Warburg Effect & Oncology

1. PHM142 Fall 2013 Instructor: Dr. Jeffrey Henderson Warburg Effect & Oncology PHM142 October 2, 2013 Alexandra Barany & Noralhuda Emad

2. What is the Warburg Effect? Proliferating or Tumor Cells Differentiated Tissue Cells -O2 +O2 Glucose Glucose +/-O2 Glucose Pyruvate Pyruvate O2 Lactate 85% Lactate Pyruvate O2 Lactate CO2 (Aerobic Glycolysis) (Oxidative Phosphorylation) (Anaerobic Glycolysis) CO2 Concept adapted from Vander et. al., 2009

3. What is the Warburg Effect? • Cells metabolize • glucose EVEN • WHEN O2 is • present • They avoid • oxidative • phosphorylation! Pasteur Effect • Glycolysis: glucose  pyruvate (2 ATP) • WITH O2  oxidative phosphorylation • WITHOUT O2 lactate • Reciprocal relationship between • anaerobic glycolysis and oxidative • phosphorylation non existent in the • Warburg effect

4. Mechanism of Action GLUT MCT Acetyl-CoA for fatty acid synthesis Glucose Glycolysis Pyruvate Lactate 1. 2. Glutamine Acetyl-CoA Citrate TCA Cycle Oxaloacetate Glutamate 2-Oxoglutarate Succinate

5. Mechanism of Action • Cancerous cells exhibit abnormal behaviours, two of which are: • 1. Production of lactate under aerobic conditions • 2. Inefficient use of glutamine (secrete a significant fraction of glutamine- derived nitrogen and carbon as waste instead of incorporating them into • macromolecule synthesis) • These abnormalities occur because of: • 1. HIF (hypoxia inducible factor) and MYC activate the expression of GLUT and • glycolytic enzymes • 2. HIF diverts pyruvate from the glycolytic TCA cycle • 3. MYC induces glutamine uptake

6. Reprogramming Cell Metabolism Hsu & Sabatini, 2008

7. Reprogramming Cell Metabolism Hsu & Sabatini, 2008

8. Regulation of HIF Fumarate Fe2+ --------| Succinate 2-Oxoglutarate pVHL pVHL --------| PHD HIF-β HIF-β HIF-β OH OH HIF-α HIF-α HIF-α O2 Ub Ub Ub HIF-α destroyed Concept adapted from Kaelin et. al., 2010

9. Regulation of HIF • HIF-αhydroxylated (addition of –OH) in the presence of oxygen • This is accomplished by the enzyme PHD • PHD itself regulated by oxygen, 2-oxoglutarate, reduced iron, • fumarate and succinate (see previous slide) • pVHL (tumour suppressor protein) recognizes –OH and adds a • ubiquitin chain  degraded by proteasome • In cancer cells, HIF active and leads to abnormal behavior

10. PI3K/Akt Pathway Thompson & Waird, 2012

11. Use and Application in Therapy • Used in diagnosis and monitoring of malignant tumors by imaging uptake of a modified radioactive hexokinase substrate using • PET • Develop anti-cancer agents that can inhibit altered metabolic pathways such as glycolysis in cancerous cells (i.e. target enzymes)

12. Use and Application in Therapy Chen et al, 2007

13. Summary • Warburg effect describes the preferred metabolic pathway exhibited by cancerous cells oxidative glycolysis • Cells generate ATP through amplified rates of glycolysis and do not go through oxidative phosphorylation as primary pathway of generating ATP, leading to high lactate levels • Warburg’s original observation has been extended to other alterations seen in the metabolism of other molecules (e.g. glutamine) that also characterize cancerous cells differently from normal cells • Cancerous cells exhibit reprogramming of metabolism, where various molecules are metabolized in a way to increase rate of replication and biosynthesis • Altered metabolism triggered by microenvironment and/or signaling pathways • Many altered signaling pathways have been observed to be hallmarks of cancer (e.g.PI3K/Akt pathway and HIF pathway) • Application of Warburg effect is seen in diagnosis of cancer and production of anti-cancer treatments

14. References • Cantley, L.C.,Thompson, C.B.,& Vander Heiden, M.G. (2009) Understanding the Warburg Effect: The Metabolic Requirements of Cell Metabolism. Science, 324, 1029-1034. • Chen, Z., Garcia-Prieto, C., Huang, P., & Lu,W. (2007) The Warburg Effect and its Cancer Therapeutic Implications. The Journal of Bioenergetics and Biomembranes, 39, 267-274. • Hsu, P.P. & Sabatini, D.M. (2008) Cancer Cell Metabolism: Warburg and Beyond. Cell, 134, 703-708. • Kroemer, G. & Pouyssegur, J. (2008) Tumour cell metabolism: cancer’s Achilles’heel. Cancer Cell, 13, 472-482. • Pathania, D., Millard, M. & Neamati, N. (2009) Opportunities in discovery and delivery of anticancer drugs targeting mitochondria and cancer cell metabolism. Adv. Drug Deliv. Rev., 61, 1250-1275. • Thompson, C.B. & Waird,P.S. (2012) Metabolic Reprogramming: A Cancer Hallmark Warburg Did Not Anticipate. Cancer Cell,21, 297-308.