AIM To investigate the effects of small interfering RNA (siRNA)-mediated inhibition of Class I phosphoinositide 3-kinase (Class I PI3K) signal transduction on the proliferation, apoptosis, and autophagy of gastric cancer SGC7901 and MGC803 cells. METHODS We constructed the recombinant replication adenovirus PI3K(I)-RNA interference (RNAi)-green fluorescent protein (GFP) and control adenovirus NC-RNAi-GFP, and infected it into human gastric cancer cells. MTT assay was used to determine the growth rate of the gastric cancer cells. Activation of autophagy was monitored with monodansylcadaverine (MDC) staining after adenovirus PI3K(I)-RNAi-GFP and control adenovirus NC-RNAi-GFP treatment. Immunofluorescence staining was used to detect the expression of microtubule-associated protein 1 light chain 3 (LC3). Mitochondrial membrane potential was measured using the fluorescent probe JC-1. The expression of autophagy was monitored with MDC, LC3 staining, and transmission electron microscopy. Western blotting was used to detect p53, Beclin-1, Bcl-2, and LC3 protein expression in the culture supernatant. RESULTS The viability of gastric cancer cells was inhibited after siRNA targeting to the Class I PI3K blocked Class I PI3K signal pathway. MTT assays revealed that, after SGC7901 cancer cells were treated with adenovirus PI3K(I)-RNAi-GFP, the rate of inhibition reached 27.48% ± 2.71% at 24 h, 41.92% ± 2.02% at 48 h, and 50.85% ± 0.91% at 72 h. After MGC803 cancer cells were treated with adenovirus PI3K(I)-RNAi-GFP, the rate of inhibition reached 24.39% ± 0.93% at 24 h, 47.00% ± 0.87% at 48 h, and 70.30% ± 0.86% at 72 h (P < 0.05 compared to control group). It was determined that when 50 MOI, the transfection efficiency was 95% ± 2.4%. Adenovirus PI3K(I)-RNAi-GFP (50 MOI) induced mitochondrial dysfunction and activated cell apoptosis in SGC7901 cells, and the results described here prove that RNAi of Class I PI3K induced apoptosis in SGC7901 cells. The results showed that adenovirus PI3K(I)-RNAi-GFP transfection induced punctate distribution of LC3 immunoreactivity, indicating increased formation of autophagosomes. The results showed that the basal level of Beclin-1 and LC3 protein in SGC7901 cells was low. After incubating with adenovirus PI3K(I)-RNAi-GFP (50 MOI), Beclin-1, LC3, and p53 protein expression was significantly increased from 24 to 72 h. We also found that Bcl-2 protein expression down-regulated with the treatment of adenovirus PI3K(I)-RNAi-GFP (50 MOI). A number of isolated membranes, possibly derived from ribosome-free endoplasmic reticulum, were seen. These isolated membranes were elongated and curved to engulf a cytoplasmic fraction and organelles. We used transmission electron microscopy to identify ultrastructural changes in SGC7901 cells after adenovirus PI3K(I)-RNAi-GFP (50 MOI) treatment. Control cells showed a round shape and contained normal-looking organelles, nucleus, and chromatin, while adenovirus PI3K(I)-RNAi-GFP (50 MOI)-treated cells exhibited the typical signs of autophagy. CONCLUSION After the Class I PI3K signaling pathway has been blocked by siRNA, the proliferation of cells was inhibited and the apoptosis of gastric cancer cells was enhanced.

Background/Aims: To study the effect of cytotoxic T-lymphocyte antigen 4 gene haplotypes to susceptibility of esophageal squamous cell carcinoma.Methodology: A gender- and age-matched case-control design was used in this study. PCR-RFLP method was used to detect the genotype of CTLA4 in 205 patients and 205 control individuals in the Anyang area. Furthermore, haplotypes were calculated by PHASE2.1 software. Finally, the conditional logistic regression analysis was carried out to analyze the relevance between the risk of ESCC and the genotypes or haplotypes of CTLA4 gene.Results: The CTLA4 rs231775 and rs4553808 genotypes in patients with ESCC were significantly different from controls (p=0.004, p=0.023, respectively). The AG and AA genotypes of rs231775 were highly correlated with the risk of ESCC (Adjusted OR=2.280, 95%CI=1.433-3.629, p=0.001; Adjusted OR=2.192, 95%CI=1.229-3.911, p=0.008, respectively), and AG genotype of rs4553808 also increased the susceptibility of ESCC (Adjusted OR=1.848, 95%CI=1.220-2.800, p=0.004). Further study suggested that AAG haplotype may enhance the risk of ESCC (Adjusted OR=5.035, 95%CI=1.599-15.860, p=0.005), but GAA haplotype played a protective role (Adjusted OR=0.413, 95%CI=0.251-0.680, p=0.001).Conclusions: Our research confirmed that CTLA4 genetic variation was related to ESCC in the Anyang area and GAA haplotype was the protective factor of ESCC.

