Background & objective: Full-length form of spleen tyrosine kinase [Syk(L)] is a tumor suppressor gene in breast cancer, which may translocate into cell nucleus and act as a transcriptional repressor. This study was to explore the mechanism of Syk(L) regulated gene transcription in breast cancer cells.
Methods: Flag-tagged Syk(L) was transfected into human embryonic kidney (HEK) 293 cells, and the interaction of Syk(L) and histone deacetylases (HDACs) was detected by immunoprecipitation. The binding of endogenous HDAC1 and Syk(L) in breast cancer cell line MB468 was also detected by immunoprecipitation. Flag-tagged Syk(L) domains SH2, KD, and IDB(L) were transfected into HEK293 cells, respectively, and their interaction with HDAC1 was detected. The activity of HDACs in the immunoprecipited complexes of Syk(L) was tested by HDAC activity detecting system.
Results: Exogenous Syk(L) was bound with HDAC1, 3, 6, and 7 in HEK293 cells, and endogenous Syk(L) was bound with HDAC1 in MB468 cells. SH2 and KD, but not IDB(L), were coimmunoprecipitated with HDAC1. The activity of HDACs was detected in the immunoprecipited complexes of Syk(L).
Conclusions: Syk(L) regulates gene transcription in breast cancer by binding with HDACs to form transcription repressive complexes.