Hexokinases in gastrointestinal cancers: From molecular insights to therapeutic opportunities.

Hexokinases (HKs) catalyze the first step in glycolysis by transferring a phosphate group to glucose to produce glucose-6-phosphate (G6P); dysregulation of HKs is a feature that leads to altered metabolism within gastrointestinal (GI) cancers-namely, gastric, colorectal, esophageal, and pancreatic cancer. Of note, HKs have been found to exert non-canonical roles beyond metabolism, particularly in regulating cell death pathways such as autophagy and apoptosis in these cancers. In this sense, HK2 promotes hepatocellular carcinoma (HCC) from apoptosis inhibition through the suppression of mitochondrial permeability transition pore formation by interaction with voltage-dependent anion channel (VDAC). Moreover, HK2 expression in HCC tumors decreases immune responsiveness and sensitivity to natural killer (NK) cytotoxicity, thus favoring immune escape. HK2 and co-expressed genes participate in esophageal cancer (ESCA) microenvironment immune response, especially in B cells, CD4 T cells, and macrophages. Most importantly, 3-BP, an HK-2 inhibitor, induces endoplasmic reticulum (ER) stress and disruption of the ER function by the accumulation of free radicals or reactive oxygen species (ROS) and the protein misfolding, thereby causing apoptosis in human HCC. Of note, it has been found that interaction of HK domain containing protein-1 (HKDC1) with ACTA2 (actin alpha 2) is required for the association of signal transducer and activator of transcription 1 (STAT1) with interferon-gamma receptor (IFNG-R) on the plasma membrane, STAT1-phosphorylation, and thus programmed cell death ligand 1 (PD-L1) expression upon stimulation with IFNγ in HCC. This review summarizes the mechanistic involvement of HKs in glycolytic reprogramming, apoptotic resistance, autophagy, immune evasion, metastasis, and drug resistance in GI cancers and the potential of HKs as diagnostic and therapeutic targets.