title: EMILIN2 down-modulates the Wnt signalling pathway and suppresses breast cancer cell growth and migration.
abstract: EMILIN2 is an extracellular matrix (ECM) protein that exerts contradictory effects within the tumour microenvironment: it induces apoptosis in a number of tumour cells, but it also enhances tumour neo-angiogenesis. In this study, we describe a new mechanism by which EMILIN2 attenuates tumour cell viability. Based on sequence homology with the cysteine-rich domain (CRD) of the Frizzled receptors, we hypothesized that EMILIN2 could affect Wnt signalling activation and demonstrate direct interaction with the Wnt1 ligand. This physical binding leads to decreased LRP6 phosphorylation and to the down-modulation of β-catenin, TAZ and their target genes. As a consequence, EMILIN2 negatively affects the viability, migration and tumourigenic potential of MDA-MB-231 breast cancer cells in a number of two- and three-dimensional in vitro assays. EMILIN2 does not modulate Wnt signalling downstream of the Wnt-Frizzled interaction, since it does not affect the activation of the pathway following treatment with the GSK3 inhibitors LiCl and CHIR99021. The interaction with Wnt1 and the subsequent biological effects require the presence of the EMI domain, as there is no effect with a deletion mutant lacking this domain. Moreover, in vivo experiments show that the ectopic expression of EMILIN2, as well as treatment with the recombinant protein, significantly reduce tumour growth and dissemination of cancer cells in nude mice. Accordingly, the tumour samples are characterized by a significant down-regulation of the Wnt signalling pathway. Altogether, these findings provide further evidence of the complex regulations governed by EMILIN2 in the tumour microenvironment, and they identify a key extracellular regulator of the Wnt signalling pathway.
authors.affiliation: Department of Translational Research, Experimental Oncology Division 2, CRO, Aviano, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Marastoni
authors.forename: Eva
authors.initials: E
authors.lastname: Andreuzzi
authors.forename: Alice
authors.initials: A
authors.lastname: Paulitti
authors.forename: Roberta
authors.initials: R
authors.lastname: Colladel
authors.forename: Rosanna
authors.initials: R
authors.lastname: Pellicani
authors.forename: Federico
authors.initials: F
authors.lastname: Todaro
authors.forename: Alvise
authors.initials: A
authors.lastname: Schiavinato
authors.forename: Paolo
authors.initials: P
authors.lastname: Bonaldo
authors.forename: Alfonso
authors.initials: A
authors.lastname: Colombatti
authors.forename: Maurizio
authors.initials: M
authors.lastname: Mongiat
mesh_terms: D000217:Acyltransferases; D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D002470:Cell Survival; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D060488:Low Density Lipoprotein Receptor-Related Protein-6 / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D009361:Neoplasm Invasiveness; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D047368:Tumor Burden; D059016:Tumor Microenvironment; D060449:Wnt Signaling Pathway; D051155:Wnt1 Protein / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism
chemical_list: C495270:CTNNB1 protein, human; C426245:EMILIN2 protein, human; D006023:Glycoproteins; C555475:LRP6 protein, human; D060488:Low Density Lipoprotein Receptor-Related Protein-6; D014157:Transcription Factors; C495247:WNT1 protein, human; D051155:Wnt1 Protein; D051176:beta Catenin; D000217:Acyltransferases; C108675:TAFAZZIN protein, human
keywords: EMILIN2; Wnt signalling; breast cancer; extracellular matrix; tumour microenvironment