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Guo-Qiang Chen

Publications and source records attributed to Guo-Qiang Chen.

At least 19 recordsLinked to original sources
PubMed2007

Effect of non-anticoagulant N-desulfated heparin on expression of vascular endothelial growth factor, angiogenesis and metastasis of orthotopic implantation of human gastric carcinoma.

AIM: To investigate the effect of N-desulfated heparin on tumor metastasis and angiogenesis, and expression of vascular endothelial growth factor (VEGF) of orthotopic implantation of human gastric carcinoma in male severe combined immune deficiency (SCID) mice. METHODS: Human gastric cancer SGC-7901 cells were orthotopically implanted into the stomach of SCID mice. The mice were randomly divided into normal saline group and N-desulfated heparin group. One week after operation, the mice in N-desulfated heparin group received i.v. injections of N-desulfated heparin (Shanghai Institute of Cell Biology, Chinese Academy of Sciences, 10 mg/kg.d) twice weekly for 3 wk. The mice in normal saline group received i.v. injections of normal saline (100 microL) twice weekly for 3 wk. The mice were sacrificed six weeks after implantation. Tumor metastasis was evaluated histologically for metastasis under microscope. Intratumoral microvessel density (MVD) and VEGF expression were evaluated immuohistochemically. VEGF mRNA expression in gastric tissue of SCID mice was detected by real time PCR. RESULTS: The tumor metastasis rate was 80% in normal saline group and 20% in N-desulfated heparin group (P < 0.05). MVD was 8.0 +/- 3.1 in normal saline group and 4.3 +/- 1.8 in N-desulfated heparin group (P < 0.05). VEGF positive immunostaining was found in cytoplasm of cancer cells. The rate of VEGF positive expression was higher in normal saline group than in N-desulfated heparin treated group (90% vs 20%, P < 0.05). VEGF mRNA expression was significantly inhibited by N-desulfated heparin and was higher in normal saline group than in N-desulfated heparin group (Ct value 19.51 +/- 1.01 vs 22.55 +/- 1.36, P < 0.05). N-desulfated heparin significantly inhibited the expression of VEGF mRNA in cancer cells. No bleeding occurred in N-desulfated heparin group. CONCLUSION: N-desulfated heparin can inhibit metastasis of gastric cancer by suppressing tumor VEGF expression and tumor angiogenesis, but has no obvious anticoagulant activity.

Animals↗
PubMed2006

Phospholipid scramblase 1.

Phospholipid scramblase 1 (PLSCR1) is a calcium-binding, multiply palmitoylated type II endofacial plasma membrane protein, while unpalmitoylated PLSCR1 protein can import into the nucleus, where it binds to genomic DNA. Although the original work showed that PLSCR1 contributes to the transbilayer movement of phospholipids, the following studies revealed that PLSCR1 expression can be induced by some cytokines such as interferon, epidermal growth factor, and also by leukemic cell differentiation-inducing agents such as all-trans retinoic acid (ATRA) and phorbol 12-myristate 13-acetate (PMA). PLSCR1 was also shown to interact with several protein kinases including c-Abl, c-Src, protein kinase Cdelta as well as some other proteins such as onzin, suggesting the roles of PLSCR1 in cell signaling. Indeed, the current evidence proposes that PLSCR1 contributes to cell proliferation, differentiation, apoptosis, and plays roles in the pathogenesis of cancers, especially leukemia.

Apoptosis↗
PubMed2006

Comparison of gene expression profiles between primary tumor and metastatic lesions in gastric cancer patients using laser microdissection and cDNA microarray.

AIM: To study the differential gene expression profiles of target cells in primary gastric cancer and its metastatic lymph nodes using laser microdissection (LMD) in combination with cDNA microarray. METHODS: Normal gastric tissue samples from 30 healthy individuals, 36 cancer tissue samples from primary gastric carcinoma and lymph node metastasis tissue samples from 58 patients during gastric cancer resection were obtained using LMD in combination with cDNA microarray independently. After P27-based amplification, aRNA from 36 of 58 patients (group 1) with lymph node metastasis and metastatic tissue specimens from the remaining 22 patients (group 2) were applied to cDNA microarray. Semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemical assay verified the results of microarray in group 2 and further identified genes differentially expressed in the progression of gastric cancer. RESULTS: The expression of 10 genes was up-regulated while the expression of 15 genes was down-regulated in 22 gastric carcinoma samples compared with that of genes in the normal controls. The results were confirmed at the level of mRNA and protein, and suggested that four genes (OPCML, RNASE1, YES1 and ACK1) could play a key role in the tumorigenesis and metastasis of gastric cancer. The expression pattern of 3 genes (OPCML, RNASE1 and YES1) was similar to tumor suppressor genes. For example, the expression level of these genes was the highest in normal gastric epithelium, which was decreased in primary carcinoma, and further decreased in metastatic lymph nodes. On the contrary, the expression pattern of gene ACK1 was similar to that of oncogene. Four genes were further identified as differentially expressed genes in the majority of the cases in the progression of gastric cancer. CONCLUSION: LMD in combination with cDNA microarray provides a unique support foe the identification of early expression profiles of differential genes and the expression pattern of 3 genes (OPCML, RNASE1 and YES1) associated with the progression of gastric cancer. Further study is needed to reveal the molecular mechanism of lymph node metastasis in patients with gastric cancer.

