Characterization of a Novel MAP4K4-SASH1 Kinase Cascade Regulating Breast Cancer Tumorigenesis and Metastasis
Year: 2020
Type: preprint
Abstract: Background: The SAM and SH3 domain containing protein 1(SASH1) was previously described as a candidate tumor-suppressor gene in breast cancer and colon cancer to mediate tumor metastasis and tumor growth. However，the underlying mechanisms by which SASH1 implements breast cancer tumorigenesis and the question why SASH1 is downregulated in most solid cancers remain unexplored. Methods: The expression and clinical relevance of SASH1 and mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) were analyzed by immunohistochemistry(IHC). The bindings of SASH1 and MAP4K4 were investigated by pull down assay, nano-flow LC-MS/MS , immunoprecipitation- western blot(IP-WB) and immunofluorescence(IF). The knockdown of SASH1- and/or MAP4K4-induced cell proliferation, apoptosis, migration and invasion were investigated by flow cytometry and transwell assays. The cell proliferation and apoptosis treated by GNE-495 were assessed by flow cytometry. The in vitro regulation relationship between SASH1 and MAP4K4 were identified by in vitro kinase assay. The functional effects of the silencing of SASH1 and/or MAP4K4 on tumorigenesis and metastasis of T47D cells-xenograft tumors were assessed by HE staining and IHC .Results: SASH1 and MAP4K4 was significantly downregulated in hormone- dependent subtypes of breast cancers and SASH1 was significantly correlated with MAP4K4 in hormone-dependent subtypes. SASH1 is identified to be a novel serine/threonine protein kinase that binds to MAP4K4, and is phosphorylated by MAP4K4. SASH1 and MAP4K4 synergistically regulate cell proliferation，migration and invasion of hormone-dependent breast cancer cells and mediate liver and lung metastasis of T47D cells-xenograft tumors.Ser801 in MAP4K4 might be the serine site for MAP4K4 to phosphorylate SASH1. GNE-495， a MAP4K4-specific inhibitors by upregulating the expression of MAP4K4 and SASH1 might be a potential reagent in treating hormone-dependent breast cancers. Conclusion: Our findings characterize a novel MAP4K4-SASH1 kinase cascade to mediate the tumorigenesis and metastasis of breast cancer, which can be of targeted intervention by GNE-495.
Authors: Yadong Li, Daoqiu Wu, Jing Hou, Jing Zhang, Xing Zeng, Lian Chen, Xin Wan, Zhixiong Wu, Jinyun Wang, Ke Wang, Dan Yang, Hongyu Chen, Zexi Xu, Lei Jia, Qianfan Liu, Zhongshu Kuang, Geli Jiang, Hui Zhang, Jie Luo, Wei Li, Xue Zou, Xiaohua Zeng, Ding'an Zhou
Language: English
Topic: Melanoma and MAPK Pathways
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
OpenAlex ID: W4233355947