Investigation of the influence of extracellular matrix proteins on normal human melanocyte morphology and melanogenic activity

SUMMARY Several studies have indicated that extracellular matrix (ECM) proteins can influence melanocyte behaviour in vitro. However. Ihe choice of medium is known to have a profound effect on meianocyte behaviour and it is currently difficult to ascribe which reported effects are due to ECM proteins and those which are attributable to the medium used in these different studies. The purpose of this study was to learn more about the influence of ECM proteins on melanocyte function by examining a range of cell-derived and individual ECM proteins for their impact on melanocyte tyrosinase activity in cells cultured under conditions of varying mitogenic drive. We found that ECM derived from human dermal fibroblasts. bovine endothelial cells and a human endothelial cell line as well as collagen I. collagen IV. fibronectin. and to a lesser extent laminin. were all capable of increasing tyrosinase activity in cultures of normal melanocytes. Effects of these ECM were seen most consistently in media with relatively few mitogens, for example ECM proteins influenced melanocyte morphology and this was seen most readily in cells cultured in medium without any mitogens (which ordinarily falls to support melanocyte survival). This study illustrates that ECM proteins can influence melanocyte morphology, proliferation, and tyrosinase activity in vitro and supports a possible role of ECM proteins in the regulation of melanocyte function in vivo.