Breast Cancer Bone Metastasis Research Articles

Select HDAC Inhibitors Enhance Osteolysis and Bone Metastasis Outgrowth but Can Be Mitigated With Bisphosphonate Therapy.

Breast cancer has a high predilection for spreading to bone with approximately 70% of patients who succumb to disease harboring bone disseminated tumor cells. Despite this high prevalence, treatments for bone metastatic breast cancer predominantly manage morbidities, including pain and hypercalcemia, rather than reducing bone metastasis incidence or growth. Histone deacetylase inhibitors (HDACi), including panobinostat, entinostat, and valproic acid, typically slow primary tumor progression and are currently in clinical trials for the treatment of many cancers, including primary and metastatic breast cancer, but their effects on bone metastatic disease have not been examined in preclinical models. We report that treatment with the HDACi panobinostat, but not entinostat or valproic acid, significantly reduced trabecular bone volume in tumor-naïve mice, consistent with previous reports of HDACi-induced bone loss. Surprisingly, treatment with entinostat or panobinostat, but not valproic acid, increased tumor burden and incidence in an experimental model of breast cancer bone metastasis. In vitro, multiple HDACi stimulated expression of pro-osteolytic genes in breast tumor cells, suggesting this may be a mechanism by which HDACi fuel tumor growth. In support of this, combination therapy of panobinostat or entinostat with the antiresorptive bisphosphonate zoledronic acid prevented bone metastatic progression; however, the addition of zoledronic acid to panobinostat therapy failed to fully correct panobinostat-induced bone loss. Together these data demonstrate that select HDACi fuel bone metastatic growth and provide potential mechanistic and therapeutic avenues to offset these effects. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Abstract IA012: Age related changes in the tumor microenvironment drive tumor progression

Abstract The stromal compartment plays a pivotal role in tumor progression. This is best illustrated in breast cancer bone metastases, where the stromal compartment supports tumor growth, albeit through poorly defined mechanisms. p38MAPKα is frequently expressed in tumor cells and surrounding stromal cells and its expression levels correlate with poor prognosis. Using clinically relevant breast cancer metastasis models, we show that orally administered, small-molecule inhibitors of p38MAPKα or its downstream kinase, MK2, each limited outgrowth of metastatic breast cancer cells in the bone and visceral organs. Further we found that this effect is mediated by inhibition of the p38MAPKα pathway within the stromal compartment. Beyond effectively limiting metastatic tumor growth, we also found that these inhibitors reduced tumor-associated and chemotherapy-induced bone loss, which is a devastating comorbidity for cancer patients that drastically impacts their quality of life. Mechanistic studies revealed that p38MAPKα’s ability to limit tumor growth within the bone is dependent on CD4 T cells and macrophages. To determine which cell types within the bone contribute to tumor growth and bone loss, we carried out single cell RNA-sequencing of stromal cells located within the bone metastatic lesion and cells outside the lesion. We found numerous differences that could explain how the stromal compartment contributes to tumor progression and bone loss and how inhibition of p38MAPKα or MK2 contribute. These data underscore the vital role stromal-derived factors play in tumor progression and identify the p38MAPK-MK2 pathway as a promising therapeutic target for metastatic disease and prevention of tumor-induced bone loss. Citation Format: Sheila A. Stewart. Age related changes in the tumor microenvironment drive tumor progression [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr IA012.

The role played by ailanthone in inhibiting bone metastasis of breast cancer by regulating tumor-bone microenvironment through the RANKL-dependent pathway.

