Biomedical subjects

Hui Peng

Publications and source records attributed to Hui Peng.

At least 37 records · Page 2Linked to original sources

PubMed2005

Electrochemical detection of DNA hybridization amplified by nanoparticles.

Detection of specific oligonucleotide (ODN) fragments has become an important field in many areas of biomedicine. We describe a novel ODN sensor based on electropolymerization of a conducting polymer (polypyrrole) in the presence of a sample containing ODN(s). The resulting trapped ODN(s) are then probed by addition of complimentary sequence ODN. By incorporating CdS nanoparticles with the probe, a significant improvement in sensor sensitivity was observed. Impedance spectroscopy suggested that optimal detection of hybridization occurred at frequencies>or=3000 Hz (for a 0.07 cm2 85 nm thick film). At these frequencies, the impedance signal was almost linear with the logarithm of ODN concentration in the range 3.7-370 nM with a detection limit of approximately 1 nM ODN (for the sensor fabricated). Importantly, the sensor could be regenerated by removing hybridized ODN with NaOH suggesting possibility of the sensor re-use.

Biosensing Techniques↗

PubMed2005

Expression profiling of ABC transporters in a drug-resistant breast cancer cell line using AmpArray.

ATP-binding cassette (ABC) membrane proteins comprise a superfamily of transporters with a wide variety of substrates. Humans have 49 members in this superfamily. Several human ABC transporters, such as ABCB1 and ABCC1, have been attributed to cause multidrug resistance (MDR) in cancer treatment when over-expressed. In the past, an MDR cancer cell line MCF7/AdVp3000 has been selected, and overexpression of ABCG2 was thought to cause MDR in this cell line. However, ectopic overexpression of ABCG2 in MCF7 cells could not explain the high drug resistance level observed with the selected cell line. In this study, we designed an AmpArray analysis to profile whether other ABC transporters were also selected to contribute to the increased drug resistance in MCF7/AdVp3000 cells. We found that 16 ABC transporters, including ABCG2, had >/=1.5-fold altered expression in MCF7/AdVp3000 compared with the parental MCF7 cells. In particular, the expression of ABCA4 and ABCC3 was increased by 132- and 459-fold, respectively, whereas ABCG2 was increased by approximately 3000-fold. Furthermore, the elevated expression of these three transporters reversed with the reversed drug resistance phenotype, and silencing ABCC3 expression in MCF7/AdVp3000 cells significantly reduced doxorubicin resistance. Thus, other ABC transporters in addition to ABCG2 are likely to contribute to the MDR selected in MCF7/AdVp3000 cells. This study also shows that AmpArray can be used as a quick and easy tool to profile the expression of ABC transporters in resistant cell lines and tumor samples for potential use in individualized design of therapy.

ATP-Binding Cassette Transporters↗

PubMed2005

Label-free electrochemical DNA sensor based on functionalised conducting copolymer.

A simple and label-free electrochemical sensor for recognition of the DNA hybridization event was prepared based on a new functionalised conducting copolymer, poly[pyrrole-co-4-(3-pyrrolyl) butanoic acid]. This precursor copolymer can be easily electrodeposited on the electrode surface and shows high electroactivity in an aqueous medium. An amino-substituted oligonucleotide (ODN) probe was covalently grafted onto the surface of the copolymer in a one step procedure and tested on hybridization with complementary ODN segments. The cyclic voltammogram of ODN probe-modified copolymer showed very little change when incubated in presence of non-complementary ODN, while a significant, and reproducible, modification of the voltammogram was observed after addition of complementary ODN. The AC impedance spectrum showed an increased charge transfer resistance (Rct) and double layer capacitance of the sensor film after hybridisation. Sensors with thinner films showed higher sensitivity than thicker films, suggesting that hybridisation at or near the surface of the film produces a larger change in electrical properties than that within the body of the film.

Biosensing Techniques↗

PubMed2005

[Haplotype and linkage analysis in Chinese hereditary mixed polyposis syndrome].

OBJECTIVE: To investigate if hereditary mixed polyposis syndrome (HMPS) locus of two Singapore Chinese HMPS families is identical with the Ashkenazi families. METHODS: Genomic DNA was extracted, multiplex polymerase chain reaction (PCR) was used to amplify 4 microsatellite markers D15S1010, D15S1007, ACTC and D15S118 in 31 individuals from two families. The HMPS locus cosecretion of the markers on 15q13 over a region of 2.8 cM was confirmed by Haplotype and linkage analysis. RESULTS: The disease of haplotype identified in one pedigree was not co-segregated with an affected individual while no definitive disease haplotype could be assigned for the second pedigree. The maximum two-point and multi-point LOD scores at ACTC for the two Chinese families are 0.20 (theta = 0.3) and -5.0 respectively. CONCLUSIONS: Haplotype and linkage analysis indicate that the Ashkenazi haplotypes is not associated with HMPS in Singapore Chinese families, which suggests genetic heterogeneity.

