Biomedical subjects

Yan Chen

Publications and source records attributed to Yan Chen.

At least 73 records · Page 4Linked to original sources

PubMed2006

Effects of trichostatin A on HDAC8 expression, proliferation and cell cycle of Molt-4 cells.

The effects of Trichostatin A (TSA) on histone deacetylase 8 (HDAC8) expression, proliferation and cell cycle arrest in T-lymphoblastic leukemia cell line Molt-4 cells in vitro were investigated. The effect of TSA on the growth of Molt-4 cells was studied by MTT assay. Flow cytometry was used to examine the cell cycle. The expression of HDAC8 was detected by using immunocytochemistry and Western blot. The results showed that proliferation of Molt-4 cells was inhibited in TSA-treated group in a time- and dose-dependent manner. The IC50 of TSA exposures for 24 h and 36 h were 254.3236 and 199.257 microg/L respectively. The cell cycle analysis revealed that Molt-4 was mostly in G0/G1 phase, and after treatment with TSA from 50 to 400 microg/L for 24 h, the percents of G0/G1 cells were decreased and cells were arrested in G2/M phase. Treatment of TSA for 24 h could significantly inhibit the expression of HDAC8 protein in Molt-4 cells (P<0.01). It was concluded that TSA could decrease the expression of HDAC8 in Molt-4 cells, which contributed to the inhibition of proliferation and induction of cell cycle arrest in Molt-4 cells.

Cell Cycle Checkpoints↗

PubMed2006

Trichostatin A regulates hGCN5 expression and cell cycle on Daudi cells in vitro.

The expression of human general control of amino acid synthesis protein 5 (hGCN5) in human Burkitt's lymphoma Daudi cells in vitro, effects of Trichostatin A (TSA) on cell proliferation and apoptosis and the molecular mechanism of TSA inhibiting proliferation of Daudi cells were investigated. The effects of TSA on the growth of Daudi cells were studied by 3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. The effect of TSA on the cell cycle of Daudi cells was assayed by a propidium iodide method. Immunochemistry and Western blot were used to detect the expression of hGCN5. The proliferation of Daudi cells was decreased in TSA-treated group with a 24 h IC50 value of 415.3979 microg/L. TSA induced apoptosis of Daudi cells in a time- and dose-dependent manner. Treatment with TSA (200 and 400 microg/L) for 24 h, the apoptosis rates of Daudi cells were (14.74+/-2.04) % and (17.63+/-1.25) %, respectively. The cell cycle was arrested in G0/G1 phase (50, 100 microg/L) and in G2/M phase (200 microg/L) by treatment with TSA for 24 h. The expression of hGCN5 protein in Daudi cells was increased in 24 h TSA-treated group by immunochemistry and Western blot (P<0.05). It was suggested that TSA as HDACIs could increase the expression of hGCN5 in Daudi cells, and might play an important role in regulating the proliferation and apoptosis of B-NHL cell line Daudi cells.

Apoptosis↗

PubMed2006

Anticancer activities of trichostatin A on maligant lymphoid cells.

The anticancer activity of trichostain A (TSA) on human B cell non-Hodgkin's lymphoma and its mechanism were explored. The effect of TSA on the growth of Raji cells and normal peripheral blood mononuclear cells (NPBMNC) was studied by MTT assay. The effect of TSA on the apoptosis of Raji cells and NPBMNC was studied by flow cytometry and TDT-mediated dUTP nick end labeling (TUNEL). The effect of TSA on the cell cycle of Raji cells was studied by propidium iodide method. The results showed that TSA potently inhibited proliferation of Raji cells at microgram concentrations and induced apoptosis of Raji cells in a time- and concentration-dependent manner. Treatment with TSA induced accumulation of cells in G0/G1 or G2/M and a concomitant decrease of cell population in S phase. However, NPBMNC was less sensitive to the cytotoxic effect of TSA than Raji cells. It was concluded that TSA may inhibit the proliferation of Raji cells by regulating the cell cycle and inducing the cell apoptosis. Moreover, TSA demonstrates low toxicity in NPBMNC but selectively induces apoptosis of Raji cells.

