A new study published by researchers at the University of Salford in the United Kingdom suggests that cancer stem cells, which fuel the growth of fatal tumors, can be knocked out by a combination of antibiotics and vitamin C.
The research, which was published in the journal, Oncotarget, found that Doxycycline (an antibiotic), followed by doses of ascorbic acid (vitamin C), was surprisingly effective in killing cancer stem cells under laboratory conditions. Researchers suggest that their method offers a new explanation for how to prevent cancer cells from becoming treatment-resistant and how combination therapies can be developed to overcome drug resistance.
Starving Cancer Cells
Lead study author, Professor Michael Lisanti, said, “We now know that a proportion of cancer cells escape chemotherapy and develop drug resistance; we established this new strategy to find out how they do it.
“We suspected the answer lay in the fact that certain cancer cells – which we call metabolically flexible – are able to switch their fuel source. Thus, when the drug treatment reduces the availability of a particular nutrient, the flexible cancer cells can feed themselves with an alternative energy source.” This new combination approach prevents cancer cells from changing their diet (metabolically inflexible), and in effect starves them, by preventing them from using any other available types of bio-fuels.
The team at the University of Salford’s Biomedical Research Centre, gradually increased the dose of Doxycycline over a three-month period, to induce metabolic inflexibility. The result was to leave the cancer cells alive, but severely attenuated and depleted, so that they would be much more susceptible to starvation.
Scientists first inhibited the tumor cell mitochondria, by restricting the cancer cells only to glucose as a fuel source; then, they took away their glucose, effectively starving the cancer cells to death.
“In this scenario, vitamin C behaves as an inhibitor of glycolysis, which fuels energy production in mitochondria, the “powerhouse” of the cell, explained co-author Dr. Federica Sotgia. The Salford team recently found vitamin C to be up to ten times more effective at stopping cancer cell growth than pharmaceuticals such as 2-DG, but they say that when vitamin C is combined with an antibiotic, it is up to ten times more effective, making it nearly 100 times more effective than 2-DG.
As Doxycycline and vitamin C are both relatively non-toxic, this could dramatically reduce the possible side effects of anti-cancer therapy. Professor Lisanti added: “This is further evidence that Vitamin C and other non-toxic compounds may have a role to play in the fight against cancer.