title: TLR4 ligand/H₂O₂ enhances TGF-β1 signaling to induce metastatic potential of non-invasive breast cancer cells by activating non-Smad pathways.
abstract: TGF-β1 has the potential to activate multiple signaling pathways required for inducing metastatic potential of tumor cells. However, TGF-β1 was inefficient in inducing metastatic potential of many non-invasive human tumor cells. Here we report that the enhancement of TGF-β1 signaling is required for inducing metastatic potential of non-invasive breast cancer cells. TGF-β1 alone could not efficiently induce the sustained activation of Smad and non-Smad pathways in non-invasive breast cancer cells. TLR4 ligand (LPS) and H₂O₂ cooperated with TGF-β1 to enhance the sustained activation of non-Smad pathways, including p38MAPK, ERK, JNK, PI3K, and NF-κB. The activation of MAPK and PI3K pathways resulted in a positive feed-back effect on TGF-β1 signaling by down-regulating Nm23-H1 expression and up-regulating the expression of TβRI and TβRII, favoring further activation of multiple signaling pathways. Moreover, the enhanced TGF-β1 signaling induced higher expression of SNAI2, which also promoted TβRII expression. Therefore, the sustained activation levels of both Smad and non-Smad pathways were gradually increased after prolonged stimulation with TGF-β1/H₂O₂/LPS. Consistent with the activation pattern of signaling pathways, the invasive capacity and anoikis-resistance of non-invasive breast cancer cells were gradually increased after prolonged stimulation with TGF-β1/H₂O₂/LPS. The metastatic potential induced by TGF-β1/H₂O₂/LPS was sufficient for tumor cells to extravasate and form metastatic foci in an experimental metastasis model in nude mice. The findings in this study suggested that the enhanced signaling is required for inducing higher metastatic capacity of tumor cells, and that targeting one of stimuli or signaling pathways might be potential approach in comprehensive strategy for tumor therapy.
authors.affiliation: Department of Biochemistry & Molecular Biology, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, PR China.
authors.forename: Yuan-Hong
authors.initials: YH
authors.lastname: Zhou
authors.forename: Sheng-Jun
authors.initials: SJ
authors.lastname: Liao
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Luo
authors.forename: Jing-Jing
authors.initials: JJ
authors.lastname: Wei
authors.forename: Bin
authors.initials: B
authors.lastname: Yan
authors.forename: Rui
authors.initials: R
authors.lastname: Sun
authors.forename: Yu
authors.initials: Y
authors.lastname: Shu
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Gui-Mei
authors.initials: GM
authors.lastname: Zhang
authors.forename: Zuo-Hua
authors.initials: ZH
authors.lastname: Feng
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D004357:Drug Synergism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D061986:MCF-7 Cells; D051379:Mice; D008819:Mice, Nude; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D054778:NM23 Nucleoside Diphosphate Kinases / Q000235:genetics; D009362:Neoplasm Metastasis; D016877:Oxidants / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects*; D051785:Smad Proteins / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000819:agonists; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D014183:Transplantation, Heterologous
chemical_list: D006861:Hydrogen Peroxide; D008070:Lipopolysaccharides; D020928:Mitogen-Activated Protein Kinases; D054778:NM23 Nucleoside Diphosphate Kinases; D016877:Oxidants; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta; D051785:Smad Proteins; D051197:Toll-Like Receptor 4; D053773:Transforming Growth Factor beta1; C517938:NME1 protein, human