VEGF Regulates The Expression Of RBP2 Through JNK Pathway In Gastric Cancer Development

Objective:Both VEGF and RBP2 play important roles in the development of gastric cancer.The upstream regulation mechanism of RBP2 needs to be more explored.We have identified that RBP2 can directly bind to the promoter of VEGF for the gastric cancer angiogenesis.During this research,we found that VEGF could also affect the expression of RBP2.Methods:The expression of RBP2,VEGF was assessed in 15 human gastric cancer samples and normal control samples.We used quantitative RT-PCR and western blot analysis characterize the change in RBP2 expression and associated biological activities induced by VEGF silencing or VEGF protein.By using the specific inhibitors of the signal pathways which were involved in VEGF-induced genes expression,we tested the RBP2 expression by qPCR and western blot.The functional assays such as clone formation and Transwell invasion assay were performed.Nude mice were used to detect the role of VEGF in vivo.Results:1.VEGF and RBP2 were both overexpressed in human gastric cancer tissue as compared with normal tissue.2.The overexpression of RBP2 could be found in VEGF-induced gastric cancer cell lines.At the same time,the inhibition of VEGF resulted in the decrease of RBP2 expression with QRT-PCR and Western blot.3.JNK pathway might take part in VEGF-correlated regulation on RBP2 expression.The western blot results showed that both the phosphorylation of JNK and the key downstream molecular P53 were inhibited by VEGF induction.4.QRT-PCR and Western blot results showed that even with RBP2 siRNA,the induction of VEGF could partially reverse the expression of RBP2 in gastric cancer cells.The results of clone formation and Transwell invasion assay indicated that VEGF could also reverse the inhibition of proliferation and invasion induced by RBP2 siRNA in gastric cancer cells.5.The tumor growth curve showed the effect of VEGF on tumor size.QRT-PCR and Immunohistochemistry results determined the positive correlation between VEGF and RBP2 expression in vivo.Conclusion:VEGF has an important role on RBP2 expression through the JNK pathway.This provided the new regulation mechanism not only for VEGF but also RBP2 which might be useful for gastric cancer development.