Breast Cancer-induced Bone Research Articles

Primary Bone Tumors and Breast Cancer-Induced Bone Metastases: In Vivo Animal Models and New Alternative Approaches

Bone is the preferential site of metastasis for the most common tumors, including breast cancer. On the other hand, osteosarcoma is the primary bone cancer that most commonly occurs and causes bone cancer-related deaths in children. Several treatment strategies have been developed so far, with little or no efficacy for patient survival and with the development of side effects. Therefore, there is an urgent need to develop more effective therapies for bone primary tumors and bone metastatic disease. This almost necessarily requires the use of in vivo animal models that better mimic human pathology and at the same time follow the ethical principles for the humane use of animal testing. In this review we aim to illustrate the main and more suitable in vivo strategies employed to model bone metastases and osteosarcoma. We will also take a look at the recent technologies implemented for a partial replacement of animal testing.

ART26.12, a novel fatty acid-binding protein 5 inhibitor, shows efficacy in multiple preclinical neuropathy models.

Painful neuropathy is a pathological condition caused by numerous factors including diabetes, chemotherapy or cancer. ART26.12 is a novel fatty acid-binding protein 5 inhibitor, which our group showed could prevent and treat persistent pain in a preclinical model of oxaliplatin-induced peripheral neuropathy. In the current study, the efficacy of orally dosed ART26.12 was tested in multiple neuropathy models of different aetiology. Paw withdrawal threshold to von Frey monofilaments and latency to escape a cold plate were used as measurements of mechanical and cold sensitivity. ART26.12 (25 and 50 mg/kg BID), dosed prior to the induction of paclitaxel-induced peripheral neuropathy (PIPN), reversed mechanical allodynia induced by paclitaxel in both male and female rats, and ART26.12 (50 mg/kg BID) prevented the induction of PIPN in female rats. ART26.12 (50 mg/kg BID) also had a protective effect on body weight in the PIPN model. ART26.12 (25 and 100 mg/kg BID) reversed mechanical allodynia when treating established streptozotocin-induced diabetic neuropathy in male rats. In a model of breast cancer-induced bone pain in female rats, ART26.12 (100 mg/kg BID) reversed mechanical allodynia within 1 h of dosing. In the same model, ART26.12 (25 mg/kg BID) reversed mechanical allodynia from day 4 of treatment. Overall, these preclinical data suggest that ART26.12 is a safe and efficacious therapeutic drug for continued development towards the prevention and treatment of peripheral neuropathy. This work now shows that ART26.12, a novel and selective inhibitor of FABP5, can prevent and treat multiple preclinical models of peripheral neuropathy. Given its excellent safety profile, further work is warranted to develop ART26.12 as a potential therapeutic tool for pain management.

Oroxylin A suppresses breast cancer-induced osteoclastogenesis and osteolysis as a natural RON inhibitor

BackgroundMalignant breast cancer cells trigger the over-activation of osteoclast precursor cells, leading to bone loss and severe pain. Targeted inhibition of osteoclast differentiation has emerged as an important strategy for treating bone syndromes induced by breast cancer. PurposeThe objective is to discover natural osteoclast inhibitor to treat osteoclastogenesis and bone destruction induced by breast cancer, and clarify the specific mechanisms. MethodsRecepteur d'origine Nantais (RON) protein was employed to search the natural osteoclast inhibitor for breast cancer-induced osteoclastogenesis by molecular docking, molecular dynamics simulation and cellular thermal shift assay (CETSA). In the in vitro experiment, breast cancer MDA-MB-231 cell-conditioned medium (MDA-MB-231 CM) was used to induce osteoclastogenesis in murine bone marrow-derived macrophages (BMMs), aiming to elucidate the effects and mechanisms of the natural osteoclast inhibitor. In the in vivo model, MDA-MB-231 cells was injected into the mouse tibia to evaluate the therapeutic effect of drug on breast cancer-induced bone destruction. ResultsWe discovered a significant increase in the expression of RON during MDA-MB-231 CM-induced osteoclast differentiation in vitro. Molecular docking analysis found that oroxylin A (OA), a flavonoid derived from the Chinese medicine Scutellaria baicalensis Georgi, showed binding ability with RON, while its impact and mechanism on breast cancer-induced osteoclastogenesis and osteolysis remains unclear. Molecular dynamics simulation and CETSA further revealed that OA bound directly to the RON protein, and it also decreased RON expression in breast cancer CM-induced osteoclastogenesis. Correspondingly, OA suppressed the MDA-MB-231 CM-induced osteoclastogenesis and bone resorption in vitro. The downstream signals of RON including Src and NFATc1, as well as the osteoclast-specific genes, were downregulated by OA. Of interesting, the suppressive effect of OA on osteoclastogenesis induced by MDA-MB-231 CM was abolished after RON was knocked down by the specific RON-siRNA, this further confirmed that OA showed inhibitory effects on osteoclasts through targeting RON. In addition, we found that OA attenuated MDA-MB-231 cell-induced osteolysis and reduced the number of osteoclasts in vivo. ConclusionOur results indicate that OA acts as a natural RON inhibitor to suppress breast cancer-induced osteoclastogenesis and osteolysis. This provides new strategy for treating breast cancer-induced bone destruction and related syndromes.

