Researchers have found that a protein, called p15, may be used as a biomarker to distinguish melanoma from nevi (non-cancerous moles in the skin). Loss of this protein, which inhibits nevus cell proliferation, is a sign that the nevi is turning into a melanoma.
Most melanomas are caused by mutations that promote a quick and unregulated production of cells (cancer). Although nevi with the same mutations do not behave the same way, they still can give rise to melanoma when certain changes in gene expression occur. In fact, dermatologists estimate that 30-40 percent of melanomas cases originate in nevi.
However, doctors still find it hard to distinguish melanoma from nevi when examining a patient biopsy, especially in cases that leave them in doubt.
Now a research team led by John Seykora, MD, PhD, from the Perelman School of Medicine at the University of Pennsylvania, has discovered that the p15 protein may help doctors make this distinction.
The team analyzed the expression levels of the gene that codes for p15, as well as its proteins levels, in 14 tissue samples of melanoma and nevi. They found that high levels of p15 corresponded to samples of benign nevi, whereas low levels were found in melanomas.
Researchers believe this test can be used to check whether a nevus is turning into a melanoma. The p15 proteins work by inhibiting cell proliferation in nevi. So, when p15 levels drop, cells start proliferating in an uncontrolled manner, leading to melanoma.
“We showed that p15 expression is a robust biomarker for distinguishing nevus from melanoma,” Seykora said in a press release. “Making this distinction has been a long-standing issue for dermatologists. We hope that this new finding will help doctors determine if a nevus has transformed to melanoma.”
“This could help doctors and patients in difficult cases,” he added. “Current research will hopefully move this into the realm of standard practice in about one to two years.”
Researchers also analyzed levels of a similar protein, p16, that was associated with development of melanoma. However, p15 seems to be the main regulator of cell division in nevus cells.