title: Tax1 enhances cancer cell proliferation via Ras-Raf-MEK-ERK signaling pathway.
abstract: Erbin is an ErbB2 binding protein, which belongs to the LAP (leucine-rich repeat (LRR) and PDZ domain) protein family. We previously reported that Tax1, a protein of the human T-cell leukemia virus type I (HTLV-I), associated with Erbin by using Erbin PDZ domain as a bait to screen a human T lymphocyte cDNA library by a yeast two hybrid strategy. In the present study, we demonstrated that Tax1 enhances cancer cell proliferation via Ras-Raf-MEK-ERK signaling pathway by using molecular section strategy. The pull-down assay showed that the four amino acid domain, that is, Tax1 350-353, might specifically interact with Erbin, but not any other Tax1 deletion mutants. The coimmunoprecipitation assay confirmed that Tax1 350-353 domain bound with Erbin in vivo. Functional study demonstrated that overexpression of Tax1 in cancer cell lines of liver cancer SMMC-7721, colon cancer HCT-116, and breast cancer MCF-7 facilitated the cell proliferation. And the transfection of Tax1 353 in MCF-7 cells with endogenous Erbin expression markedly increased phosphorylation of Ras, Raf, MEK1/2, ERK1/2, PI3K, and IkappaBalpha, suggesting that Tax1-enhanced cell proliferation tracks Ras-Raf-MEK-ERK signaling pathway.
authors.affiliation: National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Chunjiao
authors.initials: C
authors.lastname: Song
authors.forename: Weimin
authors.initials: W
authors.lastname: Wang
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Liu
authors.forename: Dexian
authors.initials: D
authors.lastname: Zheng
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction; D048490:raf Kinases / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C413364:ERBIN protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; C120635:TAX1BP1 protein, human; D048490:raf Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D018631:ras Proteins