Objective To determine the possibility of telomere seeding in human gastric cancer cell SGC7901 and the influence of telomere on the expression of luciferase reporter gene nearby and to explore the position effect of telomere in gastric cancer cell. Methods The TET-OFF regulatory system was prepared and then transfected to gastric cancer cell SGC7901 by Lipofectamine TM 2000. With doxycycline added, the activity of the fluorescence caused by the expression of the target gene (the luciferase gene) with TET-OFF regulatory system was analyzed. The luciferase reporter plasmid in which telomere fragment pBX was inserted and the control plasmid pBX-ntf (no teloemere fragment) were co-transfected to cell 7901 with pTET-OFF regulate plasmid respectively and the luciferase activity was determined with doxycycline's induction. Results With the inducing of Dox, the activity of the fluorescence caused by the expression of the luciferase gene was inhibited. Treated with deoxycyline, there was a 4-fold decrease in the activity of the fluorescence in the cells infected with pBX and pTET-OFF as compared with that in the cells infected with pBX-ntf and pTET-OFF. Conclusion With the help of Lipofect2000, the gastric cancer cell SGC7901 can be transfected by TET-OFF regulatory system successfully. Dox could repress luciferase gene expression. Telomere seeding in gastric cancer cell SGC7901 could decrease the expression of luciferase reporter gene.

Objective To study the effect of telomere seeding on the biological behaviors of gastric cancer cell line and its mechanism. Methods The plasmid pSXneo-1.6-T2AG3, containing telomere fragment, was prepared in large scale and transfected into gastric cancer cell line SGC-7901 by LipofectAMINTM 2000. G418 was used to scan the positive clones and PCR was preformed to verify the stable seeding of the exogenous telomere in cell. MTT aassay and flow cytometry were used to determine the growth and cycle distribution of cells. The expression of cell cycle-related genes was detected by RT-PCR. Results Both pSXneo-1.6-T2AG3 eukaryonic expressing vector be inserted with telomere TTAGGG fragments and control vector were transfected into gastric cancer cell line SGC-7901 with LipofectamineTM 2000 and gain clones through G418 selection respectively, which were named as SGC-7901-telo and SGC-7901-neo. The cells were examined on DNA level by PCR to determine the correction of transfection. Flow cytometric analysis displayed an accumulation in G1M and G2M phase of cell cycle and an decreased percentage in S phase and proliferative index. Expression of p21 mRNA in 7901-telo cell line was increased (P0.05). Conclusion The pSX-T2AG3-neo eukaryonic expressing vector be inserted with 1600bp telomere TTAGGG fragments was successfully transfected into gastric cancer cell line SGC-7901 with the help of LipofectamineTM 2000. The seeding decreased malignant phenotypes of gastric cancer cell line and up-regulated the expression of p21, but the seeding did not distinctly influence on caspase3 mRNA expression.

This article is to evaluate the role of DCC gene alteration in the development and progression of gastric cancer, as well as to correlate with its prognosis. Loss of heterozygosity (LOH) at DCC gene was examined in 45 cases of surgically resected gastric cancer tissue. LOH at the DCC locus was detected in 15/45(33.3%), and it was found to be closely related to clinical staging, but not to the histologic types, depth of tumor invasion or lymph node metastases. These results suggest that LOH at the DCC locus occurs in late stage of the disease and detection of LOH at the DCC locus may be useful for predicting the prognosis of the gastric cancer patients.

Objective To evaluate the relationship between hMLH1 mutation and promoter methylation and genetic instability in gastric carcinomas. Methods hMLH1 mutation was measured by two dimentional DNA electrophoresis and DNA sequencing. The methylation of hMLH1 promoter was measured with methylation specific PCR. MSI was analyzed by PCR based methods. Results Sixty eight cases of sporadic gastric carcinoma were studied for hMLH1 mutation and promoter methylation. hMLH1 mutaions were detected in three cases (4.4%) of gastric cancer. No association was observed between hMLH1 mutation and tumor size, differentiation, histological type, depth of invasion, metastasis or stages. Methylation of hMLH1 promoter was detected in 11 cases (16.2%) of gastric cancer. By using five microsatellite markers, MSI in at least one locus was detected in 17 of 68 (25%) cases of the tumors analyzed. hMLH1 mutations were all detected in MSI H(≥2 loci, n =8), but no mutation was found in MSI L (only one locus, n =9) or MSS (tumor lacking MSI or stable, n =51). Methylation frequence of hMLH1 in MSI H was significantly higher than that in MSI L or MSS ( P 0.05). Conclusion hMLH1 mutation and promoter methylation may be involved in MSI pathway in gastric cancer.

