Determination of matrix metalloproteinase-7 activity and localization with casein zymography and in situ casein zymography in colorectal cancer

Background: Colorectal cancer (CRC) that occurs at the percent in 80% of colon and 20% in rectum is now the most common cause of cancer related deaths after lung, prostate and breast cancer in Western world. There is increasing evidence to indicate that matrix metalloproteinase (MMP)-7 plays a more important role in tumor progression than other MMPs.Aim: The aim of this study is to analyze MMP-7 expression (protein and mRNA) levels and active-latent forms of MMP-7 in tumor and paired normal tissue samples that are taken from colorectal cancer patients and to develop In Situ Casein Zymography technique for detection of local endogen activation of MMP-7.Material and Methods: Thirty-one colorectal tumor and paired normal tissue samples were taken from patients with CRC. MMP-7 mRNA and protein expression levels were detected by Real Time PCR and ELISA whereas MMP-7 localization was examined by immunohistochemical staining and image analysis. Casein Zymography and In Situ Casein Zymography methods were used to detect proteolytic activity of MMP-7 and to estimate local caseinolytic activity, respectively. The results were compared with clinicopathological variables (such as gender, age, tumor localization, tumor size, tumor differentiation, histological type, distant metastasis, T-stage, N-stage, pathological stage, perineural invasion and vascular invasion).Results: MMP-7 mRNA expressions in tumor tissues were statistically higher than paired normal tissues (p = 0.001). Furthermore mRNA expression levels were positively correlated with T stage and P stage (r = 0.687 p = 0.005 and r = 0.536 p = 0.04) and negatively correlated with age (r = -0.588 p = 0.021). In the results of immunohistochemical staining, it was observed that there were cytoplasm and cell membrane staining in tumor tissues whereas there was no MMP-7 staining in paired normal tissues. Unlike there were no significant differences between tumor and paired normal tissues in MMP-7 protein expression levels (p = 0,636). When it was analyzed the correlations between MMP-7 protein expression levels of tumor tissues and clinicopathological variables, it was determined that protein expression levels positively correlated with perineural invasion (r = 0.462, p = 0.010). In addition, it was found that caseinolytic activity, localize epithelium region, was higher in tumor tissues than the paired normal tissues.Conclusions: Our results suggest that MMP-7 plays an important role in the progression of human colorectal cancer. Therefore MMP-7 may be selected as a target molecule in the use of new chemopreventive therapy in colorectal cancer.Key Words: Colorectal Cancer, Matrix Metalloproteinase-7, Casein Zymography, In Situ Casein Zymography.