Regulation of Runx2 by post-translational modifications in osteoblast differentiation

Acetylation of H3K18 activated by p300 promotes osteogenesis in human adipose-derived mesenchymal stem cells

Human adipose-derived mesenchymal stem cells (hAD-MSCs) have garnered significant interest as a viable alternative source of stem cells for applications in bone tissue engineering due to their high and ease availability. At present, the limited studies on potential epigenetic regulatory mechanism in hAD-MSCs greatly hinders its clinical application in bone repair. Histone acetylation has been identified as a critical regulator of the osteogenic differentiation of mesenchymal stem cells (MSCs), with increased levels of histone acetylation sites frequently correlating with enhanced osteogenic differentiation. However, their specific roles in MSCs osteogenesis remain unclear. In this study, we observed a significant up-regulation of H3K18 acetylation (H3K18ac) during the osteogenic induction of hAD-MSCs. This modification was notably enriched in the promoter regions of genes associated with osteogenesis, thereby facilitating osteogenic differentiation. Furthermore, the treatment of histone acetyltransferases p300 inhibitor A-485 in hAD-MSCs resulted in a reduction of H3K18 acetylation levels during the osteogenic differentiation, which corresponded with a diminished osteoblast phenotype and function. These results indicated that p300-mediated acetylation of H3K18 enhances the osteogenic differentiation of hAD-MSCs. It provides a novel insight into understanding the mechanism of osteogenic differentiation of hAD-MSCs and promoting its application in bone tissue engineering.

Design, synthesis and biological evaluation of new class of pyrazoles-dihydropyrimidinone derivatives as bone anabolic agents

This study explores a series of twenty-four newly synthesized pyrzole-dihydropyrimidinone hybrids as potential bone anabolic agents. Initially, an alkaline phosphatase assay, a common marker of bone formation, was used to screen all compounds for their ability to stimulate osteogenic potential. Initial screening identified three promising candidates (5f, 5u and 5w) that were subsequently confirmed to be non-toxic to osteoblasts. Further investigation revealed that compound 5w displayed the most potent osteoanabolic effect, promoting osteoblast differentiation and upregulating mRNAs expression of osteogenic gene. Based on the promising in vitro and in vivo activity, structure-activity relationship (SAR) analysis revealed a furan ring on the dihydropyrimidinone unit and electron-donating groups on the N-phenyl ring of the pyrazole moiety to be crucial for osteogenic activity. Additionally, molecular docking, favorable pharmacokinetic properties and In silico ADME predictions suggest potential oral bioavailability. These findings establish the pyrazole-dihydropyrimidinone scaffold as a promising hit for developing a new class of orally active bone anabolic agents.

A Systematic Review on the Molecular Mechanisms of Resveratrol in Protecting Against Osteoporosis

Osteoporosis is a prevalent metabolic bone disorder characterized by decreased bone mineral density and increased fracture risk, particularly among aging populations. While conventional pharmacological treatments exist, they often have adverse effects, necessitating the search for alternative therapies. Resveratrol, a naturally occurring polyphenol, has gained significant attention for its potential osteoprotective properties through various molecular mechanisms. This systematic review aims to comprehensively analyze the molecular pathways through which resveratrol protects against osteoporosis. Using an advanced search strategy in the Scopus, PubMed, and Web of Science databases, we identified 513 potentially relevant articles. After title and abstract screening, followed by full-text review, 28 studies met the inclusion criteria. The selected studies comprised 14 in vitro studies, 8 mixed in vitro and in vivo studies, 6 in vivo studies, and 1 cross-sectional study in postmenopausal women. Our findings indicate that resveratrol exerts its osteoprotective effects by enhancing osteoblast differentiation through the activation of the Phosphoinositide 3-Kinase/Protein Kinase B (PI3K/Akt), Sirtuin 1 (SIRT1), AMP-Activated Protein Kinase (AMPK), and GATA Binding Protein 1 (GATA-1) pathways while simultaneously inhibiting osteoclastogenesis by suppressing Mitogen-Activated Protein Kinase (MAPK) and TNF Receptor-Associated Factor 6/Transforming Growth Factor-β-Activated Kinase 1 (TRAF6/TAK1). Additionally, resveratrol mitigates oxidative stress and inflammation-induced bone loss by activating the Hippo Signaling Pathway/Yes-Associated Protein (Hippo/YAP) and Nuclear Factor Erythroid 2-Related Factor 2 (NRF2) pathways and suppressing Reactive Oxygen Species/Hypoxia-Inducible Factor-1 Alpha (ROS/HIF-1α) and NADPH Oxidase 4/Nuclear Factor Kappa-Light-Chain-Enhancer of Activated B Cells (Nox4/NF-κB). Despite promising preclinical findings, the low bioavailability of resveratrol remains a significant challenge, highlighting the need for novel delivery strategies to improve its therapeutic potential. This review provides critical insights into the molecular mechanisms of resveratrol in bone health, supporting its potential as a natural alternative for osteoporosis prevention and treatment. Further clinical studies are required to validate its efficacy and establish optimal dosing strategies.

