RANKL/RANK/OPG system beyond bone remodeling: involvement in breast cancer and clinical perspectives

Navigating skeletal wellness after breast cancer

Breast cancer is the leading cause of death in the female population. Hormone receptor-positive cancers are usually treated with surgery in combination with endocrine therapy. The latter is known to lower estrogen levels, contributing, therefore, to loss of bone density (BMD) and higher risk of fracture. Bone-modifying agents (BMAs) can regulate the bone-related adverse effects of cancer treatment. In premenopausal women, intravenous zoledronate effectively prevents bone loss. However, the evidence regarding its ability to reduce disease recurrence remains inconclusive. In postmenopausal women, denosumab demonstrates the most substantial evidence for fracture prevention, supported by one well-powered randomized controlled trial, but has not been shown to confer anticancer benefits. While bisphosphonates effectively prevent and reduce clinical vertebra fractures, their impact on overall fracture risk is unclear. In clinical practice, management of bone health in this group of patients starts with stratification for the risk of fracture. This can be done using the FRAX algorithm; measurements of bone mineral density can help to optimize stratification for individuals at higher fracture risk. Caution is advised when interpreting the results, as the FRAX algorithm has been considered to underestimate the true fracture risk in this population, given that the algorithm has not been adjusted for the effect of anti-cancer agents. Nowadays, clodronate, ibandronate, and zoledronic acid are recommended for bone protection in this group of patients, while denosumab is not. Further research is required to highlight the optimal BMA according to patient characteristics.

The Expression Profile of the RANK/RANKL/OPG Pathway in Breast Cancer Stem Cells Isolated From Breast Cancer Cell Lines

The RANK/RANKL/OPG signaling pathway plays a crucial role in breast cancer progression and metastasis. However, its expression patterns and potential implications in breast cancer stem cells remain poorly understood. This study aimed to characterize the expression profile of this pathway in breast cancer stem cells isolated from two distinct breast cancer cell lines: MDA-MB-231 and MCF-7. Mammospheres (MS), representing breast cancer stem cells, were generated using agar-coated 6 well tissue culture plates in suitable mammospheres culture conditions. Flow cytometric analysis showed enrichment of the CD44+/CD24- subpopulations in the mammospheres cultures, with MDA-MB-231 exhibiting a higher percentage compared to MCF-7. The isolated MS from both cell lines showed upregulation of stemness markers OCT4 and SOX2, with MS. MDA-MB-231 demonstrating higher expression levels. Analysis of the RANK/RANKL/OPG axis revealed differential expression patterns between the two cell lines. RANK expression was significantly upregulated in MS. MDA-MB-231 but not in MS. MCF-7. Interestingly, while OPG mRNA levels were elevated in mammospheres from both cell lines, secreted OPG protein levels were paradoxically reduced in the mammospheres conditioned media. Additionally, RUNX2, an osteoblastic marker, and a downstream target of RANK signaling, showed a decreased expression in both mammospheres compared to adherent cells. These findings suggest a complex, context-dependent regulation of the RANK/RANKL/OPG pathway in breast cancer stem cells, potentially contributing to the aggressive nature and metastatic propensity of triple-negative breast cancer. This study provides novel insights into the molecular characteristics of breast cancer stem cells and underscores the complexity of OPG/RANK/RANKL axis expression in them; a role yet to be fully elucidated.

The Role of the Receptor Activator of Nuclear Factor Kappa-B Ligand/Osteoprotegerin Ratio in Vascular Diseases: A Therapeutic Approach

Cardiovascular and bone diseases contribute independently to mortality and global health. The exact mechanisms involved in the pathophysiology shared between bone and vascular diseases are not well defined. Endothelial cells and osteoblasts communicate during osteogenesis, thus establishing a connection between angiogenesis and osteogenesis. One shared mechanism may involve osteoprotegerin (OPG) and its ligand Receptor Activator of NF-κB Ligand (RANKL). The RANKL/OPG ratio is an important modulator for the skeletal, immunological, and vascular systems. OPG levels are elevated due to either osteogenic causes or inflammatory responses in the vasculature. The data obtained from clinical and in vitro studies support the role of the RANKL/OPG ratio as a potential marker for the progression of endothelial damage. Therefore, determining the therapeutic approaches for the targeting RANKL/OPG ratio and evaluating its usage as a biomarker in cardiovascular and bone pathophysiology are needed. By integrating the protective and disease-causing role of OPG with its ligand, this review outlines the role of the RANKL/OPG ratio at the molecular level. We also consider targeted therapeutic approaches.

Global knowledge mapping of receptor activator of nuclear factor kappa-B ligand in osteoporotic fractures: a bibliometric analysis (2001-2024)

Background

Receptor activator of nuclear factor kappa-B ligand (RANKL) plays a critical role in bone metabolism and the pathogenesis of osteoporotic fractures. This study aims to conduct a bibliometric analysis of global research pertaining to RANKL and osteoporotic fractures to identify key trends, influential studies, and collaborative networks.

Methods

A literature search was conducted to identify articles found in the Web of Science Core Collection database regarding RANKL and osteoporotic fractures from 2001 to 2024. A bibliometric analysis was performed using VOSviewer, CiteSpace, and R 4.3.3 for the publication volume, country and institution contributions, journal impact, author influence, and research hotspots.

Results

A total of 214 articles were analyzed. Publication rates have steadily increased, with a peak of 21 papers in 2020. The U.S., China, and South Korea were the top contributing countries, and leading institutions included Harvard University and Dankook University. The Journal of Bone and Mineral Research, Osteoporosis International, and Bone were the journals of highest impact. At the level of authors, Heiss-Christian published the highest number and Christiansen-Claus had the strongest citation impact (1,368 citations). Research evolved from basic biological mechanisms (2001-2010) through clinical applications (2011-2017) to recent renewed interest in fundamental RANKL biology (2018-2024). Key research hotspots included postmenopausal osteoporosis, bone mineral density, and osteoclast differentiation, with emerging focus on RANKL's role beyond skeletal metabolism.

Conclusion

This bibliometric analysis provides a comprehensive overview of RANKL research in osteoporotic fractures, highlighting key priorities for future investigation. Future studies should prioritize understanding RANKL's broader physiological roles, developing better predictive markers, and optimizing personalized treatment strategies.

Role of endosomal RANKL-LGR4 signaling during osteoclast differentiation

Leucine-rich repeat-containing G-protein-coupled receptor 4 (LGR4, also known as GPR48) is a membrane receptor that negatively regulates the RANK signaling cascade during osteoclastogenesis. Traditionally, cell signaling and endocytic membrane trafficking via membrane receptors have been considered distinct processes; however, they are now recognized to be closely and bidirectionally linked. The present study investigated the difference between membrane-bound and endosomal LGR4 signaling and whether the LGR4 signaling pathway influences RANK-RANKL signaling during RANKL-induced osteoclastogenesis. We used CRISPR-Cas9 to create LGR4 conditional knock-out (CKO) in RAW 264.7 cells and Drg2 knockout (KO) in mice to study the impacts of LGR4 and DRG2 on osteoclastogenesis. LGR4 was endocytosed into endosomes after binding to RANKL in RAW 264.7 s osteoclast precursor cells. Within the early endosomes, internalized LGR4 activates LGR4-RANKL signaling. When bound to RANKL, LGR4 is endocytosed and localized in the RAB5-positive endosomes. In Lgr4 CKO RAW 264.7 cells, early endosome signaling was increased and the inhibitory phosphorylation of GSK-3β was decreased, both in the whole lysate and endosome fraction. RANKL treatment increased nuclear translocation of NFATC1 in Lgr4 CKO RAW 264.7 cells and Drg2 KO mice. Overall, our results suggested that RANKL-LGR4 signaling is regulated by membrane-to-endosomal trafficking during osteoclastogenesis. KEY MESSAGES: Bone resorption by osteoclasts is essential for bone homeostasis and remodeling. However, the mechanisms underlying the regulation of osteoclastogenesis are not yet fully understood. The present study investigated the difference between membrane-bound and endosomal LGR4 signaling, and whether the LGR4 signaling pathway influences RANK-RANKL signaling during RANKL-induced osteoclastogenesis. Our results suggested that RANKL-LGR4 signaling is regulated by membrane-to-endosomal trafficking during osteoclastogenesis.

The Role of Osteoprotegerin in Breast Cancer: Genetic Variations, Tumorigenic Pathways, and Therapeutic Potential

INTRODUCTION

Osteoprotegerin (OPG), encoded by the TNFRSF11B gene, is linked to the development of breast cancer via several pathways, including interactions with the receptor activator of nuclear factor-κB (RANK) ligands, apoptosis-inducing proteins like TRAIL, and genetic variations such as single nucleotide polymorphisms (SNPs), directly altering gene expression. This review aims to investigate the role of OPG expression in breast cancer.

METHODS

A comprehensive literature search was conducted using PubMed Medline, Google Scholar, and ScienceDirect. Only full-text English publications from inception to September 2024 were included.

RESULTS

Studies have demonstrated that certain SNPs in the OPG gene, specifically rs3102735 and rs2073618, are linked to a higher risk of breast cancer development. Additionally, OPG's function as a TRAIL decoy receptor may inhibit the death of cancer cells. Furthermore, OPG in the serum and its interactions with BRCA mutations are being investigated for their potential influence on breast cancer progression. Studies have found that OPG promotes tumorigenesis by enhancing cell proliferation, angiogenesis, and aneuploidy in normal mammary epithelial cells. Moreover, OPG mediates the tumor-promoting effects of interleukin-1 beta and may serve as a biomarker for breast cancer risk, particularly in BRCA1 mutation carriers, through its role in dysregulated RANK signaling. Lastly, the use of recombinant OPG in mouse models has been found to exert anti-tumor effects.