Introduction: Bone metastasis of breast cancer (BC) is a process in which the disruption of the bone homeostatic microenvironment leads to an increase in osteoclast differentiation. Ailanthus altissima shows an inhibitory effect on osteoclast differentiation. Ailanthone (AIL) refers to a natural compound isolated from Ailanthus altissima, a Chinese herbal medicine, and has effective anti-tumor activity in numerous cell lines. Its impact on bone metastases for BC is yet unclear. Methods: We measured the effect of AIL on MDA-MB-231 cells by wound healing experiments, Transwell and colony formation experiment. Using the Tartrate-resistant Acid Phosphatase (TRAP) staining tests, filamentous (F-actin) staining and bone resorption test to detect the effect of AIL on the osteoclast cell differentiation of the Bone Marrow-derived Macrophages (BMMs), activated by the MDA-MB-231 cell Conditioned Medium (MDA-MB-231 CM) and the Receptor Activator of Nuclear factor-κB Ligand (RANKL),and to explore its possibility Mechanisms. In vivo experiments verified the effect of AIL on bone destruction in breast cancer bone metastasis model mice. Results: In vitro, AIL significantly decrease the proliferation, migration and infiltration abilities of MDA-MB-231 cells at a safe concentration, and also reduced the expression of genes and proteins involved in osteoclast formation in MDA-MB-231 cells. Osteoclast cell differentiation of the BMMs, activated by MDA-MB-231 CM and RANKL, were suppressed by AIL in the concentration-dependent manner. Additionally, it inhibits osteoclast-specific gene and protein expression. It was noted that AIL inhibited the expression of the osteoclast differentiation-related cytokines RANKL and interleukin-1β (IL-1β) that were secreted by the MDA-MB-231 cells after upregulating the Forkhead box protein 3 (FOXP3) expression. Furthermore, AIL also inhibits the expression of the Mitogen-Activated Protein Kinase (MAPK), Phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT), and Nuclear factor-κB Ligand (NF-κB) signaling pathways, which then suppresses the MDA-MB-231CM-induced development of Osteoclasts. Conclusion: Our study shows that AIL blocks osteoclast differentiation in the bone metastasis microenvironment by inhibiting cytokines secreted by BC cells, which may be a potential agent for the treatment of BC and its secondary bone metastasis.

Construction of a prognostic score model for breast cancer based on multi-omics analysis of study on bone metastasis.

Breast cancer (BRCA) is the most common type of cancer and the second leading cause of cancer-related death in women all over the world. Metastasis to bone is an indicator of poor prognosis in BRCA patients. This study aimed to develop a prognostic score model for predicting bone metastasis in patients with BRCA. BRCA-related RNA sequencing datasets and corresponding clinical information were downloaded from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA). Differentially expressed genes (DEGs) were screened using Limma package of R software. A risk score based predictive model was constructed based on the key genes identified through univariate Cox regression and the least absolute shrinkage and selection operator (LASSO) Cox regression. The gene expression profiles in BRCA patients were analyzed by gene set variation analysis (GSVA) and gene set enrichment analysis (GSEA). Random survival forest (RSF) analysis of BRCA patients with bone metastasis was conducted to identify the key DEGs. Based on DEG analysis, a total of 677 genes were identified as genes related to bone metastasis in BRCA. By univariate Cox regression and LASSO regression, 28 DEGs were identified as signature genes to develop the prognostic model. A risk score for each patient was created by incorporating the expression values of each specific gene and weighting them with the corresponding estimated regression coefficients. Patients were divided into a low-risk and a high-risk group based on the median risk score. Overall survival (OS) was significantly lower in the high-risk group. The receiver operating characteristic (ROC) curve and multi-omics analysis indicated that the model had high training/testing accuracy and a good clinical predictive value. We used extra data from GEO database to verify the robustness of the prognostic model, and the lower OS in high-risk group and area under the curve (AUC) value indicated the model had strong predictive efficacy for prognosis of BRCA. A prognostic prediction model was constructed based on 28 key DEGs identified through multi-omics analysis of studies on bone metastasis. The model may provide a promising method for distinguishing the high-risk BRCA patients and help on decision making in addition to prognosis prediction for BRCA patients.

Probing the interaction between metastatic breast cancer cells and osteoblasts in a thread-based breast-bone co-culture device.

