BMC Cancer Research article Receptor and secreted targets of Wnt-1/β-catenin signalling in mouse mammary epithelial cells Paraic A Kenny*1,3, Tariq Enver1,4 and Alan Ashworth2 BioMed Central Open Access Address: 1Section of Gene Function and Regulation, Institute of Cancer Research, Fulham Rd., London, SW3 6JB, UK, 2Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, Fulham Rd, London, SW3 6JB, UK, 3Current Address Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, 1 Cyclotron Road, Mailstop 83-101, Berkeley, CA 94720, USA and 4Current Address Molecular Haematology Unit, The Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, OX3 9DS, UK Email: Paraic A Kenny* - pakenny@lbl.gov; Tariq Enver - tenver@gwmail.jr2.ox.ac.uk; Alan Ashworth - alana@icr.ac.uk * Corresponding author Published: 10 January 2005 BMC Cancer 2005, 5:3 doi:10.1186/1471-2407-5-3 This article is available from: http://www.biomedcentral.com/1471-2407/5/3 Received: 12 October 2004 Accepted: 10 January 2005 © 2005 Kenny et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. wntcateninmicroarrayhypoxiaangiogenesis Abstract Background: Deregulation of the Wnt/ β-catenin signal transduction pathway has been implicated in the pathogenesis of tumours in the mammary gland, colon and other tissues. Mutations in components of this pathway result in β-catenin stabilization and accumulation, and the aberrant modulation of β-catenin/TCF target genes. Such alterations in the cellular transcriptional profile are believed to underlie the pathogenesis of these cancers. We have sought to identify novel target genes of this pathway in mouse mammary epithelial cells. Methods: Gene expression microarray analysis of mouse mammary epithelial cells inducibly expressing a constitutively active mutant of β-catenin was used to identify target genes of this pathway. Results: The differential expression in response to ∆Nβ-catenin for five putative target genes, Autotaxin, Extracellular Matrix Protein 1 (Ecm1), CD14, Hypoxia-inducible gene 2 (Hig2) and Receptor Activity Modifying Protein 3 (RAMP3), was independently validated by northern blotting. Each of these genes encodes either a receptor or a secreted protein, modulation of which may underlie the interactions between Wnt/β-catenin tumour cells and between the tumour and its microenvironment. One of these genes, Hig2, previously shown to be induced by both hypoxia and glucose deprivation in human cervical carcinoma cells, was strongly repressed upon ∆Nβ-catenin induction. The predicted N-terminus of Hig2 contains a putative signal peptide suggesting it might be secreted. Consistent with this, a Hig2-EGFP fusion protein was able to enter the secretory pathway and was detected in conditioned medium. Mutation of critical residues in the putative signal sequence abolished its secretion. The expression of human HIG2 was examined in a panel of human tumours and was found to be significantly downregulated in kidney tumours compared to normal adjacent tissue. Conclusions: HIG2 represents a novel non-cell autonomous target of the Wnt pathway which is potentially involved in human cancer. Page 1 of 9 (page number not for citation purposes)