Aged↗
PubMed2006

RIG-G as a key mediator of the antiproliferative activity of interferon-related pathways through enhancing p21 and p27 proteins.

The RIG-G gene, originally isolated from an acute promyelocytic leukemia cell line NB4, codes for a 60-kDa cytoplasmic protein that is induced by all-trans retinoic acid (ATRA) treatment along with the induction of morphological differentiation of NB4 cells. Here, we provide evidence that ectopic expression of Rig-G in U937 cells can lead to a significant accumulation of cells at G(1)/S transition. Growth arrest seems to occur by modulating several major cell cycle regulatory players. Interestingly, Rig-G alters JAB1 cellular distribution through interacting with this protein and increases the intracellular level of p27 by preventing it from the JAB-1-dependent and ubiquitin/proteasome-mediated degradation. Furthermore, we demonstrate a role of Rig-G for c-myc down-regulation that results in an up-regulation of p21, tightly associated with cell cycle arrest. In addition, our studies reveal that Rig-G is a direct target of STAT1, a key transcription factor in regulating IFN responses, and may be one of the first experimentally proven molecular mediators for the antiproliferative effect of IFN-alpha. Considering that IFN-alpha and ATRA synergistically inhibit growth along the intracellular pathways triggered by the two compounds in many cell types, we suggest that Rig-G may also represent one of the key molecular nodes of signaling cross-talk between ATRA and IFN-alpha.

Base Sequence↗
PubMed2006

Microbial transformation of benzene to cis-3,5-cyclohexadien-1,2-diols by recombinant bacteria harboring toluene dioxygenase gene tod.

Toluene dioxygenase (TDO) catalyzes asymmetric cis-dihydroxylation of aromatic compounds. To achieve high efficient biotransformation of benzene to benzene cis-diols, Pseudomonas putida KT2442, Pseudomonas stutzeri 1317, and Aeromonas hydrophila 4AK4 were used as hosts to express TDO gene tod. Plasmid pSPM01, a derivative of broad-host plasmid pBBR1MCS-2 harboring tod from plasmid pKST11, was constructed and introduced into the above three strains. Their abilities to catalyze the biotransformation of benzene to benzene cis-diols, namely, cis-3,5-cyclohexadien-1,2-diols abbreviated as DHCD, were examined. In shake-flask cultivation under optimized culture media and growth condition, benzene cis-diols production by recombinant P. putida KT2442 (pSPM01), P. stutzeri 1317 (pSPM01), and A. hydrophila 4AK4 (pSPM01) were 2.68, 2.13, and 1.17 g/l, respectively. In comparison, Escherichia coli JM109 (pSPM01) and E. coli JM109 (pKST11) produced 0.45 and 0.53 g/l of DHCD, respectively. When biotransformation was run in a 6-l fermenter, DHCD production in P. putida KT2442 (pSPM01) was approximately 60 g/l; this is the highest DHCD production yield reported so far.

Aeromonas hydrophila↗
PubMed2006

Comparative proteomic analysis of human leukemic cells with and without inducible expression of leukemogenic AML1-ETO protein.

AML1-ETO is a leukemogenic fusion protein generated by chromosomal translocation t(8; 21) (q22; q22), one of the most frequent chromosomal abnormalities in acute myeloid leukemia. The fusion protein has been shown to present dichotomous functions on leukemic cells: growth arrest versus differentiation block. However, their precise molecular mechanisms are not completely clear. In this work, we try to explore potential AML1-ETO-targeted proteins through comparing two-dimensional electrophoresis (2DE)-based global protein expression profiles of leukemic U937 cells with and without inducible expression of AML1-ETO. As a result, we identified 14 unique proteins deregulated in AML1-ETO-carrying leukemic cells, including 3 up-regulated such as hairy and enhancer of split 5 (HES5) and 11 down-regulated such as MAT1 (menage a trois-1) and mitogen-activated protein kinase organizer 1 (MORG1). These proteins were widely involved in stem cell maintenance, cell cycle, signal transduction and transcription. The further investigation on their roles in leukemic cells will uncover new clues to understanding leukemogenic effects of AML1-ETO fusion protein.

