MMPs and TIMPs in inflammatory bowel diseases
Inflammatory bowel diseases (IBD) as well as adenomatous polyps (AP) of the colon inherit an increased risk to evolve into colorectal cancer. The association between colorectal cancer (CRC) and ulcerative colitis (UC) was first recognized by Crohn and Rosenberg in 1925 [1]. Since then, a multitude of epidemiological studies have confirmed this association. Based on a meta-analysis published in 2001, it is thought that CRC occurs in 8% of UC patients after 20 disease years and in 18% after 30 disease years [2]. Recent studies have shown that the risk of developing CRC in Crohn’s disease (CD) is comparable to that of patients with UC [3]. The risk of developing CRC on the basis of AP of the colon depends mainly on the histological type and the size of the adenoma [4].
MMPs have gained considerable attention in many studies on invasive tumor growth, metastasis [5-7], and neovascularization [8]. Recent studies demonstrated that CRC are characterized by increased levels of MMP-2, MMP-7, and MMP-13, whereas MMP-9 showed a differential enhancement in colon carcinoma, but not in rectal carcinoma [9-10].
The importance of some MMPs for carcinogenesis and wound repair has already been documented. Aim of this study was to illuminate the relevance of MMPs for precancerous inflammatory lesions of the colon in IBD and for AP in comparison. Several studies have shown that expression of MMPs is mainly transcriptionally regulated and that MMP protein concentrations correlate with mRNA expression in vitro [11-13]. We focused on gene expression of a broad spectrum of MMPs. MMP-2, -7, -9, -13, -14, and TIMP-1 mRNA expression of biopsy samples of UC, CD, and AP were analysed via RealTime PCR and protein expression of MMP-2, MMP-9, and TIMP-1 was additionally measured by ELISA.
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We could demonstrate that: 1) MMP-7 and MMP-13 gene expression levels were significantly increased in IBD as well as in AP; 2) the gelatinases MMP-2 and MMP-9 showed a significantly enhanced expression in IBD; and 3) up-regulation of MMP-7 and MMP-13 in AP might serve as an early surrogate parameter for precancerous potential.
MMP-7 is primarily expressed on the tumor cell surface [14]. Therefore, increased MMP-7 expression in UC, CD and AP may well be indicative for defective signalling pathways intrinsic to the cancer cell [14]. However, the histopathological examination of the IBD biopsy specimens did not reveal direct signs of malignancy such as dysplasia-associated lesion or mass (DALM) or atypical cells. But all polyps were classified LGIN. Nevertheless, median MMP-7 mRNA expression in CD, UC, and AP was significantly increased compared with control tissue. Notably, the role of MMP-7 in the development of colorectal cancer (CRC) is well documented: immunohistochemical studies addressing to the role of MMP-7 in CRC showed a correlation of MMP-7 expression with local lymph node metastasis and distant metastasis in advanced stages of CRC [15]. Moreover, MMP-7 is associated with distant metastasis and adverse outcome in early invasive CRC [16]. Since MMP-7 has a broad substrate specificity enabling this enzyme to degrade various components of the basement membrane, the amplification of CRC-cell invasion and metastasis may be directly attributable to MMP-7 [17]. Besides its direct effects, MMP-7 may contribute indirectly to colon cancer invasion and metastasis by activation of gelatinases A and B (i.e. MMP-2 and MMP-9) [18, 19]. Our results suggest that MMP-7 overexpression may contribute to the risk of developing dysplasia in patients with IBD and AP. Because MMP-7 expression was also found in AP it might not be the result of inflammatory processes. Since histopathology did not reveal dysplastic cells in analysed IBD samples, increased MMP-7 mRNA expression may be a surrogate parameter for the transformation from normal to dysplastic or even malignant cells.
MMP-13 mRNA was significantly up-regulated in AP and in inflamed mucosa of IBD compared to normal large bowel tissue of the same individuals. MMP-13 has primarily been found in tumor cells (e.g. breast cancer and malignant melanoma) [20, 21]. Leeman et al. localized MMP-13 staining to cytoplasm of tumor cells [22]. Accordingly, 33% of healthy tissue biopsies from patients with IBD did not show any MMP-13 mRNA, whereas MMP-13 mRNA was lacking in only 13% of inflamed mucosa. In patients with AP, again 31% of healthy biopsy specimens did not reveal any MMP-13 mRNA, whereas all adenomas presented transcripts of MMP-13.
MMP-13 has a central position in the MMP activation cascade. It is activated by MMP-2 and able to activate proMMP-9. Here we observed increased levels of both, MMP-13 and MMP-2 in IBD and AP. Therefore a crosstalk between several MMPs and their cellular origin, i.e. tumor cells and surrounding stromal cells, seems likely.
In polyps increased levels of MMP-2 may have relevance beyond their role in inflammation. In previous studies overexpression of MMP-2 in CRC and an enhancement of MMP-9 in carcinomas of the colon, but not in rectal carcinomas has been reported [9]. Thus, increased expression of MMP-2 transcripts in AP may not only reflect a stromal reaction of inflammation, but may also indicate a process of malignization with further progression to CRC.
