Hexokinase 2 overexpression promotes the proliferation and survival of laryngeal squamous cell carcinoma

Abstract

Proliferating cancer cells preferentially use anaerobic glycolysis rather than oxidative phosphorylation for energy production. Hexokinase 2 (HK2) is highly expressed in many malignant cells and is necessary for anaerobic glycolysis. The role of HK2 in laryngeal squamous cell carcinoma (LSCC) is unknown. In this study, the expression of HK2 in LSCC was investigated and the effect of inhibiting HK2 expression with small hairpin RNA (shRNA) on tumor growth was investigated. Using immunohistochemistry, HK2 expression was assessed in LSCC tissues. Human laryngeal carcinoma Hep-2 cells were stably transfected with a plasmid expressing HK2 shRNA (pGenesil-1.1-HK2) and were compared to control cells with respect to the cell cycle, cell viability, apoptosis, and their ability to form xenograft tumors. HK2 expression was significantly higher in LSCC than in papilloma or glottis polypus. Tumor samples of higher T, N, and TNM stage often had stronger HK2 staining. HK2 shRNA reduced HK2 mRNA, protein levels, and HK activity in Hep-2 cells. HK2 cells expressing shRNA demonstrated a higher G0-G1 ratio, increased apoptosis, and reduced viability. Xenograft tumors derived from cells expressing HK2 shRNA were smaller and had lower proliferation than those from untransfected or control-plasmid-transfected cells. In conclusion, depletion of HK2 expression resulted in reduced xenograft tumor development likely by reducing proliferation, altering the cell cycle, reducing cell viability and activating apoptosis. These data suggest that HK2 plays an important role in the development of LSCC and represents a potential therapeutic target for LSCC.