Breast Cancer Bone Metastasis Research Articles

Application value of the treatment of breast cancer bone metastases with radioactive seed 125I implantation under CT-guidance

BackgroundTo investigate the application value of the treatment of breast cancer bone metastases with radioactive seed 125I implantation under CT-guidance.MethodsA total of 90 patients with breast cancer admitted to our hospital from January 2017 to January 2018 were selected as the research objects and were divided into control group and experimental group according to random grouping, with 45 cases in each group. Conventional treatment was used in the control group, while the treatment of radioactive seed 125I implantation under CT-guidance was used in the experimental group. The clinical efficacy, pain intensity and levels of carcinoembryonic antigen (CEA), carcinoembryonic antigen 153 (CA153), carbohydrate antigen (CA125) in the two groups were compared.ResultsAs for the pain intensity, it was evidently lower in the experimental group after treatment than that in the control group (P < 0.05); as for the total effective rate, it was obviously higher in the experimental group after treatment than that in the control group (P < 0.05); as for the levels of CEA, CA153 and CA125, the data in the experimental group after treatment were much lower than the control group (P < 0.05).ConclusionRadioactive seed 125I implantation under CT-guidance can effectively improve the effect of the treatment of breast cancer bone metastases. It has curative efficacy and it is worth promoting and using.

Traditional Chinese medicine for bone metastasis of breast cancer: a systematic review and meta-analysis

Breast cancer incidence is increasing, and bone metastases in terminal breast cancer cause considerable patient suffering. Many researchers have reported that traditional Chinese medicine (TCM) benefits breast cancer patients with bone metastasis. However, no conclusive evidence can be proved for its effects. This paper assesses the effects of TCM on bone metastasis of breast cancer. Databases were searched independently for randomized controlled trials about TCM for bone metastasis of breast cancer by two reviewers. The effective rate was assessed as the primary outcome. Patient’s condition and adverse events were assessed as secondary outcomes. Thirteen articles were included in our meta-analysis. The results showed that TCM is effective for treating bone metastasis of breast cancer (RR (Risk ratio) = 1.10, 95% CI (Confidence interval)(1.04, 1.16), p &lt; 0.05). TCM can improve metastasis to the bone in breast cancer (RR = 1.52, 95% CI (1.33, 1.74), p &lt; 0.05). TCM also relieved pain in patients with bone metastasis of breast cancer (RR = 1.41, 95% CI (1.22, 1.63), p &lt; 0.05). Six studies reported adverse events (RR = 0.41, 95% CI (0.28, 0.62), p &lt; 0.05). This shows that adjuvant treatment with TCM can reduce the incidence of adverse reactions. TCM treatment is an effective and safe adjuvant therapy for bone metastasis in breast cancer patients.

Deregulated molecules and pathways in the predisposition and dissemination of breast cancer cells to bone

BackgroundBone metastasis is the most common metastatic destination in advanced breast cancer, presenting a poor prognosis and clinical challenges in management. To date, the mechanism of bone metastasis in breast cancer remains largely unclear. MethodsDifferentially expressed genes in primary tumours that developed bone metastases were systematically analysed using both TCGA-BRCA and E-MTAB-4003 databases. Adaptive phenotype in the subsequent bone lesions was analysed in the GSE46161 database. A series of biomarkers including homing, immune escape, angiogenesis, and factors involved in both osteoblastogenesis and osteoclastogenesis were included to dissect the molecular events underlying bone metastasis in breast cancer. ResultsUpregulated expressions of GDF11 expression is positively correlated with colonization, osteoblastogenesis and osteoclastogenesis, whilst CD151 is positively associated with angiogenesis and immune escape. PAFAH1B2 expression is inversely correlated with the angiogenic process. Reduced YTHDF2 may facilitate cancer cell homing, osteoclastogenesis and immune escape in breast cancer. DPP9, FAS, ZNF519, RPP14 and FAU were evaluated for their potential involvement in for the homing to bone, escaping from immune surveillance, angiogenesis, osteoblastic activity and osteoclastic activity in the multi-step process of bone metastasis. ConclusionGDF11, CD151, PAFAH1B2 and YTHDF2 may play a pivotal role in the predisposition of metastasis to the bone from breast cancer, whilst DPP9, FAS, ZNF519, RPP14 and FAU may be actively involved in the adaptative colonisation of metastatic breast cancer cells in bone.

