Glycolysis module activated by hypoxia-inducible factor 1α is related to the aggressive phenotype of hepatocellular carcinoma

Abstract

An increased level of glycolysis, an intracellular hallmark of neoplasms, enables cancer cells to survive under various conditions. To elucidate the role of increased glycolysis in the progression of hepatocellular carcinoma (HCC), we investigated the associations between the expression patterns of 14 glycolysis-related genes and clinicopathologic factors in 60 HCCs by using pooled transcriptome data. We then evaluated the therapeutic efficacy of the knockdown of ENO1, which is encoded by a glycolysis-related gene, in HCC cells. Among the 14 genes, levels of 8 genes (GPI, ALDOA, TPI1, GAPD, PGK, PGAM, ENO1 and PKM), all of which can be transcriptionally activated by hypoxia-inducible factor 1alpha (HIF-1alpha), were significantly higher in HCC with venous invasion (VI) than in HCC without VI. Our cluster analysis showed that HCC patients with activation of the 8 HIF-1alpha-regulated genes had significantly shorter overall survival (P=0.023) than did HCC patients without increased expression levels of these genes. The association between the levels of ENO1 and VI was confirmed in an independent sample set of 49 HCCs by real-time reverse-transcription PCR. The knockdown of ENO1 by small-interfering RNA significantly inhibited the proliferation of an HCC cell line (HLE cells) in both the glucose-rich and glucose-free conditions, accompanied by a decreased S phase and increased G2/M phase of the cell cycle. Collectively, these data suggest that activation of an HIF-1alpha-regulated glycolysis module is closely related to the aggressive phenotype of HCC, and that ENO1, a glycolysis module gene, might serve as a new target to circumvent HCC metastasis.