Plasma proteasome 20S activity in patients with newly diagnosed multiple myeloma

Abstract

The purpose of the study is to determine the 20S proteasome ChT-L activity in patients with newly diagnosed multiple myeloma (MM). the 20S proteasome ChT-L activity was assayed using the fluorogenic peptide substrate Suc-Leu-Leu-Val-Tyr-AMC in the presence of an artificial activator sodium dodecyl sulfate (SDS) in the plasma of healthy donors (n=20) and MM patients (n=41). The 20S proteasome ChT-L activity was higher in the plasma of MM patients at the diagnosis than in healthy subjects (median 1.24 U/mg; range 0.67-3.61 U/mg vs median 1.09 U/mg; range 0.67-1.62 U/mg). The highest 20S proteasome ChT-L activity was observed at 3rd iss score and the difference was statistically significant (median 1.25 U/mg vs median 1.09 U/mg; p=0.048). Statistically significant correlations was found between 20S plasma ChT-L activity and β₂-microglobulin level (p=0.007) as well as between 20S plasma ChT-L activity and creatinine concentration (p=0.019). The plasma 20S proteasome ChT-L activity did not correlate with age and did not depend on the gender of the patients. the results of the study point to usefulness of the 20S proteasome ChT-L activity measurement as a prognostic factor in MM patients.