Orbital metastasis of invasive lobular carcinoma of the breast

We herein report a case of orbital metastasis from the breast cancer in a 58-year-old woman presenting with visual disturbance and bilateral periorbital swelling. She had undergone radical mastectomy for right breast cancer 9 years previously and been receiving hormone therapy for bone metastasis of breast cancer for the past 4 years. Computed tomography and magnetic resonance imaging revealed an ill-defined mass in the bilateral orbits, whereas an excisional biopsy confirmed metastasis of invasive lobular carcinoma (ILC) of the breast. The appearance of eye symptoms in patients who have a history of breast cancer, especially ILC should be investigated, with a consideration of orbital metastasis.

Parathyroid hormone-related protein in breast cancer bone metastasis.

Parathyroid hormone-related protein (PTHrP) was discovered as the tumor product causing the humoral hypercalcemia of malignancy. Its structural similarity to the hormone, PTH, with 8 of the first 13 amino acids identical, was sufficient to explain the sharing by PTHrP and PTH of a common receptor, PTH1R, although the remainder of the sequences are unique. PTHrP has important roles in development of several organs, including breast and bone, and functions as a paracrine factor postnatally in these and other tissues. In addition to its hormonal role in cancer, PTHrP is produced by two thirds of primary breast cancers and 90% of bone metastases from breast cancer, leading to the concept that its production in bone by breast cancer cells promotes bone resorption, thus favoring tumor establishment and expansion, and an exit from tumor dormancy in bone through downregulation of leukemia inducing factor receptor (LIFR). Cancer production of PTHrP is increased by bone-derived growth factors, with particular attention paid to TGFβ, as well as by promoter-driven transcriptional effects, such as the hedgehog signaling factor, GLI2, and microenvironment effects including changes in underlying stiffness of substrates for cells. Although interest has been focused on PTHrP-induced bone resorption in bone metastasis, a mechanistically separate, protective effect against tumor progression has been proposed. Although there is conflicting mouse data, there are clinical studies suggesting that increased production of PTHrP by breast cancers confers upon them a less invasive phenotype, an effect distinct from the bone resorption-stimulating action that favors bone metastasis.

Breast Cancer Induced Bone Osteolysis Prediction Using Temporal Variational Autoencoders.

Objective and Impact Statement. We adopt a deep learning model for bone osteolysis prediction on computed tomography (CT) images of murine breast cancer bone metastases. Given the bone CT scans at previous time steps, the model incorporates the bone-cancer interactions learned from the sequential images and generates future CT images. Its ability of predicting the development of bone lesions in cancer-invading bones can assist in assessing the risk of impending fractures and choosing proper treatments in breast cancer bone metastasis. Introduction. Breast cancer often metastasizes to bone, causes osteolytic lesions, and results in skeletal-related events (SREs) including severe pain and even fatal fractures. Although current imaging techniques can detect macroscopic bone lesions, predicting the occurrence and progression of bone lesions remains a challenge. Methods. We adopt a temporal variational autoencoder (T-VAE) model that utilizes a combination of variational autoencoders and long short-term memory networks to predict bone lesion emergence on our micro-CT dataset containing sequential images of murine tibiae. Given the CT scans of murine tibiae at early weeks, our model can learn the distribution of their future states from data. Results. We test our model against other deep learning-based prediction models on the bone lesion progression prediction task. Our model produces much more accurate predictions than existing models under various evaluation metrics. Conclusion. We develop a deep learning framework that can accurately predict and visualize the progression of osteolytic bone lesions. It will assist in planning and evaluating treatment strategies to prevent SREs in breast cancer patients.

IL-1β in breast cancer bone metastasis.

Bone is the most common site for advanced breast cancer to metastasise. The proinflammatory cytokine, interleukin-1β (IL-1β) plays a complex and contradictory role in this process. Recent studies have demonstrated that breast cancer patients whose primary tumours express IL-1β are more likely to experience relapse in bone or other organs. Importantly, IL-1β affects different stages of the metastatic process including growth of the primary tumour, epithelial to mesenchymal transition (EMT), dissemination of tumour cells into the blood stream, tumour cell homing to the bone microenvironment and, once in bone, this cytokine participates in the interaction between cancer cells and bone cells, promoting metastatic outgrowth at this site. Interestingly, although inhibition of IL-1β signalling has been shown to have potent anti-metastatic effects, inhibition of the activity of this cytokine has contradictory effects on primary tumours, sometimes reducing but often promoting their growth. In this review, we focus on the complex roles of IL-1β on breast cancer bone metastasis: specifically, we discuss the distinct effects of IL-1β derived from tumour cells and/or microenvironment on inhibition/induction of primary breast tumour growth, induction of the metastatic process through the EMT, promotion of tumour cell dissemination into the bone metastatic niche and formation of overt metastases.

