Last month I read this article on how evil Sugar is in obesity (Guardian) & other problems.
Now, I just read this article in the NYT on how insulin & glucose are the key ingredients in feeding cancer cells. Must read with excerpts below.
Incidentally, both the NYT & Guardian article reference the Planck quotation:
“A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.”
Warburg’s personal diet is unlikely to become a path to prevention. But the Warburg revival has allowed researchers to develop a hypothesis for how the diets that are linked to our obesity and diabetes epidemics — specifically, sugar-heavy diets that can result in permanently elevated levels of the hormone insulin — may also be driving cells to the Warburg effect and cancer.
The insulin hypothesis can be traced to the research of Lewis Cantley, the director of the Meyer Cancer Center at Weill Cornell Medical College. In the 1980s, Cantley discovered how insulin, which is released by the pancreas and tells cells to take up glucose, influences what happens inside a cell. Cantley now refers to insulin and a closely related hormone, IGF-1 (insulinlike growth factor 1), as “the champion” activators of metabolic proteins linked to cancer. He’s beginning to see evidence, he says, that in some cases, “it really is insulin itself that’s getting the tumor started.” One way to think about the Warburg effect, says Cantley, is as the insulin, or IGF-1, signaling pathway “gone awry — it’s cells behaving as though insulin were telling it to take up glucose all the time and to grow.” Cantley, who avoids eating sugar as much as he can, is currently studying the effects of diet on mice that have the mutations that are commonly found in colorectal and other cancers. He says that the effects of a sugary diet on colorectal, breast and other cancer models “looks very impressive” and “rather scary.”
Elevated insulin is also strongly associated with obesity, which is expected soon to overtake smoking as the leading cause of preventable cancer. Cancers linked to obesity and diabetes have more receptors for insulin and IGF-1, and people with defective IGF-1 receptors appear to be nearly immune to cancer. Retrospective studies, which look back at patient histories, suggest that many people who develop colorectal, pancreatic or breast cancer have elevated insulin levels before diagnosis. It’s perhaps not entirely surprising, then, that when researchers want to grow breast-cancer cells in the lab, they add insulin to the tissue culture. When they remove the insulin, the cancer cells die.
“I think there’s no doubt that insulin is pro-cancer,” Watson says, with respect to the link between obesity, diabetes and cancer. “It’s as good a hypothesis as we have now.” Watson takes metformin for cancer prevention; among its many effects, metformin works to lower insulin levels. Not every cancer researcher, however, is convinced of the role of insulin and IGF-1 in cancer. Robert Weinberg, a researcher at M.I.T.’s Whitehead Institute who pioneered the discovery of cancer-causing genes in the ’80s, has remained somewhat cool to certain aspects of the cancer-metabolism revival. Weinberg says that there isn’t yet enough evidence to know whether the levels of insulin and IGF-1 present in obese people are sufficient to trigger the Warburg effect. “It’s a hypothesis,” Weinberg says. “I don’t know if it’s right or wrong.”