Down-regulation of survivin expression by small interfering RNA induces pancreatic cancer cell apoptosis and enhances its radiosensitivity

AIM： To investigate the inhibitory effect of small interfering RNA （siRNA） on the expression of survivin in pancreatic cancer cell line PC-2 and the role of siRNA in inducing PC-2 cell apoptosis and enhancing its radiosensitivity. METHODS： A siRNA plasmid expression vector against survivin was constructed and transfected into PC-2 cells with LipofectamineTM 2000. The down regulation of survivin expression was detected by semi-quantitive RT-PCR and immunohistochemical SP method and the role of siRNA in inducing PC-2 cell apoptosis and enhancing its radiosensitivity was detected by flow cytometry. RESULTS： The sequence-specific siRNA efficiently and specifically down-regulated the expression of survivin at both mRNA and protein levels. The expression inhibition ratio was 81.25% at mRNA level detected by semlquantitive RT-PCR and 74.24% at protein level detected by immunohistochemical method. Forty-eight hours after transfection,apoptosis was induced in 7.03% cells by siRNA and in 14.58% cells by siRNA combined with radiation. CONCLUSION： The siRNA plasmid expression vector against survivin can inhibit the expression of survivin in PC-2 cells efficiently and specifically. Inhibiting the expression of survivin can induce apoptosis of PC-2 cells and enhance its radiosensitivity significantly. RNAi against survivin is of potential value in gene taerapy of pancreatic cancer.

Scutellaria barbate extract induces apoptosis of hepatoma H22 cells via the mitochondrial pathway involving caspase-3

AIM： To study the growth inhibitory and apoptotic effects of Scutellaria barbata D.Don （S. barbata） and to determine the underlying mechanism of its antiturnor activity in mouse liver cancer cell line H22.METHODS： Proliferation of H22 cells was examined by MTT assay. Cellular morphology of PC-2 cells was observed under fluorescence microscope and transmission electron microscope （EM）. Mitochondrial transmembrane potential was determined under laser scanning confocal microscope （LSCM） with rhodamine 123 staining. Flow cytometry was performed to analyze the cell cycle of H22 cells with propidium iodide staining. Protein level of cytochrome C and caspase-3 was measured by semi-quantitive RT-PCR and Western blot analysis. Activity of caspase-3 enzyme was measured by spectrofluorometrv.RESULTS： M-I-I- assay showed that extracts from S. barbata （ESB） could inhibit the proliferation of H22 cells in a time-dependent manner. Among the various phasesof cell cycle, the percentage of cells in S phase was significantly decreased, while the percentage of cells in G1 phase was increased. Flow cytometry assay also showed that ESB had a positive effect on apoptosis. Typical apoptotic morphologies such as condensation and fragmentation of nuclei and blebbing membrane of apoptotic cells could be observed under transmission electron microscope and fluorescence microscope. To further investige the molecular mechanism behind ESB-induced apoptosis, ESB-treated cells rapidly lost their mitochondrial transmembrane potential, released mitochondrial cytochrome C into cytosol, and induced caspase-3 activity in a dose-dependent manner. CONCLUSION： ESB can effectively inhibit the proliferation and induce apoptosis of H22 cells involving loss of mitochondrial transmembrane potential, release of cytochrome C, and activation of caspase-3.

Expert consensus on maintenance treatment for metastatic colorectal cancer in China

The impact of maintenance therapy on progression-free survival and overall survival as well as quality of life of Chinese patients with metastatic colorectal cancer has long been under discussion.Recently,some phase III clinical trials have revealed that maintenance therapy can significantly prolong the progression-free survival while maintain an acceptable safety profile.Based on this evidence and common treatment practice in China,we now generated one Expert Consensus on Maintenance Treatment for Metastatic Colorectal Cancer in China to further specify the necessity of maintenance therapy,suitable candidates for such treatment,and appropriate regimens.