Apoptosis↗

PubMed2006

Antagonists to human and mouse vascular endothelial growth factor receptor 2 generated by directed protein evolution in vitro.

Using directed in vitro protein evolution, we generated proteins that bound and antagonized the function of vascular endothelial growth factor receptor 2 (VEGFR2). Binders to human VEGFR2 (KDR) with 10-200 nM affinities were selected by using mRNA display from a library (10(13) variants) based on the tenth human fibronectin type III domain (10Fn3) scaffold. Subsequently, a single KDR binding clone (K(d) = 11 nM) was subjected to affinity maturation. This yielded improved KDR binding molecules with affinities ranging from 0.06 to 2 nM. Molecules with dual binding specificities (human/mouse) were also isolated by using both KDR and Flk-1 (mouse VEGFR2) as targets in selection. Proteins encoded by the selected clones bound VEGFR2-expressing cells and inhibited their VEGF-dependent proliferation. Our results demonstrate the potential of these inhibitors in the development of anti-angiogenesis therapeutics.

Amino Acid Sequence↗

PubMed2006

Somatic cell and sperm cell cytogenetics in a patient with t(14; 21).

Approximately 15%-20% of clinically recognizable pregnancies end in spontaneous abortion. About half of the spontaneous abortions in the early stage of the pregnancy are due to chromosomal abnormalities. Using GTG chromosome banding and dual-color fluorescence in situ hybridization (FISH) techniques, we determined the cytogenetic aberration in the husband of a couple with spontaneous recurrent abortions. Karyotype analysis showed 46, XX in the wife and 45, XY, -14, -21, +t(14; 21) in the husband. We studied the mechanism of formation of the abnormal chromosome with Robertsonian translocation between chromosomes 14 and 21 by FISH and flow cytometric sorting in the sperm cells. The result showed that 71% of the gametes were balanced and the remaining 29% were not. As a result, the couple was given genetic counseling.

Adolescent↗

PubMed2006

Deguelin inhibits expression of IkappaBalpha protein in Raji and U937 cells.

AIM: To determine whether deguelin can regulate the expression of nuclear factor kappa B (NF-kappaB) binding protein (IkappaBalpha) in U937 human leukemia cells and Raji human B lymphoma cells. METHODS: The localization of IkappaBalpha protein was investigated by using an immunofluorescence method. The expression of IkappaBalpha and NF-kappaB /p65 proteins in Raji and U937 cells were investigated by using Western blotting. Apoptosis was detected through annexin V/PI double-labeled cytometry. RESULTS: IkappaBalpha localized in the cytoplasm in untreated and deguelin-treated cells. After treatment with tumor necrosis factor alpha (TNF-alpha) or deguelin plus TNF-alpha for 15 min, there was a substantial reduction in the amount of IkappaBalpha protein. The expression of IkappaBalpha was downregulated by deguelin in Raji and U937 cells. Deguelin induced apoptosis in U937 cells. CONCLUSION: Deguelin inhibited the expression of IkappaBalpha protein in U937 and Raji cells. The anti-proliferative activity of deguelin is related to the signal pathway of NF-kappaB.

Apoptosis↗

PubMed2006

Inhibitory effect of triptolide on lymph node metastasis in patients with non-Hodgkin lymphoma by regulating SDF-1/CXCR4 axis in vitro.