RUNX2 Phase Separation Mediates Long-Range Regulation Between Osteoporosis-Susceptibility Variant and XCR1 to Promote Osteoblast Differentiation

GWASs have identified many loci associated with osteoporosis, but the underlying genetic regulatory mechanisms and the potential drug target need to be explored. Here, a new regulatory mechanism is found that a GWAS intergenic SNP (rs4683184) functions as an enhancer to influence the binding affinity of transcription factor RUNX2, whose phase separation can mediate the long-range chromatin interaction between enhancer and target gene XCR1 (a member of the GPCR family), leading to changes of XCR1 expression and osteoblast differentiation. Bone-targeting AAV of Xcr1 can improve bone formation in osteoporosis mice, suggesting that XCR1 can be a new susceptibility gene for osteoporosis. This study is the first to link non-coding SNP with phase separation, providing a new insight into long-range chromatin regulation mechanisms with susceptibility to complex diseases, and finding a potential target for the development of osteoporosis drugs and corresponding translational research.

Mutanobactin-D, a Streptococcus mutans Non-Ribosomal Cyclic Lipopeptide, Induces Osteogenic/Odontogenic Differentiation of Human Dental Pulp Stem Cells and Human Bone Marrow Stem Cells

Bacterium-triggered carious lesions implicate dental hard tissue destruction and the simultaneous initiation of regenerative events comprising dental stem cell activation. Streptococcus mutans (S. mutans) is a prominent pathogen of the oral cavity and the principal cause of caries. S. mutans generates complex products involved in interbacterial interactions, including Mutanobactin-D (Mub-D), which belongs to a group of non-ribosomal cyclic lipopeptides. In the present study, we aimed to analyse the potential role of the synthetic Mub-D peptide in cell populations involved in tissue regenerative processes. To this end, we assessed the in vitro effects of Mub-D in human dental pulp stem cells (hDPSCs) and human bone marrow stem cells (hBMSCs). Our data demonstrated a concentration-dependent effect of Mub-D on their viability and a significant increase in their proliferation and osteogenic/odontogenic differentiation. These events were associated with specific changes in gene expression, where CCDN-1, RUNX-2, OSX, OCN, DMP-1, DSPP, and BMP-2 genes were upregulated. The ability of Mub-D to modulate the osteogenic/odontogenic differentiation of both hDPSCs and hBMSCs and considerably enhance mineralisation in a controlled and concentration-dependent manner opens new perspectives for stem cell-based regenerative approaches in the clinics.

Phytonanoparticles as novel drug carriers for enhanced osteogenesis and osseointegration

Phytonanoparticles have emerged as a promising class of biomaterials for enhancing bone regeneration and osseointegration, offering unique advantages in biocompatibility, multifunctionality, and sustainability. This comprehensive review explores the synthesis, characterization, and applications of phytonanoparticles in bone tissue engineering. The green synthesis approach, utilizing plant extracts as reducing and stabilizing agents, yields nanoparticles with intrinsic bioactive properties that can synergistically promote osteogenesis. We examine the mechanisms by which phytonanoparticles, particularly those derived from gold, silver, and zinc oxide, influence key molecular pathways in osteogenesis, including RUNX2 and Osterix signaling. The review discusses advanced strategies in phyto-nanoparticle design, such as surface functionalization and stimuli-responsive release mechanisms, which enhance their efficacy in bone regeneration applications. Preclinical studies demonstrating improved osteoblast proliferation, differentiation, and mineralization are critically analyzed, along with emerging clinical data. Despite promising results, scalability, standardization, and regulatory approval challenges persist. The review also addresses the economic and environmental implications of phyto-nanoparticle production. Looking ahead, we identify key research directions, including developing personalized therapies, combination approaches with stem cells or gene delivery, and long-term safety assessments. By harnessing the power of plant-derived nanomaterials, phytonanoparticles represent an innovative approach to addressing the complex challenges of bone regeneration, with potential applications spanning dental, orthopedic, and maxillofacial surgery.

