Toxicarioside A inhibits SGC-7901 proliferation,migration and invasion via NF-κB/bFGF signaling

AIM:To investigate the inhibitory role of toxicarioside A on the gastric cancer cell line human gastric cancer cell line(SGC-7901) and determine the underlying molecular mechanism.METHODS:After SGC-7901 cells were treated with toxicarioside A at various concentrations(0.5,1.5,4.5,9.0 μg/mL) for 24 h or 48 h,cell viability was determined by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl2H-tetrazolium bromide assay,and the motility and invasion of tumor cells were assessed by the Transwell chamber assay.Immunofluorescence staining,reverse transcription polymerase chain reaction and Western blotting were performed to detect the expression of basic fibroblast growth factor(bFGF) and fibroblast growth factor receptor-1(FGFR1),and nuclear factorkappa B(NF-κB) activation was examined by electrophoretic mobility shift assay.RESULTS:The results showed that toxicarioside A was capable of reducing cell viability,inhibiting cell growth,and suppressing cell migration and invasion activities in a time-and dose-dependent manner in SGC-7901 cells.Further analysis revealed that not only the expression of bFGF and its high-affinity receptor FGFR1 but also the NF-κB-DNA binding activity were effectively blocked by toxicarioside A in a dose-dependent manner compared with the control group(P < 0.05 or P < 0.01).Interestingly,application of the NF-κB specific inhibitor,pyrrolidinedithiocarbamate(PDTC),to SGC-7901 cells significantly potentized the toxicarioside A-induced down-regulation of bFGF compared with the control group(P < 0.05).CONCLUSION:These findings suggest that toxicarioside A has an anti-gastric cancer activity and this effect may be achieved partly through down-regulation of NF-κB and bFGF/FGFR1 signaling.

Synergistic anti-tumor effect of recombinant chicken fibroblast growth factor receptor-1-mediated anti-angiogenesis and low-dose gemcitabine in a mouse colon adenocarcinoma model

AIM: To evaluate whether the combination of recom- binant chicken fibroblast growth factor receptor -1 (FGFR-1) protein vaccine (cFR-1) combined with low- dose gemcitabine would improve anti-tumor efficacy in a mouse CT26 colon adenocarcinoma (CT26) model. METHODS: The CT26 model was established in BABL/c mice. Seven days after tumor cell injection, mice were randomly divided into four groups: combination therapy, cFR-1 alone, gemcitabine alone, and normal saline groups. Tumor growth, survival rate of tumor-bearing mice, and systemic toxicity were observed. The presence of anti-tumor auto-antibodies was detected by Western blot analysis and enzyme-linked immunospot assay, microvessel density (MVD) of the tumors and tumor cell proliferation were detected by Immunohistochemistry staining, and tumor cell apoptosis was detected by TdT- mediated biotinylated-dUTP nick end label staining. RESULTS: The combination therapy results in apparent decreases in tumor volume, microvessel density andtumor cell proliferation, and an increase in apoptosis without obvious side-effects as compared with either therapy alone or normal control groups. Also, both auto- antibodies and the antibody-producing B cells against mouse FGFR-1 were detected in mice immunized with cFR-1 vaccine alone or with combination therapy, but not in non-immunized mice. In addition, the deposition of auto-antibodies on endothelial cells from mice immunized with cFR-1 was observed by immunofluorescent stain- ing, but not on endothelial cells from control groups. Synergistic indexes of tumor volume, MVD, cell apoptosis and proliferation in the combination therapy group were 1.71 vs 1.15 vs 1.11 and 1.04, respectively, 31 d after tumor cell injection. CONCLUSION: The combination of cFR-1-mediated anti- angiogenesis and low-dose gemcitabine synergistically enhances the anti-tumor activity without overt toxicity in mice.

Immunotherapy of hepatoma with a monoclonal antibody against murine endoglin

AIM: To explore the capability of a monoclonal antibody (mAb) against murine endoglin to inhibit tumor angiogenesis and suppression of hepatoma growth in murine models. METHODS: A monoclonal antibody against murine endoglin was purified by affinity chromatography and passively transfused through tail veins in two murine hepatoma models. Tumor volume and survival time were observed at three-day intervals for 48 d. Microvessels in tumor tissues were detected by immunohistochemistry against CD31, and angiogenesis in vivo was determined by alginate encapsulated assay. In addition, tumor cell apoptosis was detected by TUNEL assay. RESULTS: Passive immunotherapy with anti-endoglin mAb could effectively suppress tumor growth, and prolonged the survival time of hepatoma-bearing mice. Angiogenesis was apparently inhibited within the tumor tissues, and the vascularization of alginate beads was also reduced in the mice passively transfused with anti- endoglin mAb. In addition, increased apoptotic cells were observed within the tumor tissues from the mice passively transfused with anti-endoglin mAb. CONCLUSION: Passive immunotherapy with anti- endoglin mAb effectively inhibits tumor growth via inhibiting tumor angiogenesis and increasing tumor cell apoptosis, which may be highly correlated with the blockage of endoglin-related signal pathway induced bya nti-endoglin mAb.