CONCLUSIONS

In this review, the role of OPG in breast cancer is examined. OPG has a multifaceted role in breast cancer tumorigenesis and exerts its effects through genetic variations (SNPs), interactions with TNF-related apoptosis-inducing ligand (TRAIL), and the modulation of the pro-tumorigenic microenvironment effects of angiogenesis, cell survival, and metastasis. Additionally, OPG's dual role as a tumor suppressor and promoter serves as a possible therapeutic target to enhance apoptosis, limit bone metastasis, and modulate the tumor microenvironment. Whilst much is now known, further studies are necessary to fully delineate the role of OPG.

Implications of Mineralization Biomarkers in Breast Cancer Outcomes Beyond Calcifications

The aim of this work was to explore the biomarkers associated with epithelial to mesenchymal transition (EMT) and mineralization processes as new prognostic factors across different breast cancer phenotypes. To this end, 133 breast biopsies, including benign and malignant lesions, with or without microcalcifications, were retrospectively collected. Immunohistochemical analysis was performed to evaluate the expression of vimentin, BMP-2, BMP-4, RANKL, Runx2, OPN, PTX3, and SDF-1, while Kaplan-Meier plots were used to assess their prognostic impact on overall survival in a dataset of 2976 breast cancer patients. The expression of vimentin, BMP-2, BMP-4, and SDF-1 was significantly higher in malignant lesions compared to benign ones, regardless of the presence of microcalcifications. Notably, these markers showed no correlation with traditional prognostic factors, such as tumor grade or hormone receptor status. The bioinformatics analysis provided valuable insights into the possible prognostic and therapeutic significance of BMP-2, BMP-4, SDF-1, and vimentin in breast cancer. In fact, all these biomarkers impact on the overall survival in specific molecular breast cancer types. In addition, high expression of SDF-1 and vimentin is able to predict the response to chemotherapy. The findings here reported suggest that vimentin, BMP-2, BMP-4, and SDF-1 could be independent prognostic biomarkers in breast cancer, providing insights beyond traditional clinical factors.

Perfluorooctanoic acid and its alternatives disrupt the osteogenesis and osteoclastogenesis balance: Evidence from the effects on cell differentiation process

In the present study, we investigated the effects of a representative of the per- and polyfluoroalkyl substance (PFAS) chemical group, namely perfluorooctanoic acid (PFOA), and its alternatives (perfluorobutanoic acid [PFBA] and the hexafluoropropylene oxide dimer acid [GenX]) on bone homeostasis, a process that mainly depends on osteoblast (OB) and osteoclast (OC) activities at the cellular level. C3H10T1/2 cells and bone marrow macrophages (BMMs) were respectively induced into OBs and OCs, and treated with PFOA, PFBA, and GenX at doses of 0.25, 2.5, and 25 μM. Real-time PCR, ALP activity analysis, ARS staining, and TRAP staining were performed to assess cell differentiation. To explore the indirect effects on OC differentiation, conditioned media were collected from 7-day PFAS-treated C3H10T1/2 cells during differentiation. RANKL/OPG expression and secretion levels in C3H10T1/2 cells were determined, and BMMs induced into OCs were incubated in conditioned media for two days. PFOA suppressed osteogenesis characterized by the decreased mRNA expression of OB-specific molecules, ALP activity, and calcium deposition, and promoted osteoclastogenesis as evidenced by upregulated osteoclastic genes and increased number of TRAP-positive cells. Although the PFOA alternatives did not affect early osteogenesis, calcium deposits were significantly reduced and osteoclastogenesis was facilitated. The results suggested that PFOA and its alternatives could directly disturb the balance between osteogenesis and osteoclastogenesis. In addition, PFOA and its alternatives enhanced the RANKL/OPG ratio during early OB differentiation, and more BMMs stimulated with the conditioned medium differentiated into OCs, indicating the indirect stimulation on OC differentiation by PFOA and its alternatives. These findings highlight the potential skeletal hazards of PFASs, particularly emerging alternatives that might be ignored, offering a toxicological basis for further exploration.

A review of the current status and future prospects of the bone remodeling process: Biological and mathematical perspectives

This review dives into the complex dynamics of bone remodeling, combining biological insights with mathematical perspectives to better understand this fundamental aspect of skeletal health. Bone, being a crucial part of our body, constantly renews itself, and with the growing number of individuals facing bone-related issues, research in this field is vital. In this review, we categorized and classified most common mathematical models used to simulate the mechanical behavior of bone under different loading and health conditions, shedding light on the evolving landscape of bone biology. While current models have effectively captured the essence of healthy bone remodeling, the ever-expanding knowledge in bone biology suggests an update in mathematical methods. Knowing the role of the skeleton in whole-body physiology, and looking at the recent discoveries about activities of bone cells emphasize the urgency of refining our mathematical descriptions of the bone remodeling process. The underexplored impact of bone diseases like osteoporosis, Paget's disease, or breast cancer on bone remodeling also points to the need for intensified research into diverse disease types and their unique effects on bone health. By reviewing a range of bone remodeling models, we show the necessity for tailor-made mathematical models to decipher their roots and enhance patient treatment strategies. Collaboration among scientists from various domains is pivotal to surmount these challenges, ensuring improved accuracy and applicability of mathematical models. Ultimately, this effort aims to deepen our understanding of bone remodeling processes and their broader implications for diverse health conditions.

Sarcopenic obesity and osteoporosis: Research progress and hot spots

Sarcopenic obesity (SO) and osteoporosis (OP) are associated with aging and obesity. The pathogenesis of SO is complex, including glucolipid and skeletal muscle metabolic disorders caused by inflammation, insulin resistance, and other factors. Growing evidence links muscle damage to bone loss. Muscle-lipid metabolism disorders of SO disrupt the balance between bone formation and bone resorption, increasing the risk of OP. Conversely, bones also play a role in fat and muscle metabolism. In the context of aging and obesity, the comprehensive review focuses on the effects of mechanical stimulation, mesenchymal stem cells (MSCs), chronic inflammation, myokines, and adipokines on musculoskeletal, at the same time, the impact of osteokines on muscle-lipid metabolism were also analyzed. So far, exercise combined with diet therapy is the most effective strategy for increasing musculoskeletal mass. A holistic treatment of musculoskeletal diseases is still in the preliminary exploration stage. Therefore, this article aims to improve the understanding of musculoskeletal -fat interactions in SO and OP, explores targets that can provide holistic treatment for SO combined with OP, and discusses current limitations and challenges. We hope to provide relevant ideas for developing specific therapies and improving disease prognosis in the future.

Nanomaterials for bone metastasis

Bone metastasis, a prevalent occurrence in primary malignant tumors, is often associated with a grim prognosis. The bone microenvironment comprises various coexisting cell types, working together in a coordinated manner. This dynamic microenvironment plays a pivotal role in the initiation and progression of bone metastases. While cancer therapies have made advancements, the available options for addressing bone metastases remain insufficient. The advent of nanotechnology has ushered in a new era for managing and preventing bone metastases because of the physicochemical and adaptable advantages of nanoplatforms. In this review, we make an introduction of the underlying mechanisms and the current clinical therapies of bone metastases, highlighting the advances of intelligent nanosystems that can stimulate vascular regeneration, promote bone regeneration, eliminate tumor cells, minimize bone damage, and expedite bone healing. The innovation surrounding bone-targeting nanoplatforms presents a fresh approach to the theranostics of bone metastases.

Endogenous osteoprotegerin (OPG) represses ERα and promotes stemness and chemoresistance in breast cancer cells

Breast cancer (BC) is the most prevalent cancer and the leading cause of death among women worldwide. The osteoprotegerin (OPG) cytokine, a decoy receptor for RANKL and a key player in bone homeostasis, has pro-and anti-carcinogenic effects in various types of cancer, including breast neoplasms. In the present study, we have shown that ectopic expression of OPG in breast epithelial/cancer cells promotes the pro-metastatic processes epithelial-to-mesenchymal transition (EMT), stemness, angiogenesis as well as the activation of breast stromal fibroblasts. Furthermore, proteomics analysis, which allows the identification and quantification of a plethora of known and unknown proteins, has shown a strong and significant correlation between OPG upregulation and the expression of proteins with functions in EMT and stemness. On the other hand, OPG knockdown in triple-negative breast cancer (TNBC) cells inhibited the formation of cancer stem cells. Importantly, while OPG upregulation significantly enhanced the resistance of luminal BC cells to cisplatin and docetaxel, OPG downregulation sensitized TNBC cells to these chemotherapeutic drugs. We have also shown that OPG negatively controls estrogen receptor α (ERα), and OPG upregulation correlated well with the expression of genes related to ER-negative claudin low cells. Collectively, these results show that OPG promotes stemness and the consequent chemoresistance of breast cancer cells.

Correlation of RANK and RANKL with mammographic density in primary breast cancer patients

PURPOSE

The receptor activator of nuclear factor kappa B (RANK) and its ligand (RANKL) have been shown to promote proliferation of the breast and breast carcinogenesis. The objective of this analysis was to investigate whether tumor-specific RANK and RANKL expression in patients with primary breast cancer is associated with high percentage mammographic density (PMD), which is a known breast cancer risk factor.

METHODS

Immunohistochemical staining of RANK and RANKL was performed in tissue microarrays (TMAs) from primary breast cancer samples of the Bavarian Breast Cancer Cases and Controls (BBCC) study. For RANK and RANKL expression, histochemical scores (H scores) with a cut-off value of > 0 vs 0 were established. PMD was measured in the contralateral, non-diseased breast. Linear regression models with PMD as outcome were calculated using common predictors of PMD (age at breast cancer diagnosis, body mass index (BMI) and parity) and RANK and RANKL H scores. Additionally, Spearman rank correlations (ρ) between PMD and RANK and RANKL H score were performed.

