Impact of PI3K /Akt /mdm2 signaling pathway on the sensitivity of gastric cancer cell line SGC7901 to doxorubicin / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore whether PI3K/Akt/mdm2 signalling pathway affect the sensitivity of gastric cancer cell line SGC7901 cells to doxorubicin.</p><p><b>METHODS</b>Gastric cancer cell line SGC7901 cells were exposed to doxorubicin and specific PI3K inhibitor wortmannin. Cell apoptosis was detected using flow cytometry. PI3K activity was detected by radioactive immunoprecipitation-kinase assay. Western blotting was employed to evaluate the expressions of PI3K-p85, pAkt-S473, Akt, pmdm2-S166 and p53.</p><p><b>RESULTS</b>The level of apoptosis in gastric cancer SGC7901 cells treated with doxorubicin was gradually increasing. wortmannin enhanced its effects significantly. PI3K activity and the expression of pAkt-S473 increased in a time-dependent manner, pmdm2-S166, p53 were also increased wortmannin inhibited phosphorylation of mdm2 and improved the p53 expression.</p><p><b>CONCLUSION</b>PI3K/Akt/mdm2 signalling pathway can be activated by doxorubicin and suppress apoptosis by promoting phosphorylation of mdm2. PI3K inhibitor wortmannin can enhance sensitivity of gastric cancer cells to chemotherapy.</p>

Effects of hFRNK on E-cadherin/beta-catenin in colon cancer cells in vitro / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the effects of human FRNK gene on E-cadherin/beta-catenin complex in colon cancer cell line Colo320WT cells stimulated with extrinsic gastrinl7.</p><p><b>METHODS</b>AdEasy system was used to construct pAdhFRNK expressing human FRNK gene by recombination in E. coli. BJ5283. pCR3.1/GR plasmid expressing gastrin receptor CCK-2 was transfected into colon cancer cell line Colo320 cells by Lipofectamine 2000 and expressing stably CCK-2R clones were screened by G418 (500 pg/ml). The expression levels of gastrin receptor in Colo320 cells and the transfected Colo320WT cells were assayed by RT-PCR. Colo320WT cells were treated by 10(-8) mol/L gastrinl7 for 12 h; and after Colo320WT cells were infected by pAdhFRNK (MOI: 100) for 2 d the cells were treated by gastrin17 for 12 h again. The expression levels of E-cadherin and beta-catenin in TX-100 soluble fraction and TX-100 insoluble fraction of Colo320WT cells were assayed by co-immunoprecipation and Western blot. E-cadherin and beta-catenin's distribution in Colo320WT cells were detected by immunocytochemistry.</p><p><b>RESULTS</b>When 10(-8) mol/L gastrin17 stimulated Colo320WT cells for 12 h, the expression levels of E-cadherin and beta-catenin in TX-100-soluble fraction decreased apparently, while the expression levels of E-cadherin and beta-catenin in TX-100-insoluble fraction increased markedly. When pAdhFRNK infected Colo320WT cells for 2 d and 10(-8) mol/L gastrin17 treated the cells for 12 h, the expression levels of E-cadherin and beta-catenin in TX-100-soluble fraction increased apparently again, and the expression levels of E-cadherin and beta-catenin in TX-100-insolutble fraction decreased markedly. Immunocytochemistry showed that the distribution of E-cadherin and beta-catenin was translocated from plasma membrane into cytoplasm and nucleus in the cells stimulated with gastrinl7, and after the cells were infected with pAdhFRNK and stimulated by gastrinl7 again. beta-catenin was mainly observed in cytoplasm and little nuclear immunoreactivity.</p><p><b>CONCLUSION</b>An adenovirus vector pAdhFRNK can inhibit abnormal distribution of E-cadherin and beta-catenin in the gastrin17-stimulated cells. The mechanism is probably that hFRNK can disphosphorylate phosphorylated FAK and block FAK pathway.</p>