Rosuvastatin/calcium carbonate co-precipitated nanoparticles: A novel synergistic approach enhancing local bone regeneration in osteoporotic rat model

This study aimed at preparing sustained release rosuvastatin (Ru) calcium carbonate (CC) co-precipitate nano-formulation for local intra-osseous application in osteoporotic rats. Nano-formulations were prepared by the co-precipitation method using different concentrations of polyvinyl alcohol (PVA) (0.2, 0.4, 0.6 %) as a stabilizer and equimolar ratios of calcium chloride and calcium carbonate (0.1, 0.3 or 0.5 M). Pre-formulation examination including; FTIR and X-ray diffraction confirmed the formation of CC nanoparticles in a crystalline structure that was preserved before and after loading with Ru. The optimized formula showing; PS of 105.71 ± 5.10 nm, PDI of 0.25 ± 0.02, ZP of -44.70 ± 0.09 mV, % EE of 60.16 ± 1.58 and a quasi-spherical nanoparticle with nano-deposition of Ru crystals adsorbed on them as seen under TEM and SEM, was then integrated in 20 % Pluronic gel. The Ru-gel exhibited good rheological behavior with a short gelation time of 20 sec and a sustained release pattern of 30 % for the optimized Ru/CC gel versus ≈ 90 % for the Ru/CC dispersion after 6 h. In-vivo, ovariectomy-induced osteoporotic rats were used to cause a bone defect in the tibial metaphysis. The drill-hole defects were then filled with the formulations under test and examined 30 days postoperatively. Through SEM-EDX scanning, histological assessments, and evaluation of bone metabolic markers, Ru/CC treatment significantly enhanced bone healing, improved bone microarchitecture, increased trabecular bone area, enhanced osteogenic gene expression, and reduced osteoclast activity. Experiments proved that Ru/CC successfully enhances osteogenesis and reduces osteoclastogenesis, proposing it as a promising therapeutic approach for enhancing bone regeneration in osteoporosis.

Exploring the In Vitro Effects of Zingerone on Differentiation and Signalling Pathways in Bone Cell Lines

OBJECTIVE

Ensuring adequate bone health is crucial for preventing conditions such as osteoporosis and fractures. Zingerone, a phytonutrient isolated from cooked ginger, has gained attention for its potential benefits in bone health. This study evaluated the osteoprotective potential of zingerone and its effects on differentiation and signalling pathways in vitro using SAOS-2 osteosarcoma and RAW264.7 macrophage cell lines, aiming to elucidate its mechanism of action in bone remodelling.

METHODS

SAOS-2 osteosarcoma and RAW264.7 macrophage cells were treated with zingerone at concentrations of 200 µM. Osteoblast differentiation was assessed by alkaline phosphatase (ALP) activity, bone mineralisation via Alizarin Red S stain, and gene expression markers (ALP, runt-related transcription factor 2 (Runx2), and osteocalcin) via quantitative polymerase chain reaction (q-PCR). Osteoclast differentiation was evaluated by tartrate-resistant acid phosphatase (TRAP) staining, TRAP activity, and mitogen-activated protein kinase (MAPK) pathways.

RESULTS

Treatment with zingerone was non-toxic at 200 µM. Zingerone (200 µM) significantly stimulated the gene expression of ALP and Runx2 in SAOS-2 cells (p < 0.05) without statistically significantly enhancing SAOS-2 mineralisation via calcium deposits. Moreover, zingerone significantly inhibited osteoclast differentiation in RAW264.7 cells as evidenced by reduced TRAP staining and activity (p < 0.05).

CONCLUSIONS

Zingerone shows promise in reducing osteoclast activity and supporting early osteoblast differentiation, suggesting its potential as a dietary supplement for bone health. Further in vivo and clinical studies are needed to confirm its role in managing osteoporosis.

The impact of RUNX2 gene variants on cleidocranial dysplasia phenotype: a systematic review

