Empty Plasmid Group Research Articles

Inhibition effect of 1-methyl-tryptophan on transplant hepatocellular carcinoma growth in mice subcutaneous

Objective To investigate the inhibitory effect of 1-methyl-tryptophan (1-MT) on transplanted hepatocellular carcinoma in mice.Methods Human hepatocellular carcinoma subcutaneous tumor models were established in mice,and the mice were divided into hepG2 group,empty plasmid group,indoleamine 2,3-dioxygenase (IDO) saline group,IDO) 5-fluoropyrimidine (5-FU) group,IDO 1-MT group,and the group combining IDO 1-MT with 5-FU treatment (n=8 in each group).The tumor growth,tumor volume and pathological examination were observed and the expression of IDO in tumor tissues was determined by immunohistochemistry.Results Compared with hepG2 and the empty vector saline groups,IDO saline group had bigger tumor,faster growth,and the differences were statistically significant (P＜0.05).Compared with IDO saline group,5-FU group,1-MT group and combination treatment groups showed smaller tumor volume and weight,and the tumor inhibitory rates were 86.54％,79.95％,94.46％,respectively.There were significant differences between these groups (P＜0.05).However,there were no significant differences in tumor volumes between 5-FU group and 1-MT group (P＞0.05).HE pathological observation of ceils in each treatment group showed reduced density,increased necrotic area and significant decrease in peripheral blood alpha-fetoprotein (P＜0.05).Conclusions IDO can promote the growth of liver cancer cells involved in immune escape.1-MT can inhibit the transplanted tumor growth in mice,and therefore may enhance the chemotherapeutic efficacy. Key words: 1-methiyl tryptophan; Indoleamine 2,3-dioxygenase; Hepatocellular carcinoma; Immune therapy

The effect of small ubiquitin-like modifier-1 modification on the formation of Lewy body-like inclusions in cytoplasm and apoptosis of HEK293 cell induced by overexpression and mutation of alpha-synuclein

To investigate the effect of small ubiquitin-like modifier (SUMO-1) modification on the formation of Lewy body like inclusions in cytoplasm and apoptosis of HEK293 cell induced by overexpression and mutation of alpha-synuclein. cDNA encoding the human alpha-synuclein without the stop codon was cloned into a pGEM T-easy vector. Restriction enzyme mapping and DNA sequencing were performed to analyze the plasmid, which was then subcloned into a pEGFP-N1 vector. The recombinant plasmid alpha-synuclein-pEGFP was transfected into HEK293 cells by lipofectamin method. Inclusions in the cultured cells were identified with HE staining. Apoptosis of the HEK293 cell was measured by Hoechst 33258 staining, MTT and Annexin V-PE flow cytometry. The Lewy-body like inclusions were found in cytoplasm of cultured cells. Hoechst staining showed that the nuclei of cells were enlarged in the wild-type and A53T mutation groups 48 h after transfection, chromatin were accumulated and appeared spot-like. The nucleus stain was equitable in the K96R and K96R-A53T groups. MTT assay showed that the viability of cells transfected with empty plasmid was 96.2%, but it dropped to 53.4% and 56.1% in cells transfected with wild-type alpha-synuclein-pEGFP and A53T mutant group, respectively. The viability was 72.3% and 69.8% in cells transfected with K96R and K96R-A53T, respectively (P<0.05). Forty eight hours after transfection, the apoptosis rate was 3.9% in empty plasmid group, 32.2% and 34.1% in cells transfected with wild-type and mutant alpha-synuclein-pEGFP, 19.4% and 20.3% in the K96R and K96R-A53T transfected cells. There was significant difference between the two groups (P<0.05). SUMO-1 modification did not have influence on the Lewy body-like inclusions formation in cytoplasm of HEK293 cell in vitro, but had a toxic effect which could increase the apoptosis induced by wild type overexpression and mutation of alpha-synuclein.

