RSPO2 and RANKL Signal Through LGR4 To Regulate Osteoclastic Premetastatic Niche Formation and Bone Metastasis

Authors

Zhiying Yue
Xin Niu
Zengjin Yuan
Qin Qin
Wenhao Jiang
Liang He
Jingduo Gao
Yi Ding
Yanxi Liu
Ziwei Xu
Zhenxi Li
Zhengfeng Yang
Rong Li
Xiwen Xue
Yankun Gao
Fei Yue
Xiang H-F Zhang
Guohong Hu
Yi Wang
Yi Li
Geng Chen
Stefan Siwko
Alison Gartland
Ning Wang
Jianru Xiao
Mingyao Liu
Jian Luo

Publication Date

1-18-2022

Journal

Journal of Clinical Investigation

DOI

10.1172/JCI144579

PMID

34847079

PMCID

PMC8759794

PubMedCentral® Posted Date

1-18-2022

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Animals, Bone Neoplasms, Breast Neoplasms, Cell Line, Tumor, Female, Humans, Intercellular Signaling Peptides and Proteins, Mice, Mice, Inbred BALB C, Mice, Nude, Neoplasm Metastasis, Neoplasm Proteins, Osteoclasts, RANK Ligand, Receptors, G-Protein-Coupled, Signal Transduction, Tumor Microenvironment, Bone Biology, Cell Biology, Bone disease, Breast cancer, Signal transduction

Abstract

Therapeutics targeting osteoclasts are commonly used treatments for bone metastasis; however, whether and how osteoclasts regulate premetastatic niche and bone tropism are largely unknown. In this study, we report that osteoclast precursors (OPs) can function as a premetastatic niche component that facilitates breast cancer (BCa) bone metastasis at early stages. At the molecular level, unbiased GPCR ligand/agonist screening in BCa cells suggested that R-spondin 2 (RSPO2) and RANKL, through interaction with their receptor LGR4, promoted osteoclastic premetastatic niche formation and enhanced BCa bone metastasis. This was achieved by RSPO2/RANKL-LGR4 signal modulating the WNT inhibitor DKK1 through Gαq and β-catenin signaling. DKK1 directly facilitated OP recruitment through suppression of its receptor LDL receptor-related protein 5 (LRP5) but not LRP6, upregulating Rnasek expression via inhibition of canonical WNT signaling. In clinical samples, RSPO2, LGR4, and DKK1 expression showed a positive correlation with BCa bone metastasis. Furthermore, soluble LGR4 extracellular domain (ECD) protein, acting as a decoy receptor for RSPO2 and RANKL, significantly alleviated bone metastasis and osteolytic lesions in a mouse bone metastasis model. These findings provide unique insights into the functional role of OPs as key components of the premetastatic niche for BCa bone metastasis and identify RSPO2/RANKL-LGR4 signaling as a promising target for inhibiting BCa bone metastasis.