Fructose Induces Transketolase Flux to Promote Pancreatic Cancer Growth Haibo Liu, Danshan Huang, David L. McArthur, Laszlo G. Boros, Nicholas Nissen, and Anthony P. Heaney Carbohydrate metabolism via glycolysis and the tricarboxylic acid cycle is pivotal for cancer growth, and increased refined carbohydrate consumption adversely affects cancer survival. 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. However, fructose intake has increased dramatically in recent decades and cellular uptake of glucose and fructose uses distinct transporters. Here, we report that fructose provides an alternative substrate to induce pancreatic cancer cell proliferation. Importantly, fructose and glucose metabolism are quite different; in comparison with glucose, fructose induces thiamine-dependent transketolase flux and is preferentially metabolized via the nonoxidative pentose phosphate pathway to synthesize nucleic acids and increase uric acid production. 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, and indicate that efforts to reduce refined fructose intake or inhibit fructose-mediated actions may disrupt cancer growth.

Here is basically what they're saying: Pancreatic cancer cells (which are among the nastiest of all) will eat fructose to make more DNA and RNA, and you can't make more cells without DNA and RNA. Glucose, on the other hand, they will use to produce energy and survive, true, but not necessarily make more of themselves. But there's the rub; as long as cancer cells do not make more of themselves, your immune system (along with treatment) will eventually beat them.

What they are also saying is that because fructose and glucose are taken into cells by entirely different systems, we may be able to stop just the fructose uptake and slow cancer proliferation down enough to let the body gain the upper hand. Cells use specific proteins to import nutrients like fructose, and just about any protein can be inactivated by finding just the right kind of chemical. Researchers have gotten very good at doing this thanks to advances in genetics, enzymology, and combinatorial chemistry.

We may also be able to specifically inhibit an enzyme called fructokinase, which tacks on a phosphate group to fructose as the first step in its metabolism. No fructokinase, no more DNA (at least in the cells studied in this paper). Glucokinase is a different enzyme altogether. Normal cells could continue to use other sugars to survive while the immune system dusted off the cancer cells. That's another angle we may get.

In addition, we may even be able to design a "fructose bomb". If normal cells prefer glucose to fructose (as many types of cells do), whereas cancer cells will eat fructose even if glucose is around, then we could use fluorinated or radioactive fructose to let the cancer cells blow themselves to smithereens. Maybe another angle.

The very simplest implication of all this is that if you have cancer or are at high risk for cancer, stop eating and drinking foods with high-fructose corn syrup right now! That means basically all sodas with sugar in them. Look at your food labels for "high-fructose corn syrup" and stay away from those foods. In fact, you may want to do that anyway, even if you are healthy. You see, mutations arise in the body all the time, and some of these can lead to cancer if the body can't tackle the mutant cells in time. Don't hand cancer cells a free ticket. Sugary soda tastes good, but it ain't THAT good.

If you see "sugar" in the ingredient list, that means sucrose, which is one glucose and one fructose linked together. The study doesn’t seem to have addressed that, so I would have to say it is not clear whether sucrose will have any effects similar to fructose. Sucrose will get broken down into glucose and fructose, but the cell may not kick on the same response that it would to fructose. More study will be required on that. Of course, we'll also want to look at other types of cancer cells as well.

^^^^^^^^^

Let me just say that federal funding is usually behind these kinds of studies, and it's just that sort of federal funding that ignorant people like Sarah Palin will ridicule. There is such a thing as the public good, and in many cases your tax dollars really do support that public good. Not for abstract social programs, but for real breakthroughs. One day the cure for cancer. The study of various organisms (yes, Sarah, that includes fruit flies), the maintenance of genetic databases, free access to literature searches and genetic computational tools, the training of graduate students – this is what the federal government enables, and it is all crucially important.

UPDATE [9:37 AM EST 8/4/10]:

Some commenters are pointing out that I am being unnecessarily harsh on high-fructose corn syrup (which also contains glucose) and not harsh enough on plain old sucrose (= glucose + fructose), and they are probably largely correct. Pounding lots of sucrose is not a great idea, either. As with most dietary questions, moderation is the key. We should not try to scrub all traces of sugar from our diets, but neither should we pound 6 Cokes a day.

UPDATE [much later]

A commenter pointed out that one should not construe this as medical advice and should consult a doctor on these matters. That is, of course, correct.