Effect and mechanism of adrenomedullin on apoptosis of renal tubular epithelial cell in rats induced by renal ischemia reperfusion injury

Objective To investigate the effect and mechanism of adrenomedullin (AM) on apoptosis of renal tubular epithelial cell in rats induced by renal ischemia reperfusion injury. Methods Thirty-two Wistar rats were randomly divided into 4 groups: control group, IRI group, empty plasmid group and AM group. One week after removing the right kidney, eukaryotic expression vector encoding rat AM gene was transfected into the left kidney using an ultrasound-microbubble mediated system. After 1 week the transfer efficiency was detected by immunohistochemical method . Renal IRI model induced by clamping left renal arteries for 45 min followed by reperfusion for 24 h. Tubular cell apoptosis was detected by TUNEL assay. Bcl-2, Bax and Fas expressions were examined by RT-PCR. The expressions of caspase-3, caspase-8 and caspase-9 were determined by Western bolt analysis. Results The expression of AM in the AM group was significantly higher than the empty plasmid group (0.51±0.09 vs 0.23±0.05; P 0.05). Conclusion AM can reduce apoptosis of renal tubular epithelial cell induced by renal IRI, the mechanism of which might be achieved by inhibiting caspase-dependent intrinsic and extrinsic pathways. Key words: Adrenomedullin; Reperfusion injury; Apoptosis; Caspase

Influence of ATP-binding cassette transporter A1 protein in eukaryocyte and its expression on arsenic resistance

Objective To examine the expression of ATP-binding cassette transporter A1(ABCA1)in eukaryotie cells and the effect of arsenic resistance after the transfection of eukaryotic expression vector containing ABCA1 gene.Methods HeLa cells were transfected with the recombinant plasmid by lipofectaonmine 2000 (recombinant plasmid group),empty plasmid and untransfected HeLa cell as the control group.The level of the mRNA was examined by real-time PCR,and the expression of ABCA1 protein wag examined by Western blot,the change of cell survival rate was examined by methyl thiazolyl tetrazolium(MTT)after exposure in a series of arsenic [0(contro1),4,8,16,32,64,128 μmol/L]for 48 hours.Results Expression level of ABCA1 mRNA in recombinant plasmid,empty plasmid and untransfeeted groups was(2.09±0.08)×10-4,(0.09±0.02)×10-4,(0.08±0.02)×10-4,there was a significant difference between the groups(F=1499.23,P<0.01).The level of ABCA1 mRNA in recombinant plasmid group was higher than empty plasmid and untransfected group(all P<0.01).Western blot showed that specific protein straps existed at 254×103 in all the three groups,with a similar size to the ABCA1 protein.The amount of the recombinant plasmid group was higher than the other two groups.MTT shows that arsenic concentration at 4,8,16,32,64,128 μmol/L,the survival rates of recombinant plasmid group was(94.8±0.9)%,(86.5 ± 2.6)%, (77.8 ± 2.0)%, (56.0 ± 2.0)%, (23.8 ± 1.7)%, (18.6 ± 0.6)%, higher than that of empty plasmid group[ (85.3 ± 1.1)%, (78.7 ± 0.6)%, (67.8 ± 2.4)%, (43.2 ± 1.5)%, (14.5 ± 1.3)%, (8.0 ± 0.4)%], the difference of survival rate had a statistical signifieance(t = 18.985,6.689,5.922,9.504,9.481,32.634, all P < 0.01). Conclusions ABCA1 protein is over expressed in HeLa cells after transfect ABCA1 gene. ABCA1 protein increases resistance of arsenic in HeLa cells. Key words: ATP-binding cassette transporter A1 gene; Plasmids; Transfection; Eukaryotic cells; Arsenic resistance

A novel Bifidobacterium infantis-mediated TK/GCV suicide gene therapy system exhibits antitumor activity in a rat model of bladder cancer

Bladder cancer is the ninth most common malignancy in the world. Successful clinical management remains a challenge. In order To search for novel targeted and efficacious treatment, we sought to investigate anti-tumor activity of BI-TK suicide gene therapy system in a rat model of bladder tumors. We first constructed and tested an anaerobic Bifidobacterium infantis-mediated thymidine kinase (BI-TK) suicide gene therapy system. To test the in vivo efficacy of this system, we established a rat model of bladder tumors, which was induced by N-methyl-nitrosourea perfusion. Bifidobacterium infantis containing the HSV-TK (i.e., BI-TK) were constructed by transformation of recombinant plasmid pGEX - TK. The engineered BI-TK was injected into tumor-bearing rats via tail vein, followed by intraperitoneal injection of ganciclovir (GCV). Using the rat model of bladder tumors, we found that bladder tumor burdens were significantly lower in the rats treated with BI-TK/GCV group than that treated with normal saline control group (p <0.05). While various degrees of apoptosis of the tumor cells were detected in all groups using in situ TUNEL assay, apoptosis was mostly notable in the BI-TK/GCV treatment group. Immunohistochemical staining further demonstrated that the BI-TK/GCV treatment group had the highest level of caspase3 protein expression than that of the empty plasmid group and normal saline group (p < 0.05). Thus, our results demonstrate that the Bifidobacterium infantis-mediated TK/GCV suicide gene therapy system can effectively inhibit rat bladder tumor growth, possibly through increasing caspase 3 expression and inducing apoptosis.