Cell Line, Tumor↗
PubMed2006

Immunodetection of human telomerase reverse-transcriptase (hTERT) re-appraised: nucleolin and telomerase cross paths.

The involvement of telomerase in cellular immortalization and senescence has often been assessed by means of telomerase expression at the RNA level and quantification of telomerase activity by the telomeric repeat amplification protocol assay. However, these methods either neglected the existence of various telomerase splice variants, or ignored the nonconventional functions of telomerase independent of its ability to elongate and maintain telomere length. Immunodetection of telomerase is now being recognized as a necessary approach to precisely elucidate its roles in oncogenesis and senescence. A few antibodies directed against the catalytic subunit of the human telomerase (hTERT) are currently used but their specificity is not always demonstrated. A survey of the literature showed inconsistencies and led us to comparatively re-evaluate the most frequently used antibodies. Surprisingly, mass spectrometry, two-dimensional gel analysis and immunofluorescent experiments revealed that the most frequently used hTERT immunoprobe, a mouse monoclonal antibody that was claimed to be directed against an hTERT protein epitope, in fact recognizes nucleolin rather than telomerase. Our findings have interesting implications regarding the biology of nucleolin and telomerase in the context of pathophysiological investigations recently carried out.

Antibodies↗
PubMed2006

Mutation on N-terminus of polyhydroxybutyrate synthase of Ralstonia eutropha enhanced PHB accumulation.

Polyhydroxyalkanoate (PHA) synthase is the central enzyme involved in the biosynthesis of PHA, a family of bacterial biodegradable polyesters. Due to its high variability, the N-terminal fragment of this enzyme was previously considered as unnecessary for a functionally active enzyme. In this study, polyhydroxybutyrate synthase from Ralstonia eutropha (PhbC(Re)) with a deletion on N-terminal 88 amino acid residues showed a significant reduced activity, as reflected by only 1.5% PHB accumulation compared with the wild type which produced 58.4% PHB of the cell dry weight. Whilst several site-specific mutagenesis results revealed the amphiphilic alpha-helix assembled by the amino acid region, D70-E88 played an important role in both maintaining the PHB synthase activity and regulating molecular weight and polydispersity of accumulated PHB homopolymer.

Acyltransferases↗
PubMed2006

The effect of D,L-beta-hydroxybutyric acid on cell death and proliferation in L929 cells.

As a prerequisite for tissue engineering applications, researchers must understand the effect on local cell types of the degradation products of biodegradable polymers. Polyhydroxybutyrate (PHB) has received special interest as an implant material, because it degrades to release a normal component of blood and tissue, D,L-beta-hydroxybutyrate (HB). We report that HB (0.02 g/l) promoted cell proliferation in cultured L929 cells plated at high cell density (1 x 10(5) cells/well) but not lower cell densities. While HB did not affect cell cycle progression, it significantly inhibited cell death. HB treatment prevented necrosis, reducing cell membrane permeability 4h following serum withdrawal from the medium, and for all subsequent time points. In summary, HB promotes proliferation of L929 cells in high-density cultures by preventing apoptotic and necrotic cell death. This property makes biodegradable polymers containing HB, such as PHBHHx, attractive candidates for tissue engineering applications, especially those requiring the regeneration of large numbers of cells.

3-Hydroxybutyric Acid↗
PubMed2006

Hypoxia inducible factor-1alpha and leukemic cell differentiation.

Arsenic trioxide (As2O3, ATO) is a recently developed drug for the effective treatment of acute promyelocytic leukemia (APL). Experimental studies showed that in vitro differentiation-inducing ability on APL cells of this drug is not significant compared with its in vivo activity. We unexpectedly found recently that hypoxia-mimetic agents and moderate real hypoxia triggered acute myeloid leukemic cells to undergo differentiation. Furthermore, intermittent hypoxia significantly prolonged the survival of the transplanted leukemic mice with inhibition of infiltration and induction of differentiation of leukemic cells. In the following works, molecular mechanisms of hypoxia-induced differentiation were investigated and some interesting results have been obtained. This review will shortly summarize the related progresses and discuss the questions remained to be further investigated.

Animals↗
PubMed2006

A lower specificity PhaC2 synthase from Pseudomonas stutzeri catalyses the production of copolyesters consisting of short-chain-length and medium-chain-length 3-hydroxyalkanoates.

