Skin equivalent: an attractive model to evaluate early melanoma metastasis

The growth patterns and morphological phenotype of four human melanoma cell lines with different metastatic potentials were investigated in submerged and in air-exposed (skin equivalent) keratinocyte-melanoma cell cc-cultures . In contrast to the submerged co-cultures, all four cell lines formed shar ply demarcated tumour cell nests within the epidermal compartment of the sk in equivalent model, with the morphology highly mimicking the in vivo situa tion. Differences among the melanoma cell lines tested were observed with r espect to the number of clusters formed and the ability to exhibit invasive growth, Only the two metastatic cell lines were able to invade the dermal compartment. Screening of cellular adhesion molecules revealed that the exp ression patterns in different cell lines were heterogeneous and remained un changed during the whole culture period, irrespective of whether the melano ma cells were located in the epidermal or dermal compartment. A correlation was found between expression of a lower number of different cellular adhes ion molecules and the ability to acquire invasive growth capability. Our re sults indicate that melanoma cells exhibit a heterogeneous growth behaviour when co-cultured with human keratinocytes, end the air exposed skin equiva lent model was shown to be suitable for studying differences in growth patt erns and potential invasive behaviour. (C) 2000 Lippincott Williams & Wilki ns.