Breast cancer metastasis to bone is a leading killer in breast cancer patients. A type I collagen-modified thread (Col-I@thread) was prepared for 3-dimensional cell culture and breast cancer bone metastasis co-culture device assembly. First, the coating of Col-I on nylon threads for promoting cell adhesion and growth was studied. Through SEM, XPS, and protein concentration measurements, it was found that the lyophilization method remarkably preserved the Col-I activity and the internal structure of the thread, thereby promoting cell attachment and proliferation. RNA-sequencing (RNA-Seq) and quantitative PCR analysis showed that osteoblast cells (MC3T3-E1) grown on Col-I@thread had elevated RUNX2, ALP, OPN, and Col-I gene expression to promote osteoblast differentiation. Single-cell analysis found that osteoblast MC3T3-E1 cells growing on Col-I@thread had higher Ca2+ secretion activity and mineralized nodules, suggesting robust cell activity and bone matrix formation than cells growing on 2D culture plates. Col-I@threads were knotted in an interdigital cross-finger frame to assemble the breast cancer-bone co-culture model. Confocal microscopy and flow cytometry tests quantified the invasive breast cancer cells. Moreover, the thread-based co-culture devices allowed us to isolate the invasive and non-invasive breast cancer cells to compare their molecular characteristics. qPCR results showed that expression of CX43, CXCR5, and CSPG4 genes was significantly increased in breast cancer cells with bone metastasis. Meanwhile, the expression of RUNX2 and OPG genes in osteoblasts was inhibited. The co-culture model based on the Col-I@thread mimics the bone tissue microenvironment to reveal the cross-talk between cancer cells and bone tissue. Moreover, the thread-based co-culture device is easy to fabricate and operate, providing a platform for exploring the cellular and molecular mechanisms of breast cancer bone metastasis, and holds potential for high-throughput screening of anti-breast cancer bone metastasis drugs.

Targeting SOST using a small-molecule compound retards breast cancer bone metastasis

BackgroundBreast cancer metastasis to the bone can be exacerbated by osteoporosis, is associated with poor long-term survival, and has limited therapeutic options. Sclerostin (SOST) is an endogenous inhibitor of bone formation, and an attractive target for treatment of osteoporosis. However, it is unclear whether SOST can be used as a therapeutic target for bone metastases of breast cancer, and whether small molecule compounds that target SOST in breast cancer cells can inhibit breast cancer bone metastasis.MethodsSOST expression in 442 breast cancer tissues was characterized by immunohistochemistry and statistically analyzed for the association with breast cancer bone metastases. Bone metastatic breast cancer SCP2 cells were induced for SOST silencing or overexpression and their bone metastatic behaviors were tested in vitro and in vivo. To identify potential therapeutics, we screened inhibitors of the interaction of SOST with STAT3 from a small chemical molecule library and tested the inhibitory effects of one inhibitor on breast cancer growth and bone metastasis in vitro and in vivo.ResultsWe found that up-regulated SOST expression was associated with breast cancer bone metastases and worse survival of breast cancer patients. SOST silencing significantly reduced the bone metastatic capacity of SCP2 cells. SOST interacted with STAT3 to enhance the TGF-β/KRAS signaling, increasing both tumor growth and bone metastasis. Treatment with one lead candidate, S6, significantly inhibited the growth of breast-cancer organoids and bone metastasis in mice.ConclusionsOur findings highlight a new class of potential therapeutics for treatment of bone metastasis in breast cancer.

The Binomial "Inflammation-Epigenetics" in Breast Cancer Progression and Bone Metastasis: IL-1β Actions Are Influenced by TET Inhibitor in MCF-7 Cell Line.

The existence of a tight relationship between inflammation and epigenetics that in primary breast tumor cells can lead to tumor progression and the formation of bone metastases was investigated. It was highlighted how the induction of tumor progression and bone metastasis by Interleukin-1 beta, in a non-metastatic breast cancer cell line, MCF-7, was dependent on the de-methylating actions of ten-eleven translocation proteins (TETs). In fact, the inhibition of their activity by the Bobcat339 molecule, an inhibitor of TET enzymes, determined on the one hand, the modulation of the epithelial-mesenchymal transition process, and on the other hand, the reduction in the expression of markers of bone metastasis, indicating that the epigenetic action of TETs is a prerequisite for IL-1β-dependent tumor progression and bone metastasis formation.