Abstract 6772: A 3D model of breast cancer-bone metastasis to mimic dysregulation of bone remodeling and drug response

Abstract Introduction: Bone metastases are common among advanced stage breast cancer patients and induce dysregulation of bone remodeling. Crosstalk between cancer cells and the bone niche drives the vicious cycle of bone loss and breast cancer growth. To accelerate discovery of targeted therapies, there is a critical need for experimental models that can mimic breast cancer-induced dysregulation of bone remodeling in patients. Mouse models are the current gold standard, but are low throughput, costly, and cannot fully recapitulate human-human cell interactions. To address these limitations, our goal is to engineer a fully human 3D in vitro model of breast cancer-bone metastasis that can mimic dysregulation of bone remodeling and drug responses in patients, and enable screening of potential new drug candidates. Methods: Two human breast cancer cell lines (MDA-MB-231, MCF-7) were chosen given their well characterized clinical features and tendency to invade bone. Our 3D model comprises an outer ring of tissue engineered (TE) bone and a center of breast cancer cells to mimic invasion through the bone marrow/long bone interface. Human mesenchymal stem cells were encapsulated in 3D gelatin microribbon scaffolds and cultured in osteogenic media for 28 days to form TE bone. Human monocyte-derived osteoclasts were seeded onto the bone, and the center was replaced with GFP-labeled breast cancer cells. Denosumab and zoledronic acid were selected as they are standard treatments for reducing bone loss in patients, and were used to treat the model at 30 µg/mL and 2 µg/mL, respectively. Intermittent parathyroid hormone (iPTH) treatment was selected as it showed efficacy in animal models, and was used to treat the model at 10 µg/mL for 6 hours daily. All groups were treated with drugs for 14 days. Bone volume was assessed using microCT. Cancer cell proliferation and invasion into bone was monitored with fluorescence confocal microscopy. Results: MicroCT imaging showed both breast cancer cell lines induced bone loss in the triculture model, compared to the control with no breast cancer cells in the center. Consistent with known clinical features, the more aggressive cell line (MDA-MB-231) induced a greater amount of bone loss than the less aggressive breast cancer cell line (MCF-7). Consistent with clinical findings, both denosumab and zoledronic acid reduced bone loss in our 3D model, and zoledronic acid further reduced breast cancer cell invasion and proliferation. Finally, the 3D model recapitulated the in vivo drug response of iPTH treatment, reducing bone resorption and breast cancer invasion. Conclusions: Here we report a fully human triculture model of breast cancer-bone metastasis that can mimic key clinical features of breast cancer-induced bone resorption and drug response in patients. Such a 3D model could enable screening of drug candidates with reduced time and cost and enable identification of novel druggable targets. Citation Format: Michelle Tai, Eva C. González Díaz, Callan E. Monette, Joy Wu, Fan Yang. A 3D model of breast cancer-bone metastasis to mimic dysregulation of bone remodeling and drug response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6772.

