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Biomedical subjects

Fang Zheng

Publications and source records attributed to Fang Zheng.

51 records · Page 3Linked to original sources
PubMed2004

Resistance to chemotherapy-induced apoptosis via decreased caspase-3 activity and overexpression of antiapoptotic proteins in ovarian cancer.

GOALS: Resistance to cisplatin is the main reason for treatment failure in ovarian cancer. Apoptosis is the main mechanism of action of most cancer chemotherapeutic agents. The apoptosis-associated proteins expressed in cisplatin-sensitive (A2780, COC1) and -resistant (A2780/DDP, COC1/DDP) ovarian cancer cell lines, as well as their effects on caspase-3 activity in these cells, were studied by reverse transcriptase polymerase chain reaction and Western blot analysis. METHODS: The apoptotic ratios of A2780, COC1, A2780/DDP, and COC1/DDP cells after treatment with cisplatin were measured by flow cytometry. RESULTS: Expression of Bcl-2 and Bcl-X(L) in A2780/DDP and COC1/DDP cells was significantly higher than that in A2780 and COC1 cells, respectively. Expression of Bax and Bcl-Xs did not differ in cisplatin-resistant and -sensitive cells. Caspase-3 activity was reduced markedly and apoptotic ratios were significantly lower in A2780/DDP and COC1/DDP cells than in A2780 and COC1 cells after treatment with cisplatin. CONCLUSION: We conclude that overexpression of antiapoptotic proteins Bcl-2 and Bcl-X(L) and down-regulation of caspase-3 activity may be associated with cisplatin resistance in human ovarian cancer.

Antineoplastic Agents↗
PubMed2004

Host response after reconstruction of abdominal wall defects with porcine dermal collagen in a rat model.

OBJECTIVE: The purpose of this study was to compare the inflammatory response after implantation of Pelvicol with Prolene in a rat model. STUDY DESIGN: Full-thickness abdominal wall defects were created in 64 Wistar rats, and reconstructed with either Pelvicol or Prolene. Animals were sacrificed on days 7, 14, 30, and 90 to evaluate the presence of herniation, infection, adhesions, and changes in thickness and tensile strength of the implants. Histopathology and immunohistochemistry were performed to evaluate the collagen deposition and the inflammatory response. Statistics were done with unpaired t test and Mann-Whitney rank test. RESULTS: Pelvicol implantation induced infiltration of granulocytes, macrophages, and NK cells, which showed up-regulated expression of surface activation markers ICAM-1 and CD11b. This inflammatory response was significantly milder, and declined faster than in Prolene-implanted rats, and was also associated with fewer adhesions. Moreover, Pelvicol induced a slower, but more orderly collagen deposition, paralleling the surface of the implant. Pelvicol implants showed a slower increase in thickness and tensile strength early on, but this difference disappeared by day 90. CONCLUSION: Pelvicol induces a milder inflammatory response, less adhesion formation, more orderly collagen deposition than Prolene, and reaches a comparable tensile strength only after 90 days.

Abdominal Wall↗
PubMed2004

[Participation of ICAM-1 in the cytotoxicity of TM-TNF-alpha mediated by TNF receptor I].

AIM: To identify membrane-associated molecules involved in the tumoricidal cytotoxicity of TM-TNF-alpha and to explore the molecular mechanism underlying the tumoricidal cytotoxicity of TM-TNF-alpha and differences of biological effects between TM-TNF-alpha and sTNF. METHODS: Antibody blocking test and RT-PCR were used to evaluate the role of ICAM-1 and VCAM-1 in the cytotoxicity of TM-TNF-alpha mediated by TNFR I or TNFR II. RESULTS: After the ICAM-1 expressed on the membrane of MCF-7 cells(expressing TNFRI) was blocked, the cytotoxicity of TM-TNF-alpha to this cell lines decreased significantly, while blocking VCAM-1 had no effect. Blocking ICAM-1 or VCAM-1 expressed on the membrane of HL-60 cells(expressing TNFRII)had no significant effects on the cytotoxicity of TM-TNF-alpha to this cell lines. CONCLUSION: ICAM-1 participates in the cytotoxicity of TM-TNF mediated by TNFRI.

Animals↗
PubMed2004

[The relationship of p53 and the cytotoxicity mediated by TM-TNF-alpha and S-TNF-alpha].