Objective To investigate the distribution of the three polymorphisms of cytotoxic T lymphocyte-associated antigen 4 (CTLA4) gene and their association with susceptibility of esophageal cancer (EC). Methods Polymerase chain reaction-restricted fragment length polymorphism (PCR-RFLP)method was used to detect the genotype of CTLA4 three polymorphism sites in 205 patients ( 113 males and 92 females) and 205 gender-age-matched control individuals. The associations of genetic polymorphisms and haplotypes of them with susceptibility of EC were analyzed by conditional logistic regression model. Results The AA and AG genotypes of + 49A/G increased the risk of EC ( P ＜ 0. 01, OR = 2. 192; P ＜0. 01, OR =2. 280, respectively). The AG genotype of -1661A/G was also more in EC group than in control group (P ＜0. 01, OR = 1. 848). The distribution of GG genotype had no difference between the two groups ( P ＞ 0. 05). - 1772 site was also not associated with ESCC susceptibility (P ＞ 0. 05). Haplotype AAG increased the risk of EC ( P ＜ 0. 01, OR = 5. 035 ), but haplotype GAA played a protective role ( P ＜0. 01, OR = 0. 413 ). Conclusion The polymorphisms of CTLA4 exon 1 + 49A/G and promoter -1661A/G are associated with susceptibility of EC. Further association study confirmed that haplotype AAG is the risk factor of EC, but GAA played a protective role.

DNA repair capacity (DRC) can be altered based on sequence variations in DNA repair genes, which may result in cancer susceptibility. The current study was to evaluate the association between genetic polymorphisms, including associated haplotypes of xeroderma pigmentosum complementary group D (XPD), and individual susceptibility to gastric cancer. Two-hundred-eight patients with gastric cancer and 339 healthy controls were enrolled in this study. Their genomic DNA was extracted from peripheral blood leukocytes. The genotypes at exon 6, 10 and 23 were identified by polymerase chain reaction (PCR). Unconditional logistic regression model was used to analyze the effects of the polymorphisms, including the corresponding haplotypes, on the susceptibility to develop gastric cancer. The proportion of genotypes GA or AA at exon 10 in cases was showed to be significantly higher than that in controls (P < 0.01, P < 0.01, respectively). The risk of genotype GA or AA carriers to develop gastric cancer was simultaneously much higher (OR = 3.38, 95% CI 2.30-4.95; OR = 6.13, 95% CI 2.45-15.31, respectively). The allele A at exon 10 was also observed to manifest a substantially higher frequency in cases compared to controls (P < 0.01), which might indicate an increased tendency to gastric cancer (OR = 2.40, 95% CI 1.81-3.17). No significant differences were found in the distribution of genotypes at exon 6 or 23 between the two groups (P = 0.23, P = 0.52; P = 0.44, P = 0.56, respectively). By haplotype analysis, haplotype AAA could individually increase incidence of gastric cancer (P < 0.01, OR = 3.39, 95% CI 2.21-5.21). In contrast, haplotypes CGA and AGA were showed a decline in gastric cancer susceptibility (OR = 0.67, 95% CI 0.46-0.97; OR = 0.58, 95% CI 0.41-0.83, respectively). The rest of haplotypes made no statistically significant difference between cases and controls. Taken together, this study demonstrates that the genetic variation at exon 10 and haplotype AAA may be contributing factors in developing gastric cancer.

：Trefoil factor 1 (TFF1)is mainly expressed in the mucosa lining the gastrointestinal tract. Changes of itsexpression in gastric cancer tissue play dual roles of carcinogenesis and anti- canceraction involved in modifying the genetic structure,delaying the transition of cellcycle,signal transduction,suppressing cell apoptosis and interaction withcyclooxygenase-2,but the specific mechanism is still unclear. Certain advances have beenmade on the diagnosis and therapy of gastric cancer.