Temporal Changes in Bone Mineral Content and Mechanical Properties During Breast-Cancer Bone Metastases

Temporal Changes in Bone Mineral Content and Mechanical Properties During Breast-Cancer Bone Metastases

Identification of biomarkers for breast cancer bone metastasis by serum exosome analysis

Identification of biomarkers for breast cancer bone metastasis by serum exosome analysis

A metastasis-on-a-chip approach to explore the sympathetic modulation of breast cancer bone metastasis.

Organ-on-a-chip models have emerged as a powerful tool to model cancer metastasis and to decipher specific crosstalk between cancer cells and relevant regulators of this particular niche. Recently, the sympathetic nervous system (SNS) was proposed as an important modulator of breast cancer bone metastasis. However, epidemiological studies concerning the benefits of the SNS targeting drugs on breast cancer survival and recurrence remain controversial. Thus, the role of SNS signaling over bone metastatic cancer cellular processes still requires further clarification. Herein, we present a novel humanized organ-on-a-chip model recapitulating neuro-breast cancer crosstalk in a bone metastatic context. We developed and validated an innovative three-dimensional printing based multi-compartment microfluidic platform, allowing both selective and dynamic multicellular paracrine signaling between sympathetic neurons, bone tropic breast cancer cells and osteoclasts. The selective multicellular crosstalk in combination with biochemical, microscopic and proteomic profiling show that synergistic paracrine signaling from sympathetic neurons and osteoclasts increase breast cancer aggressiveness demonstrated by augmented levels of pro-inflammatory cytokines (e.g. interleukin-6 and macrophage inflammatory protein 1α). Overall, this work introduced a novel and versatile platform that could potentially be used to unravel new mechanisms involved in intracellular communication at the bone metastatic niche.

Legumain Inhibitor Prevents Breast Cancer Bone Metastasis by Attenuating Osteoclast Differentiation and Function

Legumain Inhibitor Prevents Breast Cancer Bone Metastasis by Attenuating Osteoclast Differentiation and Function

Local Suppression Effect of Paclitaxel-Impregnated Hydroxyapatite/Collagen on Breast Cancer Bone Metastasis in a Rat Model

Introduction Breast cancer is one of the most frequent primary tumors that cause spinal metastases. Metastasis consequences impair both the patient's overall prognosis and quality of life. We previously developed a porous hydroxyapatite collagen composite (HAp/Col) as an osteoconductive scaffold. HAp/Col is a commercially available artificial bone that is frequently utilized in spinal fusion. Because of its high absorbance capacity, HAp/Col is regarded as a good chemical carrier. Methods This study investigated the effect of local administration of paclitaxel combined with HAp/Col scaffold on breast cancer metastasis. High-performance liquid chromatography was used to assess the in vitro release of paclitaxel from HAp/Col. In an in vivo rat model, the inhibitory effects of paclitaxel-impregnated scaffolds on local osteogenesis was examined, and then the local suppression effects on metastatic cancer were investigated. Results In vitro testing revealed that roughly 30% of the paclitaxel was released within 96 hours. Paclitaxel-impregnated HAp/Col inhibited local osteogenesis for the first 8 weeks in a rat femur. However, at 12 weeks following surgery, this negative effect appeared to have subsided. In the metastatic model, all rats in the control group reached the humane endpoint 14 days after surgery. On the other hand, the average time to the endpoint in the paclitaxel group was 26.5 days, which was substantially longer than that in the control group. Long-term survivors treated with paclitaxel had no remaining tumor cells in the femoral bone, and osteogenesis was seen surrounding the HAp/Col. Conclusions Paclitaxel-impregnated HAp/Col reduced local tumor development and extended the time to the target endpoint in rats with metastases from breast cancer. This study shows that local implantation of paclitaxel-impregnated HAp/Col may be a viable therapeutic option for the management of breast cancer metastases.

Osteocytic Connexin Hemichannels Modulate Oxidative Bone Microenvironment and Breast Cancer Growth.

