One of the reasons cancer cells are so robust against the body’s natural defenses is that they are in fact human cells, and as such they have the innate machinery not only to trick the body’s defense and maintenance systems, but even to hijack them. Therefore, discovering cancer cells’ full “bag of tricks” is key for fighting cancer.
Eduardo Moreno, principal investigator at the Champalimaud Centre for the Unknown, in Lisbon, Portugal, has taken an important step in this direction by discovering one new such “trick”: a cell-competition mechanism which he has named “fitness fingerprints”.
“We first identified this ‘fitness fingerprints’ mechanism in the model animal Drosophila melanogaster (the common fruit fly), in 2010, and now, in this new study published in the journal Nature, we were able to prove that it also exists in humans and that blocking it halts the growth of human cancer cells“, says Moreno.
Moreno and his team discovered that neighbouring cells in the body are constantly evaluating each other’s fitness level by using special markers that each cell exhibits on its surface. “We found that there are actually two types of markers: ‘Win’ fitness fingerprints, which signify that the cell is young and healthy and ‘Lose’ fitness fingerprints, which signify that the cell is old or damaged”, Moreno explains. “If a cell is less fit than its neighbours, meaning that it either has less Win or more Lose than them, then they eliminate it, thereby ensuring the health and integrity of the tissue as a whole.”
According to Moreno, his team found that this process is important for proper development, tissue regeneration after injury and to prevent premature aging, but that it can also be hijacked for tumour growth.
“Cancer cells use these fitness fingerprints to disguise themselves as super-fit cells that have relatively many more Win fitness fingerprints on their surface [than their healthy neighbours]. This makes the normal cells that surround cancer cells appear less healthy by comparison. In this way, cancer cells trick their healthy neighbours and bring about their death, consequently destroying the tissue and making room for tumour expansion.”
When fitness fingerprints were identified by Moreno’s group in the fruit fly, it was not known whether this cell competition mechanism would be conserved in humans, as it is possible that different animals use different strategies to detect unwanted cells. In fact, Moreno suspected that this mechanism might not be conserved.