KNOCKDOWN OF SURVIVIN EXPRESSION BY SMALL INTERFERING RNA SUPPRESSES PROLIFERATION OF TWO HUMAN CANCER CELL LINES

Objective To construct an expression vector of small interfering RNA （siRNA） against survivin and observe its effects on survivin expression and proliferation of human pancreatic cancer cell line PC-2 and breast cancer cell line MCF-7. Methods Constructed an expression vector of siRNA against survivin and transfected it into PC-2 and MCF-7 cells using lipofectamine^TM 2000. The expression of survivin was detected by semi-quanfifive RT-PCR and immunohistochemistry, and its effects on proliferation of PC-2 and MCF-7 cells were detected by MTT assay. Results The introduction of sequence-specific siRNA could efficiently suppress survivin expression at both mRNA and protein levels in the two cancer cell lines. In PC-2 cells, the expression inhibition rates were 81.25% at mRNA level and 74.24% at protein level In MCF-7 cells, the expression inhibition rates were 64.91% at mRNA level and 79. 72% at protein level The proliferation of PC-2 and MCF-7 cells was also suppressed, and24 and 48 hours after the cells were reseeded, the proliferation inhibition rates of PC-2 cells were 28. 00% and 33. 38%, and that of MCF-7 cells were 31.58% and 33.02%, respectively. Conclusions The expression vector of siRNA against survivin can block survivin expression in PC-2 and MCF-7 cells efficiently and specifically. Down regulation of survivin expression can suppress proliferation of PC-2 and MCF-7 cells. Survivin RNAi may have potential value in gene therapy of human cancers.

Relationship between apurinic endonuclease 1 Asp148Glu polymorphism and gastrointestinal cancer risk: An updated meta-analysis

AIM:To evaluate the relationship between apurinic endonuclease 1(APE1) Asp148 Glu polymorphism and the susceptibility to gastrointestinal(GI) cancers.METHODS:We searched Pub Med, ISI Web of Knowledge, and Chinese National Knowledge Infrastructure(CNKI) databases updated on July 15, 2014 for relevant studies.Only case-control studies comparing APE1 Asp148 Glu polymorphism and GI cancer risk were included.We excluded studies reporting only standardized incidence ratios without control groups and those without detailed genotyping data.Meta-analysis was performed on 17 studies involving 4856 cancer patients and 6136 cancer-free controls.Review Manager version 5.1 was used to perform the meta-analysis.The pooled odds ratios(ORs) and 95% confidence intervals(CIs) were estimated under the allele contrast, homozygous, heterozygous, dominant and recessive genetic models.We also conducted subgroup analyses stratified by ethnicity and cancer type.Publication bias was evaluated using Begg's test.RESULTS:The meta-analysis showed a significant association between APE1 Asp148Glu polymorphism and GI cancer risk in three genetic models in the overall population(G vs T:OR=1.18;95%CI:1.05-1.32;TG vs TT:OR=1.28;95%CI:1.08-1.52;TG+GG vs TT:OR=1.32;95%CI:1.10-1.57).Stratified analysis by ethnicity revealed a statistically increased GI cancer risk in Asians(G vs T:OR=1.27;95%CI:1.07-1.51;GG vs TT:OR=1.58;95%CI:1.05-2.38;TG vs TT:OR=1.30;95%CI,1.01-1.67;and TG+GG vs TT:OR=1.38;95%CI:1.07-1.78),but not in Caucasians.Furthersubgroup analysis by cancer type indicated that APE1Asp148Glu polymorphism may contribute to gastric cancer risk.However,Asp148Glu has no significant association with colorectal or esophageal cancer risk in any genetic model.CONCLUSION:This meta-analysis suggests that the APE1 Asp148Glu polymorphism G allele is associated with an increased GI cancer risk,especially in gastric cancer.

Prognostic Significance of MiR-34a Expression in Patients with Gastric Cancer after Radical Gastrectomy

Background： MiR-34a dysregulation has been implicated in tumorigenesis and progression of gastric cancer, but its role in prognosis of patients with gastric cancer remains unknown. The aim of this study was to investigate the expression and prognostic significance of miR-34a in gastric cancer patients after radical gastrectomy. Methods： Quantitative real-time polymerase chain reaction was performed to detect the expression of miR-34a in human gastric cancer cell lines and tissues in 76 patients with gastric adenocarcinoma from China. Results are assessed for association with clinical features and overall survival （OS） using Kaplan-Meier analysis. Prognostic values of miR-34a expression and clinical outcomes were evaluated by Cox regression analysis. A molecular prognostic stratification scheme incorporating miR-34a expression was determined using receiver operating characteristic analysis. Results： The results show that the expression level of miR-34a was decreased in human gastric cancer cell lines and tissues, and down-regulated expression of miR-34a was associated with Lauren classification （P = 0.034）. Decreased miR-34a expression in gastric cancer tissues was positively correlated with poor OS of gastric cancer patients （P = 0.0 l 3）. Further multivariate Cox regression analysis suggested that miR-34a expression was an independent prognostic indicator for gastric cancer （P = 0.027）. Applying the prognostic value of miR-34a expression to tumor node metastasis （TNM） stage system showed a better prognostic value in patients with gastric cancer than miR-34a expression （P = 0.0435） or TNM stage （P = 0.0249） alone. Conclusion： The results reinforce the critical role for the down-regulated miR-34a expression in gastric cancer and suggest that miR-34a could be a prognostic indicator for this disease.