Erianin serves as an NFATc1 inhibitor to prevent breast cancer-induced osteoclastogenesis and bone destruction

IntroductionBreast cancer-related bone metastasis can lead to skeletal-related events (SREs), which decrease patient quality of life. Inhibition of osteoclastogenesis is a key treatment for SREs; however, the availability of clinical drugs remains limited, and all existing ones disrupt physiological bone formation, while exhibiting no effect on patient survival time. ObjectivesThis study aimed to identify a novel osteoclast inhibitor for the treatment of breast cancer-induced SREs. MethodsThe MDA-MB-231 breast cancer cell-induced bone loss model was used to investigate the therapeutic effects of erianin in vivo. Then, we evaluated the inhibitory effects of erianin on osteoclastogenesis and signalling in bone marrow-derived macrophages (BMMs) induced by conditioned medium from MDA-MB-231 breast cancer cells (231 CM) and receptor activator of nuclear factor-κB ligand (RANKL) in vitro. Next, a Cellular Thermal Shift Assay and siRNA-mediate knockdown were performed, to investigate the target of erianin during osteoclast formation. The effects of erianin on human osteoclastogenesis were evaluated using CD14+ monocytes obtained from patients with breast cancer. ResultsErianin effectively improved breast cancer cells-induced bone destruction at doses of 2 and 20 mg/kg/day in vivo, while suppressing osteoclastogenesis and the upregulation of SRC-NFATc1, INTEGRIN β3-MMP9 signals induced by 231 CM and RANKL in vitro. Furthermore, erianin interacted with NFATc1 but not SRC, and Nfatc1 knockdown eliminated the inhibitory effects of erianin on osteoclastogenesis. Notably, lower expression of NFATc1 positively correlated with longer survival in patients with cancer and a high risk of bone metastasis. We further revealed that 62.5–250 nM erianin suppresses NFATc1 and excessive osteoclastogenesis in CD14+ monocytes from patients with breast cancer. ConclusionErianin acts as an NFATc1 inhibitor that attenuates breast cancer-induced osteoclastogenesis and bone destruction.

Polyphyllin VII protects from breast cancer-induced osteolysis by suppressing osteoclastogenesis via c-Fos/NFATc1 signaling

Bone is a preferred metastatic site of advanced breast cancer and the 5-year overall survival rate of breast cancer patients with bone metastasis is only 22.8%. Targeted inhibition of osteoclasts can treat skeletal-related events (SREs) in breast cancer patients. Polyphyllin VII (PP7), a pennogenyl saponin isolated from traditional Chinese herb Paris polyphylla, exhibits strong anti-inflammatory and anti-cancer activities. In this study, we evaluated the effect of PP7 on metastatic breast cancer-induced bone destruction in vivo and the underlying mechanisms. We found that intraperitoneal injection of 1 mg/kg PP7 significantly ameliorated the breast cancer MDA-MB-231 cell-induced osteolysis in mice. Mechanistically, PP7 (0.125–0.5 μM) inhibited the conditioned medium of MDA-MB-231 cells (MDA-MB-231 CM)-induced osteoclast formation in bone marrow-derived macrophages (BMMs). Furthermore, PP7 markedly reduced MDA-MB-231 CM-induced osteoclastic bone resorption and F-actin rings formation in vitro. During MDA-MB-231 CM-induced osteoclastogenesis, the activation of c-Fos and NFATc1 signaling was significantly downregulated by PP7, and finally osteoclast-related genes such as Oscar, Atp6v0d2, Mmp9 and β3 integrin were decreased. In addition, the formation of osteoblast was promoted by PP7 treatment. Our current findings revealed PP7 as a potential safe agent for preventing and treating bone destruction in breast cancer patients with bone metastases.

Solvent-dependent hypsochromic shift in the imidazole based complex [Cu(µ2-SO4)(Im)4] and ameliorative effects on breast cancer-induced bone metastases associated oxidative injury in rats

A sulfate-bridged complex [Cu(µ2-SO4)(Im)4] (1) was prepared and structurally characterized, where Im: imidazole. The X-ray structure analysis reveals that 1 crystallizes in the monoclinic system with space group C2/c. The octahedral coordination around the metal center is made up of four distinct imine nitrogen atoms in the equatorial plane, and two sulfate oxygen atoms occupying the axial sites. The covalent linkage between metals via the sulfate group, forming infinite 1D zigzag chains, ensures the entanglement of the structure. These chains, in turn, are further assembled into a 2D network through NH⋯O hydrogen bonding. Thermal analyses underline the high thermal stability of our complex, which starts to decompose at 200 °C. The infrared spectrum confirms the results obtained from the crystallographic analysis. Optical studies reveal the presence of a hypsochromic effect noticed in the absorption and photoluminescence spectra. The synthesized compound was found to reduce both oxidative injury and histopathological features, which are associated with skeletal metastases as a result of malignant Walker 256/B breast cancer cells.