Cleidocranial Dysplasia (CCD) is a rare genetic disorder characterized by skeletal abnormalities and dental anomalies, primarily caused by variants in the RUNX2 gene. Understanding the spectrum of RUNX2 variants and their effects on CCD phenotypes is crucial for accurate diagnosis and management strategies. This systematic review aimed to comprehensively analyze the genotypic and phenotypic spectra of RUNX2 variants in CCD patients, assess their distribution across functional regions, and investigate genotype-phenotype correlations. This review included 569 reported variants and 453 CCD patients from 103 articles. Of 569 variants, in-frame variants constituted 48.68%, while null variants accounted for 51.32%. Regarding locations, RUNX2 variants were predominantly located in the RHD (55.54%), followed by PST (16.34%), NMTS (6.33%), QA (4.75%), VWRPY (1.23%), and NLS (1.41%) regions while 10.19% were in non-coding regions. In-frame variants occurred primarily in the RHD (90.97%), while null variants were found across various regions of RUNX2. Data analysis revealed a correlation between variant location and specific skeletal features in CCD patients. Missense variants, predominantly found within the functionally critical RHD, were significantly associated with supernumerary teeth, macrocephaly, metopic groove, short ribs, and hypoplastic iliac wings compared to nonsense variants. They were also significantly associated with delayed fontanelle closure, metopic synostosis, hypertelorism, limited shoulder abduction, pubic symphysis abnormalities, and hypoplastic iliac wings compared to in-frame variants found in other regions. These findings underscore the critical role of the RHD, with missense RHD variants having a more severe impact than nonsense and other in-frame variants. Additionally, in-frame insertions and deletions in RUNX2 were associated with fewer CCD features, compared to missense, frameshift, and nonsense variants. Null variants in the NLS region exhibited weaker associations with delayed fontanelle closure, supernumerary teeth, Wormian bones, and femoral head hypoplasia than variants in other regions. Moreover, the NLS variants did not consistently alter nuclear localization, questioning the role of NLS region in nuclear import. In summary, this comprehensive review significantly advances our understanding of CCD, facilitating improved phenotype-genotype correlations, enhanced clinical management, and a deeper insight into RUNX2 functional domains. This knowledge has the potential to guide the development of novel therapeutic targets for skeletal disorders.

RUNX2 regulation in osteoblast differentiation: A possible therapeutic function of the lncRNA and miRNA-mediated network

Osteogenic differentiation is a crucial process in the formation of the skeleton and the remodeling of bones. It relies on a complex system of signaling pathways and transcription factors, including Runt-related transcription factor 2 (RUNX2). Non-coding RNAs (ncRNAs) control the bone-specific transcription factor RUNX2 through post-transcriptional mechanisms to regulate osteogenic differentiation. The most research has focused on microRNAs (miRNAs) and long ncRNAs (lncRNAs) in studying how they regulate RUNX2 for osteogenesis in both normal and pathological situations. This article provides a concise overview of the recent advancements in understanding the critical roles of lncRNA/miRNA/axes in controlling the expression of RUNX2 during bone formation. The possible application of miRNAs and lncRNAs as therapeutic agents for the treatment of disorders involving the bones and bones itself is also covered.

Characterization and preparation of food-derived peptides on improving osteoporosis: A review

Osteoporosis is a systemic bone disease characterized by reduced bone mass and deterioration of the microstructure of bone tissue, leading to an increased risk of fragility fractures and affecting human health worldwide. Food-derived peptides are widely used in functional foods due to their low toxicity, ease of digestion and absorption, and potential to improve osteoporosis. This review summarized and discussed methods of diagnosing osteoporosis, treatment approaches, specific peptides as alternatives to conventional drugs, and the laboratory preparation and identification methods of peptides. It was found that peptides interacting with RGD (arginine-glycine-aspartic acid)-binding active sites in integrin could alleviate osteoporosis, analyzed the interaction sites between these osteogenic peptides and integrin, and further discussed their effects on improving osteoporosis. These may provide new insights for rapid screening of osteogenic peptides, and provide a theoretical basis for their application in bone materials and functional foods.

Altered AP-1, RUNX and EGR chromatin dynamics drive fibrotic lung disease

Pulmonary fibrosis, including systemic sclerosis-associated interstitial lung disease (SSc-ILD), involves myofibroblasts and SPP1hi macrophages as drivers of fibrosis. Single-cell RNA sequencing has delineated fibroblast and macrophages transcriptomes, but limited insight into transcriptional control of profibrotic gene programs. To address this challenge, we analyzed multiomic snATAC/snRNA-seq on explanted SSc-ILD and donor control lungs. The neural network tool ChromBPNet inferred increased TF binding at single base pair resolution to profibrotic genes, including CTHRC1 and ADAM12, in fibroblasts and SPP1 and CCL18 in macrophages. The novel algorithm HALO confirmed AP-1, RUNX, and EGR TF activity controlling profibrotic gene programs and established TF-regulatory element-gene networks. This TF action atlas provides comprehensive insights into the transcriptional regulation of fibroblasts and macrophages in healthy and fibrotic human lungs.

