Tumor M2 pyruvate kinase in plasma of patients with urological tumors

The M2 isoenzyme of pyruvate kinase (M2-PK) is specifically expressed in tumor cells (TU M2-PK) and may therefore provide a tumor marker for malignancies. We have investigated the plasma concentrations of TU M2-PK in patients with renal cell carcinoma (RCC), transitional cell carcinoma of the bladder (BCA), prostate cancer (PCA) and benign prostatic hyperplasia (BPH). TU M2-PK was quantified with a commercially available enzyme-linked immunosorbent assay (ELISA) kit. Using this ELISA kit, plasma samples of 57 healthy individuals were compared to 63 patients with RCC, 36 patients with BCA, 58 patients with PCA and 28 patients with BPH. Patients with carcinomas were subdivided into those patients with nonmetastatic and those with metastatic disease. Only patients with RCC (nonmetastatic and metastatic) showed significantly increased concentrations of TU M2-PK compared to normal individuals. In metastatic RCC, TU M2-PK levels were highest and were also significantly enhanced compared to nonmetastatic RCC. The sensitivity for nonmetastatic RCC was 27.5% and for metastatic RCC 66.7% at the 95% reference value of the control group. In BCA, PCA and BPH, no significant differences could be detected. Our results indicate that TU M2-PK concentrations in plasma may be a potential biomarker of advanced RCC.