Biomedical subjects

Kun Wu

Publications and source records attributed to Kun Wu.

33 records · Page 2Linked to original sources

PubMed2005

[Effective molecular form of alpha-tocopheryl succinate in inducing apoptosis of SGC-7901 cells].

OBJECTIVE: In order to explore the effective molecular form of alpha-tocopherol succinate (alpha-TOS) in inducing apoptosis of human gastric cancer SGC-7901 cell. METHODS: Apoptosis was detected by DAPI staining and DNA ladder, prior to the treatment of cells with alpha-TOS (5 microg/ml, 10 microg/ml and 20 microg/ml) for 48h, alpha-tocopherol (alpha-TOH) (20 microg/ml) and ethanol 1 microl/ml as control groups. HPLC was also used to examine alpha-TOS and alpha-TOH in the cells as well as culture medium. RESULTS: The observation of DAPI showed that the chromatin in karyon of SGC-7901 cells in the 10 microg/ml and 20 microg/ml groups was concentrated with karyopyknosis and karyorrhexis, which were not found in other groups. Typical DNA ladders were obvious in the cells post-administration of alpha-TOS at concentrations 10 microg/ml and 20 microg/ml. It was alpha-TOS not its hydrolyzed product alpha-TOH that was screened out by HPLC in cells and culture medium. CONCLUSION: alpha-TOS was capable of inducting the apoptosis of SGC-7901 cells in its intact form and was independent of alpha-TOH.

Apoptosis↗

PubMed2004

c-Jun N-terminal kinase is required for vitamin E succinate-induced apoptosis in human gastric cancer cells.

AIM: To investigate the roles of c-Jun N-terminal kinase (JNK) signaling pathway in vitamin E succinate-induced apoptosis in human gastric cancer SGC-7901 cells. METHODS: Human gastric cancer cell lines (SGC-7901) were treated with vitamin E succinate (VES) at 5, 10, 20 mg/L. Succinic acid and vitamin E were used as vehicle controls and condition medium only as an untreated (UT) control. Apoptosis was observed by 4', 6-diamidine-2'-phenylindole dihydrochloride (DAPI) staining for morphological changes and by DNA fragmentation for biochemical alterations. Western blot analysis was applied to measure the expression of JNK and phosphorylated JNK. After the cells were transiently transfected with dominant negative mutant of JNK (DN-JNK) followed by treatment of VES, the expression of JNK and c-Jun protein was determined. RESULTS: The apoptotic changes were observed after VES treatment by DNA fragmentation. DNA ladder in the 20 mg/L VES group was more clearly seen than that in 10 mg/L VES group and was not detected following treatment of UT control, succinate and vitamin E. VES at 5, 10 and 20 mg/L increased the expression of p-JNK by 2.5-, 2.8- and 4.2-fold, respectively. VES induced the phosphorylation of JNK beginning at 1.5 h and produced a sustained increase for 24 h with the peak level at 12 h. Transient transfection of DN-JNK blocked VES-triggered apoptosis by 52%. DN-JNK significantly increased the level of JNK, while decreasing the expression of VES-induced c-Jun protein. CONCLUSION: VES-induced apoptosis in human gastric cancer SGC-7901 cells involves JNK signaling pathway via c-Jun and its downstream transcription factor.

Apoptosis↗

PubMed2004

Colored conical emission by means of second harmonic generation in a quadratically nonlinear medium.

Colored conical emission was observed experimentally in a thick beta-barium borate crystal as a result of spatiotemporal modulational instability. In the presence of both dispersion and diffraction, colored conical emission showed specific features that were characteristic of the nonlinear dynamics of the strongly coupled fundamental and harmonic fields. Experimental observation directly demonstrated that beam angular spectra were substantially modified as a result of exponential growth of perturbations by means of parametric wave mixing. Seeded amplification of colored conical emission was demonstrated to support ultrabroadband up-conversion.

