Proto-oncogenes are genes that organisms rely on for normal growth and development but, when mutated or dysregulated, can cause cells to grow uncontrollably, resulting in cancer and metastasis. In some cases, a single DNA mutation is sufficient for cancer to develop. Why then, do so many proto-oncogene promoters contain strings of guanine residues, which are extremely vulnerable to DNA damage from factors such as oxidative stress and hyperinflammation, to control transcription levels? From an evolutionary viewpoint, this is a contradiction: DNA sequences that are the most vulnerable to damage and mutation are key to regulating one of the cell’s most dangerous classes of genes. This seems to be a recipe for genomic instability and disease. Fortunately, evolution has provided a very clever solution to this potential problem.
It seems fitting that, as I write this blog entry, I am soaking up a bit of sun on a dock on a small northern Wisconsin lake. I’ve deployed many of my normal defenses against the sun’s harmful rays, including a big floppy hat and plenty of sunscreen. Recently, I learned that, as a redhead, I have another defense—a cellular defense—against the dangerous results of ultraviolet light exposure: the very same genetic mutation in the MC1R gene that probably makes my hair red in the first place.