Objective To study the effect of knockdown of signal transducer and activator of transcription 3 (STAT3) expression by short hairpin RNA (shRNA) on proliferation, apoptosis and invasion of human gastric cancer cell line MKN-45 in vitro . Methods Specific shRNA plasmids to STAT3 were constructed, and then transfected into MKN-45 cells by lipofectamine methods. Cells were divided into three groups: control group, psiRNA-H1 transfected group as negative group and psiRNA-H1/STAT3 transfected group. Semi-quantitative RT-PCR and Western blotting were used to detect the expression of STAT3 mRNA and protein, respectively. Proliferation and apoptosis of the transfected cells were observed by methyl thiazolyl tetrazolium (MTT) method and flow cytometry (FCM), respectively. The invasion of the transfected MKN-45 cells was measured by Boyden chamber. Results Compared with the negative control cells, semi-quantitative RT-PCR and Western blotting showed that the expressions of STAT3 mRNA and protein were down-regulated in the psiRNA-H1/STAT3 transfected group ( P ＜ 0.05) . The subcloned recombinant plasmid expressing shRNA effectively inhibited MKN-45 cell growth and proliferation while empty plasmid had no such specific effect. Cell apoptosis rate increased significantly in psiRNA-H1/STAT3 transfected group （ P ＜ 0.01）, and the invasion of MKN-45 cells was efficiently inhabited in psiRNA-H1/STAT3 transfected group as compared with control group and psiRNA-H1 transfected group( P ＜ 0.01).Conclusion Recombinant plasmid psiRNA-H1/STAT3 shRNA significantly inhibits the proliferation and invasion of MKN-45 cells and promotes their apoptosis.
【Abstract】Objective To investigate the apoptosis induced by TGF-β1 in human hepatic carcinoma cell lines and its relationship with p53 gene and Smad. Methods Three human hepatic carcinoma cell lines which involving in various status of the p53 gene were used in this study. TGF-β1-induced apoptosis in hepatic carcinoma cell lines was measured by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. To study the mechanism of TGF-β1-induced apoptosis, these cell lines were transfected with a TGF-β1-inducible luciferase reporter plasmid containing Smad 4 binding elements (SBE) and luciferase gene using Lipofectamine 2000, then treated with TGF-β1, relative luciferase activity was assayed. Results Of three cell lines studied with TUNEL assay, TGF-β1 induced apoptosis was observed in HepG2 cells (wild type p53). Huh-7 (mutant p53) and Hep3B (deleted p53) cell lines showed less apoptosis. Luciferase activity assay indicated that the response to TGF-β1 induction in HepG2 cells was increased dramatically but was not significant in Huh-7 and Hep3B cell lines. Conclusion HepG2 cells seem to be highly susceptible to TGF-β1-induced apoptosis compared with Hep3B and Huh7 cell lines. Smad 4 is a central mediator of the TGF-β1 signal transduction pathway.
Objective To summarize the relationship between tumor necrosis factor receptor-associated factor 6 （TRAF6） and apoptosis. Methods Domestic and international researches on progress of TRAF6 and apoptotic signaling pathway， especially focused on the functional features of TRAF6 in different system diseases were searched and reviewed. Results TRAF6 took part in several signaling pathways， which had been implicated in regulating apoptosis， and its roles differed in different system diseases and in different conditions. TRAF6 promoted tumorigenesis by inhibiting apoptosis， while it played a proapoptotic or prosurvival role in nervous system and inflammatory diseases. Conclusion TRAF6 plays an important role in apoptosis and involves in the development of tumor， nervous system disease， and inflammatory diseases.
ObjectiveTo summarize the therapeutic targets of pancreatic cancer (PC).
MethodsThe related literatures about the therapeutic targets of PC were reviewed.
ResultsPC was one of the most challenging tumor in worldwide, and was characterized as a highly aggressive disease with poor overall prognosis and a high mortality rate. The hallmark of PC was its poor response to radio-and chemo-therapy. Current chemotherapeutic regimens could not provide substantial survival benefit with a clear increase in overall survival. Recently, several new approaches which could significantly improve the clinical outcome of PC had been described, involving signal-transduction pathways, immune response, stroma reaction, and epigenetic changes.
ConclusionsMany therapeutic targets are involved in the treatment of PC. As current therapies failed to significantly improve the progression and the survival of PC, new therapeutic approaches and clinical studies are strongly required.
Objective To investigate the mechanism of adenosine-tri phosphate (ATP) activated mammal ian target of rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3) signal pathway in the physiology and pathology of spinal cord injury (SCI). Methods Ninety-six adult healthy female Sprague-Dawley rats were randomly divided into 4 groups (groups A, B, C and D, n=24). In groups A, B and C, the rats were made the SCI models at T8-10 levels by using a modified Allen’ s stall, and in group D, rats were given laminectomy without SCI. The rats were subjected to the administration of ATP (40 mg/kg) for 7 days in group A, to the administration of physiological sal ine (equal-volume) for 7 days in group B, to the administration of ATP (40 mg/kg) and rapamycin (3 mg/kg) for 7 days in group C, and to the administration of physiological sal ine (equal-volume) for 7 days in group D. Locomotor activity was evaluated using the Basso-Beattie-Bresnahan rating scale at the postoperative 1st, 2nd, 3rd, and 4th weeks. Then, the expressions of spinal cord cell marker [Nestin, neuron-specific enolase (NSE), gl ial fibrillary acidic protein (GFAP)] and the mTOR/STAT3 pathway factors (mTOR, STAT3) were detected at the postoperative 1st, 2nd, 3rd, and 4th weeks by immunohistochemistry analysis, Western blot assay, and real-time fluorescence PCR analysis. Results The BBB scores in group A showed a steady increase in the postoperative 1st-4th weeks and were significantly higher than those in groups B and C (P lt; 0.01), but were lower than that in group D (P lt; 0.01). Real-time fluorescence PCR results showed that the mRNA expressions of mTOR, STAT3, NSE of group A steadily increased, however, the Nestin mRNA expression gradually decreased in the postoperative 1st-4th weeks, which were all significantly higher than those of groups B, C, and D (P lt; 0.01). The mRNA expression of GFAP showed a steady increase in group A and was significantly less than those of groups B and C, but was higher than that of group D (P lt; 0.01). There were significant differences (Plt; 0.01) in all markers between groups B, C, and group D; there were significant differences in mTOR, P-mTOR, STAT3, and P-STAT3 mRNA between groups B and C at 1st-4th weeks (P lt; 0.05). The similar changes were found by Western blot assay. Conclusion ATP can activate the mTOR/STAT3 pathway to induce endogenic NSCs to prol iferate and differentiate into neurons in rats, it enhances the heal ing of SCI.
ObjectiveTo explore if Smad7 protein can inhibit growth of keloids by observing the gene and protein expressions of Smad7, collagen type Ⅰ, and collagen type Ⅲ and cell proliferation after over-expression vectors of Smad7 transfecting keloid fibroblasts (KFb).
MethodsFibroblasts were acquired from 10 male patient with keloids at the age of 20 to 25 years. After in vitro culture, KFb were divided into 3 groups: untransfected group (group A), pcDNA3.1 (-) transfected group (group B), and pcDNA3.1 (-)-smad7 transfected group (group C). The mRNA and protein expression levels of Smad7, collagen type Ⅰ, and collagen type Ⅲ were detected by real-time fluorescence quantitative PCR and Western blot at 48 hours after transfection. The cell proliferation ability was detected by MTT assay at 24 hours after transfection.
ResultsThe relative expression levels of mRNA and protein of Smad7 in group C were significantly higher than those in group A and group B (P < 0.01). The relative expression levels of mRNA and protein of collagen type Ⅰ and collagen type Ⅲ in group C were significantly lower than those in group A and group B (P < 0.01). The relative expression levels of mRNA of collagen type Ⅰ and collagen type Ⅲ in group B were significantly higher than those in group A (P < 0.01); and the relative expression levels of proteins of Smad7, collagen type Ⅰ, and collagen type Ⅲ were significantly lower than those in group A (P < 0.01). The cell proliferation ability in group C was significantly lower than that in group A and group B at each time point by MTT assay (P < 0.05), but no difference was found between group A and group B (P>0.05).
ConclusionGene expressions of collagen type Ⅰ, and collagen type Ⅲ and cell proliferation will be inhibited after KFb are transfected by over-expression vector of Smad7.
Objective To review the current researches about tumor necrosis factor-related apoptosis ligand (TRAIL) and its receptors in gastric carcinoma. Methods Relevant articles of researches on TRAIL and its receptors in gastric carcinoma were searched in electronic databases of PUB-MEDLINE and Chinese Journal Fulltext Database. Results The reported TRAIL expression level of gastric carcinoma was diverse, which was highly correlated to the histological differentiation degree, serosa invasion and lymph node metastasis. Its receptors DR4 and DR5 were both positive in gastric carcinoma tissue, while some researches reported DcR1 and DcR2 were also positive expressed. caspase-3, -8 and survivin were the important factors for regulation of TRAIL signal pathway. 5-Aza-CdR, doxorubicin, 5-fluorouracil, α-TOS and X-ray irradiation might enhance the TRAIL-induced apoptosis of gastric carcinoma cells. Conclusion Gastric carcinoma may be potentially sensitive to TRAIL targeting therapy, but the mechanism of TRAIL-induced apoptosis is quite complex and is regulated by multi-factors. Up to now, there are still many issues to research further, such as how to efficiently enhance and regulate the TRAIL-induced apoptosis of gastric carcinoma, whether any potential toxicities existing, etc.
ObjectiveTo investigate the effects of signaling pathway about the EGFR, MAPK, IKB/NF-κB, PI3K/Akt, WNT/beta-catenin, and the Hedgehog in development of hepatocellular carcinoma(HCC).
MethodsThe related literatures about the molecular genetic mechanism of signaling pathways were reviewed.
ResultsIn the occurrence and development of HCC, the EGFR, MAPK, IKB/NF-κB, PI3K/Akt, WNT/β-catenin, and Hedgehog signaling pathways not only interweaver with each other complexly, but also interact with each other, and some tumor markers, anticancer genes, proto-oncogenes, and miRNA may have synergistic effects for the occurrence of HCC.
ConclusionThe abnormal changes of molecular signaling pathways is a necessary condition for the occurrence and development of tumor, and there is considerable cross-talk and redundancy to many signaling pathways.
ObjectiveTo observe whether interleukin-27 (IL-27) intervention could diminish allergic airway inflammation of mouse asthma induced by ovalbumin (OVA) and to investigate the related molecular mechanisms.
MethodsSixty female C57/6J mice were randomly divided into six groups, a control group, an asthma group, two IL-27 prevention groups and two IL-27 treatment groups. Based on being sensitized and challenged with OVA in the asthma model, two kinds of IL-27 intervention asthma models were set up, one of which was low-dose multiple prevention model, the other was high-dose few times treatment model. HE stain and inflammation score were done for the lungs. CD4+ T cells were purified from mice spleen and cultured under Th2 medium with/without IL-27. Interleukin-4 (IL-4) was measured by ELISA. CD4+ T cells were cultured under different stringent Th2 medium and stimulated by IL-27. The level of total signal transducer and activator of transcription-1 (STAT1) protein and phos-STAT1 were tested by Western blot.
ResultsIn low-dose multiple prevention group, IL-27 inhibited inflammation around bronchial and vascular obviously, the inflammation score was lower than the asthma group (P < 0.05), while the treatment group had no obvious statistical significance (P > 0.05). IL-27 repressed Th2 differentiation of na?ve CD4+ T cells which was independent of interferon-γand IL-10. This effect was via STAT1 signaling pathway. CD4+ T cells from asthma mice or cultured under high-IL-4 inducing medium were found impairment of STAT1 phosphorylation.
ConclusionsIL-27 could inhibit Th2 differentiation of na?ve CD4+ T cells, but not in already committed Th2-CD4+ T cells. The inhibition effect of IL-27 for airway inflammation is obvious in prevention group, while the treatment group shows obviously resistance to inhibitory effect of IL-27. Already committed Th2-CD4+ T cells existed in asthma airway might be the reason for IL-27 resistance.
Objective To investigate the activation and role of signal transduction pathway of epidermal growth factor (EGF)-epidermal growth factor receptor (EGFR)-mitogen activated protein kinase (MAPK) in proliferation of human retinal pigment epithelial (RPE) cells. Methods Human RPE cells were stimulated with 0.1%，10% foetal calfserum (FCS) and EGF(0.1, 1, 10, 50 and 100 ng/ml)in 0.1% FCS Dulbeco′s modified Eagle′s medium (DMEM) and in 10% FCS DMEM for 3 days, respectively. Immunohistochemical staining and in situ hybridization were used to observe the expressions of EGFR protein and EGFR mRNA，respectively. Activation of MAPK was detected by immunohistochemical method with specific anti-phosphorylated ERK 1/2 antibody. Results The optimal concentrations of EGF were 10 ng/ml in 0.1% FCS DMEM and 1 ng/ml in 10% FCS DMEM. After 3 days of stimulation with EGF, phosphorylated ERK 1/2 staining was detectable in nucleus of RPE cells, whereas cells presented immunostaining for phosphorylated ERK 1/2 in the cytoplasm before stimulation. Conclusions EGF may improve the expression of EGFR protein and EGFR mRNA of RPE cells, and induced MAPK nuclear translocation in a concentration-dependent manner. EGF-EGFR-MAPK signal transduction pathway may play a key role in RPE cells proliferation, and serum exerts an important acceclerating function in the process. (Chin J Ocul Fundus Dis，2004，20：67-132)