Journal Article↗

PubMed2004

Effects of vitamin E succinate on the expression of Fas and PCNA proteins in human gastric carcinoma cells and its clinical significance.

AIM: To investigate the effects of vitamin E succinate (VES) on the expression of Fas and PCNA proteins as well as its clinical significance in human gastric carcinoma, and to explore the mechanism of VES-induced inhibition of gastric carcinoma cell growth. METHODS: Immunohistochemical methods were used to detect Fas and PCNA expression both in human gastric cancer SGC-7901 cells treated with VES at different doses and in human gastric carcinoma tissues. RESULTS: After the SGC-7901 cells were treated with VES at 5, 10, 20 mg/L for 48 h, the positive rates of Fas expression were 16%, 27% and 48%, respectively, significantly increased compared to that of control group (P< 0.05); while the positive rates of PCNA expression in groups treated with different doses of VES were 20%, 18% and 7%, respectively, which were significantly decreased compared to that of the control group (P<0.05). In human gastric carcinoma tissues, the Fas positive expression rate was 42.4%(25/59), which declined with the decrease in the degree of tumor differentiation (P<0.05) and with the existence of lymph node metastasis (P<0.001). While the PCNA positive expression rate was 91.5%(54/59), no relationship was observed between PCNA expression and clinicopathologic parameters. CONCLUSION: VES inhibited the growth of gastric cancer cells by inducing Fas expression and inhibiting PCNA expression. It is, therefore, considered that the expression of Fas and PCNA genes, through tumor cell apoptosis and proliferation, respectively, may be useful as a clinical predictive index in the application of VES to gastric carcinoma therapy, where as Fas may be of more value than PCNA.

Carcinoma↗

PubMed2004

Tra2betal regulates P19 neuronal differentiation and the splicing of FGF-2R and GluR-B minigenes.

The present study demonstrates that the expression of Tra2beta1 (Transformer 2-beta1) proteins, an SR (serine/arginine rich) protein, is developmentally up-regulated in a neural-specific pattern. The up-regulation is also observed in RA (retinoic acid) induced neural differentiation of P19 cells. Tra2betal proteins are located in the nuclei of P19 cells, which are consistent with its functional site as an SR protein. The over-expression of Tra2betal proteins promotes RA induced neuronal differentiation of P19 cells. In P19 cells, the splicing of FGF-2R (fibroblast growth factor receptor 2) minigene produces the BEK form, while the alternative splicing of GluR-B (glutamate receptor subunit B) minigene generates two products, the Flop and the Truncated isoforms. Tra2betal inhibits the BEK splicing, but it promotes the Flop splicing. The results therefore suggest that Tra2betal is involved in the regulation of alternative splicing processes during neural development, peculiarly the splicing of FGF-2R and GluR-B genes. Both FGF-2R and GluR-B genes are known to play important roles in neural differentiation.

Alternative Splicing↗

PubMed2004

[Efficient soluble expression, purification and identification of the truncated SAG1 gene of Toxoplasma gondii in Escherichia coli].

OBJECTIVE: To express truncated SAG1 gene in Escherichia coli to obtain purified recombinant SAG1, and identify the immunoreactivity of the product. METHODS: The plasmid pET-30a(+)-trSAG1 was constructed, which was cut by Nco I and HindIII to obtain truncated SAG1 gene and inserted into pET-32a(+) cut by the same two restriction enzymes. After identification by restriction enzymes, the plasmid pET-32a(+)-trSAG1 was transformed into E.coli BL21, and the soluble product induced by 0.1 mmol/L IPTG for 4 hour before purification with Ni-NTA agarose, followed by identification of the purified recombinant protein with SDS-PAGE, Western-blotting and ELISA. RESULTS: Recombinant pET-32a(+)-trSAG1 was successfully constructed and high level of truncated SAG1 expression achieved in E.coli. SDS-PAGE showed that the expressed protein was approximately 40,000 in size and expressed in a soluble form that could be easily purified by Ni-NTA agarose. Western-blotting demonstrated that the purified product could be specifically recognized by sera from rabbits immunized with native antigen of T.gondii, and could also be recognized, as shown by ELISA, by sera from human with T.gondii infection. CONCLUSIONS: The truncated SAG1 gene was successfully expressed in E.coli in a soluble form, and the recombinant protein may be of value in the diagnosis of toxoplasmosis.

