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
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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

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Figure 3

Denosumab-resistant ER+ breast cancer secretes LOs to promote RANKL-independent osteoclast activation in vitro.

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Denosumab-resistant ER+ breast cancer secretes LOs to promote RANKL-inde...
(A) Top: Representative transmission electron microscopy (TEM) images of LOs (scale bar: 1 μm), microvesicles (MVs, scale bar: 100 nm), small extracellular vesicles (SEVs, scale bar: 100 nm), and supernatant-depleted LOs (scale bar: 500 nm). Bottom: Nanoparticle tracking analysis (NTA) of LOs, MVs, and SEVs using membrane filters with pore sizes of 2,000 nm, 800 nm, and 100 nm, respectively. Immunoblot (IB) analysis of αV-integrin, ANXA1, CD9, ALIX, and CD63 expression in LOs, MVs, SEVs, and supernatant fractions. (B) Top: TRAP staining and phase-contrast microscopy images of BMMs treated with medium, LOs, MVs, sEVs, or supernatant. Scale bars: 50 μm. Bottom: Quantification of TRAP+ multinucleated cell counts and TRAP enzymatic activity from the experiments above. 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.