Tumor suppression gene Syk(L) is a transcriptional repressor in breast cancer

AIM: To study the Syk(L) biological function in breast cancer and to explore the possible mechanism of tumor suppression gene Syk(L).METHODS: Syk(L),kinase inefficient Syk(L) or the domains of Syk(L) were fused with the DNA binding domains of Gal4 to make recombinant plasmids, which were cotransfected with pFR and pCMV-β-gal into human breast cancer cells MB231 and MB435.Gal4 luciferase reporter assay was used to observe the transcriptional regulation function of Syk(L).RESULTS: Syk(L),fused with DNA binding domain of Gal4,was capable of down-regulating the expression of luciferase whose promoter contains 5 Gal4 binding sites in human breast cancer cells,MB231 and MB435.This kind of down-regulation was unrelated to Syk(L)'s kinase activity,and was decided by the SH2 domain and kinase domain of Syk(L).CONCLUSION: Syk(L) possesses transcriptional repressor function in breast cancer,which is unrelated to Syk(L)'s kinase activity.Both the SH2 domain and kinase domain of Syk(L) have the transcriptional repressor function.The tumor suppression role of Syk(L) is maybe associated with its transcriptional repression function in breast cancer.