Rb) protein. Blocking of the JNK1/c-Jun signal pathway suppresses the increases of cyclin D1 expression and Rb phosphorylation, which attenuates cell proliferation, reduces the transition from the G1 to the S phase, and thereby inhibits the neoplastic transformation of HELF cells induced by a low concentration of arsenite. Thus, activation of the JNK1/c-Jun pathway up-regulates the expression of cyclin D1, which is involved in the tumorigenesis caused by a low concentration of arsenite.

Topics: Animals; Anticarcinogenic Agents; Arsenites; Carcinogens, Environmental; Cell Line; Cell Proliferation; Cell Transformation, Neoplastic; Cyclin D1; Fibroblasts; G1 Phase; Humans; Lung; Lung Neoplasms; Mice; Mice, Nude; Mitogen-Activated Protein Kinase 8; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-jun; RNA Interference; RNA, Small Interfering; Signal Transduction; Sodium Compounds; Up-Regulation

Arsenic is a well-recognized human carcinogen that causes a number of malignant diseases, including lung cancer. Previous studies have indicated that cyclin D1 is frequently over-expressed in many cancer types. It is also known that arsenite exposure enhances cyclin D1 expression, which involves NF-kappaB activation. However, the mechanism between cyclin D1 and the NF-kappaB pathway has not been well studied. This study was designed to characterize the underlying mechanism of induced cell growth and cyclin D1 expression in response to low concentration sodium arsenic (NaAsO(2)) exposure through the NF-kappaB pathway. Cultured human bronchial epithelial cells, BEAS-2B, were exposed to low concentration sodium arsenite for the indicated durations, and cytotoxicity, gene expression, and protein activity were assessed. To profile the canonical and non-canonical NF-kappaB pathways involved in cell growth and cyclin D1 expression induced by low concentration arsenite, the NF-kappaB-specific inhibitor-phenethyl caffeate (CAPE) and NF-kappaB2 mRNA target sequences were used, and cyclin D1 expression in BEAS-2B cells was assessed. Our results demonstrated that exposure to low concentration arsenite enhanced BEAS-2B cells growth and cyclin D1 mRNA and protein expression. Activation and nuclear localization of p52 and Bcl3 in response to low concentration arsenite indicated that the non-canonical NF-kappaB pathway was involved in arsenite-induced cyclin D1 expression. Moreover, we further demonstrated that p52/Bcl3 complex formation enhanced cyclin D1 expression through the cyclin D1 gene promoter via its kappaB site. The up-regulation of cyclin D1 mediated by the p52-Bcl3 complex in response to low concentration arsenite might be important in assessing the health risk of low concentration arsenite and understanding the mechanisms of the harmful effects of arsenite.

Topics: Arsenites; B-Cell Lymphoma 3 Protein; Bronchi; Cell Line; Cell Proliferation; Cyclin D1; Dose-Response Relationship, Drug; Gene Expression; Humans; NF-kappa B p52 Subunit; Proto-Oncogene Proteins; Sodium Compounds; Transcription Factors; Translocation, Genetic

Arsenic is an established lung carcinogen, however, the carcinogenic mechanisms are currently under investigation. Phosphorylation of the epidermal growth factor receptor (EGFR) has been reported with arsenic exposure in bladder cells. EGFR is a tyrosine kinase transmembrane receptor that regulates important processes in carcinogenesis, including cell survival, cell cycle progression, tumor invasion, and angiogenesis. We investigated the mechanisms of EGFR pathway activation by levels of arsenic relevant to human exposure scenarios both in vitro using cultured lung epithelial cells, and in lung tumors samples from New England Lung Cancer Study participants. Toenail arsenic levels were used as an internal biomarker of arsenic exposure. Our in vitro data suggest that arsenic increases levels of the EGFR ligand, heparin binding-EGF, and activate EGFR phosphorylation in the lung. Downstream of EGFR, arsenic exposure increased pERK and cyclin D1 levels. These effects were inhibited by treatment of cultured cells with the EGFR tyrosine kinase inhibitor, Tarceva (erlotinib). In a consecutive series of human lung tumor specimens, pEGFR protein levels were higher in subjects with elevated toenail arsenic levels compared to those with low exposure (odds ratio adjusted for other factors, OR 4.1 (95% confidence interval 1.1-15.6) (p = 0.04). These data suggest that arsenic exposure may stimulate EGFR pathway activation in the lung. Moreover, the tumors that arise in arsenic-exposed individuals also exhibit signs of EGFR pathway dysregulation. Further work is needed to assess the clinical utility of targeting the EGFR pathway in subgroups of lung cancer patients who have been exposed to elevated levels of arsenic.

