Mathematical modelling of glycolysis in cancer cell lines

October, Craig Amos (2021-03)

Thesis (MSc)--Stellenbosch University, 2021.

Thesis

ENGLISH ABSTRACT: Most cancer cells exhibit an increase in glucose uptake and lactate produc- tion, a phenomenon known as the "Warburg effect" or aerobic glycolysis, and considered to be a hallmark of cancer metabolism. We investigated the glycolytic flux and enzyme activities in MDA-mb-231, a highly invasive triple-negative breast cancer cell. Enzyme assays were con- ducted on each glycolytic enzyme to characterise the kinetic parameters re- quired for the construction of a detailed mechanistic mathematical model. Model validation data was obtained by analysing the time dynamics of the system variables using an ion-pairing reverse liquid chromatography method for cell extract conversion of glucose to lactate. In addition, we determined glycolytic flux in MDA-mb-231 whole-cells via an extracellular flux assay, and compared it to a non-invasive cancer cell line (MCF-7). Results showed that both cell lines generate 1.7 moles of lactate per mole of glucose consumed, though the MDA-mb-231 flux was 2-fold higher than that measured in MCF-7 cells. The initial constructed model was accurate in the prediction of the glycolytic intermediates in upper glycolysis but de- viated significantly from the experimental results in lower glycolysis. We es- tablished that the model over-estimated PGM activity, as the enzyme activity is significantly lower in the experiment due to insufficient amounts of 2,3 bis- phosphoglycerate (2,3-BPG) to activate the co-factor dependent PGM. We used the model to predict both conditions: with and without the addition of 2,3-BPG. The model’s accuracy was satisfactory for the time-dynamics of gly- colytic intermediates in both conditions, although the model predictions were far from perfect, most of the variables were constantly described, resulting in a partly validated model. Based on glucose to lactate conversion, the glycolytic behaviour in whole-cells and the cell extracts appears to be distinctly different.

AFRIKAANSE OPSOMMING: Die meeste kankerselle vertoon ’n toename in glukose-opname en laktaatpro- duksie, ’n verskynsel wat bekend staan as die ”Warburg-effek” of aërobiese glikolise, en word beskou as ’n kenmerk van kankermetabolisme. Ons het die glikolitiese vloed- en ensiemaktiwiteite in MDA-mb-231, ’n ui- ters indringende drievoudige negatiewe borskankersel, ondersoek. Ensiembepa- lings is op elke glikolitiese ensiem uitgevoer om die kinetiese parameters te ken- merk wat benodig word vir die konstruksie van ’n gedetailleerde meganistiese wiskundige model. Modelvalideringsdata is verkry deur die tyddinamika van die stelselveranderlikes te ontleed deur gebruik te maak van ’n ioon-koppelende omgekeerde vloeistofchromatografie-metode vir die selekstrakte omskakeling van glukose na laktaat. Daarbenewens het ons glikolitiese vloed in MDA- mb-231 heel-selle bepaal deur middel van ’n ekstrasellulêre vloedtoets, en dit vergelyk met ’n nie-indringende kanker-sellyn (MCF-7). Die resultate het getoon dat beide sellyne ongeveer 1,7 mol laktaat per mol verbruikte glukose genereer, alhoewel die MDA-mb-231-vloed tweevoudig hoër was as wat in MCF-7-selle gemeet is. Die aanvanklike gekonstrueerde model was akkuraat in die voorspelling van die glikolitiese tussenprodukte in die boonste glikolise, maar het beduidend afgewyk van die eksperimentele re- sultate in laer glikolise. Ons het vasgestel dat die model die PGM-aktiwiteit te hoog geskat het, aangesien die ensiemaktiwiteit in die eksperiment aansienlik laer is as gevolg van onvoldoende hoeveelhede 2,3 bis-fosfoglyceraat (2,3-BPG) om die ko-faktorafhanklike PGM te aktiveer. Ons het die model gebruik om albei toestande te voorspel: met en sonder die toevoeging van 2,3-BPG. Die akkuraatheid van die model was bevredigend vir die tyddinamika van gliko- litiese tussengangers in albei toestande, alhoewel die modelvoorspellings nog lank nie perfek was nie, is die meeste veranderlikes voortdurend beskryf, wat ’n gedeeltelik gevalideerde model tot gevolg gehad het. Op grond van glukose na laktaat-omskakeling lyk die glikolitiese gedrag in heel-selle en selekstrakte duidelik anders.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/110277
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