Getting all stressed out by vitamin C
Few experimental cancer therapies have incited as much debate as vitamin C. Yet the mechanistic effect of vitamin C on cancer cells is still poorly understood. Yun et al. studied human colorectal cancer cells with KRAS or BRAF mutations and found that they “handle” vitamin C in a different way than other cells, ultimately to their detriment (see the Perspective by Reczek and Chandel). Because a certain receptor is up-regulated in the mutant cells, they take up the oxidized form of vitamin C (dehydroascorbate). This leads to oxidative stress, inactivation of a glycolytic enzyme required by the mutant cells for growth, and finally cell death. Whether the selective toxicity of vitamin C to these mutant cells can be exploited therapeutically remains unclear.
Abstract
More than half of human colorectal cancers (CRCs) carry either KRAS or BRAF mutations and are often refractory to approved targeted therapies. We found that cultured human CRC cells harboring KRAS or BRAF mutations are selectively killed when exposed to high levels of vitamin C. This effect is due to increased uptake of the oxidized form of vitamin C, dehydroascorbate (DHA), via the GLUT1 glucose transporter. Increased DHA uptake causes oxidative stress as intracellular DHA is reduced to vitamin C, depleting glutathione. Thus, reactive oxygen species accumulate and inactivate glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Inhibition of GAPDH in highly glycolytic KRAS or BRAF mutant cells leads to an energetic crisis and cell death not seen in KRAS and BRAF wild-type cells. High-dose vitamin C impairs tumor growth in Apc/KrasG12D mutant mice. These results provide a mechanistic rationale for exploring the therapeutic use of vitamin C for CRCs with KRAS or BRAF mutations.
Study and Press Releases
- Vitamin C selectively kills KRAS and BRAF mutant colorectal cancer cells by targeting GAPDH, science, 11 Dec 2015.
- High dose of vitamin C kills cancer cells in mice, arstechnica, Nov 18, 2015.
- Vitamin C ‘gives chemotherapy a boost’, BBC News, 9 February 2014.
- Research continues to confirm that high doses of vitamin C injections destroy cancer, but don’t expect to hear that from Big Pharma, newstarget.
We all know that vitamin c is good for us but science has failed to show any real cure related link for cancer. Many former propionates for its use have backed away from such claims. Many people have taken C for cancer without any results. So why is C use being paraded as a cure all again? I’ve had my share of cancer and have collected a great deal of information on this subject. I even realize that folic acid is used for some kinds of cancer treatments. But as a who science is not saying vitamin C isn’t the cure all it once said it was. So the question I have is what has changed in the data we have that suggests C is once again the cure all? Is there a new treatment using C or new data.
Don’t get me wrong I’m a firm believe in revisiting old research with fresh eyes. Have done this myself and strongly advocate this. So show me cause and effect and I’ll get onboard. For this to happen I need to see blind studies, numbers and anything that can be held up for exam.
Again we all know of the many good health effects of taking C now show me what else is new?
Among the links I added Dave, one is about a study published on 11 Dec 2015 ; one month old.
Perhaps “my” post title is slightly misguiding because the text content does certainly not say that vitamin C is “the” cure for “all”
cheers