Topics: Adult; Aged; Amphiregulin; Analysis of Variance; Arsenic; Arsenites; Biomarkers; Bronchi; Cells, Cultured; Cyclin D1; Cycloheximide; EGF Family of Proteins; Epidermal Growth Factor; Epithelial Cells; ErbB Receptors; Erlotinib Hydrochloride; Gene Expression; Glycoproteins; Heparin-binding EGF-like Growth Factor; Humans; Intercellular Signaling Peptides and Proteins; Lung; Lung Neoplasms; Middle Aged; Nails; Phosphorylation; Protein Kinase Inhibitors; Quinazolines; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Sodium Compounds

Exposure to arsenic (As) is a risk factor for the development of diabetes, vascular diseases and cancer. Several theories have been proposed to account for the mechanisms potentially responsible for As toxicity and carcinogenesis. Currently, we have investigated whether the eukaryotic translation initiation factor 4E (eIF4E), the mRNA cap binding and rate limiting factor required for translation, is a target for As-induced cytotoxicity and cell death. We have also investigated the potential cellular mechanisms underlying the As-induced de-regulation of expression of eIF4E that are most likely responsible for the cytotoxicity and cell death induced by As. Exposure of four different human cell lines - HCT15 (colorectal adenocarcinoma), PLC/PR/5 (hepatocellular carcinoma), HeLa (cervical adenocarcinoma) and Chang (likely derived from HeLa cells) to sodium arsenite (NaAsO2) for time intervals up to 24 h resulted in a concentration-dependent cytotoxicity and cell death. All the NaAsO2-treated cells exhibited significant inhibition of eIF4E gene (protein). The potential involvement of eIF4E gene expression in the NaAsO2-induced cytotoxicity and cell death was investigated by silencing the cellular expression of the eIF4E gene by employing a small interfering RNA (SiRNA) specifically targeting the eIF4E gene's expression. The SiRNA-mediated silencing of eIF4E gene expression also resulted in significant cytotoxicity and cell death suggesting that the toxicity noticed among the NaAsO2-treated cells was probably due to the chemically induced inhibition of eIF4E gene expression. The potential involvement of inhibition of eIF4E gene expression in the NaAsO2-induced cytotoxicity and cell death was further investigated by employing transgenic cell lines overexpressing the eIF4E gene. Overexpression of the eIF4E gene in the Chinese hamster ovary cell line was protective against the NaAsO2-induced cytotoxicity and cell death. Additional studies conducted to understand the potential mechanisms responsible for NaAsO2-induced inhibition of eIF4E gene expression demonstrated that exposure to NaAsO2 resulted in transcriptional down-regulation of the eIF4E gene only in HCT-15 and HeLa cells, while in the NaAsO2-treated and PLC/PR/5 and Chang cells, the eIF4E mRNA expression level was comparable to those of the corresponding control cells. Cellular levels of ubiquitin and the process of ubiquitination were significantly higher in the NaAsO2-treated cells compared with the cont

Topics: Animals; Arsenites; Cell Survival; CHO Cells; Cricetinae; Cricetulus; Cyclin D1; Dose-Response Relationship, Drug; Down-Regulation; Eukaryotic Initiation Factor-4E; Gene Expression Regulation; HeLa Cells; Humans; RNA Interference; RNA, Messenger; RNA, Small Interfering; Sodium Compounds; Transfection; Ubiquitin

