RESUMEN
In prostate cancer TIMP4 expression level fluctuates with tumor progression. The mechanism and factors influencing its expression remain unclear. The aim of the study was to test the hypothesis on regulation of TIMP4 by microRNA-200b-3p. The levels of TIMP4 and miR-200b-3p expression were determined by real time PCR in 27 prostate carcinomas and eight benign prostatic hyperplasia samples. We found that miR-200b-3p positively correlated with TIMP4 expression in cancer samples (r = 0.46; p < 0.02). Moreover, mean miR-200b-3p level and TIMP4 expression were both higher in cancer tissues compared to benign prostatic hyperplasia samples (p > 0.05). Next, to test probable mechanisms of the regulation androgen-sensitive human prostate adenocarcinoma cells (LNCaP) were transfected with synthetic-miR-200b-3p or its synthetic antagonist. Modulation of miR-200b-3p in LNCaP cells had an impact on TIMP4 expression confirming the observation made in analyzed clinical samples. Two targets of miR-200b-3p: ZEB1 and ETS1 were investigated subsequently as potential regulators of TIMP4, however, no effect of their modulation on TIMP4 expression in LNCaP cells was found. Concluding, miR-200b-3p mediates regulation of TIMP4 expression in prostate cancer but exact mechanism needs to be investigated.