RESULTS

In the final cohort of 412 patients, breast cancer-specific RANK and RANKL expression was not associated with PMD (P = 0.68). There was no correlation between PMD and RANK H score (Spearman's ρ = 0.01, P = 0.87) or RANKL H score (Spearman's ρ = 0.04, P = 0.41). RANK expression was highest in triple-negative tumors, followed by HER2-positive, luminal B-like and luminal A-like tumors, while no subtype-specific expression of RANKL was found.

CONCLUSION

Results do not provide evidence for an association of RANK and RANKL expression in primary breast cancer with PMD.

The effect of low-level laser therapy on osteoclast differentiation: Clinical implications for tooth movement and bone density

Background/purpose

Osteoclast differentiation is crucial for orchestrating both tooth movement and the maintenance of bone density. Therefore, the current study sought to explore the impact of low-level laser therapy (LLLT) on osteoclast differentiation, functional gene expression, molecular signaling pathways, and orthodontic tooth movement in clinical settings.

Materials and methods

The RAW 264.7 cell line served as the precursor for osteoclasts, and these cells underwent irradiation using a 808-nm LLLT. Osteoclast differentiation was assessed through tartrate-resistant acid phosphatase (TRAP) staining. Functional gene expression levels were evaluated using real-time quantitative polymerase chain reaction (RT-qPCR) while signaling molecules were examined through Western blot analysis. In the clinical study, 12 participants were enrolled. Their tooth movement was monitored using a TRIOS desktop scanner. Bone density measurements were conducted using Mimics software, which processed cone-beam computed tomography (CBCT) images exported in Digital Imaging and Communications in Medicine (DICOM) format.

Results

We found that LLLT effectively promoted receptor activator of nuclear factor-κB ligand (RANKL)-dependent osteoclast differentiation and the expression of osteoclast functional genes, including matrix metallopeptidase 9 (MMP9), nuclear factor of activated T-cells cytoplasmic 1(NFATc1), tartrate-resistant acid phosphatase (TRAP) and cathepsin K (CTSK) in RAW264.7 cells. Clinically, the cumulative tooth movement over 90 days was significantly higher in the laser group than in the control group.

Conclusion

Our research demonstrates that LLLT not only significantly promotes osteoclast differentiation but is also a valuable adjunct in orthodontic therapy.

Epiberberine inhibits bone metastatic breast cancer-induced osteolysis

ETHNOPHARMACOLOGICAL RELEVANCE

The anti-tumor related diseases of Coptidis Rhizoma (Huanglian) were correlated with its traditional use of removing damp-heat, clearing internal fire, and counteracting toxicity. In the recent years, Coptidis Rhizoma and its components have drawn extensive attention toward their anti-tumor related diseases. Besides, Coptidis Rhizoma is traditionally used as an anti-inflammatory herb. Epiberberine (EPI) is a significant alkaloid isolated from Coptidis Rhizoma, and exhibits multiple pharmacological activities including anti-inflammatory. However, the effect of epiberberine on breast cancer and the inflammatory factors of metastatic breast cancer-induced osteolysis has not been demonstrated clearly.

AIM OF THE STUDY

Bone metastatic breast cancer can lead to osteolysis via inflammatory factors-induced osteoclast differentiation and function. In this study, we try to analyze the effect of epiberberine on breast cancer and the inflammatory factors of metastatic breast cancer-induced osteolysis.

METHODS

To evaluate whether epiberberine could suppress bone metastatic breast cancer-induced osteolytic damage, healthy female Balb/c mice were intratibially injected with murine triple-negative breast cancer 4T1 cells. Then, we examined the inhibitory effect and underlying mechanism of epiberberine on breast cancer-induced osteoclastogenesis in vitro. Xenograft assay was used to study the effect of epiberberine on breast cancer cells in vivo. Moreover, we also studied the inhibitory effects and underlying mechanisms of epiberberine on RANKL-induced osteoclast differentiation and function in vitro.

RESULTS

The results show that epiberberine displayed potential therapeutic effects on breast cancer-induced osteolytic damage. Besides, our results show that epiberberine inhibited breast cancer cells-induced osteoclast differentiation and function by inhibiting secreted inflammatory cytokines such as IL-8. Importantly, we found that epiberberine directly inhibited RANKL-induced differentiation and function of osteoclast without cytotoxicity. Mechanistically, epiberberine inhibited RANKL-induced osteoclastogensis via Akt/c-Fos signaling pathway. Furthermore, epiberberine combined with docetaxel effectively protected against bone loss induced by metastatic breast cancer cells.

CONCLUSIONS

Our findings suggested that epiberberine may be a promising natural compound for treating bone metastatic breast cancer-induced osteolytic damage by inhibiting IL-8 and is worthy of further exploration in preclinical and clinical trials.

Characterization of a spontaneous osteopetrosis model using RANKL-dysfunctional mice

Tumor necrosis factor superfamily member 11 (TNFSF11), or receptor activator of nuclear factor-κB ligand (RANKL), is a crucial osteoclast-stimulating factor binding to RANK on osteoclast membranes. Mouse models are powerful tools for understanding the genetic mechanisms of related diseases. Here, we examined the utility of Tnfsf11 mutation in mice for understanding the mechanisms of bone remodeling and dysmorphology. The Tnfsf11gum mouse, discovered in 2011 at Jackson Laboratory, was used to study the genetic landscape associated with TNFSF11 inactivation in bone marrow tissues. Tnfsf11gum/+ and Tnfsf11+/+ mice were subjected to Micro-CT observation, ELISA analysis, histological evaluation, and massively-parallel mRNA sequencing (RNA-Seq) analysis. Tnfsf11gum/+ mice exhibited severe osteopetrotic changes in the bone marrow cavity, along with significantly lower serum RANKL levels and a reduced number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in the bone marrow compared to those in Tnfsf11+/+ mice. However, tooth eruption between Tnfsf11gum/+ and Tnfsf11+/+ mice did not differ. Furthermore, genes involved in osteoblast proliferation and differentiation, including Gli1, Slc35b2, Lrrc17, and Junb were differentially expressed. Heterozygous mutation of TNFSF11 was also associated with a slightly increased expression of genes involved in osteoclast proliferation and differentiation, including Tcirg1, Junb, Anxa2, and Atp6ap1. Overall, we demonstrate that single gene mutations in Tnfsf11 cause bone resorption instability without significantly altering the genes related to osteoblast and osteoclast activity in the bone marrow cavity, thus establishing an optimal resource as an experimental animal model for bone resorption in bone biology research.

Wemics: A Single-Base Resolution Methylation Quantification Method for Enhanced Prediction of Epigenetic Regulation

DNA methylation, an epigenetic mechanism that alters gene expression without changing DNA sequence, is essential for organism development and key biological processes like genomic imprinting and X-chromosome inactivation. Despite tremendous efforts in DNA methylation research, accurate quantification of cytosine methylation remains a challenge. Here, a single-base methylation quantification approach is introduced by weighting methylation of consecutive CpG sites (Wemics) in genomic regions. Wemics quantification of DNA methylation better predicts its regulatory impact on gene transcription and identifies differentially methylated regions (DMRs) with more biological relevance. Most Wemics-quantified DMRs in lung cancer are epigenetically conserved and recurrently occurred in other primary cancers from The Cancer Genome Atlas (TCGA), and their aberrant alterations can serve as promising pan-cancer diagnostic markers. It is further revealed that these detected DMRs are enriched in transcription factor (TF) binding motifs, and methylation of these TF binding motifs and TF expression synergistically regulate target gene expression. Using Wemics on epigenomic-transcriptomic data from the large lung cancer cohort, a dozen novel genes with oncogenic potential are discovered that are upregulated by hypomethylation but overlooked by other quantification methods. These findings increase the understanding of the epigenetic mechanism by which DNA methylation regulates gene expression.

Peripheral Mechanism of Cancer-Induced Bone Pain

Cancer-induced bone pain (CIBP) is a type of ongoing or breakthrough pain caused by a primary bone tumor or bone metastasis. CIBP constitutes a specific pain state with distinct characteristics; however, it shares similarities with inflammatory and neuropathic pain. At present, although various therapies have been developed for this condition, complete relief from CIBP in patients with cancer is yet to be achieved. Hence, it is urgent to study the mechanism underlying CIBP to develop efficient analgesic drugs. Herein, we focused on the peripheral mechanism associated with the initiation of CIBP, which involves tissue injury in the bone and changes in the tumor microenvironment (TME) and dorsal root ganglion. The nerve-cancer and cancer-immunocyte cross-talk in the TME creates circumstances that promote tumor growth and metastasis, ultimately leading to CIBP. The peripheral mechanism of CIBP and current treatments as well as potential therapeutic targets are discussed in this review.