AIM: To explore the relationship of p53 and the cytotoxicity mediated by TM-TNF-alpha and S-TNF-alpha. METHODS: P53 mutation in tumor cell was detected by PCR-SSCP. Wide type p53 expression plasmid was transfected to tumor cells with mutant p53 gene, while the mutant type p53 plasmid to tumor cell with wide type p53 gene.Then,the effects of transfection on the cytotoxicity of two types of TNF were detected. RESULTS: Mutation in the p53 gene were found in most of tumor cells (Raji, HL-60, K562) which were resistant to S-TNF-alpha. The tumor cells transfected with wild type p53 plasmid were more sensitive to S-TNF-alpha while the tumor cells transfected with mutant type p53 plasmid were less sensitive to S-TNF-alpha. But the cytotoxicity of TM-TNF-alpha was not affected by the transfection. CONCLUSION: The cytotoxicity mediated by TM-TNF-alpha is not dependent on wide type p53, which may account for the broader tumorcidal spectrum of TM-TNF-alpha than that of S-TNF-alpha.

Breast Neoplasms↗
PubMed2004

[Genetic association of apoE and apoCI gene polymorphisms with coronary heart disease].

OBJECTIVE: To study the genetic association of apolipoprotein (apo) E and apoCI gene polymorphisms with coronary heart disease (CHD) in China. METHODS: apoE genotypes were identified by multiplex amplification refractory mutation system (multi-ARMS) and the apoCI promoter polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 186 cases with CHD (age: 65.0 +/- 10.5 years) and 350 controls (age: 63.6 +/- 8.3 years). The haplotype frequencies were estimated. RESULTS: The frequencies of apoE E4/3 genotype (26.9%) and epsilon4 (14.5%) in CHD group were significantly higher than that in the control group (12.6%, 7.0%), P <0.05. The significant difference was also found for the apoCI locus and the CHD group showed higher rate of both for the H2 allele and genotypes, carrying this allele. Estimation of the haplotype frequencies indicated that the association between the apoE-CI haplotype and CHD was significantly strong. The apoE-epsilon4/apoCI-H2 was estimated to be responsible for 9.86% of CHD. CONCLUSION: When the subjects carrying both epsilon4 and H2 alleles, they would have higher risk of suffering from CHD than controls.

Adult↗
PubMed2003

[The association of sulfotransferase1A1 His allele and breast cancer in Han ethnic Chinese women].

OBJECTIVE: To assess the relationship between SULT1A1 Arg213His polymorphism and breast cancer in Hans of Chinese women, as well as the interaction of the polymorphism and related risk factor of breast cancer. METHODS: Distribution of Arg213His polymorphism of the SULT1A1 gene was detected by using PCR-RFLP in 209 cases of breast cancer and 426 matched healthy controls. The OR of susceptibility of SULT1A1 genotypes to breast cancer and the r value of interaction with exposure factors using multivariate logistic regression. RESULTS: (1) There was no significant difference in genotype of Arg/Arg, Arg/His and His/His of SULT1A1 between case and control (P = 0.12). The frequency of His allele was 13.6% and 9.5% in were determined case and control, respectively, P = 0.03; (2) Compared with Arg/Arg genotype, the risk of Arg/His and His/His was increased, P for trend = 0.04; The OR of His allele (Arg/His + His/His) was 2.60 (95% CI: 1.12 - 6.05, P = 0.04); (3) As for the interaction between gene and related exposure factors, His allele strengthen the effect of endogenous estrogen exposure (interaction index r > 1), and weaken the effect of factors related to exposure of some procarcinogen in dietary (r < 1), both being multiplicative interaction model. CONCLUSION: SULT1A1 His allele is positively associated with the risk of breast cancer, and an interaction exist between this allele and related exposure factors.

Adult↗
PubMed2003

Fundamental reaction mechanism for cocaine hydrolysis in human butyrylcholinesterase.

