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Biochemistry Research International
Volume 2011, Article ID 164197, 7 pages
Research Article

AP-1 as a Regulator of MMP-13 in the Stromal Cell of Giant Cell Tumor of Bone

1Department of Surgery, McMaster University, Hamilton, ON, Canada L8S 4L8
2Department of Surgery, Juravinski Cancer Centre, Hamilton Health Sciences, Hamilton, ON, Canada L8V 5C2
3Department of Orthopaedic, McGill University Health Centre, Montreal General Hospital, QC, Canada H3G 1A4
4Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada L8S 4L8

Received 26 August 2010; Revised 2 December 2010; Accepted 4 January 2011

Academic Editor: Martin Berchtold

Copyright © 2011 Isabella W. Y. Mak et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Matrix-metalloproteinase-13 (MMP-13) has been shown to be an important protease in inflammatory and neoplastic conditions of the skeletal system. In particular, the stromal cells of giant cell tumor of bone (GCT) express very high levels of MMP-13 in response to the cytokine-rich environment of the tumor. We have previously shown that MMP-13 expression in these cells is regulated, at least in part, by the RUNX2 transcription factor. In the current study, we identify the expression of the c-Fos and c-Jun elements of the AP-1 transcription factor in these cells by protein screening assays and real-time PCR. We then used siRNA gene knockdown to determine that these elements, in particular c-Jun, are upstream regulators of MMP-13 expression and activity in GCT stromal cells. We conclude that there was no synergy found between RUNX2 and AP-1 in the regulation of the MMP13 expression and that these transcription factors may be independently regulated in these cells.