Abstract. Matrix metalloproteinase-1 (MMP-1) is associated with cancer invasion and metastasis. The 2G allele of the polymorphic site in the MMP-1 promoter was demonstrated to have a higher transcription activity than the 1G allele. Allelic imbalance (AI) at 11q22 harboring the MMP-1 is frequently observed in various cancers and may be associated with an advanced disease. We conducted a case-control study to determine the association of the MMP-1 genotype with susceptibility to prostate cancer involving 283 prostate cancer patients and 251 controls. Furthermore, AI, retention allele of the MMP-1 promoter, and MMP-1 protein expression were analyzed in 77 prostate cancer specimens. The MMP-1 promoter polymorphism was associated with neither susceptibility nor progression of prostate cancer. Tumors with 1G/2G and 2G/2G genotypes had a significantly higher MMP-1 expression level compared to those with 1G/1G genotype (P=0.006 and 0.013, respectively). AI at 11q22 was observed in 13 (40.6%) of 32 informative cases. Retention of the 1G and 2G alleles were observed in 4 and 9 cases, respectively. AI was significantly associated with the Gleason score (P=0.003) and pathological stage (P=0.022). In addition, retention of the 2G allele showed a significant association with the pathological stage (P=0.026). AI at 11q22 region, retention of the 2G allele, specifically appeared to be involved in the progression of prostate cancer. However, the presence of the 2G allele of the MMP-1 promoter polymorphism itself seems to influence neither the susceptibility nor the progression of prostate cancer.
IntroductionTumor invasion or metastasis is one of the most crucial events for determining the outcome of cancer patients. In the first step of these events, several proteinases such as serine proteinase urokinase plasminogen activator and matrix metalloproteinases (MMPs) degrade the extra-cellular matrix (ECM), so that the tumor cells can migrate to the stromal tissue through the basement membrane (1). MMP-1, a member of MMP family, is abundantly expressed in many types of cancer cells and adjacent stromal fibroblasts (2-5), and digests various elements of the ECM including collagen types I, II, II, VII, VIII, X, and XI (6). The overexpression of MMP-1 has been shown to be associated with tumor progression and poor outcomes for cancers of the digestive system and melanoma (3,5,7,8).The expression of MMP-1 is mainly regulated by activated protein-1 (AP-1) transcription factor that mediates signal transduction from cytokines and growth factors such as interferons, interleukins, epidermal growth factor, and fibroblast growth factor (9). In the promoter region of the MMP-1, three AP-1 binding sites are located at -72, -186, and -1062 bp from the transcription start site. Insertion of an extra guanine residue adjacent to the AP-1 binding site at -1062 bp creates a new binding site for ETS transcription factor at -1602 bp (5'-AAGGAT-3'; 2G), and both the AP-1 and ETS cooperatively enhance the expression of MMP-1 (10). AP-1 binding to the -1...