Cancer Stem- Like Cells in Melanoma Progression, Resistance and Recurrence: Significance for Melanoma Treatment

Human malignant melanoma is a highly aggressive tumor which demonstrates heterogeneity and a propensity to drug resistance. Despite improved treatment options, patients with advanced malignant melanoma continue have a poor prognosis as measured by progression-free and overall survival. The cancer stem-like cell (CSC) hypothesis suggests that neoplastic clones are maintained by a small fraction of cells with stem cell properties. As has been demonstrated with other tumor types, melanoma progression, resistance to chemo- and radiotherapy, and recurrence can be attributed to a small fraction of cells termed melanoma stem-like cells (MSCs). These MSCs are characterized by a distinct protein patterns and aberrant signaling pathways, which are either in a causal or consequential relationship to tumor progression, drug resistance and recurrence. This review focuses on the mechanistic role of MSCs leading to tumor progression and metastasis, resistance and recurrence. Understanding the molecular mechanisms underlying MSCs migration, invasion, resistance to standard treatments, and recurrence may help to improve current therapeutic modalities and/or pave the way for the development of new therapeutical management strategy for tumor treatment.