Progress in research on integrins involved in uPAR signaling

OBJECTIVE: To summarize the current articles about uPAR signaling.METHODS: urokinase plasminogen activator receptor,integrins,extracellular matrix,adhesion were searched as Key words by PubMed and CHKD periodical full-text databases from 1999-01 to 2010-10.Totally 352 were obtained.Choice criteria :1) the structure and functions of uPAR;2) the mechanisms of the adhesion of extracellular matrix and cells in migration cells;3) the association of uPAR and integrins.According to the choice criteria,38 papers were finally decided as references.RESULTS: At present,it seems that integrins,which form non-covalently associated α-β heterodimers,are essential for uPAR signalling as co-receptors.They can mediate uPAR signaling and activate Ras-MAPK.Integrins can change some biological characteristics in tumor cells and promote tumor invasion and metastasis.Currently,the mechanisms of uPAR interacting with integrins have not been elucidated.CONCLUSIONS: The binding of uPAR and uPA can facilitate the conversion of plasminogen to plasmin.Plasmin can degrade most components of the extracellular matrix(ECM).More importantly,uPAR can activate many intracellular signaling pathways which have an impact on cell migration,proliferation and survival.If interactions between uPAR and integrins can be proven,these would also be attractive targets for new drugs to interfere with tumor metastasis.