Detection of the Kidney Tumor Suppressor DUSP9 in the Urine of Healthy Donors

The DUSP9/MKP-4 belongs to the family of bispecific protein phosphatases that negatively regulate MAP kinases (ERK, p38 and JNK). The expression of DUSP9 is significantly (20-80-fold) reduced compared to normal tissue in 95% of the studied human renal cell carcinoma samples. These and other scientific data indicate that DUSP9 is an attractive target for the use in clinical practice. However, so far, postoperative tumor biopsy samples remain the only source of clinical material in which expression of DUSP9 has been studied.. This significantly limits the possibilities of using DUSP9 for clinical purposes. The purpose of this work was to find out whether it would be possible to detect DUSP9 in human urine. In the study we used human kidney carcinoma ACHN cells transfected with a vector, expressing DUSP9 and urine samples from 3 healthy volunteers. DUSP9 protein was detected by the Western blot method in precipitates obtained by centrifugation. We have shown that the DUSP9 protein is present in the pellet of the urine fraction obtained by low-speed centrifugation (10000 g). It is also present in the fraction of extracellular vesicles enriched with exosomes. The obtained result indicates that the analysis of DUSP9 expression is possible using a liquid biopsy, which, in turn, can significantly expand the applicability of this analysis for clinical purposes.