1. ¹Institute of Pathology, Technical University, Munich, Germany
2. ²Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology-Delhi, New Delhi, India
3. ³Institute for Bioinformatics, GSF-National Research Center for Environment and Health, Neuherberg, Germany
4. ⁴Institute of Human Genetics, University Goettingen, Goettingen, Germany
5. ⁵Institute of Molecular Radiation Biology, GSF-National Research Center for Environment and Health, Neuherberg, Germany
6. ⁶Institute of Pathology, GSF-National Research Center for Environment and Health, Neuherberg, Germany

Correspondence: Dr K-F Becker, PhD, Institute of Pathology, Technical University, Trogerstrasse 18, Munich 81675, Germany. E-mail: kf.becker@lrz.tu-muenchen.de

Received 4 March 2004; Revised 11 June 2004; Accepted 17 June 2004; Published online 16 August 2004.

Abstract

E-cadherin is a cell–cell adhesion molecule and tumor invasion suppressor gene that is frequently altered in human cancers. It interacts through its cytoplasmic domain with -catenin which in turn interacts with the Wnt (wingless) signaling pathway. We have compared the effects of different tumor-derived E-cadherin variants with those of normal E-cadherin on Wnt signaling and on genes involved in epithelial mesenchymal transition. We established an in-house cDNA microarray composed of 1105 different, sequence verified cDNA probes corresponding to 899 unique genes that represent the majority of genes known to be involved in cadherin-dependent cell adhesion and signaling ('Adhesion/Signaling Array'). The expression signatures of E-cadherin-negative MDA-MB-435S cancer cells transfected with E-cadherin variants (in frame deletions of exon 8 or 9, D8 or D9, respectively, or a point mutation in exon 8 (D370A)) were compared to that of wild-type E-cadherin (WT) transfected cells. From the differentially expressed genes, we selected 38 that we subsequently analyzed by quantitative real-time RT-PCR and/or Northern Blot. A total of 92% of these were confirmed as differentially expressed. Most of these genes encode proteins of the cytoskeleton, cadherins/integrins, oncogenes and matrix metalloproteases. No significant expression differences of genes downstream of the Wnt-pathway were found, except in E-cadherin D8 transfected cells where upregulation of three Tcf/Lef-transcribed genes was seen. One possible reason for the lack of expression differences of the Tcf/Lef-regulated genes is upregulation of SFRP1 and SFRP3; both of which are competitive inhibitors of the Wnt proteins. Interestingly, known E-cadherin transcriptional repressors, such as SLUG (SNAI2), SIP1 (ZEB2), TWIST1, SNAIL (SNAI1) and ZEB1 (TCF8), but not E12/E47 (TCF3), had a lack of upregulation in cells expressing mutated E-cadherin compared to WT. In conclusion, E-cadherin mutations have no influence on expression of genes involved in Wnt-signaling, but they may promote their own expression by blocking upregulation of E-cadherin repressors.