Yanghe decoction attenuated pain hypersensitivity induced by michigan cancer foundation-7 injection in rats with bone metastases from breast cancer by inhibiting transient receptor potential ankyrin 1.

To study the effect and underlying mechanisms of Chinese medicine Yanghe decoction on pain relief in a rat model of bone metastasis of breast cancer induced by michigan cancer foundation-7 (MCF-7). Bone pain was induced in the tibia of rats injected with MCF-7 cells. The Chinese herbal remedy was used to decoct Yanghe decoction for the treatment of bone pain rats. The behavior study was carried out to evaluate the paw mechanical withdraw threshold and thermal withdraw latency. Liquid chromatography-mass spectrometry, Western blotting, quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay (ELISA), immunohistochemical (IHC) staining were performed for analysis. Yanghe decoction could improve the defensive behavior similar to the transient receptor potential ankyrin 1 (TRPA1) inhibitor. In morphology study, Yanghe decoction could attenuate the cellular growth as well as inflammatory infiltration in the metastasis group. Furthermore, Yanghe decoction downregulated the TRPA1 expression on the dorsal root ganglion from the metastatic rats at both transcriptional and protein level. Yanghe decoction alleviated the inflammation in metastatic tissues by hematoxylin-eosin and IHC analysis, and Yanghe decoction also reduced the inflammatory cytokines production in the serum including tumor necrosis factor-α and interleukin-6, interleukin-1 beta by ELISA. As the cytochromec oxidase subunit II/prostaglandin E2 (PGE2) is required for cancer development, Yanghe decoction reduced the expression of PGE2 in the tissue and serum. Taken together, Yanghe decoction protected the rats from breast cancer bone metastasis through TRPA1 signaling mediated neuropathic pain and additional immune modulation in tumor microenvironment.

Mesoporous nanoplatform integrating photothermal effect and enhanced drug delivery to treat breast cancer bone metastasis.

Bone metastatic breast cancer has severely threatened the survival and life quality of patients. Due to the suboptimal efficacy of anti-metastatic chemotherapeutic drugs and the complicated bone marrow microenvironments, effective treatment of metastatic breast cancer remains challenging for traditional clinical approaches. In this work, we developed a mesoporous nanoplatform (m-CuS-PEG) with the co-loading of CuS nanodots and a chemotherapeutic drug cisplatin for the combined photothermal-chemotherapy of bone-metastasized breast cancer. The CuS nanodots were decorated onto mesoporous silica (m-SiO2) surface with dendritic mesoporous channels, into which the cisplatin was accommodated. The carboxyl-terminated poly (ethylene glycol) (PEG) was further functionalized onto the surface to obtain the functional nanoplatform m-CuS-PEG. The drug release of the loaded cisplatin exhibited pH- and thermal-dual responsive manner. The attached CuS nanodots rendered the mesoporous nanoplatform with high photothermal conversion ability. Upon irradiation with a near-infrared laser in the second near-infrared (NIR-II) window, m-CuS-PEG dispersions exhibited rapid temperature elevation and high photostability. The results revealed that m-CuS-PEG had excellent biocompatibility. The cisplatin-loaded m-CuS-PEG not only showed superior cancer cell-killing effects, but also significantly inhibit the growth of metastatic tumors. The tumor-induced bone destruction was also dramatically attenuated by the mesoporous nanoplatform-mediated combined therapy. Overall, the developed functional nanoplatform integrates photothermal therapy and efficient chemotherapeutic drug delivery to offer an alternative approach for combating breast cancer bone metastasis.

Bone Metastasis of Breast Cancer: Molecular Mechanisms and Therapeutic Strategies.