In conclusion, our data suggest that increased levels of MMP-7 and MMP-13 in UC, CD and AP might be associated with the progression of these diseases to intraepithelial neoplasia. Moreover, up-regulation of MMP-7 and MMP-13 in AP may serve as a surrogate parameter for neoplasia eventually progressing to CRC. MMP-2 requires further investigation since its cellular origin remains unclear. So far it may reflect both, inflammation (IBD) and enhanced proteolytic activity in neoplastic processes (AP).
Reference List
1. Crohn BB, Rosenberg B. The sigmoidoscopic picture of chronic ulcerative colitis (nonspecific). Am J Med Sci. 1925;170:220-227.
2. Eaden JA, Abrams KR, Mayberry JF. The risk of colorectal cancer in ulcerative colitis: a meta-analysis. Gut. 2001;48:526-535.
3. Choi PM, Zelig MP. Similarity of colorectal cancer in Crohn's disease and ulcerative colitis: implications for carcinogenesis and prevention. Gut. 1994;35:950-954.
4. Muto T, Bussey HJ, Morson BC. The evolution of cancer of the colon and rectum. Cancer. 1975;36:2251-2270.
5. Matrisian LM, Wright J, Newell K, et al. Matrix-degrading metalloproteinases in tumor progression. Princess Takamatsu Symp. 1994;24:152-161.
6. Poulsom R, Pignatelli M, Stetler-Stevenson WG, et al. Stromal expression of 72 kda type IV collagenase (MMP-2) and TIMP-2 mRNAs in colorectal neoplasia. Am J Pathol. 1992;141:389-396.
7. Pyke C, Ralfkiaer E, Huhtala P, et al. Localization of messenger RNA for Mr 72,000 and 92,000 type IV collagenases in human skin cancers by in situ hybridization. Cancer Res. 1992;52:1336-1341.
8. Hiraoka N, Allen E, Apel IJ, et al. Matrix metalloproteinases regulate neovascularization by acting as pericellular fibrinolysins. Cell. 1998;95:365-377.
9. Roeb E, Dietrich CG, Winograd R, et al. Activity and cellular origin of gelatinases in patients with colon and rectal carcinoma differential activity of matrix metalloproteinase-9. Cancer. 2001;92:2680-2691.
10. Roeb E, Arndt M, Jansen B, et al. Simultaneous determination of matrix metalloproteinase (MMP)-7, MMP-1, -3, and -13 gene expression by multiplex PCR in colorectal carcinomas. Int J Colorectal Dis. 2004;19:518-524.
11. Graham MF, Willey A, Zhu YN, et al. Corticosteroids repress the interleukin 1 beta-induced secretion of collagenase in human intestinal smooth muscle cells. Gastroenterology. 1997;113:1924-1929.
12. Kohn EC, Jacobs W, Kim YS, et al. Calcium influx modulates expression of matrix metalloproteinase-2 (72-kDa type IV collagenase, gelatinase A). J Biol Chem. 1994;269:21505-21511.
13. MacNaul KL, Chartrain N, Lark M, et al. Discoordinate expression of stromelysin, collagenase, and tissue inhibitor of metalloproteinases-1 in rheumatoid human synovial fibroblasts. Synergistic effects of interleukin-1 and tumor necrosis factor-alpha on stromelysin expression. J Biol Chem. 1990;265:17238-17245.
14. Newell KJ, Witty JP, Rodgers WH, et al. Expression and localization of matrix-degrading metalloproteinases during colorectal tumorigenesis. Mol Carcinog. 1994;10:199-206.
15. Adachi Y, Yamamoto H, Itoh F, et al. Contribution of matrilysin (MMP-7) to the metastatic pathway of human colorectal cancers. Gut. 1999;45:252-258.
16. Masaki T, Matsuoka H, Sugiyama M, et al. Matrilysin (MMP-7) as a significant determinant of malignant potential of early invasive colorectal carcinomas. Br J Cancer. 2001;84:1317-1321.
17. Wilson CL, Matrisian LM. Matrilysin: an epithelial matrix metalloproteinase with potentially novel functions. Int J Biochem Cell Biol. 1996;28:123-136.
18. Crabbe T, Smith B, O'Connell J, et al. Human progelatinase A can be activated by matrilysin. FEBS Lett. 1994;345:14-16.
19. Imai K, Yokohama Y, Nakanishi I, et al. Matrix metalloproteinase 7 (matrilysin) from human rectal carcinoma cells. Activation of the precursor, interaction with other matrix metalloproteinases and enzymic properties. J Biol Chem. 1995;270:6691-6697.
20. Airola K, Karonen T, Vaalamo M, et al. Expression of collagenases-1 and -3 and their inhibitors TIMP-1 and -3 correlates with the level of invasion in malignant melanomas. Br J Cancer. 1999;80:733-743.
21. Heppner KJ, Matrisian LM, Jensen RA, et al. Expression of most matrix metalloproteinase family members in breast cancer represents a tumor-induced host response. Am J Pathol. 1996;149:273-282.
22. Leeman MF, McKay JA, Murray GI. Matrix metalloproteinase 13 activity is associated with poor prognosis in colorectal cancer. J Clin Pathol. 2002;55:758-762.