Oligomeric proanthocyanidins ameliorates osteoclastogenesis through reducing OPG/RANKL ratio in chicken's embryos

Skeletal disorders can seriously threaten the health and the performance of poultry, such as tibial dyschondroplasia (TD) and osteoporosis (OP). Oligomeric proanthocyanidins (OPC) are naturally occurring polyphenolic flavonoid compounds that can be used as potential substances to improve the bone health and the growth performance of poultry. Eighty 7-day-old green-eggshell yellow feather layer chickens were randomly divided into 4 groups: basal diet and basal diet supplementation with 25, 50, and 100 mg/kg OPC. The results have indicated that the growth performance and bone parameters of chickens were significantly improved supplementation with OPC in vivo, including the bone volume (BV), the bone mineral density (BMD) and the activities of antioxidative enzymes, but ratio of osteoprotegerin (OPG)/receptor activator of NF-κB (RANK) ligand (RANKL) was decreased. Furthermore, primary bone marrow mesenchymal stem cells (BMSCs) and bone marrow monocytes/macrophages (BMMs) were successfully isolated from femur and tibia of chickens, and co-cultured to differentiate into osteoclasts in vitro. The osteogenic differentiation derived from BMSCs was promoted treatment with high concentrations of OPC (10, 20, and 40 µmol/L) groups in vitro, but emerging the inhibition of osteoclastogenesis by increasing the ratio of OPG/RANKL. In contrary, the osteogenic differentiation was also promoted treatment with low concentrations of OPC (2.5, 5, and 10 µmol/L) groups, but osteoclastogenesis was enhanced by decreasing the ratio of OPG/RANKL in vitro. In addition, OPG inhibits the differentiation and activity of osteoclasts by increasing the autophagy in vitro. Dietary supplementation of OPC can improve the growth performance of bone and alter the balance of osteoblasts and osteoclasts, thereby improving the bone health of chickens.

The potential role of SNHG16/ miRNA-146a/ TRAF6 signaling pathway in the protective effect of zoledronate against colorectal cancer and associated osteoporosis in mouse model

Bone fracture as a consequence of colorectal cancer (CRC) and associated osteoporosis (OP) is considered a risk factor for increasing the mortality rate among CRC patients. SNHG16/ miRNA-146a/ TRAF6 signaling pathway is a substantial contributor to neoplastic evolution, progression, and metastasis. Here, we investigated the effect of zoledronate (ZOL) on the growth of CRC and associated OP in a mouse model. Thirty Balb/c mice were divided into Naïve, azoxymethane (AOM)/dextran sodium sulfate (DSS), and ZOL groups. Body weight and small nucleolar RNA host gene 16 (SNHG16) expression, microRNA-146a, and TRAF6 in bone, colon, and stool were investigated. Samples of colon and bone were collected and processed for light microscopic, immunohistochemical staining for cytokeratin 20 (CK20), nuclear protein Ki67 (pKi-67), and caudal type homeobox transcription factor 2 (CDx2) in colon and receptor activator of nuclear factor kB (RANK) and osteoprotegerin (OPG) in bone. A computerized tomography (CT) scan of the femur and tibia was studied. ZOL produced a significant decrease in the expression of SNHG16 and TRAF6 and an increase in miRNA-146a in the colon and bone. ZOL administration improved the histopathological changes in the colon, produced a significant decrease in CK20 and Ki-67, and increased CDx2 expressions. In bone, ZOL prevented osteoporotic changes and tumour cell invasion produced a significant decrease in RANK and an increase in OPG expressions, alongside improved bone mineral density in CT scans. ZOL could be a promising preventive therapy against colitis-induced cancer and associated OP via modulation expression of SNHG16, miRNA-146a, and TRAF6.

New Horizons: Translational Aspects of Osteomorphs

Osteomorphs are a newly described osteoclast lineage cell in mice, which are suggested to play a significant role in the maintenance of bone resorption. Preclinical investigations revealed that osteomorphs are generated through the fission of multinucleated bone-resorbing osteoclasts and can also re-fuse with existing osteoclasts. Modifications to RANKL signaling have been shown to alter cycles of fission and re-fusion of osteomorphs in mice. These novel findings were also shown to contribute to the rebound phenomenon after cessation of anti-RANKL therapy in mice. Moreover, the absence of osteomorph-specific genes in mice exhibits bone structural and quality phenotypes. Given these insights, it could be speculated that osteomorphs play a significant role in bone homeostasis, bone metabolic diseases, and response to therapeutics. In this review, we discuss these potential translational roles for osteomorphs. Importantly, we highlight the need for future preclinical and clinical studies to verify the presence of osteomorphs in humans and explore further the translational implications of this discovery.

Prevotella histicola Prevented Particle-Induced Osteolysis via Gut Microbiota-Dependent Modulation of Inflammation in Ti-Treated Mice

Wear particles generated from total joint replacements induce chronic osteolysis mediated by inflammatory upregulation, which leads to implant failure. Recent studies have suggested an important role of the gut microbiota in modulating the host's metabolism and immune system, leading to alterations in bone mass. Following gavage with P. histicola, micro-CT and HE staining revealed that osteolysis was significantly reduced in titanium (Ti)-treated mice. Immunofluorescence analysis revealed an increased macrophage (M)1/M2 ratio in the guts of Ti-treated mice, which decreased when P. histicola was added. P. histicola was also found to upregulate the tight junction proteins ZO-1, occludin, claudin-1, and MUC2 in the gut, reduce the levels of inflammatory factors IL-1β, IL-6, IL-8, and TNF-α, primarily in the ileum and colon, and decrease the expression of IL-1β and TNF-α and increase the level of IL-10 in the serum and cranium. Furthermore, P. histicola treatment resulted in a significant downregulation of CTX-1, RANKL, and RANKL/OPG. These findings demonstrate that P. histicola significantly mitigates osteolysis in Ti-treated mice by improving intestinal microbiota that repairs intestinal leakage and reduces systemic and local inflammation which in turn inhibits RANKL expression for bone resorption. P. histicola treatment may thus be therapeutically beneficial for particle-induced osteolysis.

Association between thyroid autoimmunity and bone mineral density in patients with type 2 diabetes mellitus: a cross-sectional study

PURPOSE

The purpose of this study was to analyze the relationship between thyroid autoimmunity and bone mineral density (BMD) in patients with type 2 diabetes mellitus (T2DM), and to further explore the influence of thyroid autoimmunity on diabetic osteoporosis.

METHODS

A total of 601 T2DM patients were included and divided into two groups according to thyroid autoantibodies, namely thyroid autoimmunity positive group (TPOAb+ or TGAb + ) and thyroid autoimmunity negative group (TPOAb- and TGAb-). Clinical data were collected and BMD was determined by dual-energy X-ray absorptiometry (DXA). SPSS26.0 software was used to data analysis. Model regression was used to analyze the influencing factors of BMD, and ROC curve was used to analyze the optimal cut-off point of thyroid peroxidase antibody (TPOAb) for screening osteoporosis.

RESULTS

TPOAb and thyroglobulin antibody (TGAb) were negatively correlated with BMD and T-score (LS, FN and WB) (P < 0.01), and TGAb was negatively correlated with 25(OH)D (P < 0.05). Multiple linear regression analysis showed that TPOAb was an independent influence factor on LS, FN and WB BMD. ROC curve analysis showed that the optimal threshold of TPOAb for predicting osteoporosis was 12.35.

CONCLUSIONS

In T2DM patients, TPOAb and TGAb levels are negatively correlated with LS, FN and WB BMD, and TPOAb is an independent influencing factor for diabetic osteoporosis, and TPOAb has a certain predictive value for the occurrence and development of diabetic osteoporosis clinically.

Computational design of anti-cancer peptides tailored to target specific tumor markers

Anti-cancer peptides (ACPs) are short peptides known for their ability to inhibit tumor cell proliferation, migration, and the formation of tumor blood vessels. In this study, we designed ACPs to target receptors often overexpressed in cancer using a systematic in silico approach. Three target receptors (CXCR1, DcR3, and OPG) were selected for their significant roles in cancer pathogenesis and tumor cell proliferation. Our peptide design strategy involved identifying interacting residues (IR) of these receptors, with their natural ligands serving as a reference for designing peptides specific to each receptor. The natural ligands of these receptors, including IL8 for CXCR1, TL1A for DcR3, and RANKL for OPG, were identified from the literature. Using the identified interacting residues (IR), we generated a peptide library through simple permutation and predicted the structure of each peptide. All peptides were analyzed using the web-based prediction server for Anticancer peptides, AntiCP. Docking simulations were then conducted to analyze the binding efficiencies of peptides with their respective target receptors, using VEGA ZZ and Chimera for interaction analysis. Our analysis identified HPKFIKELR as the interacting residues (IR) of CXCR-IL8. For DcR3, we utilized three domains from TL1A (TDSYPEP, TKEDKTF, LGLAFTK) as templates, along with two regions (SIKIPSS and PDQDATYP) from RANKL, to generate a library of peptide analogs. Subsequently, peptides for each receptor were shortlisted based on their predicted anticancer properties as determined by AntiCP and were subjected to docking analysis. After docking, peptides that exhibited the least binding energy were further analyzed for their detailed interaction with their respective receptors. Among these, peptides C9 (HPKFELY) and C7 (HPKFEWL) for CXCR1, peptides D6 (ADSYPQP) and D18 (AFSYPFP) for DcR3, and peptides P19 (PDTYPQDP) and p16 (PDQDATYP) for OPG, demonstrated the highest affinity and stronger interactions compared to the other peptides. Although in silico predictions indicated a favorable binding affinity of the designed peptides with target receptors, further experimental validation is essential to confirm their binding affinity, stability and pharmacokinetic characteristics.

The Role of Breast Cancer Cells in Bone Metastasis: Suitable Seeds for Nourishing Soil

PURPOSE OF REVIEW

The purpose of this review was to describe the characteristics of breast cancer cells prone to developing bone metastasis and determine how they are regulated by the bone microenvironment.

