Plasma levels of the MMP-9:TIMP-1 complex as prognostic biomarker in breast cancer: A retrospective study

Worldwide more than one million women are annually diagnosed with breast cancer. A considerable fraction of these women receive systemic adjuvant therapy; however, some are cured by primary surgery and radiotherapy alone.

Thorsen et al BMC Cancer 2013, 13:598 http://www.biomedcentral.com/1471-2407/13/598 RESEARCH ARTICLE Open Access Plasma levels of the MMP-9:TIMP-1 complex as prognostic biomarker in breast cancer: a retrospective study Stine B Thorsen1†, Sarah LT Christensen1†, Sidse Ø Würtz1, Martin Lundberg2, Birgitte S Nielsen1, Lena Vinther1, Mick Knowles3, Nick Gee3, Simon Fredriksson2, Susanne Møller4, Nils Brünner1, Anne-Sofie Schrohl1† and Jan Stenvang1*† Abstract Background: Worldwide more than one million women are annually diagnosed with breast cancer A considerable fraction of these women receive systemic adjuvant therapy; however, some are cured by primary surgery and radiotherapy alone Prognostic biomarkers guide stratification of patients into different risk groups and hence improve management of breast cancer patients Plasma levels of Matrix Metalloproteinase-9 (MMP-9) and its natural inhibitor Tissue inhibitor of metalloproteinase-1 (TIMP-1) have previously been associated with poor patient outcome and resistance to certain forms of chemotherapy To pursue additional prognostic information from MMP-9 and TIMP-1, the level of the MMP-9 and TIMP-1 complex (MMP-9:TIMP-1) was investigated in plasma from breast cancer patients Methods: Detection of protein:protein complexes in plasma was performed using a commercially available ELISA kit and, for the first time, the highly sensitive in-solution proximity ligation assay (PLA) We screened plasma from 465 patients with primary breast cancer for prognostic value of the MMP-9:TIMP-1 complex Both assays were validated and applied for quantification of MMP-9:TIMP-1 concentration In this retrospective study, we analyzed the association between the concentration of the MMP-9:TIMP-1 complex and clinicopathological data and disease free survival (DFS) in univariate and multivariate survival analyses Results: Following successful validation both assays were applied for MMP-9:TIMP-1 measurements Of the clinicopathological parameters, only menopausal status demonstrated significant association with the MMP-9:TIMP-1 complex; P = 0.03 and P = 0.028 for the ELISA and PLA measurements, respectively We found no correlation between the MMP-9:TIMP-1 protein complex and DFS neither in univariate nor in multivariate survival analyses Conclusions: Despite earlier reports linking MMP-9 and TIMP-1 with prognosis in breast cancer patients, we here demonstrate that plasma levels of the MMP-9:TIMP-1 protein complex hold no prognostic information in primary breast cancer as a stand-alone marker We demonstrate that the highly sensitive in-solution PLA can be employed for measurements of protein:protein complexes in plasma Keywords: Breast cancer, Plasma MMP-9:TIMP-1 complex, Proximity ligation assay, ELISA * Correspondence: stenvang@sund.ku.dk † Equal contributors Institute of Veterinary Disease Biology and Sino-Danish Breast Cancer Research Centre, Faculty of Health and Medical Sciences, University of Copenhagen, Strandboulevarden 49, DK-2100 Copenhagen, Denmark Full list of author information is available at the end of the article © 2013 Thorsen 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