According to a study published in the journal Cell Systems, some cancer cells can "cheat" by evading oxygen-deficit-induced restrictions, thereby allowing the cancer cells to keep growing. The collaborative study was conducted by researchers from UConn Health, Yale, and Johns Hopkins.

In cancers, tumours grow and become large; they run out of oxygen, and new blood vessels are created. This results in a scarcity of oxygen, called hypoxia. Under hypoxia, cells are supposed to slow down their growth, but of course, cancers continue to grow larger.

However, in their study, they found that a small number of cells were "cheating," or rewiring their signalling, to allow them to divide and grow. The researchers explained that under hypoxia, cells stabilise a protein called HIF-1, which is a master regulator of oxygen response in the cells. But when oxygen levels go down, HIF-1 signalling becomes high and takes the cells to a non-functioning state. It also directs the cell division machinery to stop working, jump-starts anaerobic respiration, and commands cells to secrete proteins to contract blood vessels.

However, the researchers noted that a small percentage of cells did not stabilise HIF-1. The protein levels are oscillated by this small percentage of cells. As a result, the cells could escape the HIF-1-imposed pause. In this way, these oscillating cells cheat and continue to divide despite very low oxygen levels. Additionally, they also found that when HIF-1 was high because of hypoxia, cells produced energy without oxygen using lactate, the same molecule that gives us cramps during exercise if the muscles are not well-oxygenated. 

(Source: https://theprint.in/health/researchers-unravel-population-of-cheating-cells-in-cancers/1269847/ )