A nanoagent for concurrent therapy of breast cancer bone metastasis and cancer-induced bone pain through SLC7A11 interruption and photodynamic therapy

Bone metastasis, a life-threatening complication of advanced breast cancer, is often accompanied by debilitating pain (cancer-induced bone pain, CIBP) that severely impairs life quality and survival. The concurrent treatment of bone metastases and CIBP remains a clinical challenge because the therapeutic options are limited. In this study, we construct a near-infrared light-activated nano-therapeutic system to meet this conundrum. In detail, sorafenib (SRF) and photosensitizer (chlorin e6, Ce6) are encapsulated into mesoporous hydroxyapatite nanoparticles (HANPs), which are further functionalized with hyaluronic acid (HA) to obtain HA-SRF/Ce6@HANPs system. The designed nanoplatform destroys tumor cells in vitro and in vivo via the synergism of SRF (interrupting the exchange of cystine/glutamate by inhibiting SLC7A11) and photodynamic therapy (PDT, inducing reactive oxygen species generation). The decrease in tumor burden and reduction of extracellular glutamate significantly attenuate CIBP in mice model with developing bone cancer. Moreover, the combination of HA-SRF/Ce6@HANPs and PDT inhibit osteoclasts activation, promote osteoblast differentiation and accelerate bone repair. Overall, the nanoagent with good biocompatibility may provide an effective therapy method for the concurrent treatment of breast cancer bone metastasis and CIBP.

Withaferin A inhibits breast cancer-induced osteoclast differentiation.

Bone is the most prone to metastatic spread of breast cancer cells for each subtype of the disease. Bone metastasis-related complications including severe pain and pathological fractures affect patients' quality of life. Current treatment options including surgery, radiation, and bone-targeted therapies (e.g., bisphosphonates) are costly or have serious adverse effects such as renal toxicity and osteonecrosis of the jaws. Therefore, a safe, inexpensive, and efficacious agent for prevention of breast cancer bone metastasis is urgently needed. Our previously published RNA sequencing analysis revealed that many genes implicated in bone remodeling and breast cancer bone metastasis were significantly downregulated by treatment with withaferin A (WA), which is a promising cancer chemopreventive agent derived from a medicinal plant (Withania somnifera). The present study investigated whether WA inhibits breast cancer induction of osteoclast differentiation. At plasma achievable doses, WA treatment inhibited osteoclast differentiation (osteoclastogenesis) induced by three different subtypes of breast cancer cells (MCF-7, SK-BR-3, and MDA-MB-231). WA and the root extract of W. somnifera were equally effective for inhibition of breast cancer induction of osteoclast differentiation. This inhibition was accompanied by suppression of interleukin (IL)-6, IL-8, and receptor activator of nuclear factor-κB ligand, which are pivotal osteoclastogenic cytokines. The expression of runt-related transcription factor 2, nuclear factor-κB, and SOX9 transcription factors, which positively regulate osteoclastogenesis, was decreased in WA-treated breast cancer cells as revealed by confocal microscopy and/or immunoblotting. Taken together, these data suggest that WA could be a promising agent for prevention of breast cancer-induced bone metastasis.

Cyclin D1 mediates pain behaviour in a rat model of breast cancer-induced bone pain by a mechanism involving regulation of the proliferation of spinal microglia.

The involvement of cyclin D1 in the proliferation of microglia, and the generation and maintenance of bone cancer pain (BCP), have not yet been clarified. We investigated the expression of microglia and cyclin D1, and the influences of cyclin D1 on pain threshold. Female Sprague Dawley (SD) rats were used to establish a rat model of BCP, and the messenger RNA (mRNA) and protein expression of ionized calcium binding adaptor molecule 1 (IBA1) and cyclin D1 were detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blot, respectively. The proliferation of spinal microglia was detected by immunohistochemistry. The pain behaviour test was assessed by quantification of spontaneous flinches, limb use, and guarding during forced ambulation, mechanical paw withdrawal threshold, and thermal paw withdrawal latency. IBA1 and cyclin D1 in the ipsilateral spinal horn increased in a time-dependent fashion. Spinal microglia proliferated in BCP rats. The microglia inhibitor minocycline attenuated the pain behaviour in BCP rats. The cyclin-dependent kinase inhibitor flavopiridol inhibited the proliferation of spinal microglia, and was associated with an improvement in pain behaviour in BCP rats. Our results revealed that the inhibition of spinal microglial proliferation was associated with a decrease in pain behaviour in a rat model of BCP. Cyclin D1 acts as a key regulator of the proliferation of spinal microglia in a rat model of BCP. Disruption of cyclin D1, the restriction-point control of cell cycle, inhibited the proliferation of microglia and attenuated the pain behaviours in BCP rats. Cyclin D1 and the proliferation of spinal microglia may be potential targets for the clinical treatment of BCP.Cite this article: Bone Joint Res2022;11(11):803-813.

