Research

Glycoproteomic analysis of two mouse mammary cell lines during transforming growth factor (TGF)-β induced epithelial to mesenchymal transition

Jennifer J Hill¹ , Tammy-Lynn Tremblay¹ , Christiane Cantin² , Maureen O'Connor-McCourt² , John F Kelly¹ and Anne EG Lenferink²

¹  Institute for Biological Sciences, National Research Council Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada

²  Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Ave., Montreal, QC H4P 2R2, Canada

author email corresponding author email

Proteome Science 2009, 7:2doi:10.1186/1477-5956-7-2

Published:	8 January 2009

Abstract

Background

TGF-β acts as an antiproliferative factor in normal epithelial cells and at early stages of oncogenesis. However, later in tumor development TGF-β can become tumor promoting through mechanisms including the induction of epithelial-to-mesenchymal transition (EMT), a process that is thought to contribute to tumor progression, invasion and metastasis. To identify EMT-related breast cancer therapeutic targets and biomarkers, we have used two proteomic approaches to find proteins that change in abundance upon the induction of EMT by TGF-β in two mouse mammary epithelial cell lines, NMuMG and BRI-JM01.

Results

Preliminary experiments based on two-dimensional electrophoresis of a hydrophobic cell fraction identified only 5 differentially expressed proteins from BRI-JM01 cells. Since 3 of these proteins were glycoproteins, we next used the lectin, wheat germ agglutinin (WGA), to enrich for glycoproteins, followed by relative quantification of tryptic peptides using a label-free LC-MS based method. Using these approaches, we identified several proteins that are modulated during the EMT process, including cell adhesion molecules (several members of the Integrin family, Fibronectin, Activated leukocyte cell adhesion molecule, and Neural cell adhesion molecule 1) and regulators of cellular signaling (Tumor-associated calcium signal transducer 2, Basigin).

Conclusion

Interestingly, despite the fact that TGF-β induces similar EMT phenotypes in NMuMG and BRI-JM01 cells, the proteomic results for the two cell lines showed only minimal overlap. These differences likely result in part from the conservative cut-off values used to define differentially-expressed proteins in these experiments. Alternatively, it is possible that the two cell lines may use different mechanisms to achieve an EMT transition.