Animals↗

PubMed2004

[Function of Tra2beta1 proteins in the splicing of neural-specific genes].

The in vitro studies have shown that Tra2beta1 proteins are important regulators in the alternative pre-mRNA splicing in mammalians. To date, the knowledge regarding the in vivo function of Tra2beta1 proteins, especially the function in regulating the splicing of neural-specific genes and the cell-type specificity of the functions is very limited. In the present study, the cell-type specific splicing of two neural-specific genes (GluR-B and SMN2), and the function of Tra2beta1 proteins in regulation of the splicing were studied in two types of cells (COS-1 and PFSK-1) using in vivo splicing models. The results showed that the splicing of GluR-B and SMN2 minigenes is cell-type specific, while Tra2beta1 proteins regulate the splicing of the minigenes in both cell lines in a similar pattern. It indicates that the Tra2beta1-regulated splicing of GluR-B and SMN2 minigenes regulated by Tra2beta1 is not cell-type specific.

Alternative Splicing↗

PubMed2004

[Structural basis of alpha-tocopherol succinate as an antineoplastic agent].

Alpha-tocopherol succinate is a redox-silent analog of alpha-tocopherol which is the major component of vitamin E. Recently, the research findings showed that, as a kind of pro-vitamin E, alpha-tocopherol succinate possesses antineoplastic activity which alpha-tocopherol lacks of. In this review paper, the link between the structure and antineoplastic activity of alpha-tocopherol succinate was focused.

Antineoplastic Agents↗

PubMed2003

[The expression and activity of caspase-8 in the process of vitamin E succinate-induced apoptosis in human gastric carcinoma SGC-7901 cells].

OBJECTIVE: To investigate the role of caspase-8 in vitamin E succinate (VES)-induced apoptosis in human gastric carcinoma cells. METHODS: The expression and activity of caspase-8 were measured by the Western Blot method with fluorescence and DAPI staining. RESULTS: VES treatment induced the expression and activity of caspase-8 in a dose-dependent manner; the apoptosis ratio induced by VES was significantly decreased in SGC-7901 cells treated with caspase-8 inhibitor. CONCLUSION: Caspase-8 plays an important role in SGC-7901 cell apoptosis induced by VES.

Apoptosis↗

PubMed2003

[Roles of ERK1/2 MAPK in vitamin E succinate-induced apoptosis in human gastric cancer SGC-7901 cells].

In order to investigate the roles of ERK1/2 mitogen-activated protein kinase in vitamin E succinate (VES)-induced apoptosis in human gastric cancer SGC-7901 cells, apoptosis was observed by DAPI staining and the phosphorylation of ERK1/2 by VES at different doses and different time points was measured by western blot. The results showed that VES obviously induced cells to undergo apoptosis and apoptotic rate after 24 h and 48 h of treatment with VES at 20 micrograms/ml. VES was 14.2% and 89.4%, respectively. The expression of p-ERK was evidently reduced by VES at 5, 10 and 20 micrograms/ml for 24 h. ERK1/2 was immediately activated by VES at 20 micrograms/ml, but the expression was decreased for 2 h, then increased again and reached the top level for 12 h. The data implicated that ERK1/2 pathway might be involved in VES-induced apoptosis, but in the proliferation eventually.

Apoptosis↗

PubMed2002

RRR-alpha-tocopheryl succinate inhibits human gastric cancer SGC-7901 cell growth by inducing apoptosis and DNA synthesis arrest.

