Adhesion-GPCRS in tumorigenesis.

Tumor growth is a highly complex, multistep process that involves tumor cell detachment, migration, invasion and metastasis accompanied by angiogenesis and extracellular matrix turn-over. Each of the steps is influenced by tumor cell interaction and interaction of the tumor cell with its microenvironment that consists of different cell types as tumor-associated fibroblasts, endothelial cells and leukocytes as well as the extracellular matrix produced by the tumor cells themselves or by the fibroblasts. Cellular communication takes place by the regulated expression of adhesion receptors. Adhesion-GPCRs are characterized by very long extracellular N-termini that have multiple domains. When considering this complex structure it is only logical that adhesion-GPCRs are involved in tumor cell interactions. Moreover, these receptors function in cell guidance and/or trafficking, which, in addition to their structure, makes them interesting for tumorigenesis. The aberrant expression of several adhesion-GPCRs on tumor cells and their involvement in tumor growth have been shown for some of the family members. This overview summarizes expression database data as well as data from original research articles of adhesion-GPCRs in tumors.