Predicting Response to Radiotherapy in Breast Cancer-Induced Bone Pain: Relationship Between Pain and Serum Cytokine Expression Levels After Radiotherapy.

Breast cancer is the second leading cause of cancer-associated death in women. Herein, we explored the associations of cytokines, pain, and bone metastasis between patients before and after radiotherapy in breast cancer with bone metastasis. The pain caused by metastasis was effectively relieved by external radiation therapy. However, the underlying mechanisms remain unknown. In this case-controlled study, we enrolled healthy individuals (n = 10) and bone metastatic cancer patients (n = 30). Peripheral venous blood samples were collected from healthy controls, and one week before and after radiotherapy, the peripheral venous blood and clinical characteristics of cancer patients were collected. We analyzed the blood cytokine profile, quality of life (QOL), and pain score of patients pre- and post-radiotherapy to explore the possible causes of pain relief. Both the pain score and QOL significantly improved after radiotherapy. The serum cytokine profiles of patients were significantly different before radiotherapy than after. Meanwhile, only three cytokines differed between post-radiotherapy and healthy controls. We believe radiotherapy stimulated local immune storms in bone tissue and promoted significant changes in cytokines pre- and post-radiotherapy. Therefore, the bone microenvironment of early breast cancer patients with bone metastasis pain can be restored after radiotherapy. Restoring a healthy bone environment can not only relieve the pain but also improve the patient's QOL. Tumor cells can effectively activate immune cells in the bone microenvironment through direct interaction, releasing many factors and promoting bone metastasis. Early local radiotherapy of bone metastases can restore the microenvironment and improve the QOL and prognosis of patients, thereby comprehending a novel target for prevention, treatment, and therapy of bone metastases.

MicroRNA-506 ameliorates breast cancer-induced osteolytic bone metastasis via the NFATc-1 signaling pathway.

Breast cancer is becoming a common life-threatening disease, especially in women, along with higher incidence and mortality. MicroRNA (miR)-506 was reported to participate in breast cancer progression, while the role of miR-506 in breast cancer-induced osteolytic bone metastasis is unclear. In the present study, we found significant downregulation of miR-506 in breast cancer tissues and cell lines. Overexpression of miR-506 notably reduced the proliferative, migratory and invasive rates of MCF7 and MDA-MB-231 cells, and reduced the production of inflammatory factors IL-6 and TNF-α in MCF7 cells. Moreover, overexpression of miR-506 obviously inhibited tumor growth in an in vivo animal model. In addition, overexpression of miR-560 efficiently attenuated breast cancer-induced osteolysis in vivo, which was characterized by increased bone volume/total volume (BT/TV), trabecular number (Tb. N), and trabecular thickness (Tb. Th), as well as the reduced trabecular separation (Tb. Sp). The nuclear factor of activated T cell cytoplasmic 1 (NFATc1) was identified as a downstream target of miR-506, and overexpression of miR-506 could inhibit breast cancer progression by targeting NFATc1. Furthermore, our results showed that NFATc-1 might participate in the inhibition of miR-506 on breast cancer-induced osteolysis. In conclusion, our findings provide insights into understanding the pathogenesis of breast cancer and breast cancer-induced osteolytic bone metastasis, and miR-506 might serve as a novel biomarker for this disease.

Phytochemicals in Breast Cancer-Induced Osteoclastogenesis and Bone Resorption: Mechanism and Future Perspective

Phytochemicals in Breast Cancer-Induced Osteoclastogenesis and Bone Resorption: Mechanism and Future Perspective

Liquid biopsies in primary and secondary bone cancers.

