A hexokinase isoenzyme switch in human liver cancer cells promotes lipogenesis and enhances innate immunity

Laure Perrin-Cocon,Marc-Thorsten Hütt,Olivier Diaz,Clémence Jacquemin,Pierre-Olivier Vidalain,Gilles Jeans Philippe Rautureau,Keedrian Olmstead,Piotr Nyczka,Baptiste Panthu,Patrice André,Vincent Lotteau,Anne Aublin-Gex,Fabian Volker Filipp,Rodrigue Rossignol,Nivea Amoedo

doi:10.1038/s42003-021-01749-3

Abstract

During the cancerous transformation of normal hepatocytes into hepatocellular carcinoma (HCC), the enzyme catalyzing the first rate-limiting step of glycolysis, namely the glucokinase (GCK), is replaced by the higher affinity isoenzyme, hexokinase 2 (HK2). Here, we show that in HCC tumors the highest expression level of HK2 is inversely correlated to GCK expression, and is associated to poor prognosis for patient survival. To further explore functional consequences of the GCK-to-HK2 isoenzyme switch occurring during carcinogenesis, HK2 was knocked-out in the HCC cell line Huh7 and replaced by GCK, to generate the Huh7-GCK+/HK2− cell line. HK2 knockdown and GCK expression rewired central carbon metabolism, stimulated mitochondrial respiration and restored essential metabolic functions of normal hepatocytes such as lipogenesis, VLDL secretion, glycogen storage. It also reactivated innate immune responses and sensitivity to natural killer cells, showing that consequences of the HK switch extend beyond metabolic reprogramming.

Highlights

During the cancerous transformation of normal hepatocytes into hepatocellular carcinoma (HCC), the enzyme catalyzing the first rate-limiting step of glycolysis, namely the glucokinase (GCK), is replaced by the higher affinity isoenzyme, hexokinase 2 (HK2)
An isoenzyme switch from GCK to HK2 has been observed during the carcinogenesis process[16], whether hexokinase isoenzymes expression is predictive of patient survival is unclear
HK1 or HK3 expression level were not associated to patient survival rate (Fig. 1a), highest expression levels of HK2 as previously described[19] and lowest expression levels of GCK in the tumors were associated with a lower survival rate

Summary

Introduction

During the cancerous transformation of normal hepatocytes into hepatocellular carcinoma (HCC), the enzyme catalyzing the first rate-limiting step of glycolysis, namely the glucokinase (GCK), is replaced by the higher affinity isoenzyme, hexokinase 2 (HK2). HK2 knockdown and GCK expression rewired central carbon metabolism, stimulated mitochondrial respiration and restored essential metabolic functions of normal hepatocytes such as lipogenesis, VLDL secretion, glycogen storage It reactivated innate immune responses and sensitivity to natural killer cells, showing that consequences of the HK switch extend beyond metabolic reprogramming. We analyzed transcriptomic data of HCC biopsies and correlated hexokinase isoenzyme expression level with patient survival. This led us to generate a new cellular model of human HCC expressing GCK instead of HK2. A comparative analysis of GCK+ vs HK2+ HCC cell lines provided a unique opportunity to look into HK isoenzyme-dependent metabolic features, lipoprotein production and resistance to immune signals of liver cancer cells

Methods

Results

Conclusion