TY - JOUR
T1 - Inhibition of G protein-coupled receptor kinase 2 promotes unbiased downregulation of IGF-1 receptor and restrains malignant cell growth
AU - Crudden, Caitrin
AU - Shibano, Takashi
AU - Song, Dawei
AU - Dragomir, Mihnea P
AU - Cismas, Sonia
AU - Serly, Julianna
AU - Nedelcu, Daniela
AU - Fuentes-Mattei, Enrique
AU - Tica, Andrei
AU - Calin, George A
AU - Girnita, Ada
AU - Girnita, Leonard
N1 - Funding Information:
We thank Drs. R.J. Lefkowitz, R. Baserga, and V. Gurivech for generously providing reagents and cell lines. We thank Anna Malmerfelt at the histology core facility, Karolinska Institutet, for technical assistance. Research support was received from the Swedish Research Council, Swedish Cancer Society, The Swedish Childhood Cancer Foundation, Crown Princess Margareta?s Foundation for the Visually Impaired, Welander Finsen Foundation, King Gustaf V Jubilee Foundation, SINF StratCan, Stockholm Cancer Society, Stockholm County, and Karolinska Institute. Dr. G.A. Calin is the Felix L. Haas Endowed Professor in Basic Science. Work in Dr. G.A. Calin?s laboratory is supported by NIH (NIH/NCATS) grant UH3TR00943?01 through the NIH Common Fund, Office of Strategic Coordination (OSC), the NCI grants 1R01 CA182905?01 and 1R01CA222007?01A1, an NIGMS 1R01GM122775?01 grant, a U54 grant #CA096297/CA096300?UPR/MDACC Partnership for Excellence in Cancer Research 2016 Pilot Project, a Team DOD (CA160445P1) grant, a Chronic Lymphocytic Leukemia Moonshot Flagship project, a CLL Global Research Foundation 2019 grant, a CLL Global Research Foundation 2020 grant, and the Estate of C.G. Johnson, Jr.
Funding Information:
C. Crudden reports grants from European Commission outside the submitted work. No disclosures were reported by the other authors.
Publisher Copyright:
©2020 American Association for Cancer Research.
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/1/15
Y1 - 2021/1/15
N2 - The ability of a receptor to preferentially activate only a subset of available downstream signal cascades is termed biased signaling. Although comprehensively recognized for the G protein–coupled receptors (GPCR), this process is scarcely explored downstream of receptor tyrosine kinases (RTK), including the cancer-relevant insulin-like growth factor-1 receptor (IGF1R). Successful IGF1R targeting requires receptor downregulation, yet therapy-mediated removal from the cell surface activates cancer-protective b-arrestin–biased signaling (b-arr-BS). As these overlapping processes are initiated by the b-arr/IGF1R interaction and controlled by GPCR-kinases (GRK), we explored GRKs as potential anticancer therapeutic targets to disconnect IGF1R downregulation and b-arr-BS. Transgenic modulation demonstrated that GRK2 inhibition or GRK6 overexpression enhanced degradation of IGF1R, but both scenarios sustained IGF1–induced b-arr-BS. Pharmacologic inhibition of GRK2 by the clinically approved antidepressant, serotonin reuptake inhibitor paroxetine (PX), recapitulated the effects of GRK2 silencing with dose- and time-dependent IGF1R downregulation without associated b-arr-BS. In vivo, PX treatment caused substantial downregulation of IGF1R, suppressing the growth of Ewing’s sarcoma xenografts. Functional studies reveal that PX exploits the antagonism between b-arrestin isoforms; in low ligand conditions, PX favored b-arrestin1/Mdm2-mediated ubiquitination/degradation of IGF1R, a scenario usually exclusive to ligand abundancy, making PX more effective than antibody-mediated IGF1R downregulation. This study provides the rationale, molecular mechanism, and validation of a clinically feasible concept for “system bias” targeting of the IGF1R to uncouple downregulation from signaling. Demonstrating system bias as an effective anticancer approach, our study reveals a novel strategy for the rational design or repurposing of therapeutics to selectively cross-target the IGF1R or other RTK. Significance: This work provides insight into the molecular and biological roles of biased signaling downstream RTK and provides a novel “system bias” strategy to increase the efficacy of anti–IGF1Rtargeted therapy in cancer.
AB - The ability of a receptor to preferentially activate only a subset of available downstream signal cascades is termed biased signaling. Although comprehensively recognized for the G protein–coupled receptors (GPCR), this process is scarcely explored downstream of receptor tyrosine kinases (RTK), including the cancer-relevant insulin-like growth factor-1 receptor (IGF1R). Successful IGF1R targeting requires receptor downregulation, yet therapy-mediated removal from the cell surface activates cancer-protective b-arrestin–biased signaling (b-arr-BS). As these overlapping processes are initiated by the b-arr/IGF1R interaction and controlled by GPCR-kinases (GRK), we explored GRKs as potential anticancer therapeutic targets to disconnect IGF1R downregulation and b-arr-BS. Transgenic modulation demonstrated that GRK2 inhibition or GRK6 overexpression enhanced degradation of IGF1R, but both scenarios sustained IGF1–induced b-arr-BS. Pharmacologic inhibition of GRK2 by the clinically approved antidepressant, serotonin reuptake inhibitor paroxetine (PX), recapitulated the effects of GRK2 silencing with dose- and time-dependent IGF1R downregulation without associated b-arr-BS. In vivo, PX treatment caused substantial downregulation of IGF1R, suppressing the growth of Ewing’s sarcoma xenografts. Functional studies reveal that PX exploits the antagonism between b-arrestin isoforms; in low ligand conditions, PX favored b-arrestin1/Mdm2-mediated ubiquitination/degradation of IGF1R, a scenario usually exclusive to ligand abundancy, making PX more effective than antibody-mediated IGF1R downregulation. This study provides the rationale, molecular mechanism, and validation of a clinically feasible concept for “system bias” targeting of the IGF1R to uncouple downregulation from signaling. Demonstrating system bias as an effective anticancer approach, our study reveals a novel strategy for the rational design or repurposing of therapeutics to selectively cross-target the IGF1R or other RTK. Significance: This work provides insight into the molecular and biological roles of biased signaling downstream RTK and provides a novel “system bias” strategy to increase the efficacy of anti–IGF1Rtargeted therapy in cancer.
UR - http://www.scopus.com/inward/record.url?scp=85100418152&partnerID=8YFLogxK
U2 - 10.1158/0008-5472.CAN-20-1662
DO - 10.1158/0008-5472.CAN-20-1662
M3 - Article
C2 - 33158816
VL - 81
SP - 501
EP - 515
JO - Cancer Research
JF - Cancer Research
SN - 0008-5472
IS - 2
ER -