Hyperglycosylation as an Indicator of Aging in the Bone Metabolome of Oryzias latipes

Chronological aging of bone tissues is a multi-faceted process that involves a complex interplay of cellular, biochemical, and molecular mechanisms. Metabolites play a crucial role for bone homeostasis, and a changed metabolome is indicative for bone aging, although bone metabolomics are currently understudied. The vertebral bone metabolome of the model fish Japanese medaka (Oryzias latipes) was employed to identify sex-specific markers of bone aging. 265 and 213 metabolites were differently expressed in 8-month-old vs. 3-month-old female and male fish, respectively. The untargeted metabolomics pathway enrichment analysis indicated a sex-independent increased hyperglycosylation in 8-month-old individuals. The upregulated glycosylation pathways included glycosphingolipids, glycosylphosphatidylinositol anchors, O-glycans, and N-glycans. UDP-sugars and sialic acid were found to be major drivers in regulating glycosylation pathways and metabolic flux. The data indicate a disruption of protein processing at the endoplasmic reticulum and changes in O-glycan biosynthesis. Dysregulation of glycosylation, particularly through the hexosamine biosynthetic pathway, may contribute to bone aging and age-related bone loss. The results warrant further investigation into the functional involvement of increased glycosylation in bone aging. The potential of glycan-based biomarkers as early warning systems for bone aging should be explored and would aid in an advanced understanding of the progression of bone diseases such as osteoporosis.

Similarity-based metric analysis approach for predicting osteogenic differentiation correlation coefficients and discovering the novel osteogenic-related gene FOXA1 in BMSCs

Background

As a powerful tool, bioinformatics analysis is playing an increasingly important role in many fields. Osteogenic differentiation is a complex biological process involving the fine regulation of numerous genes and signaling pathways.

Method

Osteogenic differentiation-related genes are collected from the online databases. Then, we proposed two indexes Jaccard similarity and Sorensen-Dice similarity to measure the topological relevance of genes in the human PPI network. Furthermore, we selected three pathways involving osteoblast-related transcription factors, osteoblast differentiation, and RUNX2 regulation of osteoblast differentiation for investigation. Subsequently, we performed functional a enrichment analysis of these top-ranked genes to check whether these candidate genes identified by similarity-based metrics are enriched in some specific biological functions and states. we performed a permutation test to investigate the similarity score with four well-known osteogenic differentiation-related pathways including hedgehog signaling pathway, BMP signaling, ERK pathway, and Wnt signaling pathway to check whether these osteogenic differentiation-related pathways can be regulated by FOXA1. Lentiviral transfection was used to knockdown and overexpress gene FOXA1 in human bone mesenchymal stem cells (hBMSCs). Alkaline phosphatase (ALP) staining and Alizarin Red staining (ARS) were employed to investigate osteogenic differentiation of hBMSCs.

Result

After data collection, human PPI network involving 19,344 genes is included in our analysis. After simplifying, we used Jaccard and Sorensen-Dice similarity to identify osteogenic differentiation-related genes and integrated into a final similarity matrix. Furthermore, we calculated the sum of similarity scores with these osteogenic differentiation-related genes for each gene and found 337 osteogenic differentiation-related genes are involved in our analysis. We selected three pathways involving osteoblast-related transcription factors, osteoblast differentiation, and RUNX2 regulation of osteoblast differentiation for investigation and performed functional enrichment analysis of these top-ranked 50 genes. The results collectively demonstrate that these candidate genes can indeed capture osteogenic differentiation-related features of hBSMCs. According to the novel analyzing method, we found that these four pathways have significantly higher similarity with FOXA1 than random noise. Moreover, knockdown FOXA1 significantly increased the ALP activity and mineral deposits. Furthermore, overexpression of FOXA1 dramatically decreased the ALP activity and mineral deposits.

Conclusion

In summary, this study showed that FOXA1 is a novel significant osteogenic differentiation-related transcription factor. Moreover, our study has tightly integrated bioinformatics analysis with biological knowledge, and developed a novel method for analyzing the osteogenic differentiation regulatory network.

Role of Pulsed Electromagnetic Field on Alveolar Bone Remodeling during Orthodontic Retention Phase in Rat Models

