12 octobre 2014

Le cancer a-t-il évolué pour nous protéger?

C'est la théorie qui est mise de l'avant par Paul Davies:

Davies teamed up with Charley Lineweaver, an astrobiologist at The Australian National University in Canberra, and Mark Vincent, an oncologist at the London Health Sciences Center in Ontario. Together they have come up with an “atavistic” model positing cancer is the reexpression of an ancient “preprogrammed” trait that has been lying dormant. In a new paper, which appeared in BioEssays in September, they argue that because cancer appears in many animals and plants, as well as humans, then it must have evolved hundreds of millions of years ago when we shared a common single-celled ancestor. At that time, cells benefited from immortality, or the ability to proliferate unchecked, as cancer does. When complex multicellular organisms developed, however, “immortality was outsourced to the eggs and sperm,” Davies says, and somatic cells (those not involved in reproduction) no longer needed this function.

The team’s hypothesis is that when faced with an environmental threat to the health of a cell—radiation, say, or a lifestyle factor—cells can revert to a “preprogrammed safe mode.” In so doing, the cells jettison higher functionality and switch their dormant ability to proliferate back on in a misguided attempt to survive. “Cancer is a fail-safe,” Davies remarks. “Once the subroutine is triggered, it implements its program ruthlessly.”

Speaking at a medical engineering conference held at Imperial College London, on September 11, Davies outlined a set of therapies for cancer based on this atavistic model. Rather than simply attacking cancer’s ability to reproduce, or “cancer’s strength,” as Davies terms it, the model exposes “cancer’s Achilles’ heel.” For instance, if the theory is correct, then cancer evolved at a time when Earth’s environment was more acidic and contained less oxygen. So the team predicts that treating patients with high levels of oxygen and reducing sugar in their diet, to lower acidity, will strain the cancer and cause tumors to shrink.



2 commentaires:

PJ a dit…

Le raisonnement ne semble pas entièrement farfelu, mais la dernière ligne semble tout droit sortie des médecines alternatives, faisant croire que l'acidité du corps cause le cancer, et qu'il faut réduire cette acidité pour prévenir ou guérir le cancer. Sans surprise, tout cela n'a pas encore passé l'évaluation par les pairs, tel qu'indiqué dans le lien sur Richarddawkins.net.

Prof Solitaire a dit…

Effectivement, tu fais bien de le souligner... mais l'idée est tout de même très intéressante...