Heterogeneity of Melanoma with Stem Cell Properties.

Metastatic melanoma continues to present a significant challenge-with a cure rate of less than 10% and a median survival of 6-9 months. Despite noteworthy advances in the field, the heterogeneity of melanoma tumors, comprised of cell subpopulations expressing a cancer stem cell (CSC) phenotype concomitant with drug resistance markers presents a formidable challenge in the design of current therapies. Particularly vexing is the ability of distinct subpopulations of melanoma cells to resist standard-of-care treatments, resulting in relapse and progression to metastasis. Recent studies have provided new information and insights into the expression and function of CSC markers associated with the aggressive melanoma phenotype, such as the embryonic morphogen Nodal and CD133, together with a drug resistance marker ABCA1. This chapter highlights major findings that demonstrate the promise of targeting Nodal as a viable option to pursue in combination with standard-of-care therapy. In recognizing that aggressive melanoma tumors utilize multiple mechanisms to survive, we must consider a more strategic approach to effectively target heterogeneity, tumor cell plasticity, and functional adaptation and resistance to current therapies-to eliminate relapse, disease progression, and metastasis.