Bone metastasis is a common complication of many types of advanced cancer, including breast cancer. Bone metastasis may cause severe pain, fractures, and hypercalcemia, rendering clinical management challenging and substantially reducing the quality of life and overall survival (OS) time of breast cancer patients. Studies have revealed that bone metastasis is related to interactions between tumor cells and the bone microenvironment, and involves complex molecular biological mechanisms, including colonization, osteolytic destruction, and an immunosuppressive bone microenvironment. Agents inhibiting bone metastasis (such as bisphosphate and denosumab) alleviate bone destruction and improve the quality of life of breast cancer patients with bone metastasis. However, the prognosis of these patients remains poor, and the specific biological mechanism of bone metastasis is incompletely understood. Additional basic and clinical studies are urgently needed, to further explore the mechanism of bone metastasis and develop new therapeutic drugs. This review presents a summary of the molecular mechanisms and therapeutic strategies of bone metastasis of breast cancer, aiming to improve the quality of life and prognosis of breast cancer patients and provide a reference for future research directions.

Mouse Models of Tumor Bone Metastasis and Invasion for Studying CCN Proteins.

Bone metastasis and bone destruction are common occurrences in human malignancies, including breast, prostate, and lung cancer, and are associated with a high morbidity rate because of intractable bone pain, pathological fractures, hypercalcemia, and nerve compression. Animal models of bone metastasis and bone destruction are important tools to investigate the pathogenesis and develop treatment strategies. However, there are few models of spontaneous bone metastasis despite the fact that animals often spontaneously develop cancer. Here, we describe methods for developing a mouse model of breast cancer bone metastasis achieved by injection of MDA-MB-231 breast cancer cells into the left cardiac ventricle. In addition, we introduce mouse model of the bone destruction by injection of SAS oral squamous cell carcinoma cells into the bone marrow space of the right tibial metaphysis. These assays can be applied to studies on roles of cellular communication network factor/connective tissue growth factor (CTGF/CCN2) protein in tumor metastasis and development of treatment strategies targeting CCN proteins.

Good clinical practice and the use of hypofractionation radiation schedules as weapons to reduce the risk of COVID-19 infections in radiation oncology unit: A mono-institutional experience.

After coronavirus disease outbreak emerged in 2019, radiotherapy departments had to adapt quickly their health system and establish new organizations and priorities. The purpose of this work is to report our experience in dealing with COVID-19 emergency, how we have reorganized our clinical activity, changed our priorities, and stressed the use of hypofractionation in the treatment of oncological diseases. The patients' circuit of first medical examinations and follow-up was reorganized; a more extensive use of hypofractionated schedules was applied; a daily triage of the patients and staff, use of personal protective equipment, hand washing, environment sanitization, social distancing and limitations for the patients' caregivers in the department, unless absolutely essential, were performed; patients with suspected or confirmed COVID-19 were treated at the end of the day. In addition, the total number of radiotherapy treatment courses, patients and sessions, in the period from February 15 to April 30, 2020, comparing the same time period in 2018 were retrospectively investigated. In particular, changes in hypofractionated schedules adopted for the treatment of breast and prostate cancer and palliative bone metastasis were analyzed. Between February 15, and April 30, 2020, an increased number of treatments was carried out: Patients treated were overall 299 compared to 284 of the same period of 2018. Stressing the use of hypofractionation, 2036 RT sessions were performed, with a mean number of fractions per course of 6.8, compared to 3566 and 12.6, respectively, in 2018. For breast cancer, the schedule in 18 fractions has been abandoned and treatment course of 13 fractions has been introduced; a 27% reduction in the use of 40.5 Gy in 15 fractions, (67 treatments in 2018-49 in 2020) was reported. An increase of 13% of stereotactic body radiation therapy for prostate cancer was showed. The use of the 20 Gy in 4 or 5 sessions for the treatment of symptomatic bone metastasis decreased of 17.5% in favor of 8 Gy-single fraction. Three patients results COVID-19 positive swab: 1 during, 2 after treatment. Only one staff member developed an asymptomatic infection. The careful application of triage, anti-contagion and protective measures, a more extensive use of hypofractionation allowed us to maintain an effective and continuous RT service with no delayed/deferred treatment as evidenced by the very low number of patients developing COVID-19 infection during or in the short period after radiotherapy. Our experience has shown how the reorganization of the ward priority, the identification of risk factors with the relative containment measures can guarantee the care of oncological patients, who are potentially at greater risk of contracting the infection.

