Expression of HIF-1α/PKM2 axis correlates to biological and clinical significance in papillary thyroid carcinoma

hypoxia inducible factor-1 alpha (HIF-1 alpha) and pyruvate kinase M2 (PKM2) are 2 key metabolic regulatory proteins, they could engage in a positive feedback loop and drive cancer growth by enhancing glycolysis. This study aimed to investigate the expression of HIF-1 alpha and PKM2 in papillary thyroid carcinoma (PTC) and its correlation with the patients clinicopathological features and with tumor invasion and metastasis. Surgically resected PTC specimens from 60 patients were collected. The expression levels of HIF-1 alpha and PKM2 in PTC tissues were examined by immunohistochemical staining. The full clinical records of all patients were collected to analyze the relevance between HIF-1 alpha and PKM2 expressions and the clinical pathological features of PTC. The results showed that the positive expressions of HIF-1 alpha, PKM2, and HIF-1 alpha/PKM2 axis (HIF-1 alpha(+)/PKM2(+)) were all significantly higher in PTC than those in normal thyroid follicular epithelium, and a positive correlation was found between HIF-1 alpha and PKM2 in PTC. Further analysis showed that in PTC, the positive expression of HIF-1 alpha and HIF-1 alpha/PKM2 axis (HIF-1 alpha(+)/PKM2(+)) were significantly associated with bigger tumor size, moreover, the positive expressions of HIF-1 alpha, PKM2 and HIF-1 alpha/PKM2 axis (HIF-1 alpha(+)/PKM2(+)) were all correlated with capsular invasion and lymph node metastasis, while they were all not correlated with gender, sex and multicentricity of tumor. This study identified HIF-1a/PKM2 axis as potential molecular marker for predicting the invasion and progression of papillary thyroid carcinoma.