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.

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

Background Bone metastases are high prevalence in advanced prostate cancer and breast cancer patients, which have a serious impact on the quality of life and survival time of patients. Abnormal expression of microRNAs (miRNAs) has been reported in different types of cancer and metastasis. However, the underlying miRNAs associated with prostate and breast cancer bone metastasis remains unknown. Methods We performed bioinformatics analysis for TCGA cohort to identify differentially expressed miRNAs (DE-miRNAs) and their targets in the metastatic process. Results QPCR confirmed that miR-524-5p expression was down-regulated in prostate and breast cancer cell. And miR-524-5p over-expression restrained cell proliferation, invasion and metastasis ability in prostate and breast cancer. Meanwhile, miR-524-5p specifically targeting MEF2C was verified by luciferase assay. Conclusions In conclusion, our data strongly suggests down-regulation of miR-524-5p appears as a precocious event in prostate and breast cancer, and MEF2C emerges as a new player in prostate and breast cancer bone metastasis.

Clinical Features and Serological Markers Risk Model Predicts Overall Survival in Patients Undergoing Breast Cancer and Bone Metastasis Surgeries

BackgroundSurgical therapy of breast cancer and bone metastasis can effectively improve the prognosis of breast cancer. However, after the first operation, the relationship between preoperative indicators and outcomes in patients who underwent metastatic bone surgery remained to be studied. Purpose 1. Recognize clinical and laboratory prognosis factors available to clinical doctors before the operation for bone metastatic breast cancer patients. 2. Develop a risk prediction model for 3-year postoperative survival in patients with breast cancer bone metastasis.MethodsFrom 2014 to 2020, patients who suffered from breast cancer bone metastasis and received therapeutic procedures in our institution were included for analyses (n=145). For patients who underwent both breast cancer radical surgery and bone metastasis surgery, comprehensive datasets of the parameters of interest (clinical features, laboratory factors, and patient prognoses) were collected (n=69). We performed Multivariate Cox regression to identify factors that were associated with postoperative outcome. 3-year survival prediction model and nomograms were established by 100 bootstrapping. Its benefit was evaluated by calibration plot, C-index, and decision curve analysis. The Surveillance, Epidemiology, and End Results database was also used for external validation.ResultsRadiotherapy for primary cancer, pathological type of metastatic breast cancer, lymph node metastasis, elevated serum alkaline phosphatase, lactate dehydrogenase were associated with postoperative prognosis. Pathological types of metastatic breast cancer, multiple bone metastasis, organ metastases, and elevated serum lactate dehydrogenase were associated with 3-year survival. Then those significant variables and serum alkaline phosphatase counts were integrated to construct nomograms for 3-year survival. The C-statistic of the established predictive model was 0.83. The calibration plot presents a graphical representation of calibration. In the decision curve analysis, the benefits are higher than those of the extreme curve. The receiver operating characteristic of the external validation of the model was 0.82, indicating a favored fitting degree of the two models.ConclusionOur study suggests that several clinical features and serological markers can predict the overall survival among the patients who are about to receive bone metastasis surgery after breast cancer surgery. The model can guide the preoperative evaluation and clinical decision-making for patients. Level of evidence Level III, prognostic study.

Circular RNA circIKBKB promotes breast cancer bone metastasis through sustaining NF-κB/bone remodeling factors signaling

Background Breast cancer (BC) has a marked tendency to spread to the bone, resulting in significant skeletal complications and mortality. Recently, circular RNAs (circRNAs) have been reported to contribute to cancer initiation and progression. However, the function and mechanism of circRNAs in BC bone metastasis (BC-BM) remain largely unknown. Methods Bone-metastatic circRNAs were screened using circRNAs deep sequencing and validated using in situ hybridization in BC tissues with or without bone metastasis. The role of circIKBKB in inducing bone pre-metastatic niche formation and bone metastasis was determined using osteoclastogenesis, immunofluorescence and bone resorption pit assays. The mechanism underlying circIKBKB-mediated activation of NF-κB/bone remodeling factors signaling and EIF4A3-induced circIKBKB were investigated using RNA pull-down, luciferase reporter, chromatin isolation by RNA purification and enzyme-linked immunosorbent assays. Results We identified that a novel circRNA, circIKBKB, was upregulated significantly in bone-metastatic BC tissues. Overexpressing circIKBKB enhanced the capability of BC cells to induce formation of bone pre-metastatic niche dramatically by promoting osteoclastogenesis in vivo and in vitro. Mechanically, circIKBKB activated NF-κB pathway via promoting IKKβ-mediated IκBα phosphorylation, inhibiting IκBα feedback loop and facilitating NF-κB to the promoters of multiple bone remodeling factors. Moreover, EIF4A3, acted acting as a pre-mRNA splicing factor, promoted cyclization of circIKBKB by directly binding to the circIKBKB flanking region. Importantly, treatment with inhibitor eIF4A3-IN-2 reduced circIKBKB expression and inhibited breast cancer bone metastasis effectively. Conclusion We revealed a plausible mechanism for circIKBKB-mediated NF-κB hyperactivation in bone-metastatic BC, which might represent a potential strategy to treat breast cancer bone metastasis.

IL-1B drives opposing responses in primary tumours and bone metastases; harnessing combination therapies to improve outcome in breast cancer

Breast cancer bone metastasis is currently incurable, ~75% of patients with late-stage breast cancer develop disease recurrence in bone and available treatments are only palliative. We have previously shown that production of the pro-inflammatory cytokine interleukin-1B (IL-1B) by breast cancer cells drives bone metastasis in patients and in preclinical in vivo models. In the current study, we have investigated how IL-1B from tumour cells and the microenvironment interact to affect primary tumour growth and bone metastasis through regulation of the immune system, and whether targeting IL-1 driven changes to the immune response improves standard of care therapy for breast cancer bone metastasis. Using syngeneic IL-1B/IL1R1 knock out mouse models in combination with genetic manipulation of tumour cells to overexpress IL-1B/IL1R1, we found that IL-1B signalling elicited an opposite response in primary tumours compared with bone metastases. In primary tumours, IL-1B inhibited growth, by impairing the infiltration of innate immune cell subsets with potential anti-cancer functions but promoted enhanced tumour cell migration. In bone, IL-1B stimulated the development of osteolytic metastases. In syngeneic models of breast cancer, combining standard of care treatments (Doxorubicin and Zoledronic acid) with the IL-1 receptor antagonist Anakinra inhibited both primary tumour growth and metastasis. Anakinra had opposite effects on the immune response compared to standard of care treatment, and its anti-inflammatory signature was maintained in the combination therapy. These data suggest that targeting IL-1B signalling may provide a useful therapeutic approach to inhibit bone metastasis and improve efficacy of current treatments for breast cancer patients.