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 8

CRKL promotes circCCDC50 biogenesis through the JNK/ATF-2/EIF4A3 axis.

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CRKL promotes circCCDC50 biogenesis through the JNK/ATF-2/EIF4A3 axis. (...
(A) Schematic workflow of RNA pull-down assay combined with mass spectrometry to identify circCCDC50-binding cyclization factors following circRNA enrichment. (B) qRT-PCR analysis of circCCDC50 expression in indicated #5 primary tumor cells. GAPDH served as the loading control. (C) qRT-PCR quantification of circCCDC50 and linear CCDC50 mRNA levels in #5 primary tumor cells overexpressing EIF4A3 versus controls. (D–G) CRKL-mediated promotion of circCCDC50 biogenesis via the JNK/ATF-2/EIF4A3 signaling axis was validated by qRT-PCR and Western blot analyses. (H) H4K5ac enrichment at the EIF4A3 promoter region was elevated in resistant cells by ChIP-qPCR. EIF4A3 promoter (+) indicates the H4K5ac enrichment at the EIF4A3 promoter region; EIF4A3 promoter (–) indicates the enrichment at a negative control region. (I) RNA pol II occupancy at the EIF4A3 promoter was elevated in resistant cells by ChIP-qPCR. EIF4A3 promoter (+) indicates the RNA pol II enrichment at the EIF4A3 promoter region; EIF4A3 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. (J) DNase I hypersensitivity assay revealed reduced chromatin openness at the EIF4A3 promoter in CRKL-knockdown cells (#5, #6) compared with nonknockdown controls. 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.