Butyrylcholinesterase (BChE)-cocaine binding and the fundamental pathway for BChE-catalyzed hydrolysis of cocaine have been studied by molecular modeling, molecular dynamics (MD) simulations, and ab initio calculations. Modeling and simulations indicate that the structures of the prereactive BChE/substrate complexes for (-)-cocaine and (+)-cocaine are all similar to that of the corresponding prereactive BChE/butyrylcholine (BCh) complex. The overall binding of BChE with (-)-cocaine and (+)-cocaine is also similar to that proposed with butyrylthiocholine and succinyldithiocholine, i.e., (-)- or (+)-cocaine first slides down the substrate-binding gorge to bind to Trp-82 and stands vertically in the gorge between Asp-70 and Trp-82 (nonprereactive complex) and then rotates to a position in the catalytic site within a favorable distance for nucleophilic attack and hydrolysis by Ser-198 (prereactive complex). In the prereactive complex, cocaine lies horizontally at the bottom of the gorge. The fundamental catalytic hydrolysis pathway, consisting of acylation and deacylation stages similar to those for ester hydrolysis by other serine hydrolases, was proposed on the basis of the simulated prereactive complex and confirmed theoretically by ab initio reaction coordinate calculations. Both the acylation and deacylation follow a double-proton-transfer mechanism. The calculated energetic results show that within the chemical reaction process the highest energy barrier and Gibbs free energy barrier are all associated with the first step of deacylation. The calculated ratio of the rate constant (k(cat)) for the catalytic hydrolysis to that (k(0)) for the spontaneous hydrolysis is approximately 9.0 x 10(7). The estimated k(cat)/k(0) value of approximately 9.0 x 10(7) is in excellent agreement with the experimentally derived k(cat)/k(0) value of approximately 7.2 x 10(7) for (+)-cocaine, whereas it is approximately 2000 times larger than the experimentally derived k(cat)/k(0) value of approximately 4.4 x 10(4) for (-)-cocaine. All of the results suggest that the rate-determining step of the BChE-catalyzed hydrolysis of (+)-cocaine is the first step of deacylation, whereas for (-)-cocaine the change from the nonprereactive complex to the prereactive complex is rate-determining and has a Gibbs free energy barrier higher than that for the first step of deacylation by approximately 4 kcal/mol. A further analysis of the structural changes from the nonprereactive complex to the prereactive complex reveals specific amino acid residues hindering the structural changes, providing initial clues for the rational design of BChE mutants with improved catalytic activity for (-)-cocaine.

Butyrylcholinesterase↗
PubMed2003

Molecular determinants of proton-sensitive N-methyl-D-aspartate receptor gating.

Extracellular protons inhibit N-methyl-D-aspartate (NMDA) receptors with an IC50 value in the physiological pH range. To identify the molecular determinants of proton sensitivity, we used scanning mutagenesis of the NR1 subunit to search for residues that control proton inhibition of NMDA receptors. Homology modeling of the extracellular domains suggested that residues at which mutations perturbed pH sensitivity were localized in discrete regions. The majority of mutations that strongly affected proton sensitivity were clustered in the extracellular end of the second transmembrane domain (M3) and adjacent linker leading to the S2 portion of the glycine-binding domain of NR1. Mutations in NR2A confirmed that the analogous region controls the pH sensitivity of this subunit and also identified the linker region between the third transmembrane domain (M4) and the S2 portion of the NR2 glutamate binding domain as an additional determinant of proton sensitivity. One mutant receptor, NR1(A649C)/NR2A(A651T), showed a 145-fold reduction in the IC50 for protons (IC50, 17.3 microM corresponding to pH 4.9). The M3-S2 linker region has been suggested to control NMDA receptor gating, leading to the hypothesis that the proton sensor and receptor gate may be structurally and functionally integrated.

Amino Acid Sequence↗
PubMed2003

[Role of apoptosis-associated genes and caspase-3 in cisplatin-resistant human ovarian cancer cell lines].

OBJECTIVE: To explore the role of apoptosis-associated genes and caspase-3 activity in cisplatin (DDP)-resistant human ovarian cancer cell lines. METHODS: The expressions of apoptosis-associated genes (bcl-2, bax, bcl-X(L) and bcl-X(S)) and the activity of caspase-3 were studied by reverse transcription-polymerase chain reaction (RT-PCR) and western blot in the cisplatin-resistant (A2780/DDP, COC1/DDP) and sensitive human ovarian cancer cells (A2780 and COC1). The apoptotic rates of A2780, COC1, A2780/DDP and COC1/DDP were measured with flow cytometry when treated with cisplatin. RESULTS: The mRNA expressions of bcl-2 and bcl-X(L) in A2780/DDP cells were 1.87 +/- 0.25 and 1.73 +/- 0.15, and significantly higher than those in A2780 cells (P < 0.05), which were 1.48 +/- 0.14 and 1.41 +/- 0.19 respectively. The protein expressions of bcl-2 and bcl-X(L) in A2780/DDP cells were 1.99 +/- 0.11 and 1.69 +/- 0.16, and significantly higher than those in A2780 cells (P < 0.05), which were 1.51 +/- 0.17 and 1.28 +/- 0.11 respectively. The expressions of bcl-2 and bcl-X(L) in COC1/DDP cells were also significantly higher than those in COC1 cells (P < 0.05). While there was no significant difference in expression of bax between A2780/DDP and A2780 as well as between COC1/DDP and COC1. No expression of bcl-X(S) was detected. When cells treated with different concentration of DDP, the caspase-3 activities, apoptotic rates and PARP expressions in A2780/DDP and COC1/DDP were significantly lower than those in A2780 and COC1 (P < 0.05), which showed dose-dependent (P < 0.05). CONCLUSION: Overexpression of anti-apoptotic genes and decrease of caspase-3 activity may relate to cisplatin resistance in human ovarian cancer cell lines.

