Living in extreme climates can have both an advantage and disadvantage when it comes to cancer.
Populations living in extremely cold or high-altitude environments have genes that boost survival but that also predispose individuals to cancer later in life, especially lung, breast, and colorectal cancer, according to researchers.
Analysis of data from the GLOBOCAN-2012 survey of worldwide cancer incidence shows that evolutionary adaptation to environments of extreme or prolonged cold produces genetic variants that interfere with tumor suppression and increase vulnerability to almost all cancers.
“This is the first study that provides evidence that high cancer risk may be a result of evolutionary adaptation in certain environmental conditions,” note Konstantinos Voskarides, PhD, of the University of Cyprus Medical School in Nicosia, and colleagues.
Notably, the findings support a “long-standing hypothesis for cancer” known as antagonistic pleiotropy, the authors say in their report, published onlineDecember 5 in Molecular Biology and Evolution.
In this gene-centered theory of evolution, genetic variants that predispose to a disease may undergo natural selection when they offer a survival advantage. The theory was proposed in 1957 by US evolutionary biologist George C. Williams, PhD, as an explanation for senescence.
“Cell resistance at low temperatures and at high altitude probably increases the probability for malignancy,” the study authors write. “This effect hardly could be filtered out by natural selection since most cancers appear later on in age after most people have their children.”
A separate analysis revealed special selection for tumor suppressor genes. This finding supports results from previous functional studies that show that reduced apoptosis ― or programmed cell death ― is beneficial in extremely cold and high-altitude environments but is caused by variants of tumor protein p53, which is responsible for tumor suppression, the researchers say.
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