Objective To investigate the effects of nu cleus transcription factor (NF)-?B, survivin, Bcl-2 and Caspase-3 on apoptos is of gastric cancer cells induced by tumor necrosis factor related apoptosis in ducing ligand(TRAIL). Methods Gastric cancer cells were cultured in RPMI-1640 and the proportions of apoptosis were analyzed by flow cytometry. The expressions of N F-?B, survivin, Bcl-2 and Caspase-3 in gastric cancer cells were evaluated b y Western blot. Results After gastric cancer cells were exposed to 50 ng/ml TRAIL f or 24 hours, the proportions of apoptosis were 24.05% in line MKN28, 7.83% in MK N45, 8.05% in AGS and 3.17% in SGC-7901 respectively; after 300 ng/ml TRAIL for 24 ho urs, the proportions of apoptosis were 36.05% in MKN28, 20.27% in MKN45, 16.50% in AGS and 11.80% in SGC-7901 respectively. The expressions of NF-?B and surv ivin under Western blot were lower in MKN28 than that in MKN45, AGS and SGC-79 0 1. In contrast, the expression of Caspase-3 was higher in MKN28 than that in MK N45, AGS a nd SGC-7901. The expression of Bcl-2 had no difference among the 4 lines of ga stric cancer cells. Conclusions The anti-tumor sensitivity of TRAIL to gastric cancer c ell may be associated with both increased expressions of NF-?B and survivin an d decreased expression of Caspase-3.

Objective To explore the relationship between mitochondrial DNA microsatellite instability(mtMSI) and expression of Bcl 2 and Bax mRNA in gastric cancer and its precancerous lesions. Methods mtMSI and expressions of Bcl 2 and Bax mRNA were detected with PCR SSCP and RT PCR. Results Expressions of Bcl 2 mRNA in intestinal metaplasia (IM,53 3%) and dysplasia (Dys, 70%) were significantly higher than that in normal control(10%, P

Objective To clarify the changes of ultrastructure of interstitial cells of Cajal in the small intestine of diabetic rats. Methods Rats were randomly divided into diabetic group and control group. The rate of the small intestinal transit was measured and the tissues of the small intestine were observed by transmission electron microscopy at 3 months after the establishment of rat model of diabetics. Results In the diabetic rats, the rate of small intestinal transit was delayed as compared with that in the control group. The number of the gap junction of interstitial cells of Cajal in the small intestine of diabetic rats decreased significantly, and the rest structures were damaged. Damaged organelles and formation of vacuoles were also found. Conclusion The changes of ultrastructure of interstitial cells of Cajal in the small intestine may be one of the mechanisms resulting in slow rate of the small intestinal transit in diabetic rats.

Objective To study the effects of demethylation agent 5-Aza-2′-deoxycytidine (5-Aza-CdR) on the antitumor activity of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) against gastric carcinoma. Methods Expression of caspase-8 mRNA was examined by RT-PCR. Antitumor activity of TRAIL protein was measured by MTT method. Results The inhibition rates of treatment with 200 ng/ml TRAIL for 72 h on gastric cell lines SGc 7901, Kato 3, and AGS were 9.83%, 11.94%, and 4.04%. After treatment with 5-Aza-CdR, the inhibition rates of 200 ng/ml TRAIL on gastric cell lines increased to 38.98%, 52.42%, and 30.72%. Before exposure to 5-Aza-CdR, expression of caspase-8 mRNA was low and an increased expression of the caspase-8 was found in the three gastric cancer cells after treatment with 5-Aza-CdR. Conclusion Treatment with 5-Aza-CdR can increase TRAIL antitumor activity on human gastric cancer and its mechanisms might be involved in the up-regulation of caspase-8 gene.

This study was aimed to establish a method for quality control of Tibetan medicine Shi-Wei Xiao-Shi-San (SWXSS). Thin layer chromatography (TLC) was established for the qualitative determination. Cinnamal and piperine were determined by HPLC. The separation was performed on Phenomenex C18 column (4.6 mm × 250 mm, 5μm). The results showed that TLC can be used in the identification of pomegranate seed and Terminalia chebula. The linear ranges of cinnamal and piperine were within the range of 0.06-0.37μg and 0.05-0.33μg, respectively. And the standard line was Y=9.273 2×106X-2.348 2×105, r=0.999 8;Y=7.315×103X-3.857, r=1.000 0. It was concluded that the identification method was specific, accurate and practical, which can be applied in the quality control of SWXSS.

Objective To study the effect of carbachol(CCH) on membrane potential of smooth muscle cells of gastric antrum of diabetic rats to verify the mechanism of gastric motility disturbance.Methods Fifty healthy Wistar rats of 2-month old,weighing 100-160 g,were divided into the control group(n=20) and diabetes mellitus group(n=30).Three months after the establishment of the rat model of diabetes by intraperitoneal injection of 60 mg/kg streptozotocin,gastric emptying time and gastric electrical activity were measured,and the resting membrane potentials of smooth muscle cells in antrum were measured by confocal laser scanning microscopy,then treated with carbachol of 10~(-9) mmol/L,10~(-8) mmol/L,10~(-7) mmol/L,the membrane potentials were measured.Results As compared with the normal rats,gastric emptying time in diabetic rats was significantly longer and abnormal gastric electric rhythm was significantly increased,the abnormal rhythm index(ARI) and the coefficient of variation(CV) of slow wave frequency in diabetic rats were significantly higher,but the resting membrane potentials remained unchanged and the sensitivity of CCH-induced membrane depolarization was increased.Conclusion The increase of sensitivity of CCH-induced membrane depolarization may be involved in the diabetes-induced gastric motor disorders.