A new study by researchers at UCLA has revealed that pancreatic cancers employ sugar fructose, common in Western diet, to trigger an important cellular pathway that causes cell division, assisting the rapid growth of cancer.
Although it's widely known that cancers use glucose, a simple sugar, to fuel their growth, this is the first time a link has been shown between fructose and cancer proliferation, said Dr. Anthony Heaney, an associate professor of medicine and neurosurgery, a Jonsson Cancer Center researcher and senior author of the study.
"The bottom line is the modern diet contains a lot of refined sugar including fructose and it's a hidden danger implicated in a lot of modern diseases, such as obesity, diabetes and fatty liver," said Heaney, who also serves as director of the Pituitary Tumor and Neuroendocrine Program at UCLA.
The source of fructose in the Western diet is high fructose corn syrup (HFCS), a corn-based sweetener that has been on the market since about 1970. HFCS accounts for more than 40 percent of the caloric sweeteners added to foods and beverages, and it is the sole sweetener used in American soft drinks.
In his study, Heaney and his team took pancreatic tumors from patients and cultured and grew the malignant cells in Petri dishes. They then added glucose to one set of cells and fructose to another. Using mass spectrometry, they were able to follow the carbon-labeled sugars in the cells to determine what exactly they were being used for and how.
Heaney found that the pancreatic cancer cells could easily distinguish between glucose and fructose even though they are very similar structurally, and contrary to conventional wisdom, the cancer cells metabolized the sugars in very different ways.
In the case of fructose, the pancreatic cancer cells used the sugar in the transketolase-driven non-oxidative pentose phosphate pathway to generate nucleic acids, the building blocks of RNA and DNA, which the cancer cells need to divide and proliferate.
"Traditionally, glucose and fructose have been considered as interchangeable monosaccharide substrates that are similarly metabolized, and little attention has been given to sugars other than glucose," the study states.
"However, fructose intake has increased dramatically in recent decades and cellular uptake of glucose and fructose uses distinct transporters ... These findings show that cancer cells can readily metabolize fructose to increase proliferation. They have major significance for cancer patients, given dietary refined fructose consumption."
The study appeared in the Aug. 1 issue of the peer-reviewed journal Cancer Research.