Cellular context- and protein level-dependent interaction of pluripotency factor OCT4A with multiple octamer motifs of the same target gene.

AIMS: To compare how OCT4A proteins interact with and regulate multiple OCT4A-octamer motifs (OMs) in different regions of the FOS gene expressed in somatic cancer cells versus pluripotent stem cells. MATERIALS AND METHODS: Two FOS reporter gene systems harboring predicted OMs or their mutational counterparts were introduced into HeLa and NCCIT cells with varying OCT4A protein levels. The transcription of dsGFP reflecting FOS expression was quantitated by RT-qPCR, the OCT4A-OMs binding and the correlation between OCT4A and FOS transcription was determined by ChIP-PCR and RNA-Seq, respectively. KEY FINDINGS: In NCCIT cells, abundant OCT4A proteins bound to and inhibited OM1 and OM2 at the promoter of the FOS gene. RA-induced OCT4A down-regulation transiently increased FOS transcription. In contrast, in HeLa cells that contain much lower levels of endogenous OCT4A proteins, OCT4A primarily bound to and activate OM1 thereby promoting FOS transcription. OCT4A KO significantly reduced FOS expression. Ectopically introduced OCT4A, at its leaked or induced expression level, promoted FOS transcription by binding to OM2/OM3 or OM1/OM3, respectively. Thus, the interaction of OCT4A proteins with different OMs is cellular context- and protein level-dependent, and such complicated OCT4A binding mode can only be reflected by a dsGFP-based reporter harboring the full-length FOS gene but not by that merely having the FOS promoter. SIGNIFICANCE: Our findings unravel an additional layer of regulatory mechanisms that account for the cellular context- and dose-related versatile functions of OCT4A protein, and further underscore the importance of precise modulation of OCT4A in the regenerative medicine and anticancer therapies.

[Ameliorative effects and the mechanism of lyceum barbarum polysaccharide on insulin resistance of HepG2 cell].

OBJECTIVE: To observe the effects of lyceum barbarum polysaccharide (LBP) on insulin resistance of HepG2 cells and investigate its possible mechanism. METHODS: IR-HepG2 cell model was induced with high glucose and high insulin in combination for 24 hours,with 104/vaccination in the 96-well plates, hole density after adherent cells (30 µg/ml、100 µg/ml、300 µg/ml) LBP cultivate 48 h, 200 µl/hole, each all had four holes. The effects of LBP at different concentrations on HepG2 cell activity and insulin resistance were tested. Intracellular malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were detected. The expressions of related proteins in insulin signal transduction pathways such as insulin receptor substrate-2(IRS-2), phosphatidylinositol-3-kinase(PI3-K), protein kinase B(Akt) and glucose transport-2(GLUT2) were determined. RESULTS: Compared with normal control group, the content of MDA was increased significantly and the activity of SOD and the expression levels of IRS-2,PI-3K,Akt and GLUT2 were decreased significantly in the IR model group. Compared with IR model group, medium and high concentrations of LBP decreased the content of MDA and increased the activity of SOD and the expression levels of IRS-2, PI-3K, Akt and GLUT2 in insulin-resistant HepG2 cells. MTT showed that at the same time, the OD value gradually decreased with the increase of LBP's concentration; under the same concentration of LBP, the OD value also gradually decreased with the extension of time, which indicated that LBP inhibited the proliferation of HepG2 cells with time and concentration-dependent manner. Glucose consumption experiment indicated that medium and high concentration of LBP could increase the glucose consumption of insulin-resistant HepG2 cells significantly, but low concentration of LBP had no significant impacted on glucose consumption of insulin-resistant HepG2 cells. CONCLUSIONS: Medium and high concentration of LBP can improve insulin resistance of HepG2 cell, its mechanisns may be associated with decreasing the level of oxidative stress and increasing the protein expressions of insulin signaling pathway.

[Effect of arecoline on proliferation and apoptosis of MCF-7 human breast cancer cells].

OBJECTIVE: To observe the effects of arecoline on proliferation and apoptosis of MCF-7 human breast cancer cells and to ex-plore its possible mechanism. METHODS: Human breast cancer MCF-7 cells were treated with arecoline at the concentrations of 0,10,30,50, 100,300,500µmol/L, the cell proliferation were detected by MTT assay, cell apoptosis were analyzed by Hoechst 33342 staining and flow cy-tometry, the protein expression of Bax,Bcl-2 and P53 were detected by Western blot. RESULTS: Low concentration(0,10,30, 50 µmol/L) arecoline had no effect on the proliferation and apoptosis of MCF-7. However, high concentration(100,300,500µmol/L) arecoline inhibited proliferation and induced apoptosis of MCF-7 cells in a concentration-dependent manner, arecoline also significantly increased P53 and Bax protein expression and decreased Bcl-2 protein expression. CONCLUSIONS: High concentration arecoline inhibited the proliferation and induced the apoptosis of MCF-7 cells, the mechanism was probably corrected with increasing P53 and Bax protein expression and decreasing Bcl-2 pro-tein expression.

