Abstract B76: TIMP-1 expression in colorectal cancer liver metastases is associated with vascular structures
Authors: Illemann Martin , Eefsen Rikke L. , Bird Nigel , Majeed Ali , Laerum Ole D. , Alpízar-Alpízar W , Ida Lund K. , Høyer-Hansen Gunilla 
Published: August 2014

Abstract
The ability of metastatic colon cancer cells to interact with a new tissue microenvironment is crucial for their growth and invasion into the liver. As a result of this interaction, two major and very distinct metastatic growth patterns can be distinguished at the histological level: desmoplastic growth pattern (DGP) and pushing growth pattern (PGP). The proteolytic activity generated by the urokinase plasminogen activator system and matrix metalloproteinase (MMPs) family is needed for the degradation of the extracellular matrix components during cancer invasion. In primary tumours from various human cancers, including colon cancer, urokinase plasminogen activator (uPA) and its receptor uPAR are highly up-regulated and located at the invasive front. In liver metastases uPA and uPAR are found at the invasive front only in those with DGP, indicating that liver metastases with PGP use an alternative invasion mechanism.
uPAR is a strong prognostic marker in colorectal cancer and this is also the case for tissue inhibitor of MMPs-1 (TIMP-1). In this study we therefore analysed the expression of TIMP-1 in 28 primary colorectal cancers and their matching liver metastases (14 with DGP and 14 with PGP) using histology. TIMP-1-mRNA was only seen in stromal fibroblast-like cells in all samples. By combining immunohistochemistry and in situ hybridisation, we have identified the TIMP-1-mRNA-positive cells to be α-SMA-positive. In all primary tumours and liver metastases with DPG, TIMP-1 was primarily expressed by myofibroblasts located at the invasive front. Some TIMP-1-positive and α-SMA-positive cells were in all samples also seen adjacent to CD34-positive endothelial cells, indicating that TIMP-1 is also expressed by pericytes. In contrast, in the liver metastases with PGP, TIMP-1 was primarily expressed by α-SMA-positive cells located within the sinusoid at the metastasis/liver parenchyma interface. As liver sinusoids do not contain pericytes, we presume that these TIMP-1-positive cells are hepatic stellate cells, which are known to be α-SMA-positive when activated. By performing in situ hybridisation for MMP-2-mRNA, we showed that MMP-2-mRNA is expressed by fibroblast-like cells adjacent to the cancer in primary colorectal cancer and liver metastases with DGP. No MMP-2-mRNA was found in liver metastases with PGP, supporting our hypothesis that PGP and DGP use different mechanisms of invasion. In conclusion, TIMP-1 is expressed by different cell populations in primary colorectal cancer and liver metastases with DGP as compared to metastases with PGP. We therefore speculate that TIMP-1 is primarily involved in the inhibition of proteolysis in the former two cases, whereas it could play a role in angiogenesis in the latter.
Citation Format: Martin Illemann, Rikke L. Eefsen, Nigel Bird, Ali Majeed, Ole D. Laerum, W Alpízar-Alpízar, Lund K. Ida, Gunilla Høyer-Hansen. TIMP-1 expression in colorectal cancer liver metastases is associated with vascular structures. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr B76.