Introduction: Breast cancer is the most commonly diagnosed cancer and second leading cause of death in women. Resistance to chemotherapy and recurrence of breast cancer are the challenges in successfully treating breast cancer patients. This highlights the urgent need for novel therapeutic strategies that go beyond traditional cytotoxic treatments.
Metabolic reprogramming is one of the main characteristics of cancer cells. Increased glycolysis also known as the “Warburg effect” is evident in many cancers including Breast Cancer. Targeting the inhibition of aerobic glycolysis in cancer cells is a promising strategy to stop cell proliferation.
Hexokinase is a rate-limiting enzyme and the first step of the glycolysis pathway that catalyzes the phosphorylation of Glucose to glucose 6 – phosphate, using a phosphate group of ATPs. The structure of hexokinase consists of a regulatory N-terminal and a catalyzing C-terminal and an α-helix that connects the two domains. The active site of hexokinase is in a cleft between two subdomains of C-terminal that can bond to glucose. There are four isoenzymes of hexokinase in human body (HK1, 2,3, and 4). Type 1 and 2 both have the ability to connect to mitochondrial outer membrane (MOM) through voltage dependent anion channels (VDACs). Out of four isoenzymes of hexokinase, Hexokinase type 2 is increased in almost every cancer and has become a promising target for anti-cancer therapeutic studies. Unlike other subtypes of hexokinase, type 2 has catalyzing activity in N-terminal and has a more dynamic connection to MOM that enables it to have access to mitochondrial ATP. Due to its connection to mitochondria via voltage dependent anion channels (VDACs), plays an important role in the prevention of apoptosis and cell survival. Which is believed to a reason for chemotherapy resistance and cancer recurrence.
Hexokinase type 2 is a promising target for anti-cancer therapeutics which has been a target for drug development for a long time. Its important and unique role in cancer cells metabolism can bring a novel therapeutic path into the light. In this study we aim to inhibit the activity of Hexokinase type 2 with small molecules (ligands) and investigate the mutations of genes, effecting the increased function and translation of Hexokinase type 2 in Breast cancer cells.
Methods: 215 of most relevant SNPs of 19 different genes, which had oncogenic effects in breast cancer according to previous publications, were selected from the National Center for Biotechnology Information (NCBI) database. Studied genes were BRCA1, BRCA2, TP53, PTEN, CDH1, PALB2, ATM, AKT1, MYC, BARD1, NBN, CHECK2, HIFA1, RAD51, RAD51C, RAD51D, BRIP1, HK2, and G6PD. The selected SNPs were analyzed with MEGAGENE, a bioinformatic tool made in IRAN.
For investigation of inhibition of Hexokinase 2, molecular docking was performed with Auto Dock software (MGL Tools). Two ligands were selected for investigation: Maltose, also known as maltobiose or malt sugar, a disaccharide formed from two units of glucose joined with an α bond, that can be a competitive inhibitor for glucose due to their structural Similarity. The other ligand is Sorbitol a six-carbon sugar alcohol, with the same structure as glucose.
Results: Analysis using the MEGAGENE software programme shows that, of the 215 selected SNPs, the greatest number of polymorphisms with carcinogenic potential are observed in the BRCA1, BRCA2, TP53, PALB2 and ATM genes. These SNPs are directly related to the primary DNA repair and cell cycle regulation pathways, and have been proposed as key markers for predicting breast cancer targets.
In the Hexokinase 2 (HK2) study using the molecular docking method, both selected ligands (maltose and sorbitol) were found to bind to the enzyme's active sites. The obtained results show: These findings suggest that HK2 with natural ligands similar to glucose could limit glucose-dependent metabolism in breast cancer cells.
Conclusion: Examining 215 SNPs from key cancer-causing genes using MEGAGENE showed that genetic variants in the BRCA1, BRCA2, TP53 and PALB2 genes play the most important role in breast cancer occurrence and can be used as important biomarkers in genetic screening. Overall, this study demonstrates that combining genetic analysis (SNPs) with molecular modelling (docking) can open up new avenues for predicting risk and designing novel breast cancer treatments.
Keywords: Breast Cancer, Hexokinase2, Genetic Variations, Molecular Docking