Tetraspanins in cancer

Tetraspanins play important roles in cancer, especially in metastasis. CD82 and CD9 are frequently down-regulated on progression of epithelial cancers in humans and this has been associated with poor prognosis. In contrast, high levels of CD151 and Tspan 8 are often observed on tumour progression and have also been linked to poor patient outcome. These observations are supported by a large body of evidence from studies in vitro and in animal models. Considerable insights into the mechanisms by which tetraspanins influence tumour behaviour are now emerging. These include effects on cell-matrix and cell-cell interactions which influence migration and invasion of surrounding tissues, as well as angiogenesis. Several tetraspanins influence the function of platelets which can promote metastasis. Tetraspanins are constitutive components of exosomes, which are most important in intercellular communication. This widens the range of tetraspanin activities in physiology and pathology and may well be particularly important during spread and settlement of metastasizing tumor cells. There is hope that the understanding of how tetraspanins contribute to tumour progression indicates novel approaches to therapy