Melanoma is a frequent and therapy-resistant human disease. Malignant 
melanocytes modulate their microenvironment in order to penetrate the 
dermal/epidermal junction and eventually invade the dermis. The small 
leucine-rich proteoglycans (SLRPs) constitute important constituents of the 
dermis extracellular matrix (ECM), participating in both the structural and the 
functional organization of the skin. The role of a keratan sulphate SLRP 
lumican, has recently been investigated in the growth and metastasis of several 
cancers. In this study, the expression of lumican was studied in two human 
melanoma cell lines (WM9, M5) as well as in normal neonatal human melanocytes 
(HEMN) using real time PCR, western blotting with antibodies against the protein 
core and keratan sulfate, and treatments with specific enzymes. Both human 
metastatic melanoma cell lines were found to express lumican mRNA and 
effectively secrete lumican in a proteoglycan form, characterized to be 
substituted mostly with keratan sulfate chains. Lumican mRNA was not detected in 
normal melanocytes. This is the first time that the synthesis and secretion of 
lumican in human melanoma cell lines is reported. The role of this proteoglycan 
in the development and progression of malignant melanoma has to be further 
investigated.