Antineoplastic Agents↗
PubMed2002

Electron affinities of Al(n) clusters and multiple-fold aromaticity of the square Al4(2-) structure.

The concept of aromaticity was first invented to account for the unusual stability of planar organic molecules with 4n + 2 delocalized pi electrons. Recent photoelectron spectroscopy experiments on all-metal MAl(4)(-) systems with an approximate square planar Al(4)(2-) unit and an alkali metal led to the suggestion that Al(4)(2-) is aromatic. The square Al(4)(2-) structure was recognized as the prototype of a new family of aromatic molecules. High-level ab initio calculations based on extrapolating CCSD(T)/aug-cc-pVxZ (x = D, T, and Q) to the complete basis set limit were used to calculate the first electron affinities of Al(n)(), n = 0-4. The calculated electron affinities, 0.41 eV (n = 0), 1.51 eV (n = 1), 1.89 eV (n = 3), and 2.18 eV (n = 4), are all in excellent agreement with available experimental data. On the basis of the high-level ab initio quantum chemical calculations, we can estimate the resonance energy and show that it is quite large, large enough to stabilize Al(4)(2-) with respect to Al(4). Analysis of the calculated results shows that the aromaticity of Al(4)(2-) is unusual and different from that of C(6)H(6). Particularly, compared to the usual (1-fold) pi aromaticity in C(6)H(6), which may be represented by two Kekulé structures sharing a common sigma bond framework, the square Al(4)(2-) structure has an unusual "multiple-fold" aromaticity determined by three independent delocalized (pi and sigma) bonding systems, each of which satisfies the 4n + 2 electron counting rule, leading to a total of 4 x 4 x 4 = 64 potential resonating Kekulé-like structures without a common sigma frame. We also discuss the 2-fold aromaticity (pi plus sigma) of the Al(3)(-) anion, which can be represented by 3 x 3 = 9 potential resonating Kekulé-like structures, each with two localized chemical bonds. These results lead us to suggest a general approach (applicable to both organic and inorganic molecules) for examining delocalized chemical bonding. The possible electronic contribution to the aromaticity of a molecule should not be limited to only one particular delocalized bonding system satisfying a certain electron counting rule of aromaticity. More than one independent delocalized bonding system can simultaneously satisfy the electron counting rule of aromaticity, and therefore, a molecular structure could have multiple-fold aromaticity.

Journal Article↗
PubMed2002

Group I metabotropic glutamate receptor-mediated enhancement of dopamine cell burst firing in rat ventral tegmental area in vitro.

Metabotropic glutamate receptor (mGluR) agonist t-ACPD produced concentration-dependent enhancement of NMDA/apamin-induced burst firing and membrane oscillations in dopamine cells, recorded intracellularly from ventral tegmental area in the rat midbrain slice. Such effects were blocked reversibly by mGluR antagonist MCPG, and mimicked by the selective agonist for group I (but not group II and III) mGluRs. Our results point out a selective involvement of group I mGluRs in facilitating burst firing of midbrain dopamine cells.

Action Potentials↗
PubMed2002

Actions of orphanin FQ/nociceptin on rat ventral tegmental area neurons in vitro.

