Positive Correlation between Matrix Metalloproteinases and Epithelial-to-Mesenchymal Transition and its Association with Clinical Outcome in Bladder Cancer Patients

Abstract

Involvement of matrix metalloproteinases (MMPs) in the pathogenesis of urothelial carcinoma elects them to be sensitive marker for clinical and prognostic implications. MMPs regulate tumor growth and invasion by inducing epithelial-to-mesenchymal transition (EMT) which is characterized by the complex reprogramming of epithelial cells and ultimately bring about major changes in the structural organization of bladder urothelium. The present study has been undertaken to evaluate the clinical relevance of MMPs in two distinct types of bladder cancer disease. Expression analysis of MMPs namely MMP-2, MMP-7, MMP-9 and EMT markers including epithelial marker, E-cadherin; mesenchymal markers, N-cadherin and Vimentin; and EMT-activating transcriptional factors (EMT-ATFs), Snail, Slug, Twist and Zeb was done in 64 cases of bladder tumor tissues [{Non-muscle invasive bladder cancer (NMIBC): 35 cases} and {Muscle invasive bladder cancer (MIBC): 29 cases}] by real-time quantitative polymerase chain reaction (RT-qPCR). Immunohistochemistry (IHC) staining was done in matched bladder tumor tissues to evaluate the protein expression and localization of E-cadherin, N-cadherin, Vimentin, Snail, and Slug. Our data showed overexpression of MMP-2, MMP-7 and MMP-9 at transcriptome level in 32.8%, 25% and 37.5% bladder tumor cases respectively. These tumor tissues were examined for higher expression of mesenchymal markers (N-cadherin and Vimentin) at mRNA and protein level and exhibited statistical association with tumor stage and tumor grade ( p = 0.02, p = 0.04, Mann-Whitney test). Significant statistical correlation in tumor tissues with overexpressed MMPs has also been observed between gain of transcriptional factors and weak expression of E-cadherin with tumor stage, grade, gender, presence of hematuria and smoking history of the patients. Gene expression patterns of EMT markers in bladder tumors with overexpressed MMPs and their significant association with clinical profile validate the important role of MMPs in the pathogenesis of urothelial carcinoma of bladder (UCB). Increased expression of specific MMPs may affect several downstream EMT programs and thus may improve its diagnostic and prognostic utility in clinical setting.