New study contradicts previous data on DNA mutations in melanoma

Researchers globally are spending significant amounts of time and money investigating cancer of various types and their causes. A recent study has upended long held beliefs about the mechanisms underlying melanoma. The study found that mutations giving rise to melanoma result from chemical conversion in DNA fueled by sunlight.

Previously, it was believed that DNA copying error was behind melanoma. With new evidence contradicting that previously held belief, investigators believe they are on a path forward for investigating the regions of other types of cancer. Study author Gerd Pfeifer says that cancers result from DNA mutations allowing defective cells to survive and invade other tissues. However, the source of the mutations is unclear in most cases complicating therapy and prevention.

However, the study has shown that in melanoma damage, sunlight primes DNA by creating pre-mutations that give way to full mutations during DNA replication. Melanoma is a serious type of skin cancer beginning in pigment-producing skin cells. It's less common than other types of skin cancer but is more likely to spread and invade other tissues.

Past large-scale sequencing studies discovered that melanoma has more DNA mutations than any other type of cancer. Melanoma is directly linked to sun exposure, specifically to UVB radiation. Most cancers are thought to begin when DNA damage directly causes a mutation that is copied in the subsequent generations of cells during normal replication.

However, the study has found that in melanoma, a different mechanism produces the disease-causing mutations. That mechanism is the introduction of a chemical base not typically found in DNA, making it prone to mutation. These mutations may not cause the disease right away; they can lay dormant for many years. Mutations are also able to accumulate as time goes on and the exposure to sunlight increases resulting in difficult to treat cancer, evading current therapeutic options. The new technique developed in the study will be used to investigate other types of DNA damage and other types of cancer in the future.