Simple SummaryEstrogen deficiency with increased oxidative stress is associated with various pathological conditions, including cancers. Oxidative stress (OS) is elevated in the bone microenvironment with estrogen deficiency, but the impact of OS on tumor growth in bone remains largely unknown. In our research, we found that elevated oxidative stress inhibits tumor cell growth and the lack of Cx43 hemichannel function in bone osteocytes could mediate this effect. Impairment of Cx43 hemichannels either under oxidative stress or in Cx43-hemichannel-impaired transgenic mice under estrogen deficiency led to the inhibition of breast cancer growth. Treatment with an antioxidant reverses the effect, showing an increase in tumor growth in mice. This study unveiled a new mechanism regarding the role of osteocytic Cx43 hemichannels in modulating an oxidative bone microenvironment and the response of breast cancer cells to local oxidative stress.Osteocytes, the most abundant bone cell types embedded in the mineral matrix, express connexin 43 (Cx43) hemichannels that play important roles in bone remodeling and osteocyte survival. Estrogen deficiency decreases osteocytic Cx43 hemichannel activity and causes a loss in osteocytes’ resistance to oxidative stress (OS). In this study, we showed that OS reduced the growth of both human (MDA-MB-231) and murine (Py8119) breast cancer cells. However, co-culturing these cells with osteocytes reduced the inhibitory effect of OS on breast cancer cells, and this effect was ablated by the inhibition of Cx43 hemichannels. Py8119 cells were intratibially implanted in the bone marrow of ovariectomized (OVX) mice to determine the role of osteocytic Cx43 hemichannels in breast cancer bone metastasis in response to OS. Two transgenic mice overexpressing dominant-negative Cx43 mutants, R76W and Δ130-136, were adopted for this study; the former inhibits gap junctions while the latter inhibits gap junctions and hemichannels. Under normal conditions, Δ130-136 mice had significantly more tumor growth in bone than that in WT and R76W mice. OVX increased tumor growth in R76W but had no significant effect on WT mice. In contrast, OVX reduced tumor growth in Δ130-136 mice. To confirm the role of OS, WT and Δ130-136 mice were administered the antioxidant N-acetyl cysteine (NAC). NAC increased tumor burden and growth in Δ130-136 mice but not in WT mice. Together, the data suggest that osteocytes and Cx43 hemichannels play pivotal roles in modulating the oxidative microenvironment and breast cancer growth in the bone.

Modular Design of High-Brightness pH-Activatable Near-Infrared BODIPY Probes for Noninvasive Fluorescence Detection of Deep-Seated Early Breast Cancer Bone Metastasis: Remarkable Axial Substituent Effect on Performance.

We herein report a series of high-brightness pH-activatable near-infrared (NIR) BODIPY probes for high-contrast intravital imaging of deep-seated early breast cancer bone metastasis by harnessing the axial substituent effect. These probes exhibit tunable pKa, higher brightness, and antiquenching capabilities in aqueous solution, which can be simultaneously adjusted by axial steric substituents. The optimized probe BODO-3 bearing axial dimethyl substituents exhibited a higher pKa value of 5.6 and a brighter NIR fluorescence under tumor acidic pH, showing 10.3-fold and 6.5-fold enhanced brightness (εΦ) at pH 5.5 and 6.5, respectively. Due to the higher brightness, BODO-3 with a brilliant NIR emission at 700 nm allows for deep optical penetrations of 5 and 8 mm at pH 6.5 and 4.5, respectively. Meanwhile, covalent functionalization with glucose (BODO-3-Glu) could further enhance breast cancer and its soft tissue metastasis imaging in vivo. Notably, covalent functionalization with bisphosphonate (BODO-3-PO3H2) allowed the successful targeting and visualization of deep-seated bone metastases of breast cancer with a high tumor to normal contrast of 8/1, outperforming X-rays in early detection. This strategy may provide insights for designing high-brightness activatable NIR probes for detecting deep-seated tumors and metastases.

Regulation of Runx2 and Its Signaling Pathways by MicroRNAs in Breast Cancer Metastasis.

As a major threat among women globally, breast cancer (BC) emerges as a primary research focus for several researchers. Although various therapeutic regimens are available, there is an increased chance of metastasis of BC cells, which raises the severity of this malignancy. Of multiple preferred secondary targets, metastasis to bone is extensively studied. Besides deemed as a bone transcription factor, Runx2 also acts as a metastatic factor that promotes growth and metastasis of BC cells. Studies have reported the significant role of microRNAs (miRNAs) in BC pathogenesis and metastasis by governing Runx2 expression. Additionally, dysregulation of the signaling pathways, including Wnt/β-catenin, TGF-β, Notch, and PI3K/AKT, has been observed to influence the expression of Runx2 in BC cells. In this review, we have aimed to highlight the regulatory role of miRNAs in targeting Runx2 both directly and indirectly by governing respective signaling pathways during bone metastasis of BC.

