Osteopontin Regulate The Biological Behaviour Of Gastric Cancer Cell By Sdf-1/cxcr4 Axis

Background:Gastric cancer is one of the most common malignancies in the world. In China, it remains the most frequently diagnosed cancer and the second most common cancer-related cause of death with a high case fatality. Recently, many studies about the mechanism of gastric cancer'pathogenesy and early diagnosis of gastric cancer are undertaked in the world. Mounting evidence shows that OPN plays an important role in tumorgenesis, tumor invasion, and metastasis in many types of cancers. Chemokines are expressed by many tumor types and can promote mitosis, modulate apoptosis, survival and angiogenesis. Interaction between the chemokine receptor CXCR4 and its ligand, stomal-cell-derived factor 1 (SDF-1 or CXCL12), has been found to play an important role in tumorigenicity, proliferation, metastasis and angiogenesis in many cancers.ObjectiveTo explore the expression of SDF-1 in peripheral blood of patients with gastric cancer and examine the expression of CXCR4 in gastric cancer and their responding para-tumorous tissues, and analyze the relationship between CXCR4 expression and clinic pathologic features; To observe the biological changes of human gastric cancer cell line SGC-7901 which was stably transfected with siRNA targeting OPN and to study the molecular mechanism related to this biological changes.Methods1. Immunofluorescence staining was used to characterize the subcellar localization of CXCR4 in SGC-7901. Plasma SDF-1 levels in gastric cancer patients and age and gender-matched healthy persons were measured using ELISA, CXCR4 protein expression was detected by immunohistochemistry in human gastric cancer and their responding para-tumorous tissues.2. SGC-7901cells were transfected with OPNsiRNA-pcDNATM6.2, pcDNATM6.2 by lipofectmine 2000, transfectants were selected and confirmed by Western blot and RT-PCR technique. The proliferation activity was detected by MTT assay, the cell cycle and cell apoptosis was tested by flow cytomety, the migration of transfected cells was assayed using transwell migration chambers.3.The expression of OPN,SDF-1,CXCR4,MMP2 on mRNA and protein level were determined by RT-PCR and Western blot .Result1. The expression of SDF-1 and CXCR4 in patients with gastric cancerCXCR4 expressed in cytoplasm, not in cellular nucleus; Plasma SDF-1 levels in gastric cancer patients was significantly lower than those in normal controls (p<0.05). There were grate differences of the CXCR4 expression between tumor tissues and para-tumorous tissues (p<0.05). High cytoplasmic CXCR4 staining was observed in 80.8% of gastric cancer, whereas in para-tumorous tissues that were much lower (26.9%).2. Effect of OPN silenced by RNA interference on the biological changes of human gastric cancer cellSGC-7901 cells were stably transfected with OPNsiRNA-pcDNATM6.2, MTT showed the growth of OPNsiRNA gene transfected cells was slower than that of empty vecter transfected cells. OPNsiRNA gene transfection can increase the apoptosis, but there was no difference in the proportion of cell cycle. The Migration of cells transfected with OPNsiRNA was suppressed compared with that cells transfected with empty vector.3. OPN and related gene expression after OPN silenced by RNA interferenceSGC7-901 cells were stably transfected with OPNsiRNA-pcDNATM6.2, the expression of CXCR4 and MMP2 were significantly supreesed after OPN silenced by RNA interference.Conclusion1. The expression of SDF-1 in the peripheral blood and the CXCR4 expression in tumor tissues of the gastric cancer patients may be regarded as markers of gastric cancer and they may have a positive relationship with the tumor progression.2. After OPN siRNA treatment, the cell proliferation and motility are supressed, and apoptosis was enhanced.3. CXCR4,MMP2 are OPN targeting genes. CXCR4,MMP2 were down-regulated obviously when siRNA interferencing OPN gene. The result indicated that inhibiting OPN could suppress angiogenesis, inhibit invasion and migration, and delay tumor growth. OBJECTIVE: Gastric cancer is the second most common fatal malignant in the world. Helicobacter pylori infection is an important factor in the pathogenesis of gastric cancer. The purpose of this meta-analysis is to systematically review the long- term effect of H. pylori eradication on gastric premalignant lesions, gastric atrophy (GA) and intestinal metaplasia (IM).METHODS: Extensive English medical literature containing information on the association between infection with H. pylori and gastric premalignant lesion (i.e. GA and IM) were identified by searching the Medline, Pubmed and EMBase database with suitable keywords up to December 2008. Review Manager 4.2.8 was used for meta-analysis.RESULTS: Significant improvement of GA at antrum, whereas improvement was not shown for GA at corpus, and IM for both antrum and corpus of stomach after H. pylori eradication. For antral GA, the pooled weighted mean differences (WMD) with 95% CI was 0.22 (0.07-0.37), p=0.004. For corpus GA, the pooled WMD was 0.32 (-0.14-0.78), p=0.17. For antral IM, the pooled WMD was 0.10 (0.00-0.21), p=0.06. For corpus IM, the pooled WMD was 0.00 (-0.05-0.05), p=0.98. CONCLUSION: Our data suggest that gastric atrophy of the antrum can be reduced or even reversed by the eradication of H. pylori, and suggests a benefit to eradication of H. pylori in patients with GA in the antrum.