Melanin, the pigment that determines hair color and skin tone, is influenced by the melanocortin-1 (MC1R) gene receptor. A certain mutation in MC1R results in the familiar physical characteristics of redheads.
Now HMS researchers have discovered that MC1R-RHC, the mutation responsible for the red-hair phenotype, also triggers an important cancer-promoting pathway. The findings, reported in the August 22 issue of Molecular Cell, help explain the molecular mechanisms that underlie redheads’ well-known risk of developing melanoma and may provide new insights for preventing and treating this dangerous type of skin cancer.
Melanoma is the least common but the most lethal of skin cancers. Accounting for 75 percent of all skin-cancer deaths, it originates in pigment-producing skin cells called melanocytes. Two types of UV radiation—UVA and UVB—can mutate DNA in these skin cells and lead to melanoma.
“In this current study, we have demonstrated that the mutation MC1R-RHC promotes the PI3K/Akt signaling pathway when a red-haired individual is exposed to UV radiation,” says co-senior author Wenyi Wei, an HMS associate professor of pathology at Beth Israel Deaconess Medical Center. PI3K/Akt is a well-known cancer-promoting pathway implicated in breast, ovarian, and lung cancers.
The team also found that in the MC1R-RHC pigment cells, elevated PI3K/Akt activity boosted cell proliferation and synchronized with another well-known cancer mutation in the BRAF gene to accelerate cancer development.