Opposing Effects of Granulocyte Colony-Stimulating Factor on the Initiation and Progression of Breast Cancer Bone Metastases.

Granulocyte colony stimulating factor (G-CSF), an essential cytokine regulating granulopoiesis, is expressed in a substantial proportion of breast cancers, and it has been implicated in cancer progression. Here, we examined effects of G-CSF on the development of bone metastases of breast cancer using immunocompetent mouse models. The expression of CXC chemokine ligand 12 (CXCL12) in bone marrow stromal cells, which plays a critical role in the maintenance of hematopoietic stem cells and also in cancer cell homing to bone, was markedly decreased in mice treated with G-CSF. Flow cytometric analysis revealed that pretreatment of mice with G-CSF reduced the number of bone-homing cancer cells. G-CSF also increased the population of myeloid-derived suppressor cells (MDSCs) in bone marrow. Depletion of MDSCs using anti-Gr-1 antibody treatment significantly decreased the metastatic tumor burden in bone. The overall effects of G-CSF on bone metastases were finally examined using two different treatment protocols. When mice were treated with G-CSF prior to the tumor cell inoculation, G-CSF did not change bone metastatic-tumor burden. In contrast, when G-CSF treatment was started after the tumor cells had homed to bone, G-CSF significantly accelerated bone metastases formation. These results suggest that G-CSF suppressed cancer cell homing to bone by downregulating CXCL12 expression in bone marrow stromal cells, whereas G-CSF stimulated the progression of bone metastases at least in part by MDSC-mediated mechanisms. IMPLICATIONS: G-CSF had opposing effects on the initiation and progression of bone metastases of breast cancer and the balance may regulate the metastatic tumor burden.

Targeting the Wnt signaling pathway for breast cancer bone metastasis therapy.

Osteolytic bone destruction is found in approximately 60% of advanced breast cancer patients. With the pathogenesis of bone metastasis being unclear, traditional antiresorptive therapeutic strategies might not be ideal for treatment. The Wnt pathway is a highly organized cascade involved in multiple stages of cancer bone metastasis, and Wnt-targeted therapeutic strategies have shown promise in achieving favorable outcomes. In this review, we summarize the current progress of pharmacological Wnt modulators against breast cancer bone metastasis, discuss emerging therapeutic strategies based on Wnt pathway-related targets for bone therapy, and highlight opportunities to better harness the Wnt pathway for bone metastasis therapeutics to further reveal the implications of the Wnt pathway in bone metastasis pathology and provide new ideas for the development of Wnt-based intervention strategies against breast cancer bone metastasis.

Diagnostic Value of VDR in Bone Metastasis and Prognosis of Patients with Breast Cancer and Expression Correlation between Vitamin D Receptor and Hairless Protein

Background: Breast cancer is more likely to metastasize to the bone. Previous researches have revealed that the vitamin D receptor (VDR) contributes to breast cancer progression and bone metastasis in mouse and human breast cells, and hairless (Hr) protein interacts with VDR in the mammalian hair cycle. This study aimed to explore the expression of VDR/Hr in breast cancer, and the correlation between VDR/Hr and prognosis, bone metastasis, and metastasis-related prognosis. Methods: The expression of VDR and Hr was analyzed on 119 breast cancer tissues and corresponding normal breast tissue from each of the breast cancer samples by immunohistochemistry staining, and the databases were supplemented as well. Results: The expression of the VDR protein was significantly decreased in breast cancer patients (p < 0.05), inversely, the UALCAN (p = 0.000) and GEPIA (p > 0.05) databases showed that the VDR mRNA expression tended to be higher in tumor tissues. The Hr protein was expressed at a low level within breast cancer specimens (p < 0.05), which was in agreement with the level of Hr mRNA in UALCAN (p = 0.005) and GEPIA (p > 0.05). The protein levels of VDR and Hr were positively correlated (p > 0.05), while the mRNA levels suggested a close relationship with GEPIA (p < 0.05). Low expression of Hr protein displayed a tendency for longer overall survival (OS) and recurrence-free survival (RFS), and its mRNA data also revealed the same trend in the Kaplan-Meier dataset (both p > 0.05). However, VDR protein and mRNA with low expression had markedly shorter OS and RFS (both p < 0.05). The downregulation of VDR protein was significantly associated with an advanced stage (p < 0.05). Low VDR protein was an independent risk factor for poor prognosis (p < 0.05) and was negatively correlated with bone metastasis (p < 0.05). VDR protein and mRNA levels were both downregulated in breast cancer with bone metastasis (both p < 0.05). The area under ROC curve (AUC) for VDR protein expression to identify patients with bone metastasis was 0.661 (p < 0.05) and the AUC for VDR level to predict 1-year, 3-year, and 5-year OS was 0.621, 0.664, and 0.805 in patients with bone metastasis, respectively (p < 0.05). VDR with low expression accelerated bone metastasis and metastasis-related poor survival (both p < 0.05). Conclusion: VDR expression is a notable prognostic factor in primary breast cancer patients for predicting bone metastases and unfavorable clinical outcome.