RECENT FINDINGS

The bone is a site of frequent breast cancer metastasis. Bone metastasis accounts for 70% of advanced breast cancer cases and remains incurable. It can lead to skeletal-related events, such as bone fracture and pain, and seriously affect the quality of life of patients. Breast cancer cells escape from the primary lesion and spread to the bone marrow in the early stages. They can then enter the dormant state and restore tumourigenicity after several years to develop overt metastasis. In the last few years, an increasing number of studies have reported on the factors promoting bone metastasis of breast cancer cells, both at the primary and metastatic sites. Identifying factors associated with bone metastasis aids in the early recognition of bone metastasis tendency. How to target these factors and minimize the side effects on the bone remains to be further explored.

3D bioprinting technology to construct bone reconstruction research model and its feasibility evaluation

Objective: To explore and construct a 3D bone remodeling research model displaying stability, repeatability, and precise simulation of the physiological and biochemical environment in vivo. Methods: In this study, 3D bioprinting was used to construct a bone reconstruction model. Sodium alginate (SA), hydroxyapatite (HA) and gelatin (Gel) were mixed into hydrogel as scaffold material. The osteoblast precursor cells MC3T3-E1 and osteoclast precursor cells RAW264.7 were used as seed cells, which may or may not be separated by polycarbonate membrane. The cytokines osteoprotegerin (OPG) and receptor activator of NF-κB ligand (RANKL) were used to induce cell differentiation. The function of scaffolds in the process of bone remodeling was analyzed by detecting the related markers of osteoblasts (alkaline phosphatase, ALP) and osteoclasts (tartrate resistant acid phosphatase, TRAP). Results: The scaffold showed good biocompatibility and low toxicity. The surface morphology aided cell adhesion and growth. The scaffold had optimum degradability, water absorption capacity and porosity, which are in line with the conditions of biological experiments. The effect of induced differentiation of cells was the best when cultured alone. After direct contact between the two types of cells at 2D or 3D level, the induced differentiation of cells was inhibited to varying degrees, although they still showed osteogenesis and osteoclast. After the cells were induced by indirect contact culture, the effect of induced differentiation improved when compared with direct contact culture, although it was still not as good as that of single culture. On the whole, the effect of inducing differentiation at 3D level was the same as that at 2D level, and its relative gene expression and enzyme activity were higher than that in the control group. Hence the scaffold used in this study could induce osteogenesis as well as osteoclast, thereby rendering it more effective in inducing new bone formation. Conclusion: This method can be used to construct the model of 3D bone remodeling mechanism.

Systemic and Local Strategies for Primary Prevention of Breast Cancer

One in eight women will develop breast cancer in the US. For women with moderate (15-20%) to average (12.5%) risk of breast cancer, there are few options available for risk reduction. For high-risk (>20%) women, such as BRCA mutation carriers, primary prevention strategies are limited to evidence-based surgical removal of breasts and/or ovaries and anti-estrogen treatment. Despite their effectiveness in risk reduction, not many high-risk individuals opt for surgical or hormonal interventions due to severe side effects and potentially life-changing outcomes as key deterrents. Thus, better communication about the benefits of existing strategies and the development of new strategies with minimal side effects are needed to offer women adequate risk-reducing interventions. We extensively review and discuss innovative investigational strategies for primary prevention. Most of these investigational strategies are at the pre-clinical stage, but some are already being evaluated in clinical trials and others are expected to lead to first-in-human clinical trials within 5 years. Likely, these strategies would be initially tested in high-risk individuals but may be applicable to lower-risk women, if shown to decrease risk at a similar rate to existing strategies, but with minimal side effects.

RANK in cancer-associated fibroblasts: A valuable prognostic determinant for metastasis in early-stage breast cancer patients

BACKGROUND

The molecular system of receptor activator of nuclear factor kappa-β (RANK) and its ligand (RANKL) plays a role in a variety of physiological and pathological processes. These encompass the regulation of bone metabolism, mammary gland development, immune function, as well as their involvement and tumorigenesis. Nevertheless, limited knowledge exists regarding their function within the tumor microenvironment.

METHODS AND RESULTS

We explored the significance of RANK expression in cancer-associated fibroblasts (CAFs) as a prognostic biomarker in early breast cancer patients (BCPs) by immunohistochemistry. Results reveal a significant correlation between high RANK expression in CAFs and an increased risk of metastasis (p= 0.006), shorter metastasis-free survival (MFS) [p= 0.007, OR (95%CI) = 2.290 (1.259-4.156)], and lower overall survival (OS) [p= 0.004, OR (95%CI) = 2.469 (1.343-4.541)]. Upon analyzing the phenotype of CD34(-) CAFs isolated from primary tumors in BCPs, we observed co-expression of RANK with CD105 marker by immunofluorescence and flow cytometry, characteristic of mesenchymal stem/stromal cells (MSCs), suggesting the possible cellular origin. Also RANKL-RANK system increase the OCT-4, SOX-2 and DKK-1 (dickkopf 1) gene expression in CD34(-) CAFs by RT-PCR. Moreover, this system plays a crucial role in the migration of these CD34(-) CAFs.

CONCLUSIONS

These results support the clinical relevance of RANK in CAFs and propose its potential as a future therapeutic target in the treatment of early BCPs.

Effect of Er:YAG Pulsed Laser-Deposited Hydroxyapatite Film on Titanium Implants on M2 Macrophage Polarization In Vitro and Osteogenesis In Vivo

In a previous study, we successfully coated hydroxyapatite (HAp) onto titanium (Ti) plates using the erbium-doped yttrium aluminum garnet pulsed-laser deposition (Er:YAG-PLD) method. In this study, we performed further experiments to validate the in vitro osteogenic properties, macrophage polarization, and in vivo osseointegration activity of HAp-coated Ti (HAp-Ti) plates and screws. Briefly, we coated a HAp film onto the surfaces of Ti plates and screws via Er:YAG-PLD. The surface morphological, elemental, and crystallographic analyses confirmed the successful surface coating. The macrophage polarization and osteogenic induction were evaluated in macrophages and rat bone marrow mesenchymal stem cells, and the in vivo osteogenic properties were studied. The results showed that needle-shaped nano-HAp promoted the early expression of osteogenic and immunogenic genes in the macrophages and induced excellent M2 polarization properties. The calcium deposition and osteocalcin production were significantly higher in the HAp-Ti than in the uncoated Ti. The implantation into rat femurs revealed that the HAp-coated materials had superior osteoinductive and osseointegration activities compared with the Ti, as assessed by microcomputed tomography and histology. Thus, HAp film on sandblasted Ti plates and screws via Er:YAG-PLD enhances hard-tissue differentiation, macrophage polarization, and new bone formation in tissues surrounding implants both in vitro and in vivo.

RANK Expression as an Independent Predictor for Response to Neoadjuvant Chemotherapy in Luminal-Like Breast Cancer: A Translational Insight from the GeparX Trial

PURPOSE

The GeparX study investigated whether denosumab as add-on treatment to nab-paclitaxel-based neoadjuvant chemotherapy (NACT) with two different schedules (125 mg/m² weekly vs. day 1, 8 every 22 days) may increase pathologic complete response (pCR) rate. The addition of denosumab to NACT did not improve pCR rates as recently published. In this study, we investigated whether receptor activator of nuclear factor-kappa B (RANK) expression, as part of the denosumab target pathway: (i) may retrospectively identify a subgroup of patients with additional clinical benefit of denosumab or (ii) may predict response to nab-paclitaxel NACT.

EXPERIMENTAL DESIGN

RANK protein was IHC-stained on pre-therapeutic core biopsies from patients of the GeparX study (n = 667) with the antibody RANK/Envision System HRP (DAB) and was analyzed for the percentage of membranous RANK tumor cell staining (>5% RANKhigh vs. ≤5% RANKlow).

RESULTS

We could not identify any patient subgroup with differential response under denosumab add-on treatment in patients with RANKhigh expression [139/667, 20.8%; OR, 0.86; 95% confidence interval (CI), 0.44-1.68; P = 0.667] or RANKlow expression (528/667 (79.2%) OR, 1.10; 95% CI, 0.78-1.56; P = 0.589; Pinteraction = 0.528). However, the pCR rate was higher in the RANKhigh subgroup compared with RANKlow (50% vs. 39%; OR, 1.52; 95% CI, 1.04-2.21; P = 0.037). RANK expression constituted an independent predictor of response to NACT frequently in patients with luminal-like subtype (HR+/HER2-; OR, 2.98; 95% CI, 1.30-6.79; P = 0.010). No predictive value of RANK expression among the different nab-paclitaxel regimens was observed.

CONCLUSION

We report RANK expression to be an independent predictive biomarker for response to NACT in patients with luminal-like breast cancer.

The m6A/m1A/m5C-Related Methylation Modification Patterns and Immune Landscapes in Rheumatoid Arthritis and Osteoarthritis Revealed by Microarray and Single-Cell Transcriptome

Purpose

The goal of this study was to explore the expression characteristics of RNA modification-related genes, reveal immune landscapes and identify novel potential diagnostic biomarkers in osteoarthritis (OA) and rheumatoid arthritis (RA) patients.

Patients and Methods

RNA microarray and single-cell sequencing (scRNA-seq) data were downloaded from gene expression omnibus (GEO) database. Differentially expressed RNA modification-related genes were identified and then functionally annotated. Univariate logistic regression and lasso regression analysis were used to identify primary disease genes for OA and RA. Validation was done using scRNA-seq analysis and immunohistochemistry (IHC) in human knee synovial tissues and a murine destabilization of the medial meniscus (DMM) model. Through WGCNA analysis, genes associated with cell pyroptosis or autophagy in OA and RA were identified, which were then combined with differentially expressed RNA modification-related genes to construct a PPI interaction network. Furthermore, hub genes were selected for ceRNA interaction network analysis, correlation analysis with OA and RA molecular subtypes, as well as correlation analysis with 22 immune cells.

