Chimps and gorillas’ genomes could help better understand human tumours

Mutations in tumor cells and in normal cells in humans are concentrated in different areas of the genome. A new IBE study explains why this is so, and how great apes can help us understand.

Txema's drawing.

Chimpanzees and gorillas accumulate mutations in the same regions as human tumors. Drawing by Txema Heredia-Genestar.

Thanks to the data from the project PanCancer, a research team from the Institute for Evolutionary Biology (IBE: CSIC-UPF) has analyzed the regions of the genome that accumulate more mutations, comparing the genome of humans, chimpanzees and gorillas, as well as that of human cancer cells. Surprisingly, researchers have confirmed that the distribution of mutations in human tumours is more similar to that of healthy chimpanzees and gorillas than that of humans.

Distribuión de las mutaciones en los genomas de humanos, chimpancés y muestras tumorales. Crédito: Txema Heredia-Genestar.
Distribution of mutations in the genome of humans, chimpanzees, and tumor samples. Credit: Txema Heredia-Genestar

The reason?

It seems that the complex evolutionary history of humans — with several ‘bottlenecks’ where the human population has dramatically decreased — has “erased” these signs of mutations accumulation that we should have. In other words, in these phases of high human mortality, when a significant part of the population disappears, the general variability decreases. And this affects above all the regions where there was more variability (that is, more mutations). This has not happened in chimpanzees or gorillas, whose populations have not suffered from these bottlenecks.

And what does this imply?

These results, published in open access, would explain why mutations in tumor cells and mutations that normally occur in healthy humans are located in very different areas of the genome. It would not be, as previously believed, because of a special behavior of cancer cells, but due human evolutionary history. Thus, according to the first author of the study (led by Arcadi Navarro), Txema Heredia, to understand how mutations accumulate in human cells and better understand tumors, it would be more useful to look at how they accumulate in great apes rather than in humans.

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