Stem cell properties in cell cultures from different stage of melanoma progression

Cutaneous Melanoma is an extremely heterogeneous human cancer. The most aggressive melanoma may contain deregulated cells with undifferentiated/stem cell-like phenotype. A critical mechanism by which melanoma cells enhance their invasive capacity is the dissolution of the intercellular adhesions and the acquisition of mesenchymal features as a part of an epithelial-to-mesenchimal transition (EMT). The aim of this study was to clarify the role of stem cell-like population in human melanomas through the in vitro analysis of melanocytic cell cultures, obtained from distinct histotypes of primary and metastatic malignant melanoma. Patients with advanced melanoma larger than 2cm diameter and/or wider than 300mm2 surface were enrolled. The melanoma cells were isolated from skin biopsies of lentigo melanoma (LM), superficial spreading (SS), nodular melanoma (NM) and metastatic melanoma (MM) and maintained in different media in order to evaluate the colony-forming unit assay, alkaline phosphatase and toluidine blue stain and the cell ability to differentiate into osteogenic and adipogenic lineages. Immunohistochemistry and flow cytometry analysis were performed in order to evaluate antigenic markers CD90, CD73, CD105, CD146, CD20, CD166 and nestin. This study confirms that melanoma can include an heterogeneous cell population with both abilities to self-renew and to give rise to differentiated progeny. Melanoma cells displayed the intra-tumoral heterogeneity and dynamic antigen phenotypes. Histologically, the transitions from normal skin to DN to LM to NM to MM was associated with a gradual increase in the expression of CD146, CD20, CD133, Nestin and CD73 by melanoma cells. These molecular evidences could be a milestone for the development of novel biomolecular targeted-therapy approaches.