Results

Six RNA modification-related genes (ADAMDEC1, IGHM, OGN, TNFRSF11B, SCARA3 and PTN) were identified as potential OA and RA pathogenesis biomarkers. Their expression was validated in human knee synovial tissues and a murine DMM model. Functional enrichment of differentially expressed RNA modification-related genes between RA and OA was analyzed using GO, KEGG, GSEA, and GSVA. Based on WGCNA and PPI analysis, the six hub genes related to pyroptosis and RNA modification (CXCL10, CXCL9, CCR7, CCL5, CXCL1, and CCR2) were identified as central nodes for ceRNA interaction, correlation with OA and RA molecular subtypes, and association with 22 immune cells.

Conclusion

Our research revealed the significance of RNA modification-related genes in the development of OA and RA pathogenesis, thereby providing a novel research direction for understanding the mechanisms, diagnosis, and treatment of OA and RA.

Study of genes polymorphisms in RANK/RANKL/OPG and WNT signaling pathways and their associations with bone parameters in broiler chicken

Limb problems are one of the most common problems with fast-growing meat-type chickens. Various bone abnormalities, which can lead to limping, bone weakness, or even fractures, bring overall discomfort to birds and a loss of production. Genetic aspects are often associated with these side effects on bone stability and are also cited as the dominant cause. These points to a close negative relationship of genetic selection for rapid growth with traits involved in bone integrity. Due to the assumption of an additive genetic background, improvements through genetic tools can be used. Our study is focused on selected genes of important signaling pathways for bone metabolism. We tried to detect polymorphisms that would show associations with selected bone parameters in a total of 48 broilers. Those were fast-growing Ross 308 hybrids and slow-growing Hubbard M22BxJA87A hybrids. The TNFRSF11A and WISP1 genes were tested. A total of fourteen polymorphisms were found, three of them were synonymous and five in the intron. In the case of four polymorphisms found in exons of the TNFRSF11A gene (c.11G > T, c.31G > A, c.37C > G, c.514G > A), associations with the observed bone parameters (bone strength, bone dimensions and bone mass) were demonstrated. The genetic architecture of bone traits is not fully understood, therefore the present study and the knowledge gained can help to increase the potential in poultry breeding processes and thus reduce the death of individuals.

OPG gene-modified adipose-derived stem cells improve bone formation around implants in osteoporotic rat maxillae

Background

Osteoporosis is a significant barrier to the use of dental implants in the elderly for the treatment of tooth defects. Adipose derived stem cells (ADSCs) have demonstrated extensive potential for tissue repair and regeneration. The present study aimed to investigate the effectiveness of ADSCs engineered to express high levels of osteoprotegerin (OPG) for the treatment of bone loss in implant dentistry caused by estrogen deficiency.

Methods

A rat model of osteoporosis was established through double oophorectomy, and the rats were treated by gene modified cells Adv-OPG-ADSCs. The effects of the treatment on maxilla tissue changes were evaluated using HE staining and micro-CT. Additionally, ALP and TRAP staining were used to assess osteoblast and osteoclast alterations. Finally, the changes in related osteoblast and osteoclast indicators were measured by RT-qPCR, Western blot, and ELISA.

Results

The successfully generated high-OPG-expressing ADSCs led to increase of cell viability, proliferation, and osteoblast differentiation. Treatment with Adv-OPG-ADSCs significantly ameliorated maxillary morphology, trabecular volume reduction, and bone mineral density decline in the model of estrogen-deficient maxillary implant dentistry. Furthermore, the treatment was beneficial to promoting the generation of osteoblasts and inhibiting the generation of osteoclast. Adv-OPG-ADSCs increased OPG, ALP, OCN, and Runx-2 expressions in the maxilla while suppressing RANKL expression, and also increased the concentration of COL I and PINP, as well as decreased the concentration of CTX-1.

Conclusion

Adv-OPG-ADSCs promote the formation of osteoblasts and inhibit the generation of osteoclasts, thereby inhibiting bone absorption, facilitating bone formation, and promoting the repair of maxillary bone after dental implantation in the presence of osteoporosis-related complications, especially in the setting of estrogen deficiency, providing scientific basis for the application of Adv-OPG-ADSCs in the treatment of implant related osteoporosis.

Advances in the study of biomarkers related to bone metastasis in breast cancer

Breast cancer is by far the most common malignancy in females. And bone is the most common site of distant metastasis in breast cancer, accounting for about 65 to 75% of all metastatic breast cancer patients.1,2Bone metastasis is an important factor affecting the prognosis of breast cancer. When patients have early-stage breast cancer without metastasis, their 5-year survival rate is as high as 90%, and once metastasis occurs, their 5-year survival rate will drop to 10%.3 Bone radionuclide imaging (ECT), X-ray, CT scan, MRI and other imaging tests to diagnose breast cancer bone metastasis are commonly used in clinical, It is currently believed that breast cancer bone metastasis is a multistep process: first, breast cancer cells need to acquire invasive and metastatic properties; breast cancer cells enter the blood circulation and migrate from blood breast cancer cells enter the blood circulation and migrate from blood vessels to bone tissue in a targeted manner; breast cancer cells adhere and remain in bone tissue and colonise it; and finally, it leads to bone destruction.4 Several key molecules are involved in breast cancer bone metastasis, and serum biomarkers are generally able to detect pathological changes earlier Several key molecules are involved in breast cancer bone metastasis, and serum biomarkers are generally able to detect pathological changes earlier than imaging.5 This review describes the progress of serum biomarkers for breast cancer bone metastasis.

RANK pathway in cancer: underlying resistance and therapeutic approaches

Cancer remains one of the deadliest diseases despite advances in treatment. Metastatic cancers are the leading cause of death for advanced cancer patients. Those with advanced cancer with osteolytic-type bone metastases have a significantly lower quality of life. A novel treatment plan is needed now more than ever for breast cancer patients with bone metastases. There are shreds of evidence that cancer cells in the bloodstream interact with the bone microenvironment and that this interaction is a contributing component to breast cancer progression. Preventing any stage of this cycle can result in anti-metastasis effects. Since RANKL interacts with its receptor RANK and plays an important role in the vicious cycle, it has proven to be a successful therapeutic target in cancer treatment. As a result, we have presented a complete overview of the RANK pathway in cancer and discussed RANK signaling and tumor microenvironment, and potential therapeutic approaches in this review.

Α Humanized RANKL Transgenic Mouse Model of Progestin-Induced Mammary Carcinogenesis for Evaluation of Novel Therapeutics

Receptor activator of nuclear factor-κB ligand (RANKL) is critically involved in mammary gland pathophysiology, while its pharmaceutical inhibition is being currently investigated in breast cancer. Herein, we investigated whether the overexpression of human RANKL in transgenic mice affects hormone-induced mammary carcinogenesis, and evaluated the efficacy of anti-RANKL treatments, such as OPG-Fc targeting both human and mouse RANKL or Denosumab against human RANKL. We established novel MPA/DMBA-driven mammary carcinogenesis models in TgRANKL mice that express both human and mouse RANKL, as well as in humanized humTgRANKL mice expressing only human RANKL, and compared them to MPA/DMBA-treated wild-type (WT) mice. Our results show that TgRANKL and WT mice have similar levels of susceptibility to mammary carcinogenesis, while OPG-Fc treatment restored mammary ductal density, and prevented ductal branching and the formation of neoplastic foci in both genotypes. humTgRANKL mice also developed MPA/DMBA-induced tumors with similar incidence and burden to those of WT and TgRANKL mice. The prophylactic treatment of humTgRANKL mice with Denosumab significantly prevented the rate of appearance of mammary tumors from 86.7% to 15.4% and the early stages of carcinogenesis, whereas therapeutic treatment did not lead to any significant attenuation of tumor incidence or tumor burden compared to control mice, suggesting the importance of RANKL primarily in the initial stages of tumorigenesis. Overall, we provide unique genetic tools for investigating the involvement of RANKL in breast carcinogenesis, and allow the preclinical evaluation of novel therapeutics that target hormone-related breast cancers.

Selected Parameters of Bone Turnover in Neuroendocrine Tumors-A Potential Clinical Use?

BACKGROUND

Currently, there are no effective markers to diagnose and monitor patients with neuroendocrine tumors (NETs). The aim of this study was to assess bone metabolism based on selected markers of bone turnover: OST, OPG, and IGFBP-3, in both the group of patients with NETs and the control group. Associations with selected sociodemographic, biochemical, and clinicopathological characteristics were examined. We also evaluated any potential associations between these markers and selected biochemical markers of NETs commonly used in clinical practice.

METHODS

The study group included 60 patients with GEP-NETs and BP-NETs, while the control group comprised 62 healthy individuals. The serum concentrations of OST, OPG and IGFBP-3 were assessed using ELISA.

RESULTS

OST and OPG levels were significantly higher in the study group compared to the control group. In the study group, we observed a significant correlation between OPG and the clinical stage and chromogranin A. Additionally, an association was found between OPG and histological grade, Ki-67, and metastasis in GEP-NET cases.

CONCLUSIONS

Markers of bone turnover cannot be used in the routine diagnostics of neuroendocrine tumors. Nonetheless, these markers may help evaluate the skeletal system in patients with NETs. Further research is needed to determine the utility of osteocalcin (OST) and osteoprotegerin (OPG) as potential biomarkers for neuroendocrine tumors.

