Melanoma-Initiating Cells and Therapy

Cancer-initiating cells, including melanoma-initiating cells (MICs), are theoretically capable of self-renewal, differentiation, and tumor maintenance. Specific targeting of MICs, therefore, represents a new paradigm for antitumor therapy, although specific markers of MICs have been difficult to identify and validate. In preclinical animal studies, investigators identified a subpopulation of MICs defined by expression of the chemoresistance mediator ABCB5.

Expression of this marker correlated with disease progression. The less-differentiated phenotype, ABCB5+ cells, were found in nonmelanized, undifferentiated regions, whereas ABCB5– cells predominated in melanized, more-differentiated tumor areas. If ABCB5 does in fact designate MICs, ABCB5…