Inorganic arsenic is a human carcinogen that can target the liver, but its carcinogenic mechanisms are still unknown. Global DNA hypomethylation occurs during arsenic-induced malignant transformation in rodent liver cells. DNA hypomethylation can increase gene expression, particularly when occurring in the promoter region CpG sites, and may be a non-genotoxic mechanism of carcinogenesis. Thus, in the present study liver samples of male mice exposed to 0 (control) or 45 p.p.m. arsenic (as NaAsO(2)) in the drinking water for 48 weeks were analyzed for gene expression and DNA methylation. Chronic arsenic exposure caused hepatic steatosis, a lesion also linked to consumption of methyl-deficient diets. Microarray analysis of liver samples showed arsenic induced aberrant gene expression including steroid-related genes, cytokines, apoptosis-related genes and cell cycle-related genes. In particular, the expression of the estrogen receptor-alpha (ER-alpha), and cyclin D1 genes were markedly increased. RT-PCR and immunohistochemistry confirmed arsenic-induced increases in hepatic ER-alpha and cyclin D1 transcription and translation products, respectively. Arsenic induced hepatic global DNA hypomethylation, as evidenced by 5-methylcytosine content of DNA and by the methyl acceptance assay. Arsenic also markedly reduced the methylation within the ER-alpha gene promoter region, as assessed by methylation-specific PCR, and this reduction was statistically significant in 8 of 13 CpG sites within the promoter region. Overall, in controls 28.3% of the ER-alpha promoter region CpG sites were methylated, but only 2.9% were methylated after chronic arsenic exposure. Thus, long-term exposure of mice to arsenic in the drinking water can induce aberrant gene expression, global DNA hypomethylation, and the hypomethylation of the ER-alpha gene promoter, all of which could potentially contribute to arsenic hepatocarcinogenesis.

Topics: Animals; Arsenites; Biomarkers, Tumor; Cell Transformation, Neoplastic; Cyclin D1; DNA Methylation; Estrogen Receptor alpha; Gene Expression Profiling; Immunoenzyme Techniques; Liver; Male; Mice; Oligonucleotide Array Sequence Analysis; Promoter Regions, Genetic; Receptors, Estrogen; Reverse Transcriptase Polymerase Chain Reaction; Sodium Compounds; Sulfhydryl Reagents; Water

It is well-known that p38 mitogen-activated protein kinase (p38MAPK) participates in cellular responses to mitogenic stimuli, environmental and genotoxic stresses, and apoptotic agents. Although there are several reports on p38MAPK in relation to cell growth and apoptosis, the exact mechanism of p38MAPK-mediated cell growth regulation remains obscure. Here, we examined possible roles of p38MAPK in the sodium arsenite-induced cell growth inhibition in NIH3T3 cells. Sodium arsenite induced transient cell growth delay with marked activation of p38MAPK. In addition, arsenite induced CDK inhibitor p21(CIP1/WAF1) and enhanced its binding to the CDK2, which resulted in inhibition of CDK2 activity. The levels of cyclin D1 expression and the CDK4 kinase activity were also significantly reduced. pRB was hypophosphorylated by sodium arsenite. SB203580, a specific inhibitor of p38MAPK, blocked arsenite-induced growth inhibition as well as the arsenite-induced p21(CIP1/WAF1) expression. Expression of dominant negative p38MAPK also blocked arsenite-induced p21(CIP1/WAF1) expression. Inhibited-CDK2 activity was also completely reversed by SB203580 or expression of dominant negative p38MAPK, while the decreased-cyclin D1 protein by the compound was not restored. These data demonstrate a possible link between the activation of p38MAPK and induction of p21(CIP1/WAF1), suggesting that the activation of p38MAPK is, at least in part, related to the cell growth inhibition by sodium arsenite.

Topics: 3T3 Cells; Animals; Arsenites; CDC2-CDC28 Kinases; Cell Division; Cyclin A; Cyclin D1; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinases; Cyclins; Enzyme Activation; Enzyme Inhibitors; Gene Expression Regulation; Imidazoles; Mice; Mitogen-Activated Protein Kinases; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Pyridines; Retinoblastoma Protein; Sodium Compounds; Transfection