Liquid biopsies are a powerful tool to non-invasively analyze tumor phenotype and progression as well as drug resistance. In the bone oncology field, liquid biopsies would be particularly important to develop, since standard biopsies can be very painful, dangerous (e.g., when found in proximity to the spinal cord), and hard to collect. In this review, we explore the recent advances in liquid biopsies in both primary (osteosarcoma and Ewing sarcoma) and secondary bone cancers (breast, prostate, and lung cancer-induced bone metastases), presenting their current role and highlighting their unexpressed potential, as well as the barriers limiting their possible adoption, including costs, scalability, reproducibility, and isolation methods. We discuss the use of circulating tumor cells, cell-free circulating tumor DNA, and extracellular vesicles for the purpose of improving diagnosis, prognosis, evaluation of therapy resistance, and driving therapy decisions in both primary and secondary bone malignancies.

Inflammatory conversion of quiescent osteoblasts by metastatic breast cancer cells through pERK1/2 aggravates cancer-induced bone destruction

Disruption of bone homeostasis caused by metastatic osteolytic breast cancer cells increases inflammatory osteolysis and decreases bone formation, thereby predisposing patients to pathological fracture and cancer growth. Alteration of osteoblast function induces skeletal diseases due to the disruption of bone homeostasis. We observed increased activation of pERK1/2 in osteolytic breast cancer cells and osteoblasts in human pathological specimens with aggressive osteolytic breast cancer metastases. We confirmed that osteolytic breast cancers with high expression of pERK1/2 disrupt bone homeostasis via osteoblastic ERK1/2 activation at the bone-breast cancer interface. The process of inflammatory osteolysis modulates ERK1/2 activation in osteoblasts and breast cancer cells through dominant-negative MEK1 expression and constitutively active MEK1 expression to promote cancer growth within bone. Trametinib, an FDA-approved MEK inhibitor, not only reduced breast cancer-induced bone destruction but also dramatically reduced cancer growth in bone by inhibiting the inflammatory skeletal microenvironment. Taken together, these findings suggest that ERK1/2 activation in both breast cancer cells and osteoblasts is required for osteolytic breast cancer-induced inflammatory osteolysis and that ERK1/2 pathway inhibitors may represent a promising adjuvant therapy for patients with aggressive osteolytic breast cancers by altering the shared cancer and bone microenvironment.

Role of miRNAs in Breast Cancer-induced Bone Disease

AbstractBone is the most common site of breast cancer recurrence. Despite the increasing knowledge about the metastatic process and treatment advances, the disease still remains incurable once the cancer cells actively proliferate in bone. Complex interactions between cancer cells and cells of the bone microenvironment (BME) regulate the initiation and progression of metastatic tumor growth in bone. In particular, breast cancer cells shift the otherwise tightly balanced bone remodeling towards increased bone resorption by osteoclasts. Cellular interactions in the metastatic BME are to a large extent regulated by secreted molecules. These include various cytokines as well as microRNAs (miRNAs), small non-coding RNAs that post transcriptionally regulate protein abundance in several cell types. Through this mechanism, miRNAs modulate physiological and pathological processes including bone remodeling, tumorigenesis and metastasis. Consequently, miRNAs have been identified as important regulators of cellular communication in the metastatic BME. Disruption of the crosstalk between cancer cells and the BME has emerged as a promising therapeutic target to prevent the establishment and progression of breast cancer bone metastasis. In this context, miRNA mimics or antagonists present innovative therapeutic approaches of high potential for interfering with pathological bone – cancer cell interactions. This review will discuss the role of miRNAs in the tumor-BME crosstalk in vivo and will emphasize how this could be targeted by miRNAs to improve therapeutic outcome for patients with breast cancer bone metastases.

Spleen tyrosine kinase (SYK) inhibitor PRT062607 protects against ovariectomy-induced bone loss and breast cancer-induced bone destruction

Osteolytic diseases, including breast cancer-induced osteolysis and postmenopausal osteoporosis, are attributed to excessive bone resorption by osteoclasts. Spleen tyrosine kinase (SYK) is involved in osteoclastogenesis and bone resorption, whose role in breast cancer though remains controversial. Effects of PRT062607 (PRT), a highly specific inhibitor of SYK, on the osteoclast and breast cancer functionalities are yet to be clarified. This study demonstrated the in vitro inhibitory actions of PRT on the osteoclast-specific gene expression, bone resorption, and osteoclastogenesis caused by receptor activator of nuclear factor kappa B ligand (RANKL), as well as its in vitro suppressive effects on the growth, migration and invasion of breast carcinoma cell line MDA-MB-231, which were achieved through PLCγ2 and PI3K-AKT-mTOR pathways. Further, we proved that PRT could prevent post-ovariectomy (OVX) loss of bone and breast cancer-induced bone destruction in vivo, which agreed with the in vitro outcomes. In conclusion, our findings suggest the potential value of PRT in managing osteolytic diseases mediated by osteoclasts.

