Injections of vitamin C could be a way to help fight blood cancer. Experiments in mice suggest that the nutrient helps tell out-of-control cells to stop dividing and die.
Some blood cancers, including acute and chronic leukaemia, often involve mutations affecting a gene called TET2. This gene usually helps ensure that a type of stem cell matures properly to make white blood cells, and then eventually dies. But when TET2 mutates, these cells can start dividing uncontrollably, leading to cancer. Mutations in TET2 are involved in around 42,500 cancers in the US a year.
Luisa Cimmino and Benjamin Neel at the New York University School of Medicine and their colleagues have genetically engineered mice to have variable TET2 function. They found that a 50 per cent reduction in TET2 activity can be enough to induce cancer, but that TET2 activity needs to remain low if the disease is to continue developing. “If we genetically restore TET2, it blocks unhealthy replication and kills the cells,” says Cimmino.
Next, the team turned to vitamin C, because it is known to have an effect in embryonic stem cells, where it can activate TET2 and help keep cell replication in check.
Oranges aren’t enough
The team injected mice with low TET2 activity with very high doses of vitamin C every day for 24 weeks and found that it slowed the progression of leukaemia. By the end of this period, a control group that got no injections had three times as many white blood cells – a sign of pre-leukaemia.
When the team exposed human leukaemia cells in a dish to a cancer drug, they found they got better results when they added vitamin C.
Neel hopes that high doses of vitamin C will eventually be incorporated into cancer therapies. People who have acute myeloid leukemia are often of advanced age, and may die from chemotherapy. Vitamin C in combination with cancer drugs may provide an alternative approach.
But taking large amounts of vitamin C is unlikely to prevent you from getting cancer, says Neel. The mice were given 100 milligrams of vitamin C in each injection, the equivalent of about two oranges. But the average person weighs about 3000 times as much as a mouse. Because the body stops taking in the vitamin after around 500 milligrams, any therapies would need to supply vitamin C intravenously. “You can’t get the levels of it necessary to achieve the effects in this study by eating oranges,” he says.
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