AIM: To investigate the effects of growth inhibition of human gastric cancer SGC-7901 cell with RRR-alpha-tocopheryl succinate (VES), a derivative of natural Vitamin E, via inducing apoptosis and DNA synthesis arrest. METHODS: Human gastric cancer SGC-7901 cells were regularly incubated in the presence of VES at 5, 10 and 20mg x L(-1) (VES was dissolved in absolute ethanol and diluted in RPMI 1640 complete condition media correspondingly to a final concentration of VES and 1 mL x L(-1) ethanol), succinic acid and ethanol equivalents as vehicle (VEH) control and condition media only as untreated (UT) control. Trypan blue dye exclusion analysis and MTT assay were applied to detect the cell proliferation. Cells were pulsed with 37kBq of tritiated thymidine and (3H) TdR uptake was measured to observe DNA synthesis. Apoptotic morphology was observed by electron microscopy and DAPI staining. Flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were performed to detect VES-triggered apoptosis. RESULTS: VES inhibited SGC-7901 cell growth in a dose-dependent manner. The growth curve showed suppression by 24.7%, 49.2% and 68.7% following 24h of VES treatment at 5, 10 and 20 mg x L(-1), respectively, similar to the findings from MTT assay. DNA synthesis was evidently reduced by 35%, 45% and 98% after 24h VES treatment at 20mg x L(-1) and 48 h at 10 and 20mg x L(-1), respectively. VES induced SGC-7901 cells to undergo apoptosis with typically apoptotic characteristics, including morphological changes of chromatin condensation, chromatin crescent formation/margination, nucleus fragmentation and apoptotic body formation, typical apoptotic sub-G1 peak by flow cytometry and increase of apoptotic cells by TUNEL assay in which 90% of cells underwent apoptosis after 48 h of VES treatment at 20 mg x L(-1). CONCLUSION: VES can inhibit human gastric cancer SGC-7901 cell growth by inducing apoptosis and DNA synthesis arrest. Inhibition of SGC-7901 cell growth by VES is dose- and time-dependent. Therefore VES can function as a potent chemotherapeutic agent against human gastric carcinogenesis.

Apoptosis↗

PubMed2002

The effects of vitamin E succinate on the expression of c-jun gene and protein in human gastric cancer SGC-7901 cells.

AIM: To investigate the effects of vitamin E succinate (VES) on the expression of c-jun gene and protein in human gastric cancer SGC-7901 cells. METHODS: After SGC-7901 cells were treated with VES at different doses (5,10,20 mg x L(-1)) at different time, reverse transcription-PCR technique was used to detect the level of c-jun mRNA; Western Blot was applied to measure the expression of c-jun protein. RESULTS: After the cells were treated with VES at 20 mg x L(-1) for 3 h, the expression rapidly reached its maximum that was 3.5 times of UT control (P<0.01). The level of c-jun mRNA was also increased following treatment of VES for 6 h. However,the expression after treatment of VES at 5 mg x L(-1) for 24 h was 1.6 times compared with UT control (P<0.01). Western blot analysis showed that the level of c-jun protein was obviously elevated in VES-treated SGC-7901 cells at 20 mg x L(-1) for 3 h. The expression of c-jun protein was gradually increased after treatment of VES at 20 mg x L(-1) for 3, 6, 12 and 24 h, respectively, with an evident time-effect relationship. CONCLUSION: The levels of c-jun mRNA and protein in VES-treated SGC-7901 cells were increased in a dose- and time-dependent manner; the expression of c-jun was prolonged by VES, indicating that c-jun is involved in VES-induced apoptosis in SGC-7901 cells.

Blotting, Western↗

PubMed2002

Roles of Fas signaling pathway in vitamin E succinate-induced apoptosis in human gastric cancer SGC-7901 cells.