Akt­mediated phosphorylation of Oct4 is associated with the proliferation of stem­like cancer cells.

Oct4 protein encoded by POU5F1 plays a pivotal role in maintaining the self­renewal of pluripotent stem cells; however, its presence in cancer cells remains controversial. In the present study, we provided evidence that the transcripts of authentic OCT4 gene (OCT4A) and its multiple pseudogenes were detected in a variety of cancer cell lines. A few major bands were also detected by western blotting using an anti­Oct4A monoclonal antibody. Moreover, an anti­Oct4­pT235 antibody was used to identify a band in the majority of the tested cancer cell lines that coincided with one of the anti­Oct4A bands which was decreasable by a specific shRNA. The Oct4­pT235 signals were also detected in human glioblastoma and liver cancer specimens by immunofluorescence microscopy and immunohistochemistry. U87 glioblastoma cells were cultured in a neural stem cell medium to induce the formation of neurospheres rich in stem­like cancer cells. The levels of Oct4­pT235 in the sphere cells were markedly increased compared to their monolayer parental cells, a result that was accompanied by upregulation of the PI3K­Akt pathway. Akti­1/2, a specific inhibitor of Akt, effectively reduced the level of Oct4­pT235 and attenuated the proliferation of U87 sphere cells. ITE, an agonist of the aryl hydrocarbon receptor, also significantly attenuated the Akt­mediated phosphorylation of Oct4 in glioblastoma and liver cancer cells, and reduced their tumorigenic potential in a xenograft tumor model. Taken together, we concluded that the Akt­mediated phosphorylation of Oct4A or its homolog protein was associated with the proliferation of stem­like cancer cells that may serve as a novel biomarker and drug target for certain types of cancer.

[The role of arecoline on hepatic insulin resistance in type 2 diabetes rats].

OBJECTIVE: To explore the effects of arecoline on hepatic insulin resistance in type 2 diabetes rats and to elucidate its possible mechanism. METHODS: Forty five Wistar rats were fed with high fructose diet for 12 weeks to induce type 2 diabetic rat model. rats were randomly divided into 5 groups (n = 8): control group, model group and model group were treated with different dose (0, 0.5, 1, 5 mg/kg) of arecoline. After 4 weeks, the fasting blood glucose, blood lipid and insulin level measured , mRNA expression of liver constitutive androstane receptor (CAR), pregnane X receptor (PXR), glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were detected by reverse transcription polymerase chain reaction (RT-PCR), the protein expression of p-AKT and glucose transporter4 (GLUT4) were detected by Western blot. RESULTS: 1.5 mg/kg arecoline could significantly decrease the level of fasting blood glucose, blood lipid, blood insulin level and liver G6Pase, PEPCK, IL-6, TNF-alpha mRNA level in type 2 diabetes rats. 1.5 mg/kg arecoline also could significantly increase CAR, PXR mRNA level and p-AKT and GLUT4 protein expression. CONCLUSION: Arecoline improved hepatic insulin resistance in type 2 diabetes rats by increasing the mRNA levels of CAR and PXR leading to the creased glucose metabolism and inflammation related genes expression.

Hydrogen sulfide prevents formaldehyde-induced neurotoxicity to PC12 cells by attenuation of mitochondrial dysfunction and pro-apoptotic potential.

Hydrogen sulfide (H(2)S) has been shown to act as a neuroprotectant and antioxidant. Numerous studies have demonstrated that exposure to formaldehyde (FA) causes neuronal damage and that oxidative stress is one of the most critical effects of FA exposure. Accumulation of FA is involved in the pathogenesis of Alzheimer's disease (AD). The aim of present study is to explore the inhibitory effects of H(2)S on FA-induced cytotoxicity and apoptosis and the molecular mechanisms underlying in PC12 cells. We show that sodium hydrosulfide (NaHS), a H(2)S donor, protects PC12 cells against FA-mediated cytotoxicity and apoptosis and that NaHS preserves the function of mitochondria by preventing FA-induced loss of mitochondrial membrane potential and release of cytochrome c in PC12 cells. Furthermore, NaHS blocks FA-exerted accumulation of intracellular reactive oxygen species (ROS), down-regulation of Bcl-2 expression, and up-regulation of Bax expression. These results indicate that H(2)S protects neuronal cells against neurotoxicity of FA by preserving mitochondrial function through attenuation of ROS accumulation, up-regulation of Bcl-2 level, and down-regulation of Bax expression. Our study suggests a promising future of H(2)S-based preventions and therapies for neuronal damage after FA exposure.