Silencing CTNND1 Mediates Triple-Negative Breast Cancer Bone Metastasis via Upregulating CXCR4/CXCL12 Axis and Neutrophils Infiltration in Bone.

Simple SummaryDistant metastasis, especially bone metastasis, is the major cause of death in breast cancer patients. However, breast cancer patients with bone metastasis are frequently complicated by delayed intervention as clinically bone metastasis cannot be detected early enough. Here, we report that CTNND1 is downregulated in both primary tumors and metastatic bone lesions of patients with triple-negative breast cancer (TNBC). Decreased CTNND1 is a crucial intrinsic contributor to homing to the bones and the survival of the breast cancer cells in the bone microenvironment. Thus, CTNND1 may be a novel biomarker for early predicting bone metastasis of triple-negative breast cancer.Bone metastasis from triple-negative breast cancer (TNBC) frequently results in poorer prognosis than other types of breast cancer due to the delay in diagnosis and intervention, lack of effective treatments and more skeletal-related complications. In the present study, we identified CTNND1 as a most reduced molecule in metastatic bone lesion from TNBC by way of high throughput sequencing of TNBC samples. In vivo experiments revealed that knockdown of CTNND1 enhanced tumor cells metastasis to bones and also increased neutrophils infiltration in bones. In vitro, we demonstrated that knockdown of CTNND1 accelerated epithelial–mesenchymal transformation (EMT) of tumor cells and their recruitment to bones. The involvement by CTNND1 in EMT and bone homing was achieved by upregulating CXCR4 via activating the PI3K/AKT/HIF-1αpathway. Moreover, TNBC cells with reduced expression of CTNND1 elicited cytotoxic T-cells responses through accelerating neutrophils infiltration by secreting more GM-CSF and IL-8. Clinically, patients with triple-negative breast cancer and lower level of CTNND1 had shorter overall survival (OS) and distant metastasis-free survival (DMFS). It was concluded that downregulation of CTNND1 played a critical role in facilitating bone metastasis of TNBC and that CTNND1 might be a potential biomarker for predicting the risk of bone metastases in TNBC.

Punicalin Attenuates Breast Cancer-Associated Osteolysis by Inhibiting the NF-κB Signaling Pathway of Osteoclasts.

Background: Breast cancer bone metastasis and osteoporosis are both severe diseases that seriously threaten human health. These diseases are closely associated with osteolytic lesions. And osteoclasts are the key targets of this pathological process. Given the lack of effective preventive or treatment options against these diseases, the exploitation of new pharmacological agents is critically required. Method: We assessed the efficacy of punicalin on receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclast formation, F-actin ring formation, gene expression, bone resorption, nuclear factor-κB (NF-κB) as well as on mitogen-activated protein kinase (MAPK) signaling pathways and molecular docking in vitro. The impact of punicalin on breast cancer-induced osteoclastogenesis, breast cancer cell proliferation, and apoptosis were examined. Transwell assays were also performed. Moreover, we evaluated in vivo effects of punicalin in postmenopausal osteoporosis models and breast cancer bone metastasis model by micro-CT scanning and histomorphometry. Results: Punicalin inhibited osteoclast formation, F-actin ring formation, bone resorption, as well as osteoclast-related gene expression by suppressing the NF-κB signaling pathway. In vitro, punicalin also suppressed the breast cancer-induced osteoclastogenesis, and proliferation, migration as well as invasion of MDA-MB-231 cells and dose-dependently promoted their apoptosis. In vivo, punicalin significantly suppressed breast cancer-induced osteolysis, breast cancer-associated bone metastasis, and ovariectomized (OVX)-mediated osteoporosis by repressing osteoclast and breast cancer cell. Conclusion: Punicalin is expected to offer a novel treatment for the prevention of osteolysis diseases, including osteoporosis and breast cancer-associated osteolysis.