Adhesion Family of G Protein-coupled Receptors and Cancer

The adhesion-class G protein-coupled receptors (adhesion-GPCRs) constitute the second largest GPCR sub-family inhumans. Adhesion-GPCRs are defined by the chimeric structure of an unusually large extracellular cell-adhesion domaina n d a G P C R - l i k e s e v e n - p a s s t r a n s m e m b r a n e d o m a i n .Adhesion-GPCRs are hence expected to display both cellularadhesion and signaling functions in many biological systems.Adhesion-GPCRs are normally expressed in the central nervous, immune, and reproductive systems in a cell type- or tissue-restricted fashion. However, aberrant expression of distinctadhesion-GPCR molecules has been identified in varioushuman cancers with some of the receptors closely associatedwith cancer development. Tumor-associated adhesion-GPCRsare thought to involve in tumorigenesis by affecting the growthof tumor cells, angiogenesis, tumor cell migration, invasionand metastasis either positively or negatively. Furthermore, some adhesion-GPCRs are considered potential biomarkers for specific types of cancers. In this review article, the expressional characteristics and functional role of cancer-associated adhesion-GPCRs are discussed in depth.