[Role of chemokines in melanoma progression]

Metastasis is the main cause of death from melanoma. Chemokines are low molecular weight chemotactic cytokines that facilitate cellular migration. Thus, cells that express receptors for a given chemokine are attracted to the site of its production. As certain chemokines are found in abundance in organs that are common targets of metastasis and receptors for these chemokines are expressed by tumor cells, it was hypothesized that chemokine gradients might selectively facilitate metastasis to these organs. A later finding that these chemokines were produced by tumor cells, with evidence of autocrine effects, obliged the modification of that hypothesis. Many chemokines are also known to have opposing effects according to the type of cell they are acting on (tumor, inflammatory/immune, or endothelial cells), their functional status, or interactions with other molecules. The expression of chemokines and their receptors by melanoma cells enhances tumor progression by altering their microenvironment, stimulating angiogenesis, and inhibiting the immune response.