Alveolar bone remodeling during the retention phase is essential for successful orthodontic treatment. Pulsed electromagnetic field (PEMF) therapy is an adjunctive therapy for bone-related diseases that induces osteogenesis and prevents bone loss. This study aimed to examine the role of PEMF exposure during the retention phase of orthodontic treatment in alveolar bone remodeling. A total of 36 male Wistar rats were divided into control, PEMF 7, and PEMF 14 groups; a 50 g force nickel-titanium closed-coil spring was inserted to create mesial movement in the first molar for 21 d. Furthermore, the spring was removed, and the interdental space was filled with glass ionomer cement. Concurrently, rats were exposed to a PEMF at 15 Hz with a maximum intensity of 2.0 mT 2 h daily, for 7 and 14 days. Afterwards, the cements were removed and the rats were euthanized on days 1, 3, 7, and 14 to evaluate the expression of Wnt5a mRNA and the levels of RANKL, OPG, ALP, and Runx2 on the tension side. The data were analyzed with ANOVA and post hoc tests, with p < 0.05 declared statistically significant. PEMF exposure significantly upregulated Wnt5a mRNA expression, OPG and ALP levels, and Runx2 expression, and decreased RANKL levels in the PEMF 7 and 14 groups compared to the control group (p < 0.05). This study showed that PEMF exposure promotes alveolar bone remodeling during the orthodontic retention phase on the tension side by increasing alveolar bone formation and inhibiting resorption.

Mild Thermotherapy-Assisted GelMA/HA/MPDA@Roxadustat 3D-Printed Scaffolds with Combined Angiogenesis-Osteogenesis Functions for Bone Regeneration

Early reconstruction of the vascular network is a prerequisite to the effective treatment of substantial bone defects. Traditional 3D printed tissue engineering scaffolds designed to repair large bone defects do not effectively regenerate the vascular network, and rely only on the porous structure within the scaffold for nutrient transfer and metabolic waste removal. This leads to delayed bone restoration and hence functional recovery. Therefore, strategies for generation scaffolds with the capacity to efficiently regenerate vascularization should be developed. This study loads roxarestat (RD), which can stabilize HIF-1α expression in a normoxic environment, onto the mesopore polydopamine nanoparticles (MPDA@RD) to enhance the reconstruction of vascular network in large bone defects. Subsequently, MPDA@RD is mixed with GelMA/HA hydrogel bioink to fabricate a multifunctional hydrogel scaffold (GHM@RD) through 3D printing. In vitro results show that the GHM@RD scaffolds achieve good angiogenic-osteogenic coupling by activating the PI3K/AKT/HSP90 pathway in BMSCs and the PI3K/AKT/HIF-1α pathway in HUVECs under mild thermotherapy. In vivo experiments reveal that RD and mild hyperthermia synergistically induce early vascularization and bone regeneration of critical bone defects. In conclusion, the designed GHM@RD drug delivery scaffold with mild hyperthermia holds great therapeutic value for future treatment of large bone defects.

Exploring the bone marrow micro environment in thalassemia patients: potential therapeutic alternatives

Genetic mutations in the β-globin gene lead to a decrease or removal of the β-globin chain, causing the build-up of unstable alpha-hemoglobin. This condition is referred to as beta-thalassemia (BT). The present treatment strategies primarily target the correction of defective erythropoiesis, with a particular emphasis on gene therapy and hematopoietic stem cell transplantation. However, the presence of inefficient erythropoiesis in BT bone marrow (BM) is likely to disturb the previously functioning BM microenvironment. This includes accumulation of various macromolecules, damage to hematopoietic function, destruction of bone cell production and damage to osteoblast(OBs), and so on. In addition, the changes of BT BM microenvironment may have a certain correlation with the occurrence of hematological malignancies. Correction of the microenvironment can be achieved through treatments such as iron chelation, antioxidants, hypoglycemia, and biologics. Hence, This review describes damage in the BT BM microenvironment and some potential remedies.

Differential but complementary roles of HIF-1α and HIF-2α in the regulation of bone homeostasis

Bone is a highly dynamic tissue undergoing continuous formation and resorption. Here, we investigated differential but complementary roles of hypoxia-inducible factor (HIF)-1α and HIF-2α in regulating bone remodeling. Using RNA-seq analysis, we identified that specific genes involved in regulating osteoblast differentiation were similarly but slightly differently governed by HIF-1α and HIF-2α. We found that increased HIF-1α expression inhibited osteoblast differentiation via inhibiting RUNX2 function by upregulation of Twist2, confirmed using Hif1a conditional knockout (KO) mouse. Ectopic expression of HIF-1α via adenovirus transduction resulted in the increased expression and activity of RANKL, while knockdown of Hif1a expression via siRNA or osteoblast-specific depletion of Hif1a in conditional KO mice had no discernible effect on osteoblast-mediated osteoclast activation. The unexpected outcome was elucidated by the upregulation of HIF-2α upon Hif1a overexpression, providing evidence that Hif2a is a transcriptional target of HIF-1α in regulating RANKL expression, verified through an experiment of HIF-2α knockdown after HIF-1α overexpression. The above results were validated in an ovariectomized- and aging-induced osteoporosis model using Hif1a conditional KO mice. Our findings conclude that HIF-1α plays an important role in regulating bone homeostasis by controlling osteoblast differentiation, and in influencing osteoclast formation through the regulation of RANKL secretion via HIF-2α modulation.

