Lumican is a member of the
small leucine-rich proteoglycan family. It is present in numerous extracellular matrices of different tissues, such as muscle, cartilage, and cornea. In skin,
lumican is present as a
glycoprotein. It plays a critical role in
collagen fibrillogenesis, as shown by knocking out of its gene in mice. A direct link between
lumican expression and
melanoma progression and
metastasis has been demonstrated.
Lumican was shown to impede tumour cell migration and invasion by directly interacting with the α2β1
integrin. In addition, an active sequence of the
lumican core
protein, called
lumcorin, was identified as being responsible for inhibition of
melanoma cell migration.
Lumican was also shown to exert angiostatic properties by downregulating the proteolytic activity associated with endothelial cell membranes, particularly
matrix metalloproteinase (MMP)-14 and MMP-9. Globally,
lumican appears to be a potent agent for inhibiting tumour progression rather than
tumorigenesis. However, progressive changes in
proteoglycans occur in the tumour environment. The complexity and diversity of
proteoglycan structure might be responsible for a variety of functions that regulate cell behaviour. Through their core
protein and their
glycosaminoglycan chains,
proteoglycans can interact with
growth factors and
chemokines. These interactions affect cell signalling, motility, adhesion, growth, and apoptosis. This review summarizes recent data concerning
lumican control of tumour progression in different
cancers, with a particular focus on its interactions with
MMPs and
integrins. Its potential therapeutic implications are discussed.