Targeting RANKL-independent osteoclastogenesis overcomes denosumab resistance in models of ER+ breast cancer bone metastasis
Qun Lin, Jinpeng Luo, Zhuxi Duan, Jieer Luo, Wei Zhang, Yuan Xia, Yinduo Zeng, Xiaolin Fang, Jiahui Liang, Jiayi Chen, Qianchong Lin, Yilin Quan, Ruiyu Hu, Hongcai Liu, Qiang Liu, Jun Li, Chang Gong
Qun Lin, Jinpeng Luo, Zhuxi Duan, Jieer Luo, Wei Zhang, Yuan Xia, Yinduo Zeng, Xiaolin Fang, Jiahui Liang, Jiayi Chen, Qianchong Lin, Yilin Quan, Ruiyu Hu, Hongcai Liu, Qiang Liu, Jun Li, Chang Gong
View: Text | PDF
Research Article Cell biology Oncology

Targeting RANKL-independent osteoclastogenesis overcomes denosumab resistance in models of ER+ breast cancer bone metastasis

Abstract

Bone metastasis remains a major cause of morbidity in estrogen receptor–positive breast cancer, with RANKL inhibitor resistance emerging as a critical clinical challenge. Nearly 40% of patients develop progressive skeletal lesions despite denosumab therapy, highlighting an urgent need to identify resistance mechanisms and alternative therapeutic strategies. We identified a RANKL-independent osteoclast activation pathway mediated by the CRKL/circCCDC50/NFATc1 axis. Mechanistically, CRKL promoted EIF4A3-dependent circCCDC50 biogenesis, which was packaged into large oncosomes and transferred to osteoclast precursors. Nuclear circCCDC50 recruited CARM1 to epigenetically activate NFATc1 transcription, establishing a self-reinforcing loop that sustained osteolysis despite RANKL blockade. Pharmacological inhibition of CARM1 (TP-064) effectively suppressed osteoclastogenesis and bone metastasis in denosumab-resistant models. These findings revealed a targetable resistance mechanism and provided a clinically actionable strategy to overcome microenvironment-driven metastasis through dual targeting of tumor and bone niches.

Authors

Qun Lin, Jinpeng Luo, Zhuxi Duan, Jieer Luo, Wei Zhang, Yuan Xia, Yinduo Zeng, Xiaolin Fang, Jiahui Liang, Jiayi Chen, Qianchong Lin, Yilin Quan, Ruiyu Hu, Hongcai Liu, Qiang Liu, Jun Li, Chang Gong

×

Figure 9

The circCCDC50/CARM1 complex enhances NFATc1 transcription to sustain osteoclastogenesis.

Options: View larger image (or click on image) Download as PowerPoint
The circCCDC50/CARM1 complex enhances NFATc1 transcription to sustain os...
(A) qRT-PCR analysis of transcriptional levels of osteoclast differentiation and activation-related genes in BMMs treated with conditioned media from distinct primary BC cells. (B) NFATc1 protein levels were evaluated in primary BC cells (denosumab-resistant lines #5, #6 and sensitive lines #3, #4). GAPDH served as a loading control. (C) RNA pol II occupancy at the NFATc1 promoter was elevated in BMMs treated with LOs derived from primary tumor cells by ChIP-qPCR. NFATc1 promoter (+) indicates the RNA pol II enrichment at the NFATc1 promoter region; NFATc1 promoter (–) indicates the RNA pol II enrichment at a negative control region; anti-RNA pol II (+) indicates ChIP with an anti-RNA polymerase II antibody; anti-RNA pol II (–) indicates ChIP with a control IgG antibody. (D) Resistant tumor-derived LOs significantly enhanced chromatin openness at the NFATc1 promoter. (E) Predicted circCCDC50-binding regions (–1,000 to –500 bp) on the NFATc1 promoter. (F) CHiRP-qPCR demonstrated significant enrichment of circCCDC50 at the NFATc1 promoter in resistant cells compared with scrambled probe controls. (G) Proteins coprecipitated with circCCDC50 were identified by ChIRP-MS. CARM1 (coactivator-associated arginine methyltransferase 1) exhibited high binding affinity. (H) RNA pull-down assay analysis of cytoplasmic and nuclear circCCDC50-interacting proteins (“probe” stands for circCCDC50 probe; “Ctrl” stands for control probe). (I) IF staining showed nuclear colocalization of circCCDC50 and CARM1 in BMMs treated with resistant tumor-derived LOs. Each error bar represents the mean ± SD of 3 independent experiments. Significant differences were determined by 1-way ANOVA with Tukey’s multiple comparison test. *P < 0.05, **P < 0.01, ***P < 0.001.