抗增殖蛋白Tob1参与雌激素受体信号通路的初步研究

Objective: to identify the mechanisms of tumor suppression function of Tob1 in breast cancer cells. Methods: The recombinant plasmid of Tob1, truncated Tob1, and LXXLL motif mutated Tob1 were constructed, transfected into human breast cancer cell lines using lipofectamine. In vitro GST-pulldown assay and immunoprecipitation assay were utilized to confirm the interaction between Tob1 and ERα. Luciferase assay was used to detect the effects of Tob1 on the transcription activity of ER and its downstream effector Cyclin D1. Results: The interaction of Tob1 and ERα was confirmed: TOB1 N-terminal fragments （1~139aa）containing btg domain and LXXLL motif interacted in vitro and in vivo with ER, as the same time, the 1~139aa truncation without LXXLL motif partially lost the ability to combined to ER. In addition, TOB1 over-expression obviuosly suppressed the transcriptional activity of ER and cyclin D1. Conclusion: This study suggested that Tob1 act as tumor suppressor in breast cancer, at least via ER signaling pathway.