AIM: To investigate the roles of Fas signaling pathway in vitamin E succinate-induced apoptosis in human gastric cancer SGC-7901 cells. METHODS: Human gastric cancer SGC-7901 cells were treated with VES at 5, 10, 20 mg x L(-1), succinic acid and vitamin E as vehicle control and condition media only as untreated (UT) control. Apoptotic morphology was observed by DAPI staining. Western blot analysis was applied to measure the expression of Fas, FADD and caspase-8 proteins. After the cells were transiently transfected with Fas and FADD antisense oligonucleotides, respectively, caspase-8 activity was determined by flurometric method. RESULTS: The morphologically apoptotic changes were observed after VES treatment by DAPI staining. 23.7 % and 89.6 % apoptosis occurred after 24 h and 48 h of 20 mg x L(-1) VES treatment, respectively. The protein levels of Fas, FADD and caspase-8 were evidently increased in a dose-dependent manner after 24 h of VES treatment. The blockage of Fas by transfection with Fas antisense oligonucleotides obviously inhibited the expression of FADD protein. After SGC-7901 cells were transfected with Fas and FADD antisense oligonucleotides, caspase-8 activity was obviously decreased (P<0.01), whereas Fas blocked more than FADD. CONCLUSION: VES-induced apoptosis in human gastric cancer SGC-7901 cells involves Fas signaling pathway including the interaction of Fas, FADD and caspase-8.

Adaptor Proteins, Signal Transducing↗

PubMed2002

[Preliminary study of cercaria antigen of Schistosoma japonicum before and after ultraviolet irradiation].

OBJECTIVE: To study the changes in the constituents of the cercaria antigen of Schistosoma japonicum before and after ultraviolet irradiation. METHODS: The cercaria of Schistosoma japonicum were exposed to ultraviolet light (UV) irradiation at a dose of 400 mgrW/cm2 for 1 min, and the UV-irradiated cercaria antigen (UVCA) and normal cercaria antigen (NCA) were simultaneously analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. RESULTS: At least 2 antigens with relative molecular mass (Mr) of 212 000 and 82 000 were identified in UVCA but not in NCA by SDS-PAGE analysis, and the concentrations of the antigens with Mr of 116 000, 26 000 and 16 000 in UVCA were significant higher than those in NCA. On the other hand, the antigenic molecule with Mr of 67 000 in NCA was recognized by serum from pigs vaccinated with UV-attenuated cercariae, but not by serum from pigs with Schistosoma japonicum infection. Antigens with Mr of 79 000 and 94 000 were apparently more strongly reactive with the former porcine serum than with the latter. CONCLUSION: The results suggest that all the novel antigens arising from or increased by UV exposure, or antigens specifically recognized by serum from pigs vaccinated by UV-attenuated carcariae may be the principal factors in the highly protective immunity provoked by irradiated cercariae.

Animals↗

PubMed2002

In vitro amplification of Toxoplasma gondii rhoptry protein 2 gene and construction of its eukaryotic expression plasmid.

OBJECTIVE: To construct a recombinant eukaryotic expression plasmid containing rhoptry protein 2 (ROP2) gene of Toxoplasma gondii. METHOD: The truncated ROP2 gene was amplified from the genomic DNA of Toxoplasma gondii RH strain and cloned into plasmid pGEX-4T-1. The PCR product was subcloned into an eukaryotic expression plasmid pcDNA3 which was identified by enzyme digestion and PCR amplification. Sequence analysis of the insert in the recombinant plasmid was performed by Sanger's method. RESULTS: The amplified DNA fragment was about 1043 bp in length, with identical sequence with the published ROP2 gene sequence. Enzyme digestion and PCR analysis showed that the truncated ROP2 gene had been successfully cloned into plasmid pGEX-4T-1 and pcDNA3. CONCLUSION: The truncated ROP2 gene of Toxoplasma gondii has been amplified and cloned into the eukaryotic expression plasmid pcDNA3.

Animals↗