Darker-skinned people may have lower risks of melanomas, a type of skin cancer, according to a new study published in the European Journal of Cancer.
The study looked at the prevalence of melanocytic lesions, which are small, irregularly shaped tumors that are the most common cause of skin cancers in people of African, Asian and Middle Eastern descent.
“There are a lot of factors that affect the development of melanosomes, and some of them are genetic,” said Dr. Nafisa Akbari, an expert in the pathogenesis of melanoblastoma at the Karolinska Institute in Stockholm, Sweden.
“The fact that darker skin tends to be associated with lower risk of developing melanomas is a clear indication that these factors are part of a common underlying genetic pathway.”
Akbary said that while there is currently no cure for melanomas — or, as they are sometimes called, “skin cancer,” they’re not curable, as other skin cancers are — the researchers hope to find ways to prevent or treat them, even if they’re rare.
“We know that melanoma is very dangerous, so we need to be very careful in terms of how we treat it, and how we react to it,” Akbarian said.
“In our study, we found that the dark-skinned group was less likely to develop melanoma than the lighter-skinned, but the dark skin group also had more of the mutations that are associated with melanoma, which could have an important impact on the development.”
Akbashi, who is also a member of the Swedish Cancer Society, said that the results also raise the possibility that darker-skinned individuals might be more susceptible to the spread of melano-associated tumors.
“I think it’s also a possible explanation for why dark skin is more susceptible,” Akbashian said.
For the study, Akbashis team used a genetic marker called rs657615 that was used to track the evolution of melanoblasts and melanoma in mice.
The researchers found that darker people had higher levels of the gene that controls the development and growth of melanocytes, the body’s immune system cells that attack and destroy cancerous cells.
The scientists also found that dark skin was more likely to have mutations in the gene called melanotransferase (MTF), which is involved in producing melanocytes.
MTF is responsible for making melanocytes more resistant to the attack of the body and helping them to become more resistant against melanoma.
“These mutations in MTF have been found in melanoma patients, and it seems that these mutations are responsible for dark skin,” Akbani said.
Although melanosomal tumors can cause severe disease and may even require surgical treatment, Akbayi said that darker colored people are more likely than their lighter counterparts to develop the disease and be unable to get treated.
“People who are dark-complexioned have higher rates of skin diseases, and so the melanoma risk may be higher,” she said.
A melanoma-free future in the U.S. The research team also found the darkness of skin affected the expression of genes involved in cell survival and migration in melanocytes in mice, which can have long-term consequences for the disease.
In a mouse model, darker-colored mice that had been treated with MTF mutations showed fewer melanocytes than mice that were treated with mutations that did not affect the gene.
“When you add the genes that are affected by MTF and melanocytes to the MTF gene, it leads to increased expression of a melanocyte-specific gene called mTOR,” Akbari said, which controls cell proliferation.
“This causes melanocytes not to be able to form the new melanocytes that they need to make new melanomas.
The expression of this gene increases in dark-colored people, and that can be an important factor for the development or spread of these tumors.”
The study also showed that melanosome growth and metastasis in mice was reduced in mice that received a treatment that changed the expression level of the MTR gene, which was linked to melanocyte growth and tumor growth.
Akbashiani said that melanomas have been linked to a host of other genes, including genes that regulate the immune system and brain function, that could be affected by dark skin.
The genetic changes that affect melanocyte survival and growth could also contribute to melanoma development in the human population, she said, and this may explain why darker-looking people are at a higher risk for developing the disease than lighter-colored ones.
“Our data is definitely showing that dark-skinned people are a risk group, and if this association is replicated in the general population, we should be seeing this association in the population,” Akberi said