Researchers have shown how cancer cells reprogram themselves to produce lactic acid and to tolerate the acidic environment that exists around tumours. The breakthrough is the result of more than 13 years of work. The next step in research could redirect the treatment of cancer, reports Phys.org. The explanation for the new findings lies in something you have likely experienced: when you run or cycle fast, you may suddenly lose strength in your legs, and they feel heavy and powerless. Lactic acid buildup causes your muscles to become flooded with waste products. Lactic acid is produced by the body when it works harder and needs more energy than the lungs can supply with oxygen. After training, you gasp for air, and your body is able to remove the lactic acid with the help of oxygen. Oxygen is important when the body needs to convert sugar into energy. Muscle cells in particular produce lactic acid, but cancer cells that form in healthy cells in the body also begin to produce lactic acid. The cancer cells don’t typically have this ability until cancer enters precisely the same cells. Just like muscle cells, cancer cells have to be able to function even when not much oxygen is available. The area around tumours is acidic and contains little oxygen. In order to survive in such an environment, the cells need to be able to grow when little oxygen is available – that is, in conditions quite similar to when a muscle cell produces lactic acid. For more than 100 years, we have known that cancer cells prefer to break down sugar into lactic acid, but how they reprogram themselves has not been thoroughly studied. Researchers Pegah Abdollahi, Esten Vandsemb and colleagues recently published two articles showing that the PRL-3 protein reprograms the cells to prefer lactic acid both when a little or a lot of oxygen is available. Now the goal is to turn off the molecule that allows the cells to reprogram themselves.