Targeted Inhibition of HK-II Reversed the Warburg Effect to Improve the Radiosensitivity of Laryngeal Carcinoma

Abstract

Purpose

Hexokinase-II (HK-II) is the key enzyme in the first rate-limiting step of glycolysis that catalyzes the conversion of glucose to glucose-6-phosphate. Here, we examined the association between HK-II expression and radioresistance in laryngeal carcinoma and whether the inhibition of HK-II expression can enhance the radiosensitivity of these tumors.

Methods

The effects of HK-II small interfering RNA (siRNA) on the radiosensitivity of Tu212 cells were examined in vitro and in vivo in a mouse model. Cells were irradiated using a 6-MV linear accelerator. The cell viability, cell survival, proliferation, apoptosis, and cell cycle of Tu212 cells were evaluated using trypan blue staining, colony formation assays, CCK-8 assays, and flow cytometry, respectively. Oxygen consumption, lactic acid production, glucose consumption, and the ATP level of Tu212 cells were also examined. The expression of glycolytic and regulatory enzymes involved in the tricarboxylic acid cycle was assessed using Western blotting.

Results

The HK-II siRNA and X-ray combination treatment led to a significantly greater reduction of cell viability, inhibition of cell survival and proliferation, increased apoptosis, and increased G2 phase arrest compared to either treatment alone (all, P<0.01). HK-II siRNA increased the oxygen consumption rate of cells, significantly inhibited lactic acid production and glucose consumption, and significantly suppressed the upregulation of HK-II, pyruvate kinase M2 (PKM2), pyruvate dehydrogenase (PDH), phosphofructokinase platelet (PFKP), lactate dehydrogenase (LD), and citrate synthase (CS) (all, P<0.01).

Conclusion

The inhibition of HK-II by siRNA enhances the radiosensitivity of laryngeal carcinoma Tu212 cells by inhibiting glycolysis and partially inhibiting oxidative phosphorylation.

Keywords:

• laryngeal carcinoma
• hexokinase-II
• siRNA
• radiosensitivity
• Warburg effect

Acknowledgment

This work was supported by Science and technology plan project of Medical and health of Zhejiang province, China (No. 2018KY801), and Basic public welfare research plan of Zhejiang Province, China (No. LGF18H130001).

Data Sharing Statement

Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.

Ethics Approval and Informed Consent

This study was conducted under the guidelines and with the approval of Second Hospital of Jiaxing City, Jiaxing City, Zhejiang Province, 314000, China (No. jxey-2017013).

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors declare that they have no competing interests in this work.