Aspirin Stimulates the Osteogenic Differentiation of Human Adipose Tissue-Derived Stem Cells In Vitro

This study investigates the impact of acetylsalicylic acid (ASA), also known as aspirin, on adipose tissue-derived stem cells (ASCs), aiming to elucidate its dose-dependent effects on morphology, viability, proliferation, and osteogenic differentiation. Isolated and characterized human ASCs were exposed to 0 µM, 100 µM, 200 µM, 400 µM, 800 µM, 1000 µM, 10,000 µM, and 16,000 µM of ASA in vitro. Cell morphology, viability, and proliferation were evaluated with fluorescent live/dead staining, alamarBlue viability reagent, and CyQUANT® cell proliferation assay, respectively. Osteogenic differentiation under stimulation with 400 µM or 1000 µM of ASA was assessed with alizarin red staining and qPCR of selected osteogenic differentiation markers (RUNX2, SPP1, ALPL, BGLAP) over a 3- and 21-day-period. ASA doses ≤ 1000 µM showed no significant impact on cell viability and proliferation. Live/dead staining revealed a visible reduction in viable cell confluency for ASA concentrations ≥ 1000 µM. Doses of 10,000 µM and 16,000 µM of ASA exhibited a strong cytotoxic and anti-proliferative effect in ASCs. Alizarin red staining revealed enhanced calcium accretion under the influence of ASA, which was macro- and microscopically visible and significant for 1000 µM of ASA (p = 0.0092) in quantification if compared to osteogenic differentiation without ASA addition over a 21-day-period. This enhancement correlated with a more pronounced upregulation of osteogenic markers under ASA exposure (ns). Our results indicate a stimulatory effect of 1000 µM of ASA on the osteogenic differentiation of ASCs. Further research is needed to elucidate the precise molecular mechanisms underlying this effect; however, this discovery suggests promising opportunities for enhancing bone tissue engineering with ASCs as cell source.

Hypomethylation of the RUNX2 Gene Is a New Potential Biomarker of Primary Osteoporosis in Men and Women

The search for the molecular markers of osteoporosis (OP), based on the analysis of differential deoxyribonucleic acid (DNA) methylation in bone cells and peripheral blood cells, is promising for developments in the field of the early diagnosis and targeted therapy of the disease. The Runt-related transcription factor 2 (RUNX2) gene is one of the key genes of bone metabolism, which is of interest in the search for epigenetic signatures and aberrations associated with the risk of developing OP. Based on pyrosequencing, the analysis of the RUNX2 methylation profile from a pool of peripheral blood cells in men and women over 50 years of age of Russian ethnicity from the Volga-Ural region of Russia was carried out. The level of DNA methylation in three CpG sites of the RUNX2 gene was assessed and statistically significant hypomethylation was revealed in all three studied CpG sites in men (U = 746.5, p = 0.004; U = 784, p = 0.01; U = 788.5, p = 0.01, respectively) and in one CpG site in women (U = 537, p = 0.03) with primary OP compared with control. In the general sample, associations were preserved for the first CpG site (U = 2561, p = 0.0001766). The results were obtained for the first time and indicate the existence of potentially new epigenetic signatures of RUNX2 in individuals with OP.

Sodium-glucose cotransporter 2 inhibitors attenuate vascular calcification by suppressing endoplasmic reticulum protein thioredoxin domain containing 5 dependent osteogenic reprogramming

AIMS

Vascular calcification is strongly linked to the development of major adverse cardiovascular events, but effective treatments are lacking. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are an emerging category of oral hypoglycemic drugs that have displayed marked effects on metabolic and cardiovascular diseases, including recently reported vascular medial calcification. However, the roles and underlying mechanisms of SGLT2 inhibitors in vascular calcification have not been fully elucidated. Thus, we aimed to further determine whether SGLT2 inhibitors protect against vascular calcification and to investigate the mechanisms involved.

