β-Arrestin links endothelin A receptor to β-catenin signaling to induce ovarian cancer cell invasion and metastasis

Abstract

The activation of endothelin-A receptor (ETAR) by endothelin-1 (ET-1) has a critical role in ovarian tumorigenesis and progression. To define the molecular mechanism in ET-1-induced tumor invasion and metastasis, we focused on ␤-arrestins as scaffold and signaling proteins of G protein-coupled receptors. Here, we demonstrate that, in ovarian cancer cells, ␤-arrestin is recruited to ETAR to form two trimeric complexes: one through the interaction with Src leading to epithelial growth factor receptor (EGFR) transactivation and ␤-catenin Tyr phosphorylation, and the second through the physical association with axin, contributing to release and inactivation of glycogen synthase kinase (GSK)-3␤ and ␤-catenin stabilization. The engagement of ␤-arrestin in these two signaling complexes concurs to activate ␤-catenin signaling pathways. We then demonstrate that silencing of both ␤-arrestin-1 and ␤-arrestin-2 inhibits ETAR-driven signaling, causing suppression of Src, mitogen-activated protein kinase (MAPK), AKT activation, as well as EGFR transactivation and a complete inhibition of ET-1-induced ␤-catenin/TCF transcriptional activity and cell invasion. ETAR blockade with the specific ETAR antagonist ZD4054 abrogates the engagement of ␤-arrestin in the interplay between ETAR and the ␤-catenin pathway in the invasive program. Finally, ETAR is expressed in 85% of human ovarian cancers and is preferentially co-expressed with ␤-arrestin-1 in the advanced tumors. In a xenograft model of ovarian metastasis, HEY cancer cells expressing ␤-arrestin-1 mutant metastasize at a reduced rate, highlighting the importance of this molecule in promoting metastases. ZD4054 treatment significantly inhibits metastases, suggesting that specific ETAR antagonists, by disabling multiple signaling activated by ETAR/␤-arrestin, may represent new therapeutic opportunities for ovarian cancer.beta-arrestin ͉ beta-catenin ͉ endothelin A receptor ͉ metastasis ͉ ovarian cancer

GPCRs and cancer

“…In addition, prostaglandin E2 induced the association of prostaglandin E receptor 4 with β-arrestin 1 and c-Src, that formed a signaling complex able to induce the migration and metastasis of colorectal carcinoma cells [171] . In accordance with these data, β-arrestin 1 interacting with Src and ET A R triggered EGFR transactivation and β-catenin phosphorylation, which stimulated invasion and metastasis in ovarian cancer cells [172] . Moreover, β-arrestin 1 forming a trimeric complex with ET A R and axin contributed to the inactivation of glycogen synthase kinase (GSK)-3 and stabilization of β-catenin [172] .…”

“…In accordance with these data, β-arrestin 1 interacting with Src and ET A R triggered EGFR transactivation and β-catenin phosphorylation, which stimulated invasion and metastasis in ovarian cancer cells [172] . Moreover, β-arrestin 1 forming a trimeric complex with ET A R and axin contributed to the inactivation of glycogen synthase kinase (GSK)-3 and stabilization of β-catenin [172] . Collectively, these results indicate that β-arrestins exert an important role in GPCR-mediated signaling as well as a pivotal role in cancer invasion and metastasis.…”

Essential requirement for β-arrestin2 in mouse intestinal tumors with elevated Wnt signaling

“…Depletion of Dvl2 decreases tumor number in Apc Min/+ mice (24), which is in favor of the fact that Dvl2 can affect β-catenin/Tcf-4 activity even in a context whereby the β-catenin degradation complex is lost. Furthermore, the interaction of Dvl2 with Src has been shown to be required for the tyrosine phosphorylation of β-catenin that promotes β-catenin/Tcf-4 activity involved in ovarian cancer cell invasion and metastasis (11). Thus, in our model, Dvl2 and Src might be potential partners by which Arrb2 regulates Apc mutationinduced tumorigenesis.…”

“…Because the inhibitory effects of Arrb2 depletion is only detected in models in which the β-catenin degradation complex (Apc/ Gsk3β/Axin) is at best poorly effective (Apc Δ14/+ mice or Apc Min/+ cells treated with Apc siRNA), and because the expression of a constitutively activated β-catenin mutant reversed Arrb2 siRNA inhibition on Wnt activity and colony formation induced by Apc depletion in Apc Min/+ cells, it is tempting to speculate that Arrb2 regulates Wnt signaling upstream from that complex. Several proteins known to interact with Arrb2 and involved in the Wnt signaling pathway could thus be potential candidates, such as Dvl2 (14) and Src (11). Depletion of Dvl2 decreases tumor number in Apc Min/+ mice (24), which is in favor of the fact that Dvl2 can affect β-catenin/Tcf-4 activity even in a context whereby the β-catenin degradation complex is lost.…”

“…As an example, Arrb modulate ERK, c-Jun NH2-terminal kinase, and phospho-inositide 3-kinase, kinases that are strongly activated in malignant cells (6). Arrb are overexpressed in late-stage cancers, such as human glioblastomas (7) and breast cancer (8), and have been assigned several functions in tumor cells, including proliferation (9), apoptosis (10), migration, and invasion (11). Arrb were also reported to regulate Wnt signaling in nonintestinal models (12).…”