By Dr. Gabe Mirkin
We have known for many years that cancer cells take in way too much sugar, but have not known whether cancer causes the increased use of sugar by cancer cells or that sugar causes normal cells to become cancerous. This month, Mina Bissell of the Lawrence Berkeley National Laboratory presented research confirming that cancer may be caused by a marked increase in the amount of sugar used for energy in the presence of oxygen (Journal of Clinical Investigation, published online December 9, 2013).
Why This Research is So Important
In 1924, Nobel Prize winner Otto Warburg showed that cancer cells use far more sugar for energy with oxygen than normal cells do. Now, almost ninety years later, Bissell’s paper shows that a marked increase in the action of GLUT3 (the chemical that carries sugar into cells) causes normal breast cells to become breast cancer cells. Indeed, the concentration of GLUT3 is 400 times greater in breast cancer cells than it is in normal cells. The authors also showed that reducing the entry of sugar into breast cancer cells appears to turn them into normal cells. Thus if we could block the uptake of sugar only into cancer cells, we might be able to cure cancer.
How Cells Get Their Energy
Cells get energy from two major pathways:
1) The use of sugar and fat with oxygen, inside the mitochondria (called the Krebs Cycle); or
2) The use of sugar with or without oxygen, inside the cell but outside of the mitochondria (called glycolysis).
Every cell in our body except mature red blood cells has many tiny compartments called mitochondria. Cancer cells have defective mitochondria and so need to get most of their energy from glycolysis.
Cancer Cells are Different from Normal Cells
Normal cells divide certain number of times and then die. This is called apoptosis. Cancer cells lose the genetic signal to divide only so many times and then die, so they can live and divide indefinitely. The cancer cells do not kill you by being just cancer, they kill by invading other tissues. Breast cancer doesn’t kill you when it is in the breast; it kills when it spreads to the brain, the liver or other essential organs and keeps them from functioning properly.
Apoptosis depends on normal mitochondria. Because cancer cells have defective mitochondria, they lose apoptosis and kill by spreading through your body. Since cancer cells lack mitochondria, they have to depend completely on sugar for energy.
High Blood Sugar Increases Risk for Cancer
Everything that raises blood sugar increases cancer risk: diabetes, obesity, lack of exercise and a diet high in sugared drinks and sugar-added foods. Drugs such as metformin that reduce blood sugar levels help to prevent cancer (Public Library of Science Medicine, January, 2010). We do not yet know how to block sugar from cancer cells without also blocking sugar from normal cells, but a healthful lifestyle that protects you from high rises in blood sugar will reduce your risk for breast cancer and many other types of cancers:
* Exercise daily
* Lose weight if overweight
* Enlarge muscles and reduce fat
* Avoid sugared drinks, sugar added foods, red meat, fried foods
* Eat plenty of fruits and vegetables
* Keep blood levels of hydroxy-vitamin D above 75 nmol/L
* Do not smoke
* Do not drink alcohol
Dr. Gabe Mirkin is a Villager. Learn more at www.drmirkin.com
