title: CCN6 (WISP3) decreases ZEB1-mediated EMT and invasion by attenuation of IGF-1 receptor signaling in breast cancer.
abstract: During progression of breast cancer, CCN6 protein exerts tumor inhibitory functions. CCN6 is a secreted protein that modulates the insulin-like growth factor-1 (IGF-1) signaling pathway. Knockdown of CCN6 in benign mammary epithelial cells triggers an epithelial to mesenchymal transition (EMT), with upregulation of the transcription factor ZEB1/δEF1. How CCN6 regulates ZEB1 expression is unknown. We hypothesized that CCN6 might regulate ZEB1, EMT and breast cancer invasion by modulating IGF-1 signaling. Exogenously added human recombinant CCN6 protein was sufficient to downregulate ZEB1 mRNA and protein levels in CCN6-deficient (CCN6 KD) HME cells and MDA-MB-231 breast cancer cells. Recombinant CCN6 protein decreased invasion of CCN6 KD cells compared with controls. We discovered that knockdown of CCN6 induced IGF-1 secretion in HME cells cultivated in serum-free medium to higher concentrations than found in MDA-MB-231 cells. Treatment with recombinant CCN6 protein was sufficient to decrease IGF-1 protein and mRNA to control levels, rescuing the effect of CCN6 knockdown. Specific inhibition of IGF-1 receptors using the pharmacological inhibitor NVP-AE541 or short hairpin shRNAs revealed that ZEB1 upregulation due to knockdown of CCN6 requires activation of IGF-1 receptor signaling. Recombinant CCN6 blunted IGF-1-induced ZEB1 upregulation in MDA-MB-231 cells. Our data define a pathway in which CCN6 attenuates IGF-1 signaling to decrease ZEB1 expression and invasion in breast cancer. These results suggest that CCN6 could be a target to prevent or halt breast cancer invasion.
authors.affiliation: CIBICI-CONICET, Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Lorenzatti
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Anupama
authors.initials: A
authors.lastname: Pal
authors.forename: Ana M
authors.initials: AM
authors.lastname: Cabanillas
authors.forename: Celina G
authors.initials: CG
authors.lastname: Kleer
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D055511:CCN Intercellular Signaling Proteins; D054337:Cell Dedifferentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D015536:Down-Regulation; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005260:Female; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D000071799:Zinc Finger E-box-Binding Homeobox 1
chemical_list: D055511:CCN Intercellular Signaling Proteins; C400081:CCN6 protein, human; D018398:Homeodomain Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014157:Transcription Factors; C486307:ZEB1 protein, human; D000071799:Zinc Finger E-box-Binding Homeobox 1; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1