1. ¹Ontario Cancer Research, University of Toronto, Toronto, Ontario, Canada
2. ²University of Ontario Institute of Technology, Ontario, Oshawa, Canada

Correspondence: Dr R Khokha, Experimental Therapeutics, Ontario Cancer Institute, University of Toronto, 610 University Avenue, Room 10 328, Toronto, Ontario, Canada M5G 2M9. E-mail: rkhokha@uhnres.utoronto.ca

Received 27 November 2005; Revised 3 April 2006; Accepted 4 April 2006; Published online 15 May 2006.

Abstract

Identifying versatile inhibitors of metastasis that operate in multiple sites against distinct cancer cell types is important for designing novel therapeutics for metastasis. We show that multiple tissues of timp-3^-/- mice are more susceptible to metastatic colonization. Overall, a 5–14-fold increase in liver and kidney colonization occurred by EL-4 lymphoma cells, and a twofold increase upon targeting B16F10 melanoma cells to the bone or lung of timp-3^-/- mice. There was a general lack of macrophage or neutrophil localization to metastases in the liver, kidney and lung, and of osteoclasts to bone in both genotypes. Analysis of lung showed that proliferation or angiogenesis were unaltered within the metastatic colonies. Lung-trap assays revealed that initial tumor cell trapping was similar in the lung vasculature of timp-3^-/- and wild-type mice. However, more tumor cells were found in timp-3^-/- lungs at 48 and 96 h after tumor cell injection indicating more efficient extravasation and initial proliferation. Activation of pro-MMP-2 was greater in timp-3^-/- lungs at these time points. These data demonstrate TIMP-3 functions to inhibit metastatic dissemination of diverse cancer cells to multiple organs. TIMP-3 regulates MMP-2 activation to limit tumor cell extravasation and subsequent colonization of the lung, without augmenting inflammatory cell response.