Marine bacteria may provide a new weapon against melanoma.
However, melanoma causes the majority of skin cancer deaths, primarily because once it metastasizes, there are limited treatment options.
According to estimates, doctors will diagnose 96,480 new cases of melanoma in the United States this year, and there will be 7,230 related deaths.
Melanoma occurs most often in older adults, but it is also one of the most common cancers in younger people.
Over the last 50 years, melanoma rates have risen at a worryingly rapid pace. Although increased levels of screening account for some of this change, they do not tell the whole story.
As mortality rates are relatively high for melanoma, and the number of cases is increasing, finding a new way of attacking this type of cancer is urgent.
New avenues to explore
Relatively recently, a class of drugs called BRAF inhibitors has shown promise for the treatment of melanoma. However, close to 50 percent of people do not respond to these drugs, and those who do tend to become resistant within months, making the treatment ineffective.
The race is on to uncover a new way to fight melanoma. Recently, researchers from the University of California in San Diego and Universidade Federal de São Paulo and Universidade de São Paulo in Brazil have taken inspiration from an unusual source: marine bacteria. William Fenical, James J. La Clair, and Leticia Costa-Lotufo led the team of researchers, who published their most recent investigation in ACS Medicinal Chemistry Letters.
Their latest work follows on from a paper that they published in 2014. In this previous study, the researchers investigated a chemical called seriniquinone, which they isolated from rare marine bacteria of the genus Serinicoccus.
In the laboratory, seriniquinone selectively destroyed melanoma cells by inducing cell death. It achieved this by targeting a cancer-protective protein called dermcidin. This study was the first to identify a small molecule that could directly attack malignant cells.
Of course, finding a chemical that works against free-floating cancer cells in a test tube is a far cry from creating a drug that can successfully defeat cancer in a living person. As the authors write:
"The translation of [seriniquinone] into a chemotherapeutic agent is complex. It requires significant medicinal chemistry efforts to generate a large number of derivatives to improve its 'drug-like' properties."
Closer to a new drug
The researchers' recent work brings them closer to designing a usable drug. Specifically, they managed to identify the parts of the seriniquinone molecule that furnish it with its anticancer activity.
Next, they altered other parts of the molecule to make it water-soluble and easier to purify. Both of these properties are essential to make seriniquinone a functional drug.
Importantly, the alterations did not affect seriniquinone's anticancer activity. The authors write:
"Overall, these studies suggest that it is feasible to design melanoma-specific seriniquinone derivatives with drug-like properties."
Although this work has brought the team closer to developing a suitable drug, more work is necessary. The authors are committed to continuing along this path and are already working on ways to purify and improve the action of these seriniquinone derivatives.
They hope that, eventually, they can bring a powerful melanoma drug to market. Although there is much work ahead, identifying a new potential way of attacking melanoma is a significant breakthrough.