A polyhydroxyalkanoate (PHA) synthase gene phaC2 (Ps) from Pseudomonas stutzeri strain 1317 was introduced into a PHA synthase gene phbC (Re) negative mutant, Ralstonia eutropha PHB(-)4. It conferred on the host strain the ability to synthesize PHA, the monomer compositions of which varied widely when grown on different carbon sources. During cultivation on gluconate, the presence of phaC2 (Ps) in R. eutropha PHB(-)4 led to the accumulation of polyhydroxybutyrate (PHB) homopolymer in an amount of 40.9 wt% in dry cells. With fatty acids, the recombinant successfully produced PHA copolyesters containing both short-chain-length and medium-chain-length 3-hydroxyalkanoate (3HA) of 4-12 carbon atoms in length. When cultivated on a mixture of gluconate and fatty acid, the monomer composition of accumulated PHA was greatly affected and the monomer content was easily regulated by the addition of fatty acids in the cultivation medium. After the (R)-3-hydroxydecanol-ACP:CoA transacylase gene phaG (Pp) from Pseudomonas putida was introduced into phaC2(Ps)-containing R. eutropha PHB(-)4, poly(3HB-co-3HA) copolyester with a very high 3-hydroxybutyrate (3HB) fraction (97.3 mol%) was produced from gluconate and the monomer compositions of PHA synthesized from fatty acids were also altered. This study clearly demonstrated that PhaC2(Ps) cloned from P. stutzeri 1317 has extraordinarily low substrate specificity in vivo, though it has only 54% identity in comparison to a previously described low-substrate-specificity PHA synthase PhaC1(Ps) from Pseudomonas sp. 61-3. This study also indicated that the monomer composition and content of the synthesized PHA can be effectively modulated by controlling the addition of carbon sources or by modifying metabolic pathways in the hosts.

Acyltransferases↗
PubMed2006

Effect of 3-hydroxyhexanoate content in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) on in vitro growth and differentiation of smooth muscle cells.

In this paper, comprehensive characteristics including cell attachment, cell proliferation status, cell cycle progression and phenotypic changes of smooth muscle cells from rabbit aorta (RaSMCs) were studied on poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) containing 0-20% HHx (mol%) in comparison with tissue culture plates (TCPs). Results demonstrated that RaSMCs adhered better on PHBHHx containing 12% HHx (12%HHx) although they proliferated better on 20%HHx-containing PHBHHx films (20%HHx). This was explained by the difference in cell cycle progression observed using flow cytometry, as it was found that only 20%HHx-containing polymer could maintain the normal cell cycle evolution as TCPs did after 3 d incubation. The highest expression level and typical spindle-like distribution of alpha-actin on 20%HHx-containing polymer were characterized as the contractile-like phenotype, suggesting that RaSMCs tended to differentiate rather than proliferate compared to the cells grown on 12%HHx polymer. Results obtained above suggested that 20%HHx was suitable for RaSMCs proliferation, leading to its change to contractile phenotype. This study extends the potential applications of PHBHHx in SMCs-related graft scaffold fabrication for tissue engineering.

3-Hydroxybutyric Acid↗
PubMed2006

Leukemogenic AML1-ETO fusion protein upregulates expression of connexin 43: the role in AML 1-ETO-induced growth arrest in leukemic cells.

AML1-ETO, a fusion protein generated by the chromosomal translocation t(8;21), is frequently associated with acute myeloid leukemia (AML). In addition to blocking differentiation, AML1-ETO is also shown to induce growth arrest in AML cells, which is unfavorable for leukemogenesis harboring the t(8;21) translocation. However, its precise mechanism is still unclear. Here we provide the first demonstration that the conditional expression of AML1-ETO by the ecdysone-inducible system dramatically increases the expression of connexin 43 (CX43), together with growth arrest at G1 phase in leukemic U937 cells. We also show that the CX43 induction inhibits the proliferation of U937 cells at G1 phase, while the suppression of CX43 expression by small interfering RNA (siRNA) effectively overcomes the growth-inhibitory effect of AML1 -ETO in leukemic cells. Furthermore, either AML1-ETO or CX43 induction elevates cell-cycle negative regulator P27(kip1) protein by inhibiting its degradation, which is antagonized by siRNA against CX43. Taken together, our data indicate that CX43 plays a role in AML1-ETO-induced growth arrest possibly through the accumulation of P27(kip1) protein. The potential mutation or/and epigenetic alterations of CX43 and its related gene(s) deserve to be explored in AML1-ETO-positive AML patients.

