Limited clinical significance of dimeric form of pyruvate kinase as a diagnostic and prognostic biomarker in non-small cell lung cancer

Abstract

Metabolism of tumor tissue differs from the normal one by the intensity of protein synthesis and glycolysis. The dimeric pyruvate kinase (PKM2) is a specific enzyme for tumor glycolysis. The aim of this study was to determine the relationship between the activity of PKM2 and the type and stage of non-small cell lung cancer (NSCLC). A second objective was to compare the expression of PKM2 with disease progression and prognosis. We studied 65 patients divided into two groups: 45 patients with lung cancer and 20 non-cancer healthy subjects taken as control. The serum activity of PKM2 was assessed spectrophotometrically. We found that PKM2 activity was greater, on average, by 136 % for adenocarcinoma and for 126 % for squamous cell carcinoma compared with that present in control subjects. The higher PKM2 activity was associated only with Stage III of cancer (p < 0.001). Sensitivity of PKM2 as a cancer marker was 79 % for adenocarcinoma and 81 % for squamous cell carcinoma and specificity was 50 % for both cancer types. We conclude that PKM2 activity is higher in patients with NSCLC than in healthy subjects. The level of PKM2 activity is associated with advanced stage of cancer. Nonetheless, low specificity of PKM2 assessment makes it of limited utility in NSCLC diagnosis or evaluation of cancer progression.