AIM: To investigate the antiproliferative effect of triptolide on B-NHL cell line Raji cells, to study its effect on lymph node metastasis in patients with non-Hodgkin's lymphoma (NHL) in vitro, and to explore the underlying mechanism regulating SDF-1/CXCR4 axis. METHODS: The effects of triptolide on the growth of Raji cells were studied by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. The effects of triptolide on SDF-1 mRNA expression in lymph node stromal cells from patients with NHL were determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The effects of triptolide on CXCR4 expression on lymphoma cells freshly isolated from the lymph nodes of these patients were studied by flow cytometric analysis. Chemotaxis assays were performed to observe the effects of triptolide on migration of primary lymphoma cells towards recombinant human SDF-1 alpha (rhSDF-1 alpha) or cultured lymph node stromal cells in vitro. RESULTS: Triptolide inhibited the proliferation of B-NHL cell line Raji cells in a dose- and time-dependent manner with a 24-h IC50 value of 43.06 nmol/L and a 36-h IC50 value of 25.08 nmol/L. The expression of SDF-1alpha mRNA in lymph node stromal cells obtained from patients with NHL was decreased after treatment by triptolide at concentrations of 25 and 50 nmol/L for 24 h. Flow cytometry analysis showed that the CXCR4 expression on primary lymphoma cells were downregulated gradually in a dose-dependent manner following triptolide treatment. Chemotaxis assays revealed that the migration of freshly isolated lymphoma cells towards either rhSDF-1 or cultured lymph node stromal cells was markedly inhibited by the addition of triptolide in vitro, and the inhibition was dose-dependent. CONCLUSION: Triptolide can inhibit the proliferation of B-NHL cell line Raji cells. Moreover, triptolide is able to inhibit the migration of lymphoma cells via lymph nodes in vitro. The potential antitumor mechanisms of triptolide are related to the antiproliferative effect and the blockage of SDF-1/CXCR4 axis.

Antineoplastic Agents, Alkylating↗

PubMed2006

Increased glutathione synthesis through an ARE-Nrf2-dependent pathway by zinc in the RPE: implication for protection against oxidative stress.

PURPOSE: To determine the molecular mechanisms underlying the protective effects of zinc against oxidative stress in cultured retinal pigment epithelial (RPE) cells. METHODS: Cultured ARPE-19 cells were treated with different concentrations of zinc for various times. Cellular glutathione (GSH) and glutathione disulfide (GSSG) levels were measured by high-performance liquid chromatography (HPLC). Glutamate-cysteine ligase (GCL) expression was measured by quantitative reverse transcription-PCR (RT-PCR). Nuclear factor erythroid2-related factor (Nrf2) activity was measured in a dual luciferase assay after transfection of reporter plasmids containing the antioxidant response element (ARE). The small interference (si)RNA approach was used to knock down the expression of Nrf2. RESULTS: Zinc significantly increased GSH levels in ARPE-19 cells through induction of the de novo synthesis pathway. At 150 microM, zinc increased the GSH level by 70%. At similar concentrations, zinc upregulated the mRNA level of GCL and activated the ARE-Nrf2 pathway. The effects of zinc on ARE activation and GSH synthesis were inhibited by knockdown of Nrf2 expression using the siRNA approach. CONCLUSIONS: Induction of the ARE-Nrf2 pathway by zinc provides powerful and prolonged antioxidation and detoxification that may explain the beneficial effects of zinc observed in the treatment of age-related macular degeneration (AMD).

Cells, Cultured↗

PubMed2006

Overexpression of heat shock factor 1 inhibits butyrate-induced differentiation in colon cancer cells.

Produced by dietary fiber, butyrate is a potential chemopreventive agent against colon cancer. It stimulates proliferation of normal colonic epithelial cells but induces growth inhibition, differentiation, apoptosis, or a combination of effects in colon carcinoma cells. In this study, we used cDNA membrane arrays and real-time reverse transcriptase-polymerase chain reaction to identify stress genes that were differentially regulated by sodium butyrate (NaB) in HT 29 human colon carcinoma cells. The results indicated that a group of heat shock protein (hsp) genes were upregulated by 3 mM NaB within the first 24 hours of exposure. Because the transcription of hsp genes is under the control of heat shock factors (HSFs), we measured the effects of overexpressed HSF-1 on the responses of HT 29 cells to NaB. Overexpression of HSF-1 inhibited NaB-induced differentiation as measured by alkaline phosphatase activity and carcinoembryonic antigen expression. These results suggest that increased expression of HSFs and Hsps might render colon carcinoma cells resistant to the chemopreventive effects of butyrate.

Butyrates↗

PubMed2006

Automated method, based on micro-sequential injection, for the study of enzyme kinetics and inhibition.

