Overexpression of metabolic markers PKM 2 and LDH 5 correlates with aggressive clinicopathological features and adverse patient prognosis in tongue cancer

Aims Pyruvate kinase M 2 ( PKM 2) and lactate dehydrogenase 5 ( LDH 5) are two metabolic and oncogenic markers of cancer. In this study, we sought to investigate their expression patterns and prognostic value in tongue squamous cell carcinoma ( TSCC ). Methods and results The expression and subcellular localization of PKM 2 and LDH 5 in TSCC cell lines were determined by W estern blot and immunofluorescence. PKM 2 and LDH 5 abundance was examined by immunohistochemistry in 63 TSCC tumour specimens; their association with multiple clinicopathological parameters and overall patient survival was assessed. The protein levels of PKM 2 and LDH 5 were both significantly higher in TSCC cells than in an immortalized oral epithelial cell line. Overexpression of PKM 2 associated significantly with cervical node metastasis ( P  =   0.0373), while elevated LDH 5 levels correlated significantly with tumour size ( P  =   0.0094), pathological grade ( P  =   0.0052), cervical node metastasis ( P  =   0.0023) and clinical stage ( P  =   0.0024). Patients with tumours showing an increase in either PKM 2 or LDH 5 expression displayed significantly reduced overall survival, while patients with tumours overexpressing both proteins showed the worst prognosis with lowest overall survival. Furthermore, PKM 2 and LDH 5 were identified as independent prognostic predictors for overall patient survival in TSCC . Conclusion Our data indicate that overexpression of PKM 2 and LDH 5 associates with key clinicopathological features and unfavourable prognosis in TSCC .