Messages from the Mineral: How Bone Cells Communicate with Other Tissues

Bone is a highly dynamic tissue, and the constant actions of bone-forming and bone-resorbing cells are responsible for attaining peak bone mass, maintaining bone mass in the adults, and the subsequent bone loss with aging and menopause, as well as skeletal complications of diseases and drug side-effects. It is now accepted that the generation and activity of bone-forming osteoblasts and bone-resorbing osteoclasts is modulated by osteocytes, osteoblast-derived cells embedded in the bone matrix. The interaction among bone cells occurs through direct contact and via secreted molecules. In addition to the regulation of bone cell function, molecules released by these cells are also able to reach the circulation and have effects in other tissues and organs in healthy individuals. Moreover, bone cell products have also been associated with the establishment or progression of diseases, including cancer and muscle weakness. In this review, we will discuss the role of bone as an endocrine organ, and the effect of selected, osteoblast-, osteocyte-, and osteoclast-secreted molecules on other tissues.

The High Level of RANKL Improves IκB/p65/Cyclin D1 Expression and Decreases p-Stat5 Expression in Firm Udder of Dairy Goats

Udder traits, influencing udder health and function, are positively correlated with lactation performance. Among them, breast texture influences heritability and impacts on the milk yield of cattle; however, there is a lack of systematic research on its underlying mechanism in dairy goats in particular. Here, we showed the structure of firm udders with developed connective tissue and smaller acini per lobule during lactation and confirmed that there were lower serum levels of estradiol (E₂) and progesterone (PROG), and higher mammary expression of estrogen nuclear receptor (ER) α and progesterone receptor (PR), in dairy goats with firm udders. The results of transcriptome sequencing of the mammary gland revealed that the downstream pathway of PR, the receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL) signal, participated in the formation of firm mammary glands. During the culture of goat mammary epithelial cells (GMECs), high RANKL level additions promote the Inhibitor kappaB (IκB)/p65/Cyclin D1 expression related to cell proliferation and decrease the phosphorylated signal transduction and transcription activator 5 (Stat5) expression related to milk-protein synthesis of GMECs, which is consistent with electron microscope results showing that there are fewer lactoprotein particles in the acinar cavity of a firm mammary. Furthermore, co-culturing with adipocyte-like cells for 7 d is beneficial for the acinar structure formation of GMECs, while there is a slightly negative effect of high RANKL level on it. In conclusion, the results of this study revealed the structure of firm udders structure and confirmed the serum hormone levels and their receptor expression in the mammary glands of dairy goats with firm udders. The underlying mechanism leading to firm udders and a decrease in milk yield were explored preliminarily, which provided an important foundation for the prevention and amelioration of firm udders and improving udder health and milk yield.

RANKL and RANK in Cancer Therapy

Receptor activator of nuclear factor-κB (RANK) and its ligand (RANKL) are key regulators of mammalian physiology such as bone metabolism, immune tolerance and antitumor immunity, and mammary gland biology. Here, we explore the multiple functions of RANKL/RANK in physiology and pathophysiology and discuss underlying principles and strategies to modulate the RANKL/RANK pathway as a therapeutic target in immune-mediated cancer treatment.

Rhinovirus-induced epithelial RIG-I inflammasome suppresses antiviral immunity and promotes inflammation in asthma and COVID-19

Rhinoviruses and allergens, such as house dust mite are major agents responsible for asthma exacerbations. The influence of pre-existing airway inflammation on the infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is largely unknown. We analyse mechanisms of response to viral infection in experimental in vivo rhinovirus infection in healthy controls and patients with asthma, and in in vitro experiments with house dust mite, rhinovirus and SARS-CoV-2 in human primary airway epithelium. Here, we show that rhinovirus infection in patients with asthma leads to an excessive RIG-I inflammasome activation, which diminishes its accessibility for type I/III interferon responses, leading to their early functional impairment, delayed resolution, prolonged viral clearance and unresolved inflammation in vitro and in vivo. Pre-exposure to house dust mite augments this phenomenon by inflammasome priming and auxiliary inhibition of early type I/III interferon responses. Prior infection with rhinovirus followed by SARS-CoV-2 infection augments RIG-I inflammasome activation and epithelial inflammation. Timely inhibition of the epithelial RIG-I inflammasome may lead to more efficient viral clearance and lower the burden of rhinovirus and SARS-CoV-2 infections.

Postdiagnosis circulating osteoprotegerin and TRAIL concentrations and survival and recurrence after a breast cancer diagnosis: results from the MARIE patient cohort

BACKGROUND

Experimental studies suggest a role for osteoprotegerin (OPG) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in mammary tumor development and progression. These biomarkers have been minimally investigated with respect to outcomes in breast cancer patients.

METHODS

OPG and TRAIL were evaluated in blood samples collected from 2459 breast cancer patients enrolled in the MARIE study, a prospective population-based patient cohort, at median of 129 days after diagnosis. Participants were between ages 50 and 74 at diagnosis and recruited from 2002 to 2005 in two regions of Germany. Follow-up for recurrence and mortality was conducted through June 2015. Delayed-entry Cox proportional hazards regression was used to assess associations between OPG and TRAIL with all-cause and breast cancer-specific mortality, and recurrence, both overall and by tumor hormone receptor status.

RESULTS

Median follow-up time was 11.7 years, with 485 deaths reported (277 breast cancer-specific). Higher OPG concentrations were associated with a higher risk of all-cause mortality (hazard ratio for 1-unit log2-transformed concentration (HR_log2) = 1.24 (95% confidence interval 1.03-1.49). Associations were observed in women diagnosed with ER-PR- tumors or discordant hormone receptor status (ER-PR-, HR_log2 = 1.93 (1.20-3.10); discordant ERPR, 1.70 (1.03-2.81)), but not for women with ER + PR + tumors (HR_log2 = 1.06 (0.83-1.35)). OPG was associated with a higher risk of recurrence among women with ER-PR- disease (HR_log2 = 2.18 (1.39-3.40)). We observed no associations between OPG and breast cancer-specific survival, or for TRAIL and any outcome.

CONCLUSIONS

Higher circulating OPG may be a biomarker of a higher risk of poor outcome among women diagnosed with ER- breast cancer. Further mechanistic studies are warranted.

Isoliensinine suppresses bone loss by targeted inhibition of RANKL-RANK binding

BACKGROUND

Osteoporosis, a systemic metabolic bone disease, is often caused by the disruption of dynamic equilibrium between osteoclasts and osteoblasts. Overactive bone resorption, in which osteoclasts play a major role, is one of the most common and major causes of osteoporosis. Less costly and more effective drug treatments for this disease are needed. Based on the combination of molecular docking techniques and in vitro cell assays, this study aimed to explore the mechanism by which Isoliensinine (ILS) protects the bone loss by inhibiting osteoclast differentiation.

METHODS

A virtual docking model based on molecular docking technology was used to investigate the interactions between ILS and the Receptor Activator of Nuclear Kappa-B (RANK)/Receptor Activator of Nuclear Kappa-B Ligand (RANKL).In this study, we determined the effective dose of action of ILS to inhibit osteoclast differentiation in vitro and, using bone resorption experiments, RT-CPR and Western Blot investigated the effects of ILS on bone resorption function and normal expression of osteoclast-associated genes and proteins, and validated potential mechanistic pathways. In vivo experiments revealed that ILS could inhibit bone loss through Micro-CT results. Finally, the molecular interaction between ILS and RANK/RANKL was investigated using biomolecular interaction experiments to verify the correctness and accuracy of the computational results.

RESULTS

ILS binds to RANK and RANKL proteins, respectively, through virtual molecular docking. The Surface Plasmon Resonance (SPR) experiment results revealed that phosphorylated JNK, ERK, P38, and P65 expression was significantly downregulated when ILS were targeted to inhibit RANKL/RANK binding. At the same time, the expression of IKB-a was significantly increased under the stimulation of ILS, which rescued the degradation of IKB-a. ILS can significantly inhibit the levels of Reactive Oxygen Species (ROS) and Ca2 + concentration in vitro. Finally, the results of Micro-CT showed that ILS can significantly inhibit bone loss in vivo, indicating that ILS has a potential role in the treatment of osteoporosis.

CONCLUSION

ILS inhibits osteoclast differentiation and bone loss by preventing the normal binding of RANKL/RANK, affecting downstream signaling pathways, including MAPK.NF-KB, ROS, Ca2+, genes, and proteins.

Expression of RANKL in breast cancer tissue in patients with fibrous dysplasia/McCune-Albright syndrome

BACKGROUND

In fibrous dysplasia/McCune-Albright syndrome (FD/MAS), mosaic mutations in the GNAS gene lead to locally abnormal bone turnover. Additionally, patients with FD/MAS, particularly with thoracic lesions, have an increased risk for breast cancer. Development and progression of breast cancer has been associated with expression of Receptor Activator of NF-κB ligand (RANKL) in mammary tissue, and due to the GNAS mutation, RANKL is systemically increased in patients with FD/MAS. Yet it is unknown whether breast cancer in FD/MAS is also dependent on RANKL. We hypothesized that the GNAS mutation might induce RANKL overproduction and an oncogenic niche in mammary tissue, and examined RANKL expression in breast cancer tissue of patients with FD/MAS compared to controls.

METHODS

Nine patients with FD/MAS and breast cancer were included and clinical data were retrieved. Patients were matched to controls with breast cancer without FD/MAS based on age and tumor type. Three pregnant breast cancer patients were included as positive controls. Immunohistochemical detection of RANKL was performed on formalin-fixed paraffin-embedded breast cancer specimens. Staining intensity was classified as weak, moderate or intense. The area of positive RANKL staining divided by the total ductal-lobular area was assessed (positive area percentage, PAP). Number of patients with RANKL expression was compared between FD/MAS and control group by chi-square (χ²) test, the PAP by Mann-Whitney U test (MWU).

