A team of Israeli and German scientists has discovered how melanoma metastasizes, and how to stop its spread, they say.

“Our study is an important step on the road to a full remedy for the deadliest skin cancer,” stated the leader of the research team, Dr. Carmit Levy, of Tel Aviv University. “We hope that our findings will help turn melanoma into a nonthreatening, easily curable disease.”

Melanoma is considered the most aggressive of skin cancers. It starts in the melanocytes, skin cells that produce pigment. One corollary of this is that most melanomas take on the appearance of a dark-colored mole, although they may be the same color as one’s skin, or even white. Once the cancer spreads beyond the upper skin to the vascular system – the blood vessels – it can turn deadly.

“The threat of melanoma is not in the initial tumor that appears on the skin, but rather in its metastasis – cancer cells sent off to colonize in vital organs like the brain, lungs, liver and bones,” says Levy, slightly anthropomorphizing the "motive" of the disease.

Open gallery view A photo from the American Academy of Dermatology that shows a typical presentation of a suspicious mole that eventually was diagnosed as melanoma. Credit: American Academy of Dermatology/AP

It is true that melanoma is rare: Israel's Health Ministry reported that some 1,634 new cases were diagnosed in 2013 (roughly double the number diagnosed in 1980; the cause of the worldwide ramp-up in melanoma is debatable). But ultraviolet exposure is considered a risk factor, hence the urgency to understand the disease better in sun-kissed Israel.

Before spreading to other organs, the melanoma tumor emits vesicles – microscopic bubbles – containing molecules of genetic material, in the form of microRNA, the scientists from Tel Aviv University and the German Cancer Research Center in Heidelberg explained in their article, published Sunday in Nature Cell Biology. These bubble-born genes spur changes in the skin cells, which prepare to receive and transport cancer cells.

If caught very early, the “bad” mole will be excised, possibly with some of the surrounding skin for caution’s sake, and that’s that. If it has begun to metastasize, however, therapy will likely include surgical removal of affected lymph nodes and therapies ranging from chemo to radiation and even, possibly, to newfangled “immunological” treatment that strengthens the natural cancer-fighting systems of the body.

Crucially, the cancer researchers say they also identified not one but two chemicals that can inhibit the process and could be candidates for drug treatment. One of them, SB202190, inhibits the vesicles’ journey from the tumor to the skin. The other, U0126, blocks the skin from undergoing changes to receive the cancer cells, even after the “gene bubbles” have arrived.

The Tel Aviv University group worked with Prof. Jorg Hoheisel and Laureen Sander at the center in Heidelberg, as well as with Dr. Shoshi Greenberger at Sheba Medical Center, Tel Hashomer, and Dr. Ronen Brenner at Wolfson Medical Center in Holon.