Inhibition of hydrogen sulfide generation contributes to 1-methy-4-phenylpyridinium ion-induced neurotoxicity.

Reactive oxygen species (ROS) overproduction contributes to the neurotoxicity of 1-methy-4-phenylpyridinium ion (MPP(+)). Increasing studies have shown that hydrogen sulfide (H(2)S) is an endogenous antioxidant gas. We have hypothesized that MPP(+)-caused neurotoxicity may involve the imbalance of proportion to this endogenous protective antioxidant gas. The aim of this study is to evaluate whether MPP(+) disturbs H(2)S synthesis in PC12 cells, a clonal rat pheochromocytoma cell line, and whether disturbance of H(2)S generation induced by MPP(+) is an underlying mechanism of MPP(+)-induced neurotoxicity. We show that exposure of PC12 cells to MPP(+) causes a significant decrease in H(2)S generation and results in remarkable cell damage. We find that cystathionine-ß-synthetase (CBS) is catalyzed in PC12 cells to generate H(2)S, and that both expression and activity of CBS are inhibited by MPP(+) treatment. Exposure of sodium hydrosulfide (NaHS), a donor of H(2)S, extenuates MPP(+)-induced cytotoxicity and ROS accumulation in PC12 cells, while inhibition of CBS by amino-oxyacetate (AOAA) exacerbates the effects of MPP(+). These results indicate that MPP(+) neurotoxicity involves reduction of H(2)S production, which is caused by inhibition of CBS. This study provides novel insights into cell death observed in neurodegenerative disease such as Parkinson's disease.

[miRNA expression change of differentiation of mice marrow mesenchymal stem cells into adipocytes].

OBJECTIVE: To explore miRNA expression change of differentiation of mice marrow mesenchymal stem cells (MSCs) into adipocytes, which lay the foundation for further studies on molecular mechanism of miRNA regulating the differentiation of MSCs into adipocytes. METHODS: C57BL/6 mice MSCs were isolated, cultured through the whole bone marrow method, amplified by the differential adherent method. Cell growth was observed by morphology and the expression of superficial antigen CD29, CD44, CD34 were detected through immunohistochemistry. MSCs was induced to differentiation into adipocytes with adipocyte differentiation medium, and adipogenic differentiation of MSCs was analyzed by oil Red O staining. MicroRNA microarray was used to investigate the differentially expressed miRNAs in MSCs and adipocytes. RESULTS: (1) The fifth passage of MSCs had high purity under an inverted m icroscope. Immunohistochemistry staining showed that CD29, CD44 were positive and CD34 was negative in more than 90% MSCs. There were a large number of lipid droplets in cytoplasm after MSCs were induced with adipocyte differentiation medium, Oil O staining was positive. (2) The microarray experiment showed that 75 differentially expressed miRNAs were obtained in adipocytes compared with MSCs, 20 up-regulated and 55 down-regulated miRNAs were observed among them. CONCLUSION: There was a expression change of miRNA of differentiation of MSCs into adipocytes, some miRNAs might play important roles in MSCs adipogenic differentiation.

Hydrogen sulfide antagonizes homocysteine-induced neurotoxicity in PC12 cells.

Hydrogen sulfide (H2S) has been shown to protect neurons against oxidative stress. Lower levels of H(2)S as well as accumulation of homocysteine (Hcy), a strong risk of Alzheimer's disease (AD), are reported in the brains of AD patients. The aim of present study is to explore the protection of H2S against Hcy-induced cytotoxicity and apoptosis and the molecular mechanisms underlying in PC12 cells. We show that sodium hydrosulfide (NaHS), a H2S donor, protects PC12 cells against Hcy-mediated cytotoxicity and apoptosis by preventing both the loss of mitochondrial membrane potential (MMP) and the increase in intracellular reactive oxygen species (ROS) induced by Hcy. NaHS not only promotes the expression of bcl-2, but also blocks the down-regulation of bcl-2 by Hcy. These results indicate that H2S protects neuronal cells against neurotoxicity of Hcy by preserving MMP and attenuating ROS accumulation through up-regulation of bcl-2 level. Our study suggests a promising future of H2S-based therapies for neurodegenerative diseases such as AD.

Hydrogen sulfide inhibits MPP(+)-induced apoptosis in PC12 cells.