Adenomatous Polyposis Coli↗

PubMed2005

[Specific targeting cytotoxicity to resistant leukemia cells mediated by anti-Pgp/anti-CD3 diabody].

OBJECTIVE: To study the specific targeting cytotoxicity to drug-resistant leukemia cells mediated by anti-Pgp/anti-CD3 diabody. METHODS: The diabody was purified by affinity chromatography and identified by SDS-PAGE and FACS. The effect of the anti-Pgp/anti-CD3 diabody mediated lysis of Pgp-expressing tumor cells was assayed by human leukemia nude mice xenograft model in vivo. RESULTS: The diabody was produced in E.coli in a soluble functional form and could bind both Jurkat cells (CD3(+)) and K562/A02 cells (Pgp(+)). The binding rates were 86.25% and 86.26%, respectively. It could inhibit tumor growth by 98.57% and prolonged the survival of mice bearing xenografted K562/A02 cells. CONCLUSION: The diabody was proved to be a potent agent for mediating T lymphocyte cytotoxicity to lyse Pgp expressing tumor cells in vitro and in vivo.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

[Improvement of heavy metal removing strain by protoplast combination mutant].

Ultraviolet and HNO2 were selected as the mutagens to perform the single factor and multi-factor induction mutation towards Candida utilis CR-001. Six mutant strains which possessed high heavy metal removal efficiency and high resistance to Cr6+ were obtained through combined induction with UV and HNO2. After they were subcultured for 10 generations, the diameter of bacteriostatic circle of CRC2811-1 and CRC7-2 was reduced to 1.7 mm and 1.2 mm respectively, while the Cr6+ removal efficiency of CRC2811-1 was increased from 80.2% to 95.2%, and that of CRC7-2 was from 81.2% to 94.7%. The stability of the other 4 mutant strains was rather stable. Furthermore, precipitation of chromium outside or inside the cell was studied by using combined technique of scanning electron microscopy(SEM), transmission electron microscopy (TEM), and atomic force microscopy(AFM), and the mechanism of chromium removal improvement by the mutant strains was discussed.

Biodegradation, Environmental↗

PubMed2005

[An anti-P-gp/anti-CD3 bispecific antibody cytotoxic to human multidrug resistant KB cells].

OBJECTIVE: To study the specific cytotoxicity mediated by anti-P-gp/anti-CD(3) diabodies in multidrug resistant solid tumor using P-gp as target. METHODS: The anti-P-gp/anti-CD(3) diabodies were secreted from E. coli strain 16C9 containing the expression plasmid PAYZDCP, grown at 30 degrees C in a shaker flask; the diabodies were purified by affinity chromatography and identified by SDS-PAGE; the effect of the anti-P-gp/anti-CD(3) diabody mediated lysis of P-gp-expressing tumor cells was assayed by (51)Cr release assay in vitro, and by human KB nude mouse xenograft models in vivo. RESULTS: The diabodies were generated by bacteria as a soluble functional form and purified by one-step affinity chromatography with a yield > 4 mg/L culture medium. In (51)Cr release assay, the diabodies targeted human activated T cells to lyse P-gp(+)-KB/MDR cells in a dose-dependent manner. It suggested that the diabody was able to induce an efficient lysis of the target cells by human T cells in vitro. When combined with activated human T cells, the diabody significantly inhibited the growth of KB/MDR, but had no effect on KB xenografts. CONCLUSION: The anti-P-gp/anti-CD(3) bispecific antibody is a potent agent for targeting human T lymphocytes to lyse solid tumor cells overexpressing P-gp in vitro and in vivo.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

Retinoid-modulated MAT1 ubiquitination and CAK activity.

