Introduction
The ability to metabolize glucose at an increased rate is a critical feature of many malignancies, particularly the most aggressive, and is clinically recognized by positron emission tomography (PET). This trait gives cancer cells a unique competitive advantage over normal cells, especially those involved in metastasis. The highly glycolytic phenotype is supported by hexokinase (mainly HK II).
What Is Hexokinase 2?
Hexokinase 2 is overexpressed and bound to the outer mitochondrial membrane via the porin-like protein voltage-dependent anion channel (VDAC) after fast glucose entry into cancer cells via the glucose transporter. This protein and the adenine nucleotide transporter carry ATP (adenosine triphosphate) from the inner membrane ATP synthase to active sites on Hexokinase 2. The plentiful Hexokinase 2 binds both the ATP and the incoming glucose, creating glucose-6-phosphate at an increased rate. This vital molecule subsequently acts as a biosynthetic precursor to enhance cell proliferation and as a precursor for lactic acid.
What Is the Function of Hexokinases 2?
Hexokinases are a class of exposed-phosphorylating enzymes that prepare glucose for intracellular use. The most active isozyme in the family, hexokinase 2 (HK2), is found mainly in insulin-sensitive tissues. In most neoplastic cells, hexokinase 2 activation leads to metabolic rewiring toward aerobic glycolysis, and its genetic ablation slows malignant development. In addition, HK2 can attach to mitochondria, providing autophagy control and cell death inhibition actions independent of its enzymatic activity. The new characterization of hexokinase 2 localization to mitochondria-associated membranes (MAMs), which are contact areas between mitochondria and endoplasmic reticulum, has unique hexokinase 2 roles in regulating intracellular Ca2+ fluxes.
What Is the Role of Hexokinase 2 in Cancer?
Hexokinase 2 acts as a precursor for lactic acid and exits cancer cells, and creates an unfavorable environment for normal cells. Although hexokinase 2 facilitates chemical warfare, its mitochondrial location also reduces cancer cell death, increasing the risk of metastasis and the eventual demise of the human host. For these reasons, various laboratories are actively investigating targeting this critical enzyme as part of a plan to create innovative medicines that may reverse the tide in the ongoing battle to find effective cancer cures.
How Is Hexokinase 2 Regulated?
The factors that regulate hexokinase 2 have the following variables:
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Transcriptional.
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Translational.
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Post-translational.
Hexokinase 2 protects against stress conditions and aids in average tissue growth. It is activated by growth factors such as fibroblast growth factor (FGF) or transforming growth factor (TGF), which operate on the transcription factor c-MY. Fibroblast growth factor (FGF) signaling is required for vascularization, and hexokinase 2 ablation in endothelial and lymphatic cells causes blood and lymphatic vascular abnormalities similar to those seen in fibroblast growth factor receptor (FGFR). In fibroblasts, hexokinase 2 increases transforming growth factors (TGF) pro-fibrotic action, whereas knocking down hexokinase 2 lowers transforming growth factor(TGF)—stimulated fibrogenic process. Ectopic Hexokinase 2 gene overexpression in the substantia nigra of the brain protects dopaminergic neurons from degeneration in Parkinson's disease.
What Is the Role of Hexokinase 2 in Cervical Cancer?
Hexokinase 2 (HK2) is a member of the hexokinase (HK) family associated with malignant development in many malignancies as a crucial regulator during glucose metabolism. Hexokinase 2 expression was stimulated in squamous cervical cancer (SCC) tissues. It increased cervical cancer cell proliferation in vitro and tumor development in the following ways:
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Speeding cell cycle progression.
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Upregulating cyclin A1.
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Downregulating p27 expression.
Furthermore, transcriptome sequencing research indicated that MAPK3 (ERK1) was increased in HeLa cells overexpressing hexokinase 2. Further investigation revealed that p-Raf, p-MEK1/2, ERK1/2, and p-ERK1/2 protein levels were elevated in hexokinase 2 over-expressing SiHa and HeLa cells.
Does Inhibiting Hexokinase 2 Treat Cancer?
In the first stage of glycolysis, the hexokinase 2 enzyme catalyzes the phosphorylation of glucose molecules into G6P. This enzyme is present in practically all body cells. However, it is particularly prevalent in musculoskeletal and hepatic cells. Hexokinase 2 is significant because glycolysis is critical in providing adequate energy molecules. The hexokinase 2 gene is up-regulated in hypoxia as a survival strategy under oxygen stress. Hexokinase 2 also attaches to mitochondria, preventing apoptosis and promoting cancer cell survival. As a result, suppressing the activity of the HK2 enzyme and the production of its gene starves cancer cells, allowing them to die. As a result, this approach can be used to treat several forms of cancer.
For example, the oncogene Kras promotes the expression of the hexokinase 2 gene; therefore, inhibiting it would have the same impact on hexokinase 2. The phosphorylation properties of hexokinase 2 , the Warburg effect, play a critical role in guaranteeing glycolysis in cancer cells. Furthermore, hexokinase 2 promotes tumor cell viability by blocking apoptosis. 3-Bromopyruvate is a potent inhibitor of hexokinase 2. It works by covalently modifying sulfhydryl groups in the enzyme, causing it to dissociate from the mitochondrial membrane.
What Are the Applications of Hexokinase 2?
The inhibition of hexokinase 2 in tumor cell control is used in chemistry, biology, and medicine as part of cancer therapy. In chemistry, it creates compounds that block the activity or expression of hexokinase 2. These chemicals might be developed further into medications that could be used in the field of medicine to treat various types of cancer. In biology, investigating and utilizing the activity of hexokinase 2 would help understand how diverse pathways may be employed to block the enzyme's movement and the production of its gene in cancer therapy. Thus, understanding how hexokinase 2 works are crucial in chemistry, biology, and medicine since the three research fields interact to generate cancer therapy regimens.
Conclusion
Cancer cells frequently exhibit accelerated glucose consumption. Hexokinases are enzymes that catalyze the first committed step in glucose metabolism. Hexokinase 2 (HK2) is highly expressed in cancer cells but only in a few normal adult organs. However, in many kinds of cancer, hexokinase 2 is essential for tumor start and maintenance, as well as tumor spread and growth. Therefore, to prevent its glucose phosphorylation properties and the mitochondria binding mechanism, hexokinase 2 might be blocked in various methods.