RESULTS

RANKL expression was observed in 3 patients with FD/MAS (38 %), mainly in healthy tissue, and none of the control patients (χ²p = 0.055). The FD/MAS group demonstrated considerably more intense staining than the control group, comparable to positive controls. The median PAP was 0.64 % (range 0.14-2.04 %) in the 3 FD/MAS patients with RANKL expression, 0.01 % (Q1-Q3: 0.0003-0.514 %) in the entire FD/MAS group, 0.006 % (Q1-Q3: 0.001-0.012 %) in the control group (MWU = 0.574), and 0.19 % (0.08-0.32 %) in the pregnant patients. All patients with FD/MAS and RANKL expression had thoracic bone lesions, but no correlation was observed between RANKL expression and presence of the GNAS mutation or FD disease burden.

CONCLUSIONS

The triad of a higher number of patients, higher positive area percentage and stronger intensity in the FD/MAS compared to the control group indicates that RANKL may be upregulated in mammary tissue in a subset of patients with FD/MAS, which may explain the increased risk for breast cancer, although the clinical significance remains unclear. Further research is needed to establish risk profiles for the development of RANKL-positive breast cancer and to improve early screening and treatment.

Comparative study of the synovial levels of RANKL and OPG in rheumatoid arthritis, spondyloarthritis and osteoarthritis

INTRODUCTION

In chronic arthropathies, there are several mechanisms of joint destruction. In recent years, studies have reported the implication of receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) in the process of activation and differentiation of osteoclasts, a key cell in the development of bone erosion. The RANKL/OPG ratio is increased in the serum of patients with malignant diseases and lytic bone disease, as well as rheumatoid arthritis (RA). The objective of this study was to measure and compare the concentrations of OPG and RANKL in the synovial fluid (SF) of patients with rheumatoid arthritis, spondyloarthritis (SpA) and osteoarthritis (OA).

METHODS

This was an observational and cross-sectional study with 83 patients, 33 with RA, 32 with SpA and 18 with OA, followed up regularly in the outpatient clinics of the Rheumatology Department of the Clinics Hospital of the Ribeirão Preto Medical School-USP. All patients were assessed for indications for arthrocentesis by the attending physicians at the time of SF collection and were evaluated for demographic variables and medication use. Disease activity was assessed in individuals with RA and SpA. The quantification of SF OPG and RANKL levels was performed by ELISA, and the correlations of the results with clinical, laboratory and radiological parameters were assessed.

RESULTS

We found no statistically significant difference in the RANKL and OPG levels among the groups. Patients with RA showed a positive correlation between the SF cell count and RANKL level (r = 0.59; p < 0.05) and the RANKL/OPG ratio (r = 0.55; p < 0.05). Patients with OA showed a strong correlation between C-reactive protein (CRP) and the RANKL/OPG ratio (r = 0.82; p < 0.05). There was no correlation between the OPG and RANKL levels and markers of inflammatory activity or the disease activity index in patients with RA or SpA.

CONCLUSION

Within this patient cohort, the RANKL/OPG ratio was correlated with the SF cell count in patients with RA and with serum CRP in patients with OA, which may suggest a relationship with active inflammation and more destructive joint disease.

Current comprehensive understanding of denosumab (the RANKL neutralizing antibody) in the treatment of bone metastasis of malignant tumors, including pharmacological mechanism and clinical trials

Denosumab, a fully humanized monoclonal neutralizing antibody, inhibits activation of the RANK/RANKL/OPG signaling pathway through competitive binding with RANKL, thereby inhibiting osteoclast-mediated bone resorption. Denosumab inhibits bone loss; therefore, it is used to treat metabolic bone diseases (including postmenopausal osteoporosis, male osteoporosis, and glucocorticoid-induced osteoporosis), in clinical practice. Since then, multiple effects of denosumab have been discovered. A growing body of evidence suggests that denosumab has a variety of pharmacological activities and broad potential in clinical diseases such as osteoarthritis, bone tumors, and other autoimmune diseases. Currently, Denosumab is emerging as a treatment for patients with malignancy bone metastases, and it also shows direct or indirect anti-tumor effects in preclinical models and clinical applications. However, as an innovative drug, its clinical use for bone metastasis of malignant tumors is still insufficient, and its mechanism of action needs to be further investigated. This review systematically summarizes the pharmacological mechanism of action of denosumab and the current understanding and clinical practice of the use of denosumab for bone metastasis of malignant tumors to help clinicians and researchers deepen their understanding of denosumab.

Lactate secreted via MCT4 from bone‑colonizing breast cancer excites sensory neurons via GPR81

Breast cancer (BC) bone metastasis causes bone pain (BP), which detrimentally damages the quality of life and outcome of patients with BC. However, the mechanism of BC‑BP is poorly understood, and effective treatments are limited. The present study demonstrated a novel mechanism of BC‑BP using a mouse model of bone pain, in which mouse (EO771) and human (MDA‑MB‑231) BC cells were injected in the bone marrow cavity of tibiae. Western blot analysis using sensory nerves, in vivo assessment of cancer pain and in vitro calcium flux analysis were performed. These mice developed progressive BC‑BP in tibiae in conjunction with an upregulation of phosphorylated pERK1/2 and cAMP‑response element‑binding protein (pCREB), which are molecular indicators of neuron excitation, in the dorsal root ganglia (DRG) of sensory nerves. Importantly, mice injected with BC cells, in which the expression of the lactic acid transporter monocarboxylate transporter 4 (MCT4) was silenced, exhibited decreased BC‑BP with downregulated expression of pERK1/2 and pCREB in the DRG and reduced circulating levels of lactate compared with mice injected with parental BC cells. Further, silencing of the cell‑surface orphan receptor for lactate, G protein‑coupled receptor 81 (GPR81), in the F11 sensory neuron cells decreased lactate‑promoted upregulation of pERK1/2 and Ca²⁺ influx, suggesting that the sensory neuron excitation was inhibited. These results suggested that lactate released from BC cells via MCT4 induced BC‑BP through the activation of GPR81 of sensory neurons. In conclusion, the activation of GPR81 of sensory neurons by lactate released via MCT4 from BC was demonstrated to contribute to the induction of BC‑BP, and disruption of the interactions among lactate, MCT4 and GPR81 may be a novel approach to control BC‑BP.

RANKL up-regulated by progesterone aggravates lipopolysaccharide-induced acute lung injury during pregnancy

Acute lung injury (ALI) is a common acute respiratory disease with high morbidity and mortality rate in pregnant women. Receptor activator of NF-κB ligand (TNFSF11, also known as RANKL) exerts either pro-inflammatory or anti-inflammatory effects on the immune response. LPS administration reduced the survival time (n = 10, p < 0.01), increased wet/dry ratio (n = 10, p < 0.001) and lung injury score (n = 10, p < 0.001), the elevated proportions of plasmacytoid dendritic cells (pDCs) (n = 10, p < 0.0001), tissue-resident DCs (resDCs) (n = 10, p < 0.0001), macrophages (n = 10, p < 0.0001), and neutrophils (n = 10, p < 0.0001), and the expressions of costimulatory molecules and inflammation cytokines (n = 10, p < 0.05) in lungs of pregnant mice, compared with non-pregnant mice. In vitro, progesterone up-regulated the expression of RANKL (n > 6, p < 0.05) on pulmonary fibroblasts. The results of cytokine arrays showed that the cytokines associated with inflammatory response and leukocyte differentiation were decreased in pulmonary fibroblasts after treatment with anti-RANKL neutralizing antibody, compared with control pulmonary fibroblasts. More notably, we found that Tnfsf11-/- pregnant mice had longer survival durations (n = 10, p < 0.01), lower lung injury scores (n = 10, p < 0.05), and lower immune cell infiltration (n = 10, p < 0.05). These data imply that the RANKL/RANK axis plays an essential role in LPS-induced ALI during pregnancy possibly through a variety of pathways.

Epimedii Folium and Ligustri Lucidi Fructus Promote Osteoblastogenesis and Inhibit Osteoclastogenesis against Osteoporosis via Acting on Osteoblast-Osteoclast Communication

Osteoblast (OB) and osteoclast (OC) play important roles in bone formation and bone resorption, which can communicate with each other through cytokine paracrine. Previous studies have confirmed that Epimedii Folium (EF) and Ligustri Lucidi Fructus (LLF) used alone or in combination can treat osteoporosis (OP) through regulating bone remodeling, but the effects of EF and LLF on osteoblastogenesis, osteoclastogenesis, and OB-OC communication are unclear. In this study, we investigated the direct and indirect effects of EF and LLF on OBs and OCs via monoculture and coculture (transwell) models of OBs and OCs. We found that the combination of EF and LLF (EF&LLF) could promote osteoblastogenesis and inhibit osteoclastogenesis directly and indirectly. In order to study the mechanisms of EF&LLF on indirectly regulating osteoblastogenesis and osteoclastogenesis, we detected the expression of cytokines by which OBs and OCs could communicate with each other. We found that EF&LLF could downregulate the expression of RANKL and M-CSF and the protein ratio of RANKL/OPG of OBs and Atp6v0d2 expression of OCs and upregulate the expression of OPG and TGF-β1 of OBs and the expression of TGF-β1, BMP-2, and IGF-1 of OCs, indicating that EF&LLF could regulate cytokine expressions of OBs/OCs to affect OB-OC communication. In addition, EF&LLF had a better effect on regulating cytokines of OBs and OCs than EF or LLF in single use. This study suggested that EF&LLF exhibited the effects of promoting osteoblastogenesis and inhibiting osteoclastogenesis via acting on OB-OC communication and provided some scientific evidences for EF&LLF against OP.