The study of miRNA-200c expression and epithelial-to-mesenchymal transition-related transcription factors in the primary bladder urothelial carcinoma.

Background: Epithelial-mesenchymal transition (EMT) plays an important role in bladder carcinoma (BC) invasiveness and metastasis. Studies have shown that muscle-invasive BC (MIBC) and non-MIBC (NMIBC) are different at the molecular level owing to different EMT-related programming. Recent studies suggest that dysregulation of specific miRNAs is linked to EMT in BC. With this background, we aimed to study the immunoexpression of EMT-markers and its correlation with miRNA-200c expression in a series of MIBCs and NMIBCs.

Materials and methods: Quantitative real-time-polymerase chain reaction for the quantification of miR-200c expression was performed on 50 cases of urinary BC obtained from transurethral resection of bladder tumor (TURBT), cystectomy specimens, and ten peritumoral bladder tissue. Immunohistochemistry for ZEB1, ZEB2, TWIST, E-cadherin, and β-catenin was performed on tumor and peritumoral bladder tissue.

Results: Thirty-five TURBT and 15 cystectomy specimens were assessed. Among MIBC, loss of expression of E-cadherin (72.3%), β-catenin (66.7%), and ZEB1, ZEB2, and TWIST2 immunoreactivity was noted in 53.3%, 86.7%, and 73.3% of cases, respectively. Among NMIBC, loss of expression of E-cadherin (22.5%), β-catenin (17.1%) and ZEB1, ZEB2, and TWIST immunoreactivity was noted in 11.5%, 51.4%, and 91.4% of cases, respectively. Upregulation of miRNA-200c was noted in cases with retained E-cadherin and negative TWIST expression. Downregulation of miRNA-200c expression was noted in all the cases showing loss of E-cadherin, β-catenin, and in cases immunoreactive for ZEB1, ZEB2, and TWIST in MIBC. Downregulation of miRNA-200c expression was also noted in cases of MIBC with retained β-catenin and those immunonegative for ZEB1 and ZEB2. A similar trend was noted in NMIBC. Median miRNA-200c expression was low in both high-grade and low-grade NMIBC compared to peritumoral bladder tissue and was not statistically significant.

Conclusion: This study for the first time explores the relation of miR200C with E-cadherin, b-catenin, and its direct transcriptional regulators, namely Zeb1, Zeb2, and Twist in the same cohort of BC. We observed that miRNA-200c is downregulated in both MIBC and NMIBC. We identified novel expression of TWIST in cases of BC showing downregulation of miR200Cs suggesting that it is one of the protein targets of altered miRNA-200c expression contributing to EMT and can serve as a promising diagnostic marker and therapeutic target. Loss of E-cadherin and ZEB1 immunoexpression in high-grade NMIBC suggests an aggressive clinical behavior. However, ZEB2 heterogeneous expression in BC limits its diagnostic and prognostic utility.