METHODS AND RESULTS

A computed tomography angiography investigation of coronary arteries from 1554 patients with type 2 diabetes revealed that SGLT2 inhibitor use was correlated with a lower Agatston calcification score. In the vitamin D3 overdose, 5/6 nephrectomy chronic kidney disease-induced medial calcification and Western diet-induced atherosclerotic intimal calcification models, dapagliflozin (DAPA) substantially alleviated vascular calcification in the aorta. Furthermore, we showed that DAPA reduced vascular calcification via Runx2-dependent osteogenic transdifferentiation in vascular smooth muscle cells (VSMCs). Transcriptome profiling revealed that thioredoxin domain containing 5 (TXNDC5) was involved in the attenuation of vascular calcification by DAPA. Rescue experiments showed that DAPA-induced TXNDC5 downregulation in VSMCs blocked the protective effect on vascular calcification. Furthermore, TXNDC5 downregulation disrupted protein folding-dependent Runx2 stability and promoted subsequent proteasomal degradation. Moreover, DAPA downregulated TXNDC5 expression via amelioration of oxidative stress and ATF6-dependent endoplasmic reticulum stress. Consistently, the class effects of SGLT2 inhibitors on vascular calcification were validated with empagliflozin in intimal and medial calcification models.

CONCLUSIONS

SGLT2 inhibitors ameliorate vascular calcification through blocking endoplasmic reticulum stress-dependent TXNDC5 upregulation and promoting subsequent Runx2 proteasomal degradation, suggesting that SGLT2 inhibitors are potentially beneficial for vascular calcification treatment and prevention.

FoxO1 knockdown inhibits RANKL-induced osteoclastogenesis by blocking NLRP3 inflammasome activation

OBJECTIVES

This study aimed to elucidate the connection between osteoclastic forkhead transcription factor O1 (FoxO1) and periodontitis and explore the underlying mechanism by which FoxO1 knockdown regulates osteoclast formation.

MATERIALS AND METHODS

A conventional ligature-induced periodontitis model was constructed to reveal the alterations in the proportion of osteoclastic FoxO1 in periodontitis via immunofluorescence staining. Additionally, RNA sequencing (RNA-seq) was performed to explore the underlying mechanisms of FoxO1 knockdown-mediated osteoclastogenesis, followed by western blotting, quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay.

RESULTS

FoxO1+ osteoclasts were enriched in the alveolar bone in experimental periodontitis. Moreover, FoxO1 knockdown led to impaired osteoclastogenesis with low expression of osteoclast differentiation-related genes, accompanied by an insufficient osteoclast maturation phenotype. Mechanistically, RNA-seq revealed that the nuclear factor kappa B (NF-κB) and nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome signaling pathways were inhibited in FoxO1-knockdown osteoclasts. Consistent with this, MCC950, an effective inhibitor of the NLRP3 inflammasome, substantially attenuated osteoclast formation.

CONCLUSIONS

FoxO1 knockdown contributed to the inhibition of osteoclastogenesis by effectively suppressing NF-κB signaling and NLRP3 inflammasome activation. This prospective study reveals the role of FoxO1 in mediating osteoclastogenesis and provides a viable therapeutic target for periodontitis treatment.

A Multifunctional Therapeutic Strategy Using P7C3 as A Countermeasure Against Bone Loss and Fragility in An Ovariectomized Rat Model of Postmenopausal Osteoporosis

By 2060, an estimated one in four Americans will be elderly. Consequently, the prevalence of osteoporosis and fragility fractures will also increase. Presently, no available intervention definitively prevents or manages osteoporosis. This study explores whether Pool 7 Compound 3 (P7C3) reduces progressive bone loss and fragility following the onset of ovariectomy (OVX)-induced osteoporosis. Results confirm OVX-induced weakened, osteoporotic bone together with a significant gain in adipogenic body weight. Treatment with P7C3 significantly reduced osteoclastic activity, bone marrow adiposity, whole-body weight gain, and preserved bone area, architecture, and mechanical strength. Analyses reveal significantly upregulated platelet derived growth factor-BB and leukemia inhibitory factor, with downregulation of interleukin-1 R6, and receptor activator of nuclear factor kappa-B (RANK). Together, proteomic data suggest the targeting of several key regulators of inflammation, bone, and adipose turnover, via transforming growth factor-beta/SMAD, and Wingless-related integration site/be-catenin signaling pathways. To the best of the knowledge, this is first evidence of an intervention that drives against bone loss via RANK. Metatranscriptomic analyses of the gut microbiota show P7C3 increased Porphyromonadaceae bacterium, Candidatus Melainabacteria, and Ruminococcaceae bacterium abundance, potentially contributing to the favorable inflammatory, and adipo-osteogenic metabolic regulation observed. The results reveal an undiscovered, and multifunctional therapeutic strategy to prevent the pathological progression of OVX-induced bone loss.

O-GlcNAcylation: roles and potential therapeutic target for bone pathophysiology

O-linked N-acetylglucosamine (O-GlcNAc) protein modification (O-GlcNAcylation) is a critