Background/aim Endothelin-1 (ET-1) is overexpressed in many types of cancer, inhibiting the release of the microRNA 15a (miR-15a) and inducing the production of Mxi-2. Our aim was to identify a molecular complex regulating p53 activity in prostate cancer (PCa). Materials and methods DU145 cells were treated with ET-1, MAPK p38 inhibitor, Endothelin A receptor inhibitor (ETAR inhibitor) and Endothelin B receptor inhibitor (ETBR inhibitor). Extracts were analysed using Western Blot, immunoprecipitation and qRT-PCR. Furthermore, prostate cancer patient samples were analysed using qRT-PCR and ELISA. Results The hypothesised molecular complex was identified, with miR-15a, microRNA 1285 (miR-1285) and Mxi-2 levels up-regulated in patients in relation to increasing aggressiveness of PCa. Conclusion A complex composed of Argonaut 2 (Ago2)/Mxi-2/miR-1285 is involved in PCa. The expression of Mxi-2 correlates with increasing PCa aggressiveness and might be used as a non-invasive marker for the diagnosis and progression of PCa.