A micro-reactor system with continual spectrophotometric detection has been operated in Sequential Injection lab-on-valve (SI-LOV) mode and applied to enzyme kinetics and inhibition studies, using acetylcholinesterase (AChE) and angiotensin-converting enzyme (ACE) as model systems. With the advantages of automation, real-time kinetic measurement, and thorough mixing, the SI-LOV micro-reactor system allows for the monitoring of initial reaction rates and determination of reactant concentrations in the reaction mixture, both of which are essential for the determination of kinetic constants for enzymes and inhibitors. Enzyme, substrate, and inhibitor are precisely metered by the syringe pump and delivered to a stirred micro-reactor, followed by a reference scan that establishes the baseline for the following reaction rate measurement. Michaelis constants (Km) for AChE and ACE were determined to be 0.16 mM and 0.30 mM, respectively, which are consistent with literature values. The type of inhibition (competitive, uncompetitive, or mixed), the dissociation constants for the inhibitors, and the inhibitor dose-response curves were also determined.

Acetylcholinesterase↗

PubMed2006

[Effect of nitric oxide on Toll-like receptor 2/4 gene expression in the liver in acute hemorrhagic necrotizing pancreatitis in rats].

OBJECTIVE: To investigate the effect of nitric oxide (NO) on Toll-like receptors 2 and 4 (TLR 2/4) gene expression in the liver in acute hemorrhagic necrotizing pancreatitis (AHNP) in rats. METHODS: Seventy SD male rats were randomly divided into sham-operated group (n=10), AHNP group (n=30) and L-arginine (L-Arg) treatment group (n=30). Blood samples and liver tissues were obtained at 6 hours in sham-operated group, and 3, 6, 12 hours respectively in AHNP group and L-Arg-treated group. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), amylase in serum, NO, tumor necrosis factor-alpha (TNF-alpha) in liver tissue were determined. TLR2/4 mRNA expressions in the liver tissue were measured by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: TLR2/4 mRNA could be detected in the liver with low values in sham-operated group [(1.150+/-0.725)x10(-6), (11.450+/-1.724)x10(-4)], but they were markedly upregulated at 3 hours in AHNP group [(1.970+/-0.362)x10(-3), (175.000+/-0.111)x10(-3)], and peaked at 12 hours [(29.400+/-3.155)x10(-4), (267.300+/-8838)x10(-2), P<0.01). At the same time serum levels of amylase, ALT and AST increased, hepatic injuries were aggravated, the levels of TNF-alpha in the liver were increased and levels of NO in the liver were lowered (P<0.05 or P<0.01). Treatment with L-rg could effectively inhibit TLR2/4 mRNA expression [3 h: (3.510+/-1.528)x10(-4), (13.500+/-2.231)x10(-2); 6 h: (21.000+/-5.346)x10(-4), (18.700+/-2.685)x10(-2); 12 h: (26.200+/-2.076)x10(-4), 1.959+/-0.270, P<0.05 or P<0.01] and alleviate hepatic injuries. The levels of serum amylase, ALT and AST lowered, and the levels of TNF-alpha in the liver were lowered and the levels of NO were markedly increased (P<0.05 or P<0.01). CONCLUSION: These findings suggest that the expression of TLR2/4 mRNA is increased in the liver in AHNP, and the hepatic injuries are aggravated. NO could markedly inhibit TLR 2/4 mRNA gene expression in the liver in AHNP.

Animals↗

PubMed2006

[Application of multi-slice spiral CT angiography after endoluminal exclusion of aortic diseases].

OBJECTIVE: To study the application of multi-slice spiral CT angiography (MSCTA) after endoluminal exclusion of aortic diseases. METHODS: 16-slice CT angiography was performed in 15 patients with aortic dissection and 4 patients with aortic aneurysm after endovascular exclusion. Two observers analysed the images and interpreted the outcomes and complications after endovascular exclusions of aortic dissection and aortic aneurysm. RESULTS: In 19 patients, thrombus was found in all the false lumens of aortic dissection and the outer-stent cavity of aortic aneurysm. However, one patient with aortic aneurysm graft thrombosis; 4 patients had endo-leak (3 with type I endo-leak, 1 with type III endo-leak complicating graft deformation); one achieved perfusion recovery, and one experienced thrombolysis of superior mesenteric artery. CONCLUSION: MSCTA can be an objective tool for the post-operative evaluation of endovascular exclusion of aortic diseases.

Adult↗

PubMed2006

[Isolation, culture, identification and biological characteristics of chicken skeletal muscle satellite cells].

