Direct correlation between MUC18 expression and metastatic potential of human melanoma cells

The expression of the glycoprotein MUC18 in melanoma biopsies has previously been shown to increase with increasing tumour thickness, and thus to correlate with the probability of metastasis development. We have examined the expression of this molecule by nine human melanoma cell lines with known metastatic ability (both spontaneous and experimental) in nude mice. Examination of the expression of both the MUC18 mRNA and of the glycoprotein on the cell surface revealed a statistically significant correlation (P = 0.040) between its expression and the ability to form metastases in vivo. Although MUC18 shows sequence similarity to neural cell adhesion molecules, no correlation was observed between the site of origin of the metastatic lesions (brain, lymph node) and MUC18 expression.