Effects of green tea extract on expression of human papillomavirus type 16 oncoproteins-induced hypoxia-inducible factor-1alpha and vascular endothelial growth factor in human cervical carcinoma cells

To investigate the effects of green tea extract (GTE) and its major component (-)-epigallocatechin-3-gallate (EGCG) on the human papillomavirus (HPV) type 16 oncoproteins (E6 and E7)-induced expression of hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) in human cervical carcinoma cells. Human cervical carcinoma cells of the line C-33A were divided to 4 groups to be transiently transfected with the plasmid HA-pSG5-HPV-16E6 containing the HPV type 16 oncoprotein E6, HA-pSG5-HPV-16 E7, or empty plasmid HA-pSG5, or just exposed to the transfection reagent Lipofectamine 2000 as mock transfection control group. Western blotting and ELISA were used to detect the protein expression of HIF-1alpha and the protein expression of VEGF 18, 24, and 48 h after the transfection. Twenty-four hours after the transfection, the transfected-cells were treated with GTE (40 microg/ml) or EGCG (50 micromol/L) for 8, 16, and 24 h respectively, or treated with GTE of the concentrations of 20, 40, and 80 microg/ml or EGCG of the concentrations of 25, 50, and 100 micromol/L respectively for 16 h. The HIF-1alpha and VEGF protein levels were analyzed by Western blotting and ELISA respectively and the HIF-1alpha and VEGF mRNA levels were determined with real-time PCR. Twenty-four hours after transfection, the HIF-1alpha protein expression of the 16E6 and 16E7 groups were significantly decreased, and the VEGF protein levels of the 16E6 and 16E7 groups were (870+/-66) and (1487+/-51) pg/ml respectively, both significantly higher than that of the empty plasmid group [(366+/-65) pg/ml, both P<0.01]. Treated by 40 microg/ml of GTE or 50 micromol/L of EGCG for 16 h, (1) the HIF-1alpha protein levels of the 16E6 and 16E7 groups were significantly decreased; (2) the VEGF protein levels of the 16E6 group were (476+/-34) and (477+/-65) pg/ml respectively, and the VEGF mRNA levels of the 16E6 group were 1.208+/-0.196 and 1.174+/-0.208 respectively, all significantly lower than those of the untreated group [(870+/-66) pg/ml and 1.805+/-0.081 respectively, all P<0.01]; and (3) the VEGF protein levels of the 16E7 group were (649+/-55) and (514+/-37) pg/ml respectively, and the VEGF mRNA levels of the 16E7 group were 1.442+/-0.136 and 1.399+/-0.064 respectively, all significantly lower than those of untreated group [(1487+/-51) pg/ml and 2.123+/-0.120 respectively, all P<0.01]. The 80 microg/ml of GTE or 100 micromol/L of EGCG showed much stronger effects on the inhibition of VEGF protein expression than 40 microg/ml of GTE or 50 micromol/L of EGCG (both P<0.01). GTE and EGCG can remarkably inhibit the HPV-16 oncoproteins-induced expression of HIF-1alpha protein, and VEGF protein and mRNA in human cervical carcinoma cells. Moreover, GTE and EGCG decrease the VEGF protein expression dose-dependently.