Base Sequence↗
PubMed2006

Differential protein expression in hypertrophic heart with and without hypertension in spontaneously hypertensive rats.

Although cardiac hypertrophy in hypertension has been well recognized, the molecular mechanisms for the development of hypertrophy are still largely unknown. In this study, the protein expression profiles of left ventricular myocardia in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats at different ages were analyzed using 2-DE in combination with MALDI-TOF/TOF MS/MS. The results showed that 20 proteins were modulated in the hypertrophic myocardium. Out of these modulated proteins, 13 proteins presented significant changes in SHR at an early stage prior to the development of sustained hypertension, while the changes of the other 7 protein expressions occurred only at a late stage in SHR when the blood pressure was significantly elevated, and were largely reversible by treatment with rennin-angiotensin-aldosterone system inhibitors losartan or enalapril. These data demonstrate that the changes in energy metabolism in the hypertrophied heart favor an increase in glycolysis and a decrease in oxidation of fatty acid and glucose, which occur at an early stage in SHR without hypertension. Our results also provide evidence to support the hypothesis that oxidative stress plays an important role in the development of hypertensive cardiac hypertrophy.

Age Factors↗
PubMed2006

Comparative proteomic analysis of hypoxia-treated and untreated human leukemic U937 cells.

We reported recently that moderate hypoxia and hypoxia-mimetic agents could induce growth arrest and differentiation of leukemic cells via the mediation of hypoxia-inducible factor 1 alpha (HIF-1alpha), but the exact molecular mechanisms remain largely unknown. In this study, human acute promonocytic leukemic U937 cells were incubated under 2% O2 or in 50 microM of the hypoxia mimetic agent cobalt chloride (CoCl2) and normal oxygen for 24 h, and their protein expression profiles were compared by 2-DE coupled with MALDI-TOF/TOF MS/MS. We identified 62 and 16 proteins that were significantly deregulated by hypoxia and CoCl2 treatment, respectively. These proteins were mainly involved in metabolism, gene expression regulation, signal transduction, cell proliferation, differentiation and apoptosis. As an example, N-myc downstream regulated gene 1 (NDRG1), a putative differentiation-related gene, was up-regulated in both 2% O2- and CoCl2-treated U937 cells. Moreover, enforced HIF-1alpha expression also elevated NDRG1 mRNA and protein in U937 cells. These data will provide some clues for understanding mechanisms by which leukemic cells response to hypoxia.

Apoptosis↗
PubMed2006

Anion exchanger 2 mediates the action of arsenic trioxide.

Anion exchanger 2 (AE2) mediates the exchange of C1-/HCO3- across the plasma membrane and plays a role in the regulation of intracellular pH. The present study showed that AE2 protein expression was upregulated immediately after exposure to either low (0.5 micromol/l) or high (1 and 2 micromol/l) concentrations of arsenic trioxide. This suggests that arsenic trioxide may act via regulation of intracellular pH. Changing the culture pH in NB4 cells modulated the degradation of promyelocytic leukaemia-retinoic acid receptor-alpha (PML-RARalpha), PML and RARalpha, which supported this hypothesis. DIDS (4,4'-diisothiocyanodihydrostilbene-2,2'-disulphonic acid) inhibited AE2 function, preventing the arsenic trioxide-induced degradation of RARalpha and low concentration showed synergistic effects on the expression of CD11c, which is related with cell differentiation. In addition, DIDS rescued the cells from 1 micromol/l arsenic trioxide-induced apoptosis. In conclusion, AE2 mediated the action of arsenic trioxide via regulation of intracellular pH and a novel pathway for the mechanism of action of arsenic trioxide is reported.

Anion Transport Proteins↗
PubMed2006

[Detection and significance of 16S rDNA in the prostatic secretions of patients with chronic prostatitis].

OBJECTIVE: To evaluate the expression and significance of 16S rDNA in prostatic secretions (EPS) of chronic prostatitis. METHODS: 16S rDNA was detected in EPS of 116 patients with chronic prostatitis by PCR. RESULTS: 16S rDNA were positively expressed in all 29 cases of II type chronic bacterial prostatitis and 71 out of 87 cases of III type chronic prostatitis (82%). The positive rates were 94% (45/48) and 67% (26/39) in lIIA and IIIB chronic prostatitis respectively. There was a statistical difference in 16S rDNA positive rate between IIIA and IlB chronic prostatitis (P < 0.01). CONCLUSION: Detection of 16s rDNA may be a useful index for the diagnosis and classification of chronic prostatitis.

Adult↗