Human cyclin-dependent kinase (CDK)-activating kinase (CAK) has a dual function in cross-regulation of cell cycle and differentiation, whereas menage a trois 1 (MAT1) assembles CAK and determines CAK's substrate specificity. Although the dynamic state of MAT1 protein levels is found to modulate CAK activity, how intracellular regulation of MAT1 controls CAK activity is unknown. Recent studies demonstrate that retinoic acid (RA)-induced human HL60 cell proliferation/differentiation (P/D) transition is accompanied by MAT1 degradation and decreased CAK phosphorylation of retinoic acid receptor alpha (RARa). Thus, we investigated the biochemical pathway of MAT1 degradation and its relationship with CAK phosphorylation of RARa. We find that RA induces ubiquitination-proteolysis of MAT1 and that ubiquitin-proteasome targets CAK-free MAT1 only. RA-induced MAT1 ubiquitination reduces CAK abundance and decreases CAK phosphorylation of RARalpha, whereas inhibition of MAT1 ubiquitination resists this RA-effect. These findings reveal that RA induces MAT1 ubiquitination to decrease CAK phosphorylation of RARalpha, suggesting a novel mechanism of RA-mediated P/D transition in which MAT1 ubiquitination may act as an integral part of RA-effect to decrease CAK activity in the switch from proliferation to differentiation.

Cell Differentiation↗

PubMed2004

Pyronaridine, a novel modulator of P-glycoprotein-mediated multidrug resistance in tumor cells in vitro and in vivo.

One of the major mechanisms of multidrug resistance (MDR) in cancer therapy is the overexpression of P-glycoprotein (Pgp). We previously reported that pyronaridine (PND), a synthetic quinoline derivative in the clinic for the treatment of malaria infections, was capable of reversing MDR phenotype in Pgp-overexpressing tumor cells. Here we further evaluated the reversal activity of PND using two Pgp-overexpressing human tumor cell lines: K562/A02 and MCF-7/ADR. PND significantly enhanced the sensitivity of K562/A02 and MCF-7/ADR cells to doxorubicin (DOX), but had no such effect on the parent K562 and MCF-7 cells. The MDR-modulating effect of PND persisted for longer than 24h after removal of the agent from the culture. In nude mice bearing K562/A02 xenografts PND significantly enhanced the antitumor activity of DOX when given intraperitoneally or orally without increasing the toxicity of DOX. Our observations suggest that PND represents a promising agent for overcoming MDR in cancer therapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

MAT1-modulated cyclin-dependent kinase-activating kinase activity cross-regulates neuroblastoma cell G1 arrest and neurite outgrowth.

Cyclin-dependent kinase-activating kinase (CAK) regulates cell cycle G1 exit, where cells commonly commit either to proliferate or to differentiate. CAK activity in G1 regulation is determined by its assembly factor and targeting subunit, ménage à trois 1 (MAT1). The precise mechanism of how proliferation/differentiation transition is induced from cancer cell G1 arrest remains unknown. We present evidence that in neuroblastoma CHP126 cells, CAK interacts with and phosphorylates retinoblastoma tumor suppressor protein (pRb) and retinoid X receptor alpha (RXRalpha). Retinoic acid (RA)-induced neuroblastoma cell proliferation/differentiation transition is associated with decreased CAK activity, as evidenced by a switch from CAK hyperphosphorylation of pRb and RXRalpha to hypophosphorylation of pRb and RXRalpha. Manipulation of MAT1 abundance shows that MAT1 reduction mimics RA-induced hypophosphorylation of pRb/RXRalpha, proliferation inhibition, and neurite outgrowth, whereas MAT1 overexpression resists these RA actions. Thus, these findings reveal an important mechanism by which MAT1-modulated CAK activity is crucial in the switch from proliferation to differentiation in neuroblastoma cells.

Alitretinoin↗

PubMed2004

Stromal cell-derived factor 1-mediated CXCR4 signaling in rat and human cortical neural progenitor cells.

Stromal cell-derived factor 1 (SDF-1) and the chemokine receptor CXCR4 are highly expressed in the nervous system. Knockout studies have suggested that both SDF-1 and CXCR4 play essential roles in cerebellar, hippocampal, and neocortical neural cell migration during embryogenesis. To extend these observations, CXCR4 signaling events in rat and human neural progenitor cells (NPCs) were examined. Our results show that CXCR4 is expressed in abundance on rat and human NPCs. Moreover, SDF-1alpha induced increased NPCs levels of inositol 1,4,5-triphosphate, extracellular signal-regulated kinases 1/2, Akt, c-Jun N-terminal kinase, and intracellular calcium whereas it diminished cyclic adenosine monophosphate. Finally, SDF-1alpha can induce human NPC chemotaxis in vitro, suggesting that CXCR4 plays a functional role in NPC migration. Both T140, a CXCR4 antagonist, and pertussis toxin (PTX), an inactivator of G protein-coupled receptors, abrogated these events. Ultimately, this study suggested that SDF-1alpha can influence NPC function through CXCR4 and that CXCR4 is functional on NPC.

Animals↗

PubMed2004

Inhibition of human B-cell lymphoma by an anti-CD20 antibody and its chimeric F(ab')2 fragment via induction of apoptosis.

