Oral tongue squamous cell carcinoma (OTSCC) is a highly malignant type of
tumor. The 5-year survival rate of patients with advanced tongue
squamous cell carcinoma is only ~50%.
Pyruvate kinase M2 (PKM2) is the key rate-limiting
enzyme of glycolysis, maintaining the Warburg effect in
tumor cells. The present study aimed to investigate the relationship between PKM2 expression and the poor prognosis of patients with OTSCC and to determine oral
squamous carcinoma tumor cell proliferation and apoptosis. Reverse transcription-quantitative (RT-q) PCR, western blotting and immunohistochemistry were used to analyze the expression levels of PKM2 in OTSCC, and the clinicopathological characteristics and prognosis of patients with OTSCC were further analyzed by statistical analysis. The results from RT-qPCR and immunohistochemistry demonstrated that PKM2 was upregulated in OTSCC tissues and highly expressed in advanced stage OTSCC tissues compared with paired adjacent tissues and lower stage OTSCC tissues. Patients with OTSCC and high PKM2 expression had shorter overall survival (OS) compared with those with low PKM2 expression. Furthermore, high expression of PKM2 was significantly associated with
Tumor-Node-
Metastasis (TNM) stage. TNM stage and PKM2 expression were independent predictive factors for OS in patients with OTSCC. In addition, PKM2 knockdown inhibited the proliferation and increased the apoptosis of oral
squamous carcinoma tumor cells. Furthermore, PKM2 knockdown could regulate the expression of cell cycle and apoptosis-related
proteins by activating Hippo signaling pathway, as confirmed by the decreased expression of yes-associated
protein 1 (YAP), Bcl-2 and Ki-67 and the increased expression of large
tumor suppressor
kinase 1, phosphorylated YAP and Bax. Taken together, the findings from this study demonstrated that PKM2 may be considered as a potential target for the diagnosis and treatment of OTSCC.