Effects of WWOX gene transfection on cell growth of epithelial ovarian cancer

To study the effects of anti-oncogene WWOX on cell growth of epithelial ovarian cancer,in order to find a new approach of gene therapy for ovarian cancer. A eukaryotic expression vector containing WWOX was transfected into ovarian cancer cell line HO8910 in vitro (recombinant plasmid group), and positive cell clones were selected and amplified. Expression of WWOX protein was detected by western blot. Untransfected cell (blank contrast group) and transfected empty plasmid cell (empty plasmid group) were served as control groups. In vitro, the biology effect of WWOX on HO8910 cell was analyzed through the methyl thiazolyl tetrazolium test, transwell chamber cell invasion assay in vitro, agarose clony-formation and flow cytometry. In vivo, the cell of transfection was transplanted intraperitoneally in to BALB/c nude mice. The survival time and growth ability of nude mice were observed. (1) Recombinant plasmid group cell could steadily express WWOX protein, while in empty plasmid group and blank control group the expression of WWOX protein were not detected. (2) The growth rate of recombinant plasmid group cell was inhibited. (3) The agarose clony-formation rate of recombinant plasmid group (19.8%) was significantly lower than that of the empty plasmid group (54.5%) and blank control group (56.0%, P < 0.05). (4) Flow cytometry showed that (72.08 +/- 0. 39)% of cells was arrested at G0/G1 stage in recombinant plasmid group, while in empty plasmid group and blank control group G0/G1 stage cells were at (41.02 +/- 1.08)% and (39.31 +/- 0.67)% (P < 0.05). (5) In vitro invasion assay showed that invasion cell number in recombinant plasmid group (89.7 +/- 3.1) was not significantly different from that of empty plasmid group (91.2 +/- 1.3) and blank control group (91.4 +/- 1.3, P > 0.05). (6) In vivo test in nude mice showed that WWOX gene could inhibit tumor growth of the HO8910 cells. Tumor suppressor gene WWOX could interfere with the cell cycles of ovarian cancer cell and inhibit cell proliferation. As a new valuable tool, it promises to have application in the gene therapy of ovarian cancer.

504 THE EFFECT OF FAK-RELATED NON-KINASE PLASMID TRANSFECTION ON FIBRONECTIN-STIMULATED HEPATIC STELLATE CELLS BEHAVIOURS

BACKGROUND AND AIMS The main cells responsible for liver fibrosis are hepatic stellate cells (HSC), which undergo activation, proliferation and increased production of extracellular matrix following liver injury. Focal adhesion kinase (FAK) plays an important role in integrinmediated signal transduction pathways and its C-terminal noncatalytic domain FAK-related non-kinase (FRNK), which is autonomously expressed, acts as an inhibitor of FAK phosphorylation. In the present study, we therefore investigated the effects of FRNK on proliferation, apoptosis and cell cycle in HSC stimulated by fibronectin (FN). The signal transduction molecules-extracellular signal-regulated kinase 1/2(ERK1/2) was also investigated. METHODS We have used rat immortalized hepatic stellate cell lines CFSC, and cells were divided into 5 groups as below: blank control group; FN-treated group; liposome group; empty plasmid group and FRNK plasmid group. FRNK plasmids were transfected into HSCs mediated by lipofectamine 2000 reagent. Improved MTT assay was used to determine cell proliferation, and flow cytometry (FCM)was used to detect cell cycle phase. Apoptosis was examined by Annexin-V/PI double-labelled FCM, gel electrophoresis and transmission electron microscope. The expression of FRNK, FAK, P-FAK (Tyr397), ERK1/2 and cell cycle related protein (Cyclin D1 and CDK4) were detected by Western blot and RT-PCR. RESULTS Transfection of FRNK decreased FAK phosphorylation on Tyr397 without changing total FAK level, coincident with a large increase in FRNK expression. After FRNK transfection, the proliferation inhibition rates in HSC were 20.07%, 26.16% and 29.77% at 12 h, 24 h, and 48 h, respectively. Meanwhile, the apoptotic rate in HSC exposed to FRNK plasmid for 48 h was higher than that in the empty plasmid group (25.37%±1.92% vs 9.28%±1.05%), P<0.01. The morphology changes of HSC observed by transmission electron microscopy also revealed that the apoptosis of HSC was increased by FRNK. Consistent with this, apoptotic DNA Ladder was detected in HSC exposed to FRNK. The percentage of cells at G0/G1 phase was significantly higher in FRNK plasmid group than that in empty plasmid group (71.4±2.81 vs 48.9±1.66), P<0.01, accompanied by down-regulation of Cyclin D1 and CDK4. Additionally, we found that FRNK attenuated ERK1/2 phosphorylation and resulted in a down-regulation of ERK1/2 mRNA. CONCLUSION FRNK may inhibit the proliferation and induce the apoptosis of HSC and arrested HSC at G0/G1 phase via decreasing phosphorylation levels at FAK and ERK1/2. The inhibition of FAK/ERK1/2 pathway may be a potential therapeutic strategy for preventing liver fibrogenesis.