Chicken skeletal muscle satellite cells were obtained by a two-step method of collagenase-I and trypsin digestion, followed by in vitro culture. They were further identified by specific gene expression assays. In addition, cell biological characteristics and myogenic genes expression were analyzed. Results showed that satellite cells from chicken skeletal muscle tissue expressed pax7, desmin, and possessed ability to proliferate and differentiate. The technical platform was established to study the mechanism of myogenic proliferation, differentiation and muscle regeneration.

Animals↗

PubMed2006

[Regulatory effect of curcumin on p300 and HDAC1 in B-NHL cells].

The purpose of this study was to investigate the effect of curcumin on proliferation of B-NHL Raji cell line and explore the relationship between this effect and regulatory expression of p300 and HDAC1 transcription. The in vitro cultured Raji cells were treated with curcumin at various concentrations (6.25-50 micromol/L) and at different time points (0, 6, 12, 24 and 48 hours), the inhibitory ratio of cell growth was measured by MTT assay, the cell apoptosis rate was detected by flow cytometry with Annexin V-FITC/PI double staining, the changes of p300 and HDAC1 mRNA expression and protein level in Raji cells were determined by RT-PCR and Western blot. The results showed that the curcumin could inhibit Raji cell proliferation in significant time-and concentration-dependent manners, IC50 at 24 hours was 25 micromol/L; the curcumin could induce apoptosis of Raji cells in concentration-dependent manner, apoptosis rate was 14.38%-61.18%. The curcumin significantly inhibited activity and expression of p300 and HDAC1. At IC50 concentration, expression of p300 and HDAC1 mRNA and protein level decreased with time-dependent manner, difference between tested and control groups was significant (P < 0.05). It is concluded that the curcumin can inhibit proliferation of B-NHL Raji cells and promote apoptosis of those cells. Curcumin can inhibit the activity and expression of the transcriptional co-activator p300 and HDAC1, which may be involved in its pharmacological mechanisms on B lymphoma cells.

Antineoplastic Agents↗

PubMed2006

[Research progress on trehalose used in lyophilization of blood cells--review].

Lyophilization is the best method for preservation of blood cells at present. Lyophilized blood cells could be stored at room temperature for long periods of time, while maintaining a high degree of viability. Lyophilized blood cells facilitates transportation and the costs are low. However, the membrane of blood cells is damaged and viability of blood cells is decreased in lyophilization. Trehalose has been shown to protect membrane, proteins and nucleic acids during freezing and desiccation. Now, researchers present a methor for loading blood cells with trehalose. In this paper, damage effect of lyophilization on blood cells, the mechanism of trehalose protection and the experimental studies on trehalose were reviewed.

Blood Preservation↗

PubMed2006

[Involvement of bcl-2 in multidrug resistance in human small cell lung cancer cell subline H446/DDP].

OBJECTIVE: To study the mechanism of bcl-2 involvement in multidrug resistance in human small cell lung cancer (SCLC) cell subline H446/DDP. METHODS: After the construction of pLXSN-bcl-2, in which the full length of bcl-2 cDNA amplified from total RNA of H446/DDP cells was integrated into the mammalian expression vector pLXSN, allowing transcription of a bicistronic mRNA, and the synthesis in vitro of 20-mer ODNs targeting the coding region of bcl-2 mRNA and the scrambled ODNs used as the control, the cationic lipid DOTAP was used to transfect them into H446 and H446/DDP cells, respectively. When H446 cells were transfected with mammalian expression vector pLXSN, the cells were divided into 3 groups, including cells transfected with the recombinant pLXSN-bcl-2, cells transfected with the vector pLXSN and cells untransfected (control); when H446 cells and H446/DDP cells were transfected with PS-ODNs, the cells were divided into 3 groups, including cells transfected with AS-PS-ODNs, cells transfected with NS-PS-ODNs and cells untransfected (control), respectively. After transfection, Western blot were carried out to detect the expression level of bcl-2 in the control cells and the transfected cells, respectively. Meanwhile flow cytometry (FCM) was used to detect cell apoptosis in the control cells and the transfected cells. RESULTS: (1) The data from Western blot showed that compared with the control H446 cells (gray-scale value 0.103 +/- 0.005), the expression level of bcl-2 in the pLXSN-bcl-2 transfected H446 cells (gray-scale value 0.854 +/- 0.016) was increased significantly (P < 0.01); and the apoptosis from DNA content analysis decreased significantly in the pLXSN-bcl-2 transfected H446 cells [(20.9 +/- 0.2)%] compared with that of the control H446 cells [(31.1 +/- 0.2)%] by DNA content analysis (P < 0.01). (2) The results from Western blot showed that bcl-2 expression in the AS-PS-ODNs transfected H446/DDP cells (gray-scale value 0.695 +/- 0.014) was significantly reduced compared with that of the control H446/DDP cells (gray-scale value 0.942 +/- 0.018), although not totally reduced to the level of the control H446 cells (P < 0.01); and the data from DNA content analysis indicated that the sensitivity of the AS-PS-ODNs transfected H446/DDP cells to 5 microg/ml DDP-induced apoptosis was strongly increased as compared with that of the control H446/DDP cells (P < 0.01). CONCLUSION: Targeting to inhibit antiapoptotic mitochondrial gene Bcl-2 expression may be one of the important therapeutic approaches to overcoming chemoresistance in human SCLC.

