Metabolic rewiring is observed in almost all cancer types and is considered one of the hallmarks of cancer. The Warburg effect, also named aerobic glycolysis, is characterised by an increased conversion of glucose to lactate and was first observed by Otto Warburg in the 1920s. Studies have shown a correlation between aerobic glycolysis and metastatic properties of cancer. The cancer-specific metabolic rewiring raises the question of whether the flux control distribution over the glycolytic pathway has changed compared to normal cells, and whether such a redistribution could be exploited for drug target identification. Work by Shestov et al. (2016) highlighted glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as a good glycolytic target to perturb aerobic glycolysis in cancer. In a combined experimental and modelling approach we investigated aerobic glycolysis in the MDA-mb-231 cell line - a highly invasive and hormone-independent breast cancer cell line, to study the flux control distribution, particularly the control by GAPDH.

For the construction of a detailed mathematical model for the glycolytic pathway, we kinetically characterised all 12 glycolytic enzymes. Kinetic parameters were obtained by performing a global fit on the enzyme’s initial rate kinetics using the corresponding rate equations. A set of ordinary differential equations was defined with parameterised rate equations based on the kinetic data. The model was successfully tested in its capacity to predict intermediate dynamics upon a pulse of 14C labelled glucose to cell free extracts and in its prediction of the effect of inhibition of GAPDH by iodoacetic acid.
Subsequently, the glucose transporter was characterised, and we are busy integrating the transporter kinetics with the glycolytic enzymes to simulate glucose metabolism in intact cells.

Inhibitor titrations of intact cells revealed that the flux control coefficient of GAPDH is very low, Kouril et al. (2023), making the enzyme a poor therapeutic target in this highly invasive breast cancer cell line. We are currently investigating whether the high flux control observed by Shestov is cell line dependent, by analysing more sensitive cell lines. Once the intact cell model has been validated, we will apply MCA for drug target identification.

Shestov, A.A., Liu, X., Ser, Z., Cluntun, A.A., Hung, Y.P., Huang, L., Kim, D., Le, A., Yellen, G., Albeck, J.G. and Locasale, J.W., 2014. Quantitative determinants of aerobic glycolysis identify flux through the enzyme GAPDH as a limiting step. elife, 3, p.e03342.

Kouril, T., October, C., Hollocks, S., Odendaal, C., van Niekerk, D.D. and Snoep, J.L., 2023. Inhibitor titrations reveal low control of glyceraldehyde 3-phosphate dehydrogenase and high control of hexokinase on glycolytic flux in an aggressive triple-negative breast cancer cell line. Biosystems, 231, p.104969.