Antioxidants are accomplices of metastases
They do not slow down, but accelerate the spread of the tumor through the body
Polina Loseva, "The Attic"
Swedish scientists have thoroughly understood the relationship of cancer with antioxidants. It turned out that a small level of oxidative stress prevents cells from moving. And antioxidants, reducing stress, allow them to migrate and absorb more glucose from the environment, injuring neighboring cells.
The life of a tumor cell is often accompanied by the accumulation of reactive oxygen species, because they are formed during cellular respiration, and the tumor breathes, that is, breaks down food, very actively. Previously, it was believed that reactive oxygen species help cancer cells grow and multiply. Therefore, people – both sick and healthy – took antioxidants, including vitamin E, to prevent the appearance or spread of a tumor. Despite the fact that many clinical studies have not confirmed the effectiveness of such prevention, faith in the medicinal properties of antioxidants remains.
A group of scientists from Sweden decided to finally understand exactly how reactive oxygen species and antioxidants affect the life of a tumor cell. They studied model mice suffering from lung cancer, the most deadly form of cancer among humans. The researchers fed the mice with vitamin E and another antioxidant for three weeks and found that this did not affect the growth of the primary tumor in any way, but significantly increased the number of metastases.
Figures from the article by Wiel et al. BACH1 Stabilization by Antioxidants Stimulates Lung Cancer Metastasis (Cell, 2019) – VM.
After checking which genes were triggered in cancer cells, scientists found that many of them reacted to the VASN1 protein, and that, in turn, begins its work in conditions of low oxidative stress, that is, small concentrations of reactive oxygen species. In total, the process looks like this: we feed the cell with antioxidants, the level of oxidative stress decreases, VASN1 becomes active and blocks the production of its own antioxidants by the cell.
Then the researchers proved that the work of VASN1 affects the ability of cancer cells to metastasize. If the VASN1 gene is turned off, then the cell cannot migrate. If, on the contrary, its expression is additionally stimulated, then the migration of cancer cells through the body begins even in the absence of antioxidants.
Finally, scientists have identified the genes whose work is triggered by VASN1 itself. Among them were the genes responsible for aerobic glycolysis – the process of oxygen-free glucose breakdown, which tumor cells use even in the presence of oxygen. Moreover, the launch of glycolysis was enough for the cancer cells to start moving.
It is still unknown exactly how oxygen-free glucose breakdown helps tumors to metastasize. Perhaps it's lactic acid, which is formed during glycolysis, destroys the intercellular substance and poisons neighboring cells. Or maybe this pathway just allows the tumor cell to quickly get enough energy to move.
Anyway, Swedish researchers, in their own words, have finally found the "missing piece of the puzzle in the biology of cancer cells" – the protein VASN1, which links oxidative stress with metabolism and movement. The authors hope that new antitumor drugs that block either the work of VASN1 or glycolysis caused by it will prove to be a good remedy against aggressive lung cancer – at least more effective than vitamin E.
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