Anterior Gradient 2 is a Significant Prognostic Biomarker in Bone Metastasis of Breast Cancer.

Background: The study aimed to detect DEGs associated with BRCA bone metastasis, filter prognosis biomarkers, and explore possible pathways. Methods: GSE175692 dataset was used to detect DEGs between BRCA bone metastatic cases and non-bone metastatic cases, followed by the construction of a PPI network among DEGs. The main module among the PPI network was then determined and pathway analysis on genes within the module was performed. Through performing Cox regression, Kaplan-Meier, nomogram, and ROC curve analyses using GSE175692 and GSE124647 datasets at the same time, the most significant prognostic biomarker was gradually filtered. Finally, important pathways associated with prognostic biomarkers were explored by GSEA analysis. Results: The 74 DEGs were detected between bone metastasis and non-bone metastasis groups. A total of 15 nodes were included in the main module among the whole PPI network and they mainly correlated with the IL-17 signaling pathway. We then performed Cox analysis on 15 genes using two datasets and only enrolled the genes with p < 0.05 in Cox analysis into the further analyses. Kaplan-Meier analyses using two datasets showed that the common biomarker AGR2 expression was related to the survival time of BRCA metastatic cases. Further, the nomogram determined the greatest contribution of AGR2 on the survival probability and the ROC curve revealed its optimal prognostic performance. More importantly, high expression of AGR2 prolonged the survival time of BRCA bone metastatic patients. These results all suggested the importance of AGR2 in metastatic BRCA. Finally, we performed the GSEA analysis and found that AGR2 was negatively related to IL-17 and NF-kβ signaling pathways. Conclusion: AGR2 was finally determined as the most important prognostic biomarker in BRCA bone metastasis, and it may play a vital role in cancer progression by regulating IL-17 and NF-kB signaling pathways.

Pigment epithelium-derived factor downregulation in oestrogen receptor positive breast cancer bone metastases is associated with menopause

Pigment epithelium-derived factor (PEDF) has a critical role in bone development and anti-tumour function in breast cancer (BC). As the expression and role of PEDF in BC bone metastases is unknown, we aimed to characterise PEDF in primary and metastatic BC. Subcellular PEDF localisation was semi-quantitatively analysed via immunohistochemistry in patient-matched, archived formalin-fixed paraffin-embedded primary BC and liver, lung, and decalcified bone metastases specimens. PEDF localisation was evaluated in 23 metastatic BC patients diagnosed with ER+, human epidermal growth factor receptor-2 (HER2) negative BC or TNBC. Cytoplasmic (p = 0.019) and membrane (p = 0.048) PEDF was lower in bone metastases compared to primary ER+/HER2- BC. In contrast, nuclear PEDF scores were higher in metastases compared to primary TNBC (p = 0.027), and increased membrane PEDF in metastatic tissue had improved disease-free interval (p = 0.016). Nuclear PEDF was decreased in bone metastases compared to primary ER+//HER2- BC in post-menopausal patients (p = 0.029). These novel findings indicate PEDF plays a role in clinical BC metastasis. Significantly lower PEDF levels in the post-menopausal compared to pre-menopausal setting suggests future PEDF research may have greater clinical importance in the post-menopausal ER+/HER2- BC population.

Intravascular Administration of Acridine Orange and Zoledronate in a Bone Metastasis Model of Breast Cancer.

