Scientists have developed an unusual new way to fight cancer stem cells (CSCs) - combining antibiotics with vitamin C. Not only could the compound help treat tumours, it could also reduce the chance of the cancer returning.
Therapies mixing doxycycline and vitamin C (ascorbic acid) were up to 100 times more effective at killing off CSCs in the lab when compared with another anti-cancer agent being tested, 2-Deoxy-D-glucose.
The new study actually builds on previous work by the same team from the University of Salford in the UK, which looked at how vitamin C could be used to kill off CSCs by stopping cell mitochondria (the cell's main engine rooms) from producing energy.
First the antibiotic stops the cancerous cells from switching between different types of energy source to stay alive, forcing them to rely solely on glucose. In technical terms, it makes the cells metabolically inflexible, and it's enough to kill some cancer cells on its own.
It doesn't take all of them though, and scientists think this is why certain tumours become drug-resistant - they switch to an alternative source of nutrients to keep growing in the body.
With that restriction in place, the vitamin C then comes in and acts as a "second punch", removing the source of that glucose and effectively starving the CSCs to death.
"In this scenario, vitamin C behaves as an inhibitor of glycolysis, which fuels energy production in mitochondria, the 'powerhouse' of the cell," says one of the team, Federica Sotgia.
As both doxycycline and vitamin C are non-toxic, the hope is that treatments can be developed with minimal side effects.
Though it's important to note this research only uses laboratory tests, and we've yet to see it work in animals or humans, so definitely don't attempt to recreate this at home.
The study also focusses exclusively on breast cancer cells, so we don't yet know how it would work with other types of the disease.
Still, this is promising stuff, especially as it involves cancer stem cells - these types of cells are thought to be the main agents behind tumours growing and returning, and could also play a role in blocking traditional drug treatments.
Our regular stem cells can turn into any other cell type in the body, helping to sustain our natural growth and biological functions, and the current hypothesis is that maybe CSCs do the same for tumours. If we can knock out those CSCs, we can strike at the heart of cancer.
The next step in finding out is going to be trials on cancer cells in animals and humans.
"This is further evidence that vitamin C and other non-toxic compounds may have a role to play in the fight against cancer," explains one of the team, Michael Lisanti.
"Our results indicate it is a promising agent for clinical trials, and as an add-on to more conventional therapies, to prevent tumour recurrence, further disease progression and metastasis."
The findings have been published in Oncotarget.