Cell Line, Tumor↗

PubMed2006

[Effect of curcumin on acetylation of histone H3 in human lymphoma cell line Raji].

BACKGROUND & OBJECTIVE: Epigenetic change is an important mechanism of oncogenesis. The inhibitors of methyltransferases and deacetylases, with epigenetic modificative effects, could inhibit proliferation and induce apoptosis of tumor cells. This study was to investigate the effects of curcumin on the acetylation of histone H3 and the expression of p21(WAF1/CIP1) gene in human lymphoma cell line Raji. METHODS: Raji cells were treated with 25 micromol/L curcumin. The levels of acetylated histone H3 and p21WAF1/CIP1 were detected by Western blot, the expression of p21(WAF1/CIP1) gene was detected by reverse transcription-polymerase chain reaction (RT-PCR), and the level of acetylated histone H3 at the site of p21(WAF1/CIP1) promoter gene was examined by chromatin immunoprecipitation assay. Cell cycle distribution was studied by flow cytometry. RESULTS: Curcumin induced hyperacetylation of histone H3 at the site of p21(WAF1/CIP1) promoter by 1.9 folds, and enhanced the levels of p21(WAF1/CIP1) mRNA by 4.2 folds and protein by 5.1 folds 24 h after treatment. Raji cells were arrested at G(2)/M phase when treated with curcumin for 24 h, and at G(0)/G(1) phase when treated for 36 h. CONCLUSION: Curcumin, with epigenetic modificative effects, could enhance the acetylayion of histone H3 at the site of p21(WAF1/CIP1) promoter gene, improve transcription of p21(WAF1/CIP1) gene, and arrest cell cycle progression of Raji cells.

Acetylation↗

PubMed2006

[Functional activity mapping during anticipation of dental pain].

OBJECTIVE: To reveal functional activity mapping during anticipation of dental pain with non-invasive fMRI technique, and to offer therapeutic possibilities for treating chronic oral facial pain psychologically. METHODS: 8 right handed patients with dentinalgia of the right maxillary bicuspid were included in this study. Block design was adopted, BOLD level during anticipation epoch (on) was contrasted with that of rest (off). Functional MRI scan covering the whole brain was carried out. The fMRI data were analyzed by SPM2 software with t-test to generate the activation map. RESULTS: Increased BOLD signals during dental pain anticipation were found dominantly on the left side in inferior, middle frontal gyrus/BA10,46, postcentral gyrus/BA2,3, middle frontal gyrus/BA8, precentral gyrus/BA44 and cerebellum. CONCLUSION: Anticipation of dental pain by itself can activate brain regions, especially prefrontal areas, SI, SMA and cerebellum. The results of pain anticipation are consisted with previous studies except that there is no activation in insula and cingulate cortex. Sensory, motor, cognitive and emotional activation in dental pain anticipation may indicate that brain nociceptive network can be affected by hint.

Adult↗