Methods to Investigate β-Arrestin-1/β-Catenin Signaling in Ovarian Cancer Cells.

Endothelin-1 (ET-1), which acts through the endothelin A receptor (ET _A R) or ET _B R, belonging to the large family of G-protein coupled receptors (GPCR), is involved in physiopathological processes, such as cancer. In epithelial ovarian cancer, a pervasively activated ET-1/ET _A R axis drives different steps of tumor progression and confers drug resistance. In this malignancy, one major aspect associated with the ET _A R signaling machinery resides in the fact that this receptor may use β-arrestin-1 (β-arr1) function to spatially and temporally activate key oncogenic pathways. This results in specificity of ET-1/ET _A R signal transduction mechanisms and downstream signaling pathways. As such, β-arr1 has been recognized as an important signal transducer involved in multiple cross talks with other signaling pathways, including those activated by tyrosine kinase receptors. The interaction with diverse sets of partners positions β-arr1 as a critical regulator of GPCR signal transduction and permits the integration of ET _A R-mediated signals with other cytoplasmic or nuclear inputs. In particular, the scaffolding function of β-arr1 provides an essential link in translating ET _A R function by altering β-catenin localization and function, promoting β-catenin-related transcriptional activity and gene transcription relevant to tumor progression. This chapter outlines the methodologies for the measurement of β-arr1/β-catenin protein interactions and functional activity in tumor cells.