This study evaluated the effect of haematogenous administration of acridine orange (AO) alone and in combination with zoledronate (ZOL) on bone metastases. E0771 cells (1.0×105 cells/10 μl) were injected directly into the right femur of female mice. The mice were divided into five groups according to treatment (drugs and irradiation) and were reared and sacrificed after 6 weeks. Micro-computed tomography (μCT) was performed to calculate the destruction rate of the femur bone. We measured tumour weight and volume at sacrifice and performed terminal deoxynucleotidyl transferase dUTP Nick-End Labelling staining of tumours. At 4 weeks, the bone destruction rate was lower in the AO+ZOL group than in the radiation group. At 6 weeks, the AO+ZOL group had a lower bone destruction rate than the control and radiation groups; the ZOL group had a lower rate than the radiation group. The AO and AO+ZOL groups had suppressed tumour weight and volume compared to the control and radiation groups. The number of extraosseous apoptotic cells was higher in the AO+ZOL group than in all other groups except the AO group. In a model of local bone metastasis of breast cancer, haematogenous administration of AO reduced tumour size and more so when combined with ZOL.

YTHDF2-mediated FGF14-AS2 decay promotes osteolytic metastasis of breast cancer by enhancing RUNX2 mRNA translation.

LncRNA FGF14-AS2 is a critical suppressor in breast cancer (BCa) metastasis. However, whether FGF14-AS2 plays a role in the bone metastasis of BCa remains unknown. TRAP assay and intratibial injection were carried out to evaluate the role of FGF14-AS2 in BCa bone metastasis in vitro and in vivo. Polyribosome profiling was done to examine the translation level. RNA pulldown combined with LC/MS was performed to identify the lncRNA-binding partner, RIP, dual-luciferase assay, and Co-IP assays as well to testify these physical interactions. The prognostic value of FGF14-AS2 expression level in BCa patients was analysed using Kaplan-Meier Plotter. We found that FGF14-AS2 suppresses osteoclast differentiation and osteolytic metastasis of BCa. Mechanistically, FGF14-AS2 suppresses the translation of RUNX2 by inhibiting the assembly of eIF4E/eIF4G complex and the phosphorylation of eIF4E, thereby reducing the transcription of RANKL, an essential regulator of osteoclast differentiation. Moreover, FGF14-AS2 is downregulated by YTHDF2-mediated RNA degradation in an m6A-dependent manner. Clinically, patients with high YTHDF2 and low FGF14-AS2 expression levels showed worse distant metastasis-free survival (DMFS). FGF14-AS2 plays a crucial role in osteolytic metastasis, and may serve as a promising prognostic biomarker and therapeutic target for BCa bone metastasis.

Novel Methods of Targeting IL-1 Signalling for the Treatment of Breast Cancer Bone Metastasis.

Simple SummaryThe pro-inflammatory cytokine, IL1β, plays a pivotal role in breast cancer bone metastasis. Inhibiting IL-1 signalling with the IL1β specific antibody, Canakinumab, or the IL1R1 antagonist Anakinra almost eliminates bone metastases but has adverse effects on tumours growing outside of the bone and immune regulation. This current study demonstrated that pharmacological inhibition of other members of the IL-1 signalling pathway Caspase-1, IL1β and IL1R reduced migration and invasion of E0771 and Py8119 cells in vitro and also reduced spontaneous metastasis and metastatic outgrowth of breast cancer in the bone, in vivo. Interestingly, targeting IRAK1 had no anti-tumour effects. Importantly, inhibiting Caspase-1 reduces bone metastasis without adversely affecting tumours outside of bone or immune cell regulation, suggesting that targeting immediately upstream of IL1β may be a good therapeutic strategy for treating patients with breast-cancer-induced bone disease.Breast cancer bone metastasis is currently incurable. Evidence suggests that inhibiting IL-1 signalling with the IL1R antagonist, Anakinra, or the IL1β antibody, Canakinumab, prevents metastasis and almost eliminates breast cancer growth in the bone. However, these drugs increase primary tumour growth. We, therefore, investigated whether targeting other members of the IL-1 pathway (Caspase-1, IL1β or IRAK1) could reduce bone metastases without increasing tumour growth outside of the bone. Inhibition of IL-1 via MLX01 (IL1β secretion inhibitor), VRT043198/VX765 (Caspase-1 inhibitor), Pacritinib (IRAK1 inhibitor) or Anakinra (IL1R antagonist) on tumour cell viability, migration and invasion were assessed in mouse mammary E0771 and Py8119 cells in vitro and on primary tumour growth, spontaneous metastasis and metastatic outgrowth in vivo. In vitro, Inhibition of IL-1 signalling by MLX01, VRT043198 and Anakinra reduced migration of E0771 and Py8119 cells and reversed tumour-derived IL1β induced-increased invasion and migration towards bone cells. In vivo, VX765 and Anakinra significantly reduced spontaneous metastasis and metastatic outgrowth in the bone, whereas MLX01 reduced primary tumour growth and bone metastasis. Pacritinib had no effect on metastasis in vitro or in vivo. Targeting IL-1 signalling with small molecule inhibitors may provide a new therapeutic strategy for breast cancer bone metastasis.