Plasmid-mediated VEGF gene transfer induces cardiomyogenesis and reduces myocardial infarct size in sheep

We have recently reported that in pigs with chronic myocardial ischemia heart transfection with a plasmid encoding the 165 isoform of human vascular endothelial growth factor (pVEGF165) induces an increase in the mitotic index of adult cardiomyocytes and cardiomyocyte hyperplasia. On these bases we hypothesized that VEGF gene transfer could also modify the evolution of experimental myocardial infarct. In adult sheep pVEGF165 (3.8 mg, n=7) or empty plasmid (n=7) was injected intramyocardially 1 h after coronary artery ligation. After 15 days infarct area was 11.3+/-1.3% of the left ventricle in the VEGF group and 18.2+/-2.1% in the empty plasmid group (P<0.02). The mechanisms involved in infarct size reduction (assessed in additional sheep at 7 and 10 days after infarction) included an increase in early angiogenesis and arteriogenesis, a decrease in peri-infarct fibrosis, a decrease in myofibroblast proliferation, enhanced cardiomyoblast proliferation and mitosis of adult cardiomyocytes with occasional cytokinesis. Resting myocardial perfusion (99mTc-sestamibi SPECT) was higher in VEGF-treated group than in empty plasmid group 15 days after myocardial infarction. We conclude that plasmid-mediated VEGF gene transfer reduces myocardial infarct size by a combination of effects including neovascular proliferation, modification of fibrosis and cardiomyocyte regeneration.

Antitumor immunity induced by DNA vaccine encoding alpha-fetoprotein/heat shock protein 70.

To construct a DNA vaccine encoding human alpha-fetoprotein (hAFP)/heat shock protein 70 (HSP70), and to study its ability to induce specific CTL response and its protective effect against AFP-expressing tumor. A DNA vaccine was constructed by combining hAFP gene with HSP70 gene. SP2/0 cells were stably transfected with pBBS212-hAFP and pBBS212-hAFP/HSP70 eukaryotic expression vectors. Mice were primed and boosted with DNA vaccine hAFP/HSP70 by intramuscular injection, whereas plasmid with hAFP or HSP70 was used as controls. ELISPOT and ELISA were used to detect IFN-gamma-producing splenocytes and the level of serum anti-AFP antibody from immunized mice respectively. In vivo tumor challenge was measured to assess the immune effect of the DNA vaccine. By DNA vaccine immunization, the results of ELISPOT and ELISA showed that the number of IFN-gamma-producing splenocytes and the level of serum anti-AFP antibody were significantly higher in rhAFP/HSP70 group than in hAFP and empty plasmid groups (95.50+/-10.90 IFN-gamma spots/10(6) cells vs 23.60+/-11.80 IFN-gamma spots/10(6) cells, 7.17+/-4.24 IFN-gamma spots/10(6) cells, P<0.01; 126.50+/-8.22 microg/mL vs 51.72+/-3.40 microg/mL, 5.83+/-3.79 microg/mL, P<0.01). The tumor volume in rhAFP/HSP70 group was significantly smaller than that in pBBS212-hAFP and empty plasmid groups (37.41+/-7.34 mm(3) vs 381.13+/-15.48 mm(3), 817.51+/-16.25 mm(3), P<0.01). Sequential immunization with a recombinant DNA vaccine encoding AFP and heat shock protein70 could generate effective AFP-specific T cell responses and induce definite antitumor effects on AFP-producing tumors, which may be suitable for some clinical testing as a vaccine for HCC.

Gene transfer of GM-CSF, CD80 and CD154 cDNA enhances survival in a murine model of acute leukemia with persistence of a minimal residual disease.

Gene transfer of various cytokines and co-stimulatory molecules has been reported to induce a potent antileukemic immunity in murine models, however, the relative efficiency and possible synergistic effects between candidate genes have not been extensively investigated. We analyzed in a murine model of BCR/ABL acute leukemia whether gene transfer of CD154, CD80 or GM-CSF as a single agent or combination of CD154 + GM-CSF, CD80 + CD154 and GM-CSF + CD80 in leukemic cells could enhance survival. We observed that CD154 gene transfer induced a marked inhibition of leukemogenicity, and also that CD154 and combination of GM-CSF and CD80 gene transfer protected mice against subsequent challenge with leukemic cells and had a therapeutic effect for a pre-established leukemia disease. We also found minimal residual leukemic disease by RT-PCR for 6 to 12 months in 0 to 25% of animals injected with transduced leukemic cells and surviving the challenge without evidence of disease, except in the control empty plasmid group where very few mice survived the challenge but all of those were positive by RT-PCR. These findings suggest that leukemic cell vaccination by gene transfer can induce a tumor dormancy phenomenon compatible with long-term survival.