Anales RANF

P.21 ANALYSIS OF CD73 IN SERUM OF CANCER PATIENTS AND HEALTHY DONORS R. Turiello 1,2 , M. Capone 3 , G. Madonna 3 , E. Simeone 3 , A. Pinto 1 , P.A. Ascierto 3 , S. Morello 1 . 1 . University of Salerno, Italy; 2 . PhD Program in Drug Discovery and Development, University of Salerno, Italy; 3 . National Institute of Cancer Research “G. Pascale”, Naples, Italy. CD73 is an ectoenzyme able to hydrolyze AMP into extracellular adenosine and inorganic phosphate (Pi). In pathological conditions, adenosine has been observed to have anti-inflammatory and immunosuppressive effects. CD73 is up-regulated in several human cancers, and its overexpression is often related to poor prognosis. A soluble form of CD73 has been individuated in biological fluids. The aim of this study was to characterize CD73 expression and activity in serum of cancer patients and healthy donors. Serum samples were collected at National Cancer Institute “G. Pascale” (Naples, Italy). Specifically, this study involved 91 patients with malignant melanoma (MM), 40 patients with other solid tumors (including head and neck cancer, bladder, gastric and kidney cancer), and 115 healthy donors. All the individuals provided written informed consent for blood donation. CD73 enzymatic activity was determined by Malachite Green assay, which allows the measurement of Pi released after adding AMP as substrate. The Pi neat value was obtained subtracting the basal Pi, determined in absence of AMP. CD73 activity was expressed as Pi released (pmol/min/mg protein) and the values were associated with clinical pathological characteristics of patients. The CD73 protein levels in serum was determined by ELISA assay. The enzymatic activity of CD73 resulted increased in serum of cancer patients (n=131, median= 39.41 pmol/min/mg protein), compared to healthy donors (n=115, median= 0 pmol/min/mg protein). Furthermore, the highest CD73 activity levels among cancer patients were measured in serum of MM patients (n=91, median= 56.47 pmol/min/mg protein). Elevated enzymatic activity was associated with male gender but not with other variables. CD73 expression showed the same trend, resulting higher in serum of cancer patients, compared to healthy donors. Overall, our results suggest that CD73 could be a potential therapeutic target for MM patients.