Identification of hub genes for early detection of bone metastasis in breast cancer.

BackgroundGlobally, among all women, the most frequently detected and diagnosed and the most lethal type of cancer is breast cancer (BC). In particular, bone is one of the most frequent distant metastases 24in breast cancer patients and bone metastasis arises in approximately 80% of advanced patients. Thus, we need to identify and validate early detection markers that can differentiate metastasis from non-metastasis breast cancers.MethodsGSE55715, GSE103357, and GSE146661 gene expression profiling data were downloaded from the GEO database. There was 14 breast cancer with bone metastasis samples and 8 breast cancer tissue samples. GEO2R was used to screen for differentially expressed genes (DEGs). The volcano plots, Venn diagrams, and annular heatmap were generated by using the ggplot2 package. By using the cluster Profiler R package, KEGG and GO enrichment analyses of DEGs were conducted. Through PPI network construction using the STRING database, key hub genes were identified by cytoHubba. Finally, K-M survival and ROC curves were generated to validate hub gene expression.ResultsBy GO enrichment analysis, 143 DEGs were enriched in the following GO terms: extracellular structure organization, extracellular matrix organization, leukocyte migration class II protein complex, collagen tridermic protein complex, extracellular matrix structural constituent, growth factor binding, and platelet-derived growth factor binding. In the KEGG pathway enrichment analysis, DEGs were enriched in Staphylococcus aureus infection, Complement and coagulation cascades, and Asthma. By PPI network analysis, we selected the top 10 genes, including SLCO2B1, STAB1, SERPING1, HLA-DOA, AIF1, GIMAP4, C1orf162, HLA-DMB, ADAP2, and HAVCR2. By using TCGA and THPA databases, we validated 2 genes, SERPING1 and GIMAP4, that were related to the early detection of bone metastasis in BC.Conclusions2 abnormally expressed hub genes could play a pivotal role in the breast cancer with bone metastasis by affecting bone homeostasis imbalance in the bone microenvironment.

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.

Integrative Bioinformatics Analysis Reveals That miR-524-5p/MEF2C Regulates Bone Metastasis in Prostate Cancer and Breast Cancer.

Bone metastases are highly prevalent in patients with advanced prostate cancer and breast cancer and have a serious impact on the survival time and quality of life of these patients. It has been reported that microRNAs (miRNAs) are expressed abnormally in different types of cancer and metastases. However, it remains unknown whether the underlying miRNAs are associated with prostate and breast cancer bone metastasis. Differentially expressed miRNAs (DE-miRNAs) and their potential targets in the metastatic process were identified by bioinformatics analysis. Additionally, qPCR confirmed that the miR-524-5p expression was downregulated in prostate and breast cancer cells. The overexpression of miR-524-5p restrained cell proliferation, invasion, and metastasis in prostate and breast cancer cells. Meanwhile, miR-524-5p could target and inhibit the expression of MEF2C, which was verified by a luciferase assay. In conclusion, our data strongly suggest that downregulation of miR-524-5p appears to be a precocious event in prostate and breast cancer, and the miR-524-5p/MEF2C axis plays a novel role in bone metastases from prostate and breast cancers.