AIMS: Hydrogen sulfide (H2S) is a well-known cytotoxic gas. Recently it has been shown to protect neurons against oxidative stress caused by glutamate, hypochlorous acid (HOCl), and beta-amyloid. The aim of the present study is to explore the cytoprotection of H2S against 1-methyl-4-phenylpyridinium ion (MPP(+))-induced apoptosis and the molecular mechanisms underlying in PC12 cells, a rat cell line derived from pheochromocytoma cells. MAIN METHODS: Cell viability was determined by the conventional 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. Apoptosis was assessed by Hoechst 33258 nuclear staining and flow cytometric (FCM) analysis after propidium iodide staining. The mitochondrial membrane potential (MMP) was measured by rhodamine 123 (Rh123) probe and reactive oxygen species (ROS) were measured by dihydrorhodamine probe using FCM analysis. KEY FINDINGS: MPP(+) reduced the cell viability and induced apoptosis of PC12 cells along with dissipation of MMP as well as overproduction of ROS. Sodium hydrosulfide (NaHS), a H2S donor, protected PC12 cells against MPP(+)-induced cytotoxicity and apoptosis not only by reducing the loss of MMP, but also by attenuating an increase in intracellular ROS. SIGNIFICANCE: H2S significantly protected PC12 cells against cytotoxicity and apoptosis induced by MPP(+), which was associated with the inhibition by H(2)S of MPP(+)-induced dissipation of MMP and overproduction of ROS. These findings can significantly advance therapeutic approaches to the neurodegenerative diseases which are associated with oxidative stress, such as Parkinson's disease.

Association between TRAIL expression on peripheral blood lymphocytes and liver damage in chronic hepatitis B.

AIM: To explore a novel mechanism for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), upregulation of CD4(+) and CD8(+) T lymphocytes participating in the patho-physiological process of chronic hepatitis B (CHB). METHODS: The levels of serum soluble TRAIL (sTRAIL), serum IFN-gamma and membrane-bound TRAIL expression on peripheral leucocytes from 58 CHB patients were examined by ELISA and flow cytometry respectively. The levels of TRAIL were compared with the baseline levels of 17 healthy controls, and correlation analysis was performed between ALT, TBIL, PT, morphological change in hepatic tissues, and serum IFN-gamma. RESULTS: The results showed that TRAIL levels on membranes of CD4(+), CD8(+) T cells in CHB patients were much higher than those in healthy controls (P<0.001), and were correlated with serum TBIL (r = 0.354, P = 0.008 for CD4(+) and r = 0.522, P = 0.000 for CD8(+), respectively), ALT (r = 0.393, P = 0.003 for CD8(+)), PT (r = 0.385, P = 0.004 for CD8(+)) and serum IFN-gamma level (r = 0.302, P = 0.011 for CD4(+) and r = 0.307, P = 0.009 for CD8(+)). On the contrary to membrane-bound TRAIL expression, serum level of sTRAIL was not correlated with that of TBIL and PT, though it was higher than that of the normal population and was positively correlated with serum HBeAg expression (r = 0.695, P = 0.001). CONCLUSION: The expression level of TRAIL on the membrane of lymphocytes was upregulated and associated with the liver injury in CHB patients. These findings suggest that upregulation of TRAIL expression may be induced by virus antigen and inflammatory cytokine IFN-gamma.

[Involvement of TRAIL up-regulation of CD4+, CD8+ T cells in liver injury in chronic hepatitis B].

OBJECTIVE: To describe a novel mechanism for TRAIL up-regulation of CD4+, CD8+ T cells to participate in the pathophysiological process in patients with chronic hepatitis B (CHB). METHODS: The serum levels of soluble TRAIL (sTRAIL), IFN-gamma and membrane bound TRAIL expression on peripheral leucocytes from 58 CHB patients were examined by ELISA and flow cytometry respectively. The levels of TRAIL were compared with the baseline levels of 15 healthy controls, and correlation analysis were performed between ALT, TBil and PT, morphological change in hepatic tissues. RESULTS: The results showed that TRAIL levels on membranes of CD4+, CD8+ T cells in CHB patients were much higher than the healthy controls (P < 0.001), which of CD4+ T cells positively correlated with serum TBil (r=0.354, P = 0.008), Serum IFN-gamma level (r=0.302, P = 0.011) and which of CD8+ T cells positively correlated with serum TBil (r=0.522, P = 0.000), ALT (r=0.393, P = 0.003), PT (r=0.385, P = 0.004), serum IFN-gamma level (r=0.307, P = 0.009). The serum levels of soluble TRAIL only correlated with serum HBeAg expression (r=0.695, P = 0.001). CONCLUSION: These findings suggest that the expression of TRAIL on the membranes of lymphocytes was up-regulated, which may take part in the immunopathogenesis in CHB patients. TRAIL expression can be induced either by virus-specific protein expression or by inflammation cytokine IFN-gamma