Monoclonal antibodies (mAb) directed against CD20, either unmodified or in radiolabeled forms, have been successfully used in clinic as effective therapeutic agents in the management of non-Hodgkin's B-cell lymphoma. Despite all clinical success the exact mechanisms of action of various anti-CD20 antibodies remains mostly unclear. Several mechanisms have been proposed to be responsible for the therapeutic activity of anti-CD20 antibodies, including antibody-dependent cell-mediated cytotoxicity, complement-mediated cytotoxicity, and direct inhibition of tumor growth via induction of apoptosis. We previously produced an anti-CD20 mAb, HI47, and showed that the antibody effectively blocked human B-cell proliferation in vitro and inhibited xenografted B-cell lymphoma in nude mice. In this study, we engineered the chimeric versions of both the Fab and F(ab)'2 fragments of HI47 and produced the fragments in E. coli. Both fragments competed efficiently with HI47 for binding to CD20+ B cells, and inhibited proliferation of B-lymphoma cells in a dose-dependent manner. Mechanistic studies revealed that both antibody fragments induced significant degree of B-cell apoptosis that is independent of any cross-linking agents. Further, both the F(ab)'2 and Fab fragments when administered in vivo significantly inhibited the growth of human B-cell lymphoma xenografts in nude mice. The bivalent F(ab)'2 fragment showed consistently better efficacy compared to its monovalent Fab counterpart in inducing apoptosis and inhibiting B-cell lymphoma growth both in vitro and in vivo. Taken together, these observations suggest that HI47 and its fragments most likely exert their antitumor activity through induction of cell apoptosis, and cross-linking/dimerization of CD20 molecules on B- cell surface is an important, but not essential, process for therapeutic efficacy of HI47 and its fragments.

Animals↗

PubMed2004

TNF-related apoptosis-inducing ligand mediates human neuronal apoptosis: links to HIV-1-associated dementia.

TNF-related apoptosis-inducing ligand (TRAIL) is a type II integral membrane protein that interacts with multiple receptors and cell types including neurons. In this report, TRAIL protein levels were increased in human monocyte-derived macrophages (MDM) after HIV-1 infection and immune activation. In HIV-1 encephalitic (HIVE) human brain tissue, TRAIL-expressing macrophages were found in association with active caspase-3 positive neurons. Cytotoxic TRAIL receptors 1 and 2 were expressed on neurons in primary human fetal cultures and HIV-1 encephalitic brain tissue. Furthermore, TRAIL induced a dose-dependent effect on neuronal apoptosis. These results support a role for TRAIL in mononuclear phagocyte (MP)-mediated neurotoxicity in HIV-1-associated dementia (HAD).

AIDS Dementia Complex↗

PubMed2004

Classification of HIV-1-mediated neuronal dendritic and synaptic damage using multiple criteria linear programming.

The ability to identify neuronal damage in the dendritic arbor during HIV-1-associated dementia (HAD) is crucial for designing specific therapies for the treatment of HAD. To study this process, we utilized a computer-based image analysis method to quantitatively assess HIV-1 viral protein gp120 and glutamate-mediated individual neuronal damage in cultured cortical neurons. Changes in the number of neurites, arbors, branch nodes, cell body area, and average arbor lengths were determined and a database was formed (http://dm.ist.unomaha. edu/database.htm). We further proposed a two-class model of multiple criteria linear programming (MCLP) to classify such HIV-1-mediated neuronal dendritic and synaptic damages. Given certain classes, including treatments with brain-derived neurotrophic factor (BDNF), glutamate, gp120 or non-treatment controls from our in vitro experimental systems, we used the two-class MCLP model to determine the data patterns between classes in order to gain insight about neuronal dendritic damages. This knowledge can be applied in principle to the design and study of specific therapies for the prevention or reversal of neuronal damage associated with HAD. Finally, the MCLP method was compared with a well-known artificial neural network algorithm to test for the relative potential of different data mining applications in HAD research.

Animals↗

PubMed2004

[Molecular design and biological activity of BCR-ABL tyrosine kinase inhibitors].

