RECONSTRUCTED HUMAN SKIN MODEL TO STUDY MELANOMA AT DIFFERENT STAGES OF PROGRESSION.

The incidence of cutaneous melanoma (CM) has dramatically increased in the last few decades.  The changes leading from treatable radial growth phase (RGP) melanoma, to high risk vertical growth phase (VGP), and finally to the metastatic melanoma (MM) phenotype are not well understood.  Development of specific RGP, VGP, and MM tissue models along with their specific microenvironments and cell-matrix and cell-to-cell communication are crucial for understanding disease progression and for the development of CM therapies.  A serum-free (SF) culture system, in which the precise effects of growth factors and chemo-therapeutic compounds can be tested without interference from the many undetermined components in serum, is presented.  The culture system is based on the highly differentiated full thickness skin model system, EpiDermTM Full Thickness (EFT-300), which exhibits a fully developed basement membrane zone.  Single cell suspensions of normal human epidermal keratinocytes and A375 or SK-Mel-28 melanoma cells were seeded on fibroblast-containing collagen gels and induced to differentiate in SF medium.  Initially, cultures adopted an RGP phenotype in which small A375 melanoma nodes in the epidermis were detected as early as day 4.  Between day 4 and 11, these nodes progressively grew at the dermal/epidermal junction, and subsequently adopted VGP (day 18) and MM phenotypes (day 25).  The progression of the less aggressive SK-Mel-28 nodes lagged behind that of the A375 nodes.  Expression of the adhesion molecule, N-cadherin, by melanoma cells in the reconstructed skin model paralleled in vivo expression in stage-specific melanoma.  The development of three dimensional, serum-free tissue culture models, containing melanoma cells at different stages of malignancy, will provide researchers with valuable tools to study, understand, and develop preventative and therapeutic treatments for this serious malignancy.

A375, Cutaneous melanoma, EpidermFT, Histology ,  Human skin model, Immunohistochemistry, Melanoma, Metastatic melanoma (MM), N-cadherin, Normal human epidermal keratinocytes (NHEK), Radial growth phase (GGP) melanoma, SK-MEL-28, Transmission electron microscopy (TEM), Vertical growth phase (VGP) melanoma, Depth of Invasion, S-100