Graphene-modified CePO4 nanorods effectively treat breast cancer-induced bone metastases and regulate macrophage polarization to improve osteo-inductive ability

BackgroundBreast cancer bone metastasis has become one of the most common complications; however, it may cause cancer recurrence and bone nonunion, as well as local bone defects.MethodsHerein, In vitro, we verified the effect of bioscaffold materials on cell proliferation and apoptosis through a CCK8 trial, staining of live/dead cells, and flow cytometry. We used immunofluorescence technology and flow cytometry to verify whether bioscaffold materials regulate macrophage polarization, and we used ALP staining, alizarin red staining and PCR to verify whether bioscaffold material promotes bone regeneration. In vivo, we once again studied the effect of bioscaffold materials on tumors by measuring tumor volume in mice, Tunel staining, and caspase-3 immunofluorescence. We also constructed a mouse skull ultimate defect model to verify the effect on bone regeneration.ResultsGraphene oxide (GO) nanoparticles, hydrated CePO4 nanorods and bioactive chitosan (CS) are combined to form a bioactive multifunctional CePO4/CS/GO scaffold, with characteristics such as photothermal therapy to kill tumors, macrophage polarization to promote blood vessel formation, and induction of bone formation. CePO4/CS/GO scaffold activates the caspase-3 proteasein local tumor cells, thereby lysing the DNA between nucleosomes and causing apoptosis. On the one hand, the as-released Ce3+ ions promote M2 polarization of macrophages, which secretes vascular endothelial growth factor (VEGF) and Arginase-1 (Arg-1), which promotes angiogenesis. On the other hand, the as-released Ce3+ ions also activated the BMP-2/Smad signaling pathway which facilitated bone tissue regeneration.ConclusionThe multifunctional CePO4/CS/GO scaffolds may become a promising platform for therapy of breast cancer bone metastases.

A novel sulfate-bridged binuclear copper(ii) complex: structure, optical, ADMET andin vivoapproach in a murine model of bone metastasis

A novel complex, formulated as [Cu2(μ3-SO4)2(C4H6N2)4], showed significant ameliorative effects on tumor osteolytic lesions in malignant Walker 256/B breast cancer-induced bone metastases.

Asperolide A prevents bone metastatic breast cancer via the PI3K/AKT/mTOR/c-Fos/NFATc1 signaling pathway.

BackgroundBreast cancer is the leading cause of death among women with malignant tumors worldwide. Bone metastasis is the main factor affecting the prognosis of breast cancer. Therefore, both antitumor and anti‐breast‐cancer‐induced osteolysis agents are urgently needed.MethodsWe examined the effect of Asperolide A (AA), a marine‐derived agent, on osteolysis and RANKL‐induced phosphoinositide 3‐kinase (PI3K)/AKT/mTOR/c‐FOS/nuclear factor‐activated T cell 1 (NFATc1) pathway activation, F‐actin ring formation, and reactive oxygen species (ROS) generation in vitro. We evaluated AA effect on breast cancer MDA‐MB‐231 and MDA‐MB‐436 cells in vitro through CCK8 assay, wound healing assay, transwell assay, Annexin V‐FITC/PI staining for cell apoptosis, and cell cycle assay. Furthermore, we assessed the effect of AA in vivo using a breast cancer‐induced bone osteolysis nude mouse model, followed by micro‐computed tomography, tartrate‐resistant acid phosphatase staining, and hematoxylin and eosin staining.ResultsAsperolide A inhibited osteoclast formation and differentiation, bone resorption, F‐actin belt formation, ROS activity, and osteoclast‐specific gene and protein expressions and prevented PI3K/AKT/mTOR/c‐FOS/NFATc1 signaling activation in a dose‐dependent manner in vitro. AA also inhibited breast cancer growth and breast cancer‐induced bone osteolysis by reducing osteoclast formation and function and inactivated PI3K/AKT/mTOR signaling in vivo.ConclusionsOur study demonstrated that AA suppressed bone metastatic breast cancer. These findings indicate AA as a potential, novel curative drug candidate for patients with bone metastatic breast cancer.