The role of p38 MAPK in gastrin-induced u-PA expression in human colon cancer cells / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To study the effect of gastrin on the mRNA and protein expression of urokinase-type plasminogen activator (u-PA) in human colon cancer cells and detect the role of p38 MAPK in this process.</p><p><b>METHODS</b>Lipofectin method was used to transfect pCR3. 1/CCK2R vector expressing gastrin receptor into a colon cancer cell line colo320. Gastrin and gastrin antagonist were used to up-regulate and down-regulate the signaling pathway, respectively. Human colon cancer colo320 cells and colo320/ CCK2,R cells were cultured and then stimulated with gastrin for different time; SB203580 was added into culture medium to prevent p38 kinase pathway before incubating with gastrin; Western blot and RT-PCR were used to examine the u-PA expression. Western blot was employed to detect p38 kinase phosphorylation.</p><p><b>RESULTS</b>Gastrin increased evidently the mRNA and protein expressions of u-PA and induced p38 kinase phosphorylation in colo320/CCK,R cells time-dependently. However, the extent of enhancement of u-PA and p38 MAPK expression in colo320 cells was much less than that in colo320/CCK2R cells. The gastrin antagonist L-365, 260 showed an effect of competitive inhibition on gastrin-induced u-PA expression and p38 kinase phosphorylation. The inhibitor SB203580 could sufficiently suppress gastrin-induced p38 kinase phosphorylation and significantly attenuate gastrin-induced u-PA mRNA and protein expressions in colo320/ CCK2 R cells in a dose-dependent manner.</p><p><b>CONCLUSION</b>Gastrin-gastrin receptor signal transduction pathway can obviously induce u-PA expression in human colon cancer cells via activating the phosphorylation of p38 kinase.</p>

Effects of nuclear factor kappaB and transforming growth factor beta1 in the anti-liver fibrosis process using Ginkgo biloba extract / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To evaluate the effects of Ginkgo biloba extract (EGB) on CCl(4)-induced liver fibrosis and to investigate the underlying mechanisms.</p><p><b>METHODS</b>Rats were divided into the following groups: normal control group, CCl(4) model group, low dose EGB group, moderate dose EGB group and high dose EGB group. The rat liver fibrosis model was induced by intraperitoneal injection of CCl(4) twice a week for 8 weeks. The model rats of the three EGB treated groups were given 0.25 g/kg, 0.5 g/kg, 1.0 g/kg of EGB by stomach tubes every day. At the end of the eighth week, the blood and liver specimens were obtained. The expressions of nuclear factor kappaB (NF-kappaB) P65, and alpha-smooth muscle actin (alpha-SMA) were detected by immunohistochemistry. Radioimmunoassay was exploited to evaluate serum hyaluronic acid (HA) and laminin (LN) levels. Electrophoretic mobility shift assay (EMSA) was used to confirm the nuclear translocation activity of NF-kappaB in liver tissues. The mRNA expression of transforming growth factor-beta1 (TGFbeta1) and collagen I was determined by RT-PCR. Malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in liver tissues and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the sera were also examined.</p><p><b>RESULTS</b>CCl(4) administration induced liver fibrosis, which was inhibited by EGB in a dose-dependent manner. The histopathologic scores of liver fibrosis, the levels of serum ALT, AST, HA and LN were significantly lower in the rats treated with EGB compared with those not treated (P <0.01 or P <0.05). SOD and GSH-Px activities were notably elevated and MDA content was significantly lower in the rats treated with EGB (P <0.01 or P <0.05), indicating reduced oxidative stress. Immunohistochemical staining demonstrated inhibition of hepatic stellate cell (HSC) activation (in terms of alpha-SMA expression) and NF-kappaB P65 expression in the livers of the EGB-treated rats. As determined by EMSA and RT-PCR, activation of NF-kappaB, the mRNA expression of TGFbeta1 and collagen I were significantly higher in model group rats, but obviously lower in EGB treated rats.</p><p><b>CONCLUSION</b>EGB is able to ameliorate liver injury and prevent rats from CCl(4)-induced liver fibrosis by suppressing oxidative stress. This process may be related to inhibiting the expression of TGFbeta1 and the induction of NF-kappaB on HSC activation.</p>

