The Study On The Interaction Between EphA3 And SGEF

With the intensifying of the aging of China's population , the incidence of prostate cancer is increasing year by year, therefore, It is very important to research on the molecular mechanism of occurrence of prostate cancer, so as to find out effective targeted therapy drugs. Eph receptors belong to receptor tyrosine kinases family and are one of the biggest branchs, EphA3 is a member of EphA receptor. Recent studies have found that EphA3 and the development of cancer are closely related. In all human tissues EphA3 has the highest expression in prostate ,which relates to the degree of malignancy of the prostate cancer , is an important carcinogenic factor. SGEF belongs to ephexin family, is a SH3-containing Guanine Nucleotide Exchange Factor (GEF). We found that in the LNCaP cells, PC-1 can make the expression of EphA3 up-regulation in the level of RNA and protein while make the expression of SGEF down-regulation in RNA and protein level. We have proved that the interaction between the EphA3 and SGEF molecules using co-immunoprecipitation experiment. The interaction between the EphA3 and SGEF is relevant to phosphorylation of EphA3 and can be strengthen with the induction of Ephrin - A5 . Then using GST pull down we further validated that EphA3 interact with the SGEF segment 216-420 of N-terminal and PS domain .we constructed the fluorescence expression vectors, transfecting into C4-2 cells, EphA3 and SGEF molecules can be observed in cytoplasm; cotransfecting into C4-2 cells , both molecules colocalized in the cytoplasm. In C4-2 cells ,which EphA3 and SGEF both have high expression,after the induction by Ephrin-A5 , MTT test shows that activated by Ephrin-A5, EphA3 has little impact on the growth of cells , Wound healing test shows which may be work on the migration and invasive of cells . We think that Ephrin-A5 activates the EphA3 by phosphorylation then EphA3 interacts with SGEF, then activates Rho G. Thus, we think SGEF may be a molecule in the downstream of EphA3, EphA3 activates SGEF, then activates its downstream molecule Rho G and series of signal molecules , which influence the occurrence and development of prostate cancer.