Toxicarioside A,isolated from tropical Antiaris toxicaria,blocks endoglin/TGF-βsignaling in a bone marrow stromal cell line

Objective:To investigate possible mechanism of toxicarioside A in HS-5 bone stromal cells.Methods:HS-5 bone stromal cells were cultured in media supplemented with various concentrations of toxicarioside A or control DMSO(not treatment).Endoglin and TGF-βwere detected by Northern and Western blot analysis and quantified in a standard method. Downstream molecules of endoglin and TGF-β(Smad1,Smad2 and their active phosphorylated counterparts,pSmad1 and pSmad2) were also detected and quantified by Western blot analysis. In addition,cell proliferation assay and small interfering RNA(siRNA) against endoglin were used to certificate the function of endolgin in the HS-5 cells.Results:Compared with the not treated(0μg/mL) or DMSO treated control HS-5 cells,HS-5 cells treated with toxicarioside A were found significant attenuation of endolgin and TGF-βexpression.Significant inhibition of cell proliferation was also found in the HS-5 cells treated with toxicarioside A.ALK1-related Smad1 and ALK5-related Smad2 were decreased in HS-5 cells treated with toxicarioside A.In addition,phosphorylated Smad1(pSmad1) and Smad2(pSmad2) were also found attenuation in toxicarioside A-treated HS-5 cells.RNA interference showed that blockage of endoglin by siRNA also decreased Smad1 and Smad2 expression in HS-5 cells.Conclusions:Our results indicate that toxicarioside A can influence bone marrow stromal HS-5’s function and inhibit HS-5 cell proliferation by alteration of endoglin-related ALK1(Smad1) and ALK5(Smad2) signaling.

Cytochalasin D,a tropical fungal metabolite,inhibits CT26 tumor growth and angiogenesis

Objective:To investigate whether eytochalasin D can induce antitumor activities in a tumor model.Methods:Murine CT26 colorectal carcinoma cells were cultured hi vitro and cytochalasin D was used as a cytotoxic agent to detect its capabilities of inhibiting CT26 cell proliferation and inducing cell apoptosis by MTT and a TUNEL-based apoptosis assay.Murine CT26 tumor model was established to observe the tumor growth and survival time.Tumor tissues were used to detect the mierovessel density by immunohistochemistry.In addition,alginate encapsulated tumor cell assay was used to quantify the tumor angiogenesis in vivo.Results:Cytochalasin D inhibited CT26 tumor cell proliferation in lime and dose dependent manner and induced signiflcanl CT26 cell apoptosis,which almost reached the level induced by the positive control nuclease.The optimum effective dose of cytochalasin D for in vivo therapy was about 50 mg/kg.Cytochalasin D in vivo treatment significandy inhibited tumor growth and prolonged the survival times in CT26 tumor-bearing mice.The results of immunohistochemistry analysis and alginate encapsulation assay indicated that the cytochalasin D could effectively inhibited tumor angiogenesis. Conclusions:Cytochalasin D inhibits CT26 tumor growth potentially through inhibition of cell proliferation,induction of cell apoptosis and suppression of tumor angiogenesis.

RNA interference against interleukin-5 attenuates airway inflammation and hyperresponsiveness in an asthma model

Interleukin-5 (IL-5) accompanies the development of airway inflammation and hyperresponsiveness through the activation of eosinophils. Therefore, interference of IL-5 expression in lung tissue seems to be an accepted approach in asthma therapy. In this study, we designed a small interfering RNA (siRNA) to inhibit the expression of IL-5. The siRNAs against IL-5 were constructed in a lentivirus expressing system, and 1.5×106 IFU (inclusion-forming unit) lentiviruses were administered intratracheally to ovalbumin (OVA)-sensitized murine asthmatic models. Our results show that lentivirus-delivered siRNA against IL-5 efficiently inhibited the IL-5 messenger ribonucleic acid (mRNA) expression and significantly attenuated the inflammation in lung tissue. Significant decrease of eosinophils and inflammatory cells were found in peripheral blood, bronchoalveolar lavage fluid (BALF), and lung tissue. In addition, significant inhibition of airway hyperresponsiveness (AHR) was found in the mice treated with siRNA against IL-5. These observations demonstrate that siRNA delivered by means of the lentivirus system is possibly an efficacious therapeutic approach for asthma.