1: Non-dopamine (putative GABAergic) neurons in the ventral tegmental area are in a position to influence mesolimbic functions by their inhibitory terminals that impinge locally on dopamine neurons and via their GABAergic efferents that innervate mesolimbic structures. In the present study we investigated responses of non-dopamine and dopamine neurons, recorded intracellularly in the rat midbrain slice, to orphanin FQ/nociceptin, the endogenous ligand for opioid receptor-like orphan receptors. 2: When recording in either non-dopamine or dopamine neurons, orphanin FQ/nociceptin reduced the frequency of spike firing and caused membrane hyperpolarization under current-clamp, or produced outward current under voltage-clamp. Such responses were concentration-dependent and reversed at -108 mV and -102 mV in non-dopamine and dopamine neurons, respectively. 3: Hyperpolarizations to orphanin FQ/nociceptin were not altered by tetrodotoxin or the opioid receptor antagonist naloxone, but were reduced by the opioid receptor-like orphan receptor antagonist [Phe1(1)phiCH(2)-NH)Gly(2)]NC(1-13)NH(2) (1 microM). 4: In dopamine neurons, orphanin FQ/nociceptin reduced the frequency of bicuculline- and tetrodotoxin-sensitive spontaneous inhibitory postsynaptic potentials, and reduced the amplitude of stimulus-evoked inhibitory postsynaptic potentials. 5: Taken together, the above data provide evidence that both non-dopamine and dopamine neurons are important substrates for orphanin FQ/nociceptin within the ventral tegmental area. Simultaneous inhibition of both non-dopamine and dopamine pathways by orphanin FQ/nociceptin may account for its influences on various ventral tegmental area-related functions.

Analysis of Variance↗
PubMed2002

[Relationship between expression of apoptosis-associated proteins and caspase-3 activity in cisplatin-resistant human ovarian cancer cell line].

BACKGROUND & OBJECTIVE: Cisplatin-based chemotherapy is an important way for treatment of ovarian cancer, but resistance to cisplatin is one of the reasons of treatment failure of ovarian cancer. This study was designed to investigate the relationship between apoptosis-associated proteins and caspase-3 activity as well as their effects on chemoresistance in human ovarian cancer cell lines. METHODS: The expression of apoptosis-associated proteins (bcl-2, bcl-xL, bax, bcl-xs), the activity of caspase-3 and cleavage of poly ADP-ribose polymerase (PARP) were determined with Western blot analysis in the cisplatin-resistant cell (COC1/DDP) and cisplatin-sensitive human ovarian cancer cell (COC1). The apoptotic ratios of COC1 and COC1/DDP were measured with flow cytometry after treated with different concentration of cisplatin. RESULTS: The expression of bcl-2 and bcl-XL in COC1/DDP cell was significantly higher than that in COC1 cell, whereas the expression of bax showed no change in COC1/DDP and COC1. There was no bcl-xs expression in both COC1 and COC1/DDP cells. The activity of caspase-3, the amount of PARP fragments, and apoptotic ratio in COC1/DDP reduced much more than COC1 did after treated with cisplatin. CONCLUSIONS: Cisplatin-resistance in human ovarian cancer cell lines may associated with the overexpression of anti-apoptotic protein bcl-2 and downregulation of caspase-3 activity, but not associated with the expression of bax and bcl-xs.

Antineoplastic Agents↗
PubMed2002

[Relationship between cytochrome c-mediated caspase-3 activity and chemoresistance in cisplatin-resistant human ovarian cancer cell lines].

OBJECTIVE: To investigate the effects of anti-apoptosis gene (bcl-X(L)), cytochrome c and caspase-3 activity on chemoresistance in cisplatin-resistant human ovarian cancer cell lines (A2780/DDP, COC1/DDP). METHODS: The expression of bcl-X(L) cisplatin treated cytochrome c and caspase-3 activity were monitored by RT-PCR and Western blot in cisplatin-resistant (A2780/DDP, COC1/DDP) and cisplatin-sensitive (A2780, COC1) cell lines. The apoptotic rates of A2780, COC1, A2780/DDP and COC1/DDP were detected with flow cytometry after having been treated by cisplatin. RESULTS: The expression of bcl-X(L) in A2780/DDP and COC1/DDP was significantly higher than that in A2780 and COC1 cells, whereas the expression of cytochrome c, caspase-3 activity and apoptotic rates of A2780/DDP and COC1/DDP were significantly reduced more than those of A2780 and COC1 after having been treated by cisplatin (P < 0.05). CONCLUSION: The overexpression of anti-apoptotic gene bcl-X(L), which downregulates cytochrome c and decreases caspase-3 activity, may be related to cisplatin-resistance in human ovarian cancer cell lines.

Antineoplastic Agents↗