The α‐Arrestin ARRDC3 Suppresses Breast Carcinoma Invasion by Regulating GPCR Lysosomal Sorting and Signaling

Abstract

G protein‐coupled receptor (GPCR) signaling regulates cancer cell proliferation, invasion, migration and survival at metastatic sites. However, despite the success and promise of GPCRs as therapeutic targets, there are currently no FDA‐approved drugs targeting GPCRs for cancer. Protease‐activated receptor‐1 (PAR1) is a GPCR that promotes breast cancer progression. PAR1 is overexpressed in breast cancer patient tissue biopsies and in breast carcinoma cell lines, and correlates with increased rates of metastasis and poor prognosis and increased invasion and metastatic potential, respectively. One mechanism that leads to PAR1 aberrant over‐expression is defective lysosomal trafficking. The dysregulation of PAR1 trafficking leads to persistent G protein signaling and promotes breast cancer invasion. However, the mechanisms responsible for aberrant PAR1 trafficking remain unknown. Here we show that arrestin domain containing protein‐3 (ARRDC3), an adaptor protein for E3 ubiquitin ligases, functions as a tumor suppressor by controlling PAR1 trafficking in breast carcinoma cells. We used a tetracyclineinducible pSLIK lentiviral vector to restore expression of ARRDC3 in highly invasive, basal‐like MDA‐MB‐231 cells, which exhibit high PAR1 and low ARRDC3 expression. Re‐expression of ARRDC3 restored agonist‐induced PAR1 degradation, attenuated JNK and Hippo‐YAP signaling, and further inhibited PAR1‐mediated breast carcinoma cell invasion. Our studies suggest a crucial role for ARRDC3 in regulating normal PAR1 lysosomal degradation and signaling, with loss of ARRDC3 resulting in aberrant PAR1 signaling, leading to tumor progression in breast cancer. A better understanding of the mechanisms by which PAR1 contributes to breast cancer progression may lead to new potential therapeutic targets for the treatment or prevention of metastatic breast cancer.Support or Funding InformationFunding for this project was provided by the UCSD Tribal Membership Initiative Graduate Fellowship, UCSD Graduate Training Program in Cellular and Molecular Pharmacology through NIH General Medical Sciences, T32 GM007752 (Aleena Arakaki) and by the National Institute of Health NIGMS R01 GM090689 (JoAnn Trejo).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.