OBJECTIVE: To discover BCR-ABL tyrosine kinase inhibitors through structure based virtual screening. METHODS: Docking screening against the distinctive inactive conformation of the catalytic domain of BCR-ABL tyrosine kinase was performed on 3D database. The MTT assay was performed to assess the viability of the tumor cells treated with selected compounds. The amount and kinase activity of BCR-ABL protein were detected in the presence of compounds by Western blot analysis and immunoprecipitation. RESULTS: From the top 1,000 compounds with the best DOCK energy score, 15 compounds were selected for biological assay. Eight out of 15 compounds showed notable inhibitory activity against Ph+ human K562 cells with IC50 values ranging from 10 to 200 micromol/L. In cell-based assays of ABL tyrosine phosphorylation, the ability of two kinds of novel, structurally diverse, lead compounds to inhibit ABL kinase activity was observed. However, no significant differences in the amount of BCR-ABL protein were noted on the ABL immunoblot in the presence of these lead compounds. CONCLUSIONS: Two promising lead compounds were discovered to inhibit BCR-ABL tyrosine kinase activity. Virtual screening technique has been proven to narrow down the size of screening compound libraries to the most prospective drug candidates with high success rates.

Computer Simulation↗

PubMed2004

[Establishment of an imatinib resistant cell line K562/G01 and its characterization].

OBJECTIVE: To establish a BCR/ABL+ cell line with resistance to imatinib, and investigate the possible mechanisms of the acquired resistance. METHODS: K562 cells were cultured in gradually increased concentrations of imatinib over a period of several months to generate their resistance line. MTT assay, RT-PCR, Western blotting, and FISH were used to study the possible molecular mechanisms of the resistance. RESULTS: A resistant cell line, K562/G01, was established with 15.2 +/- 3.0-fold resistant to imatinib as compared with that of the parental sensitive cell line. The resistant cell line also had the cross-resistance to a broad spectrum of other anticancer agents excepting for DOX. There was no difference between the two cell lines in terms of the cell morphology, proliferation doubling time, and fraction distribution of cell cycle. K562/G01 cells showed increased levels of BCR/ABL, mdr1 mRNA and their coding proteins and the increased tyrosine kinase activity. No point mutation in the BCR/ABL ATP-binding site was detected while the copies of BCR/ABL fusion gene were increased in K562/G01 cells. CONCLUSION: An imatinib-resistant human leukemia cell line, K562/G01, was established. The mechanisms of resistance of K562/G01 cells to imatinib involved increased expression of BCR/ABL and mdr1/P-gp, amplification of BCR/ABL fusion gene, and increased activity of BCR/ABL.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2004

[Identification of differentially expressed genes involved in multidrug resistance in K562/A02 by cDNA microarray].

OBJECTIVE: To study the molecular mechanism underlying multidrug resistance (MDR) and identify unknown genes that might be involved in drug resistance development in K562/A02 cells. METHODS: K562/A02 was induced by gradually increasing the ADM concentration in culture medium of K562 cells, the differential expression of associated genes between K562 and K562/A02 was determined with cDNA microarray. Overexpression of neurofilament protein NF-H gene in K562/A02 cells was confirmed with RT-PCR and immunocytochemistry. Anti-sense oligodeoxynucleotides were transfected into K562/A02 cells by lipofectamine in order to further analyze the role of NF-H in drug resistance. RESULTS: Comparing with the expression profiles, we found upregulation of 5 transcripts and downregulation of 7 transcripts in response to MDR of K562/A02 cells. The overexpression of NF-H, one of the 5 upregulated genes, was confirmed. After being treated with antisense oligodeoxynucleotides of NF-H and mdr1, the cellular adriamycin concentration increased significantly, but antisense NF-H alone did not have significant effect on drug resistance phenotype. CONCLUSION: The development of MDR in K562/A02 cells is multifactorial. NF-H may be involved in the drug resistance of K562/A02, which may provide a new marker of diagnosis and a new target of therapy.

Doxorubicin↗

PubMed2004

[Adsorbing capability of chromium-galvanized waste water by yeast-activated sludge].

The capability of bioadsorption and bioreduction of chromium-galvanized wastewater by Candida lipolytica 1977, Candida utilis 1225, and activated sludge was discussed in this paper. The experimental results showed that the feasible pH range for C. lipolytica 1977 adsorption was wide. The removal and reduction ratios of C. lipolytica 1977 towards chromium-galvanized wastewater were 85.0%, and 100%, when pH was 3.2-6.0, and the concentrations of Cr(total) and Cr6+ were 30.2 mg/L, 27.7 mg/L respectively. The removal ratio increased to 91.1%, when the chromium-galvanized wastewater was treated by two strains together. The aerobic bioadsorption treatment of chromium-galvanized wastewater was investigated. The results demonstrated that this method was the optimal one for the treatment of this kind of wastewater in the study, the removal ratio was 93.8%, when the concentrations of yeast, activated sludge, Cr(total) and Cr6+ were 10 g/L, 5 g/L, 50.3 mg/L and 46.2 mg/L, respectively. The removal ratio increased to 99.5% accordingly, when the activated sludge content was 10 g/L.

Adsorption↗