Effect of gastrin on invasiveness of human colon cancer cells / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the effect of gastrin on invasiveness of human colon cancer cells and the role of gastrin receptor-focal adhesion kinase (FAK) signal transduction pathway in this proess.</p><p><b>METHODS</b>pCR3.1/GR vector expressing gastrin receptor was transfected into a colorectal cancer cell line Colo320 with lipofectamine 2000, and screened by G418. The expression levels of gastrin receptor of the parental cell line Colo320 and the transfected cell line Colo320/GR were assayed by RT-PCR. On the other hand, antisense oligonucleotide of FAK was used to block its expression. The mock transfected Colo320 and sense oligonucleotide Colo320 cells were used as controls. Colo320 and Colo320/GR cells were treated with increasing doses (0 approximately 100 nmol/L) of gastrin. Invasiveness of Colo320 and Colo320/GR cells was determined by Boyden chamber. Phosphorylation of focal adhesion kinase (FAK) tyr-397 was examined by immunoprecipitation and Western-blot.</p><p><b>RESULTS</b>RT-PCR results showed that the Colo320/GR cells had an mRNA level four times as high as that of Colo320 cells. Western blot showed that FAK tyr397 phosphorylation of Colo320 cells was apparently decreased. Colo320 and Colo320/GR cells showed a dose-dependent response to gastrin on invasiveness and phosphorylation of FAK tyr-397. Invasiveness of Colo320 cells reached its climax when concentration of gastrin was 100 nmol/L, and FAK tyr-397 phosphorylation was marked when concentration of gastrin was 10 nmol/L, but the latter decreased when gastrin concentration was increased to 100 nmol/L. Colo320/GR cells had the same tendency as Colo320 cells, but showed an even stronger invasiveness and a higher level of FAK tyr-397 phosphorylation than Colo320 cells. Before gastrin stimulation, the invasiveness of Colo320 cells transfected with antisense oligonucleotides and the controls showed no difference. After gastrin stimulation, the increase in invasiveness was much less than that in the controls.</p><p><b>CONCLUSION</b>Gastrin can evidently promote invasiveness of Colo320 cells via gastrin-gastrin receptor-FAK signal transduction pathway.</p>

Nimesulide, a selective cyclooxygenase-2 inhibitor inhibits telomerase activity by blocking activation of PKB in gastric cancer cell line / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To study the effects of nimesulide, a selective COX-2 inhibitor, on cell viability, telomerase and PKB activities in human gastric cancer cell line SGC7901 and to explore its molecular mechanism of selective growth inhibition.</p><p><b>METHODS</b>MTT assay was used to determine cell viability after incubation for 0, 12, 24, and 48 h in different concentrations (0, 25, 50, 100, 200 micro mol/L) of nimesulide and/or okadaic acid (300 nmol/L). Telomerase and protein kinase B (PKB) activities were detected using TRAP PCR-ELISA and nonradioactive IP-kinase assay.</p><p><b>RESULTS</b>Nimsulide caused a time and dose-dependent reduction of cell numbers of SGC7901. The telomerase and PKB activities were significantly inhibited, and the inhibition of telomerase activity was partly associated with decrease in PKB activity.</p><p><b>CONCLUSION</b>Selective COX-2 inhibitor nimesulide inhibits telomerase activity of gastric cancer cells by partly blocking the activation of protein kinase B. The results suggest an additional signaling pathway underlying the anti-cancer effect of COX-2 inhibitor.</p>

Relationship between alterations of p16INK4a and p14ARF genes of CDKN2A locus and gastric carcinogenesis / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between alterations of p16INK4a and p14ARF genes and gastric carcinogenesis.</p><p><b>METHODS</b>Tumors and gastric tissues neighboring carcinoma from 48 patients with gastric cancer were studied. Homozygous deletion, mutation, methylation of the CpG islands, mRNA expression of p16INK4a and p14ARF genes were assessed by polymerase chain reaction (PCR), PCR-single strand conformation polymorphism (SSCP), PCR based methylation assay, and reverse transcription (RT)-PCR.</p><p><b>RESULTS</b>(1) The overall homozygous deletion rate of p16INK4a and p14ARF was 35.4% (17/48), and no homozygous deletion was examined in all the gastric tissues neighboring tumor. (2) There was no point mutation of p16INK4a and p14ARF in 31 gastric cancers without homozygous deletion and in the matched gastric tissues adjacent to tumor. (3) Methylation of the CpG islands of p16INK4a and p14ARF was detected in 47.9% (23/48) of gastric cancers, while methylation was observed only in 2 of 48 gastric tissues neighboring cancers with a significant difference (P <0.01). (4) The rate of p16INK4a mRNA loss was 47.9% (23/48) in gastric cancer, and the cases of combined methylation of exons 1alpha and 2 had a higher loss rate (100%, 6/6) of p16INK4a mRNA than those of methylation form the other exons (11.8%, 2/17) (P <0.01). The loss rate of p14ARF mRNA was 45.8% (22/48) in gastric cancer, and patients with combined methylation of exons 1beta and 2 had a higher loss rate (100%, 3/3) of p14ARF mRNA than those of the methylation from the other exons (15%, 3/20) (P < 0.05). (5) The combined loss of p16INK4a and p14ARF mRNAs was examined in 1 (5.6%) of 18 cases of well and moderately-differentiated carcinomas, and 11 (36.7%) of 30 cases of poorly and not-differentiated carcinomas with significant difference (P <0.05).</p><p><b>CONCLUSION</b>p16INK4a and p14ARF genes were frequently inactivated by homozygous deletion and methylation of the 5' CpG islands in gastric cancer, which might have played an important role in the development of gastric cancer.</p>

Effect of gastrin on E-cadherin/?-catenin complex in focal adhesion kinase pathway of CoLo320WT cell lines / 中华消化杂志

Objective To explore the effect of gastrin_(17) on E cadherin/?-catenin complex,a down- stream effector of FAK pathway,in colonic carcinoma cell line CoLo320WT.Methods pCR3.1/GR plasmid expressing gastrin receptor CCK 2R was transfected into colonic carcinoma cell line CoLo320 by Lipofectamine~(TM) 2000 and expressing stably CCK 2R clones was screened by G418.The expression levels of gastrin receptor of Coi.o320 and the transfected cell line Colo320WT were assayed by RT PCR. CoLo320WT cells were treated by 10~(-8)mmol/L gastrin_(17) at distinct time points (0 hr,1 hr,6 hr,12 hr, 24 hr,48 hr),whilst treated by 10_(-6) mmol/L L365,260 (gastrin_(17) receptor blocker) simultaneously for 30 minutes and then treated by gastrin_(17) again for 12 hr.Expression levels of phosphorylated FAK Tyr397 and total FAK in CoLo320WT under gastrin_(17)intervention were detected hy Western blot.Ex- pression levels of E-cadherin and?-catenin complex in TX-100 solution fraction and TX-100 insolution fraction of CoLo320WT cells were detected by coimmunoprecipitation and Western blot.Distribution of E-cadherin and?-catenin in CoLoWT320 were observed by immunocytochemistry.Results Phosphoryla- ted FAK Tyr397 expression in CoLo320WT cells increased in time dependent fashion under gastrin_(17) intervention and peaked at 12 hour after intervention,while decreased by L365,260 inhibition.But gas trine_(17) had no effect on total FAK in CoLo320WT cells.Expresion levels of E-cadherin and?-catenin com- plex in TX-100 solution fraction were decreased apparently,but increased again after L365,260 block- ing.On the contrary,the expression levels of E-cadherin and?-eatenin complex in TX-100 solution frac tion differed from that in TX-100 solution.Cytoehemistry observation had revealed that E-cadherin and?-catenin transferred from cell membranes into cndochylemas,nuclei and cytoskeleton under gastrin_(17) in- tervention.Conclusions Gastrin_(17)affected significantly the distribution of E cadherin/?-catenin complex in CoLo320WT by phosphorating FAK Tyr397 and activating FAK pathway when it bound to its recep- tor CCK-2,therefore promoted invasion and metastasis of CoLo320WT.