PET reveal glucose suppressant tumors (lung masses here) which may be susceptible to the therapy of vitamin C.
from Cane Medical Imaging Source Ltd./Science
Maybe Linus Pauling was on to something after all. There decades chemist Nobel Prize has been relegated to the periphery of medicine after defending the idea that vitamin C could fight against a host of diseases, including cancer. Now a study published online today in Science reports that vitamin C can kill tumor cells that carry a mutation common cancer-causing and - mice can slow growth of tumors with the mutation.
If the results hold in people, the researchers could find a way to treat a wide band tumors that lacked effective drugs. "This [could] be an answer to everyone fighting for," says molecular biologist Channing Der, University of North Carolina, Chapel Hill, one of many researchers who are trying to target cancers with mutation. The study is also rewarding for the handful of researchers who pursue vitamin C or ascorbic acid as a drug against cancer. "I'm encouraged. Maybe people will finally pay attention, "says vitamin C researcher Mark Levine of the National Institute of Diabetes and Digestive and Kidney Diseases.
In 1971, Pauling began collaborating with a Scottish doctor who had successful treatment of cancer patients with vitamin C. But the failure of two clinical trials of vitamin C pills, carried the late 1970s and early 1980s at the Mayo Clinic in Rochester, Minnesota reported, dampened enthusiasm for the idea of Pauling. Studies conducted by Levine's group later suggested that vitamin must be administered intravenously to reach high enough doses to kill cancer cells. Some recent small trials over the five years - to pancreatic and ovarian cancer - suggested that the treatment of IV vitamin C combined with chemotherapy can prolong survival Cancer. But skeptics are not influenced. "The atmosphere was poisoned" by previous failures, says Levine.
thereA few years Jihye Yun, a graduate student at Johns Hopkins University in Baltimore, Maryland, found that colon cancer cells whose growth is driven by mutations in the gene KRAS or less frequently mutated gene, BRAF , make exceptionally large quantities of a protein which transports glucose across the cell membrane. The carrier, GLUT1, provides the cells with high levels of glucose they need to survive. GLUT1 also carries the oxidized form of vitamin C, dehydroascorbic acid (DHA) in the cell, bad news for cancer cells, because Yun found that DHA may deplete the supply of a cell of a product chemical that sops free radicals. Because free radicals can harm a variety of ways cell, the conclusion suggested "vulnerability" if the cells were flooded with DHA, says Lewis Cantley at Weill Cornell Medicine in New York City, where Yun is now a postdoc.
[1945018laboratoireetcollaborateurs] Cantley found that high doses of vitamin C actually kill colon cancer cells cultured with BRAF or KRAS mutations by increasing levels of free radicals, which in turn inactivates an enzyme needed to metabolize glucose, depriving the energy cells. Then they gave daily injections of high doses - equivalent to a person eating 300 orange - to modified mice to develop KRAS focused on tumors colon. Mice developed fewer and smaller tumors colon compared to control mice.Cantley hopes to soon start clinical trials that select patients with cancer based on KRAS or BRAF mutations and possibly GLUT1 state. New research from his group "indicates you should get the drug and who should not," he said. Bert Vogelstein cancer geneticist at the University Johns Hopkins, in whose laboratory Yun GLUT1 noticed the connection, is excited about the therapy of vitamin C, not only as a possible treatment for KRAS -mutated colon tumors, which account for about 40% of all colon cancers, but also for pancreatic cancer, a usually fatal cancer caused by KRAS . "No KRAS -targeted therapeutic emerged despite decades of effort and hundreds of millions of dollars [spent] industry and academia," says Vogelstein.
D others warn that the effects observed in mice may not hold up in humans. But because the high dose vitamin C is already known to be safe, says the researcher Vuk Stambolic cancer of the University of Toronto, Canada, oncologists "can quickly move forward in the clinic."
a disadvantage is that patients have to come to a clinic for infusions of vitamin C, ideally every day for months because vitamin C seems to take this time to kill cancer cells, Levine notes But Cantley said, it may be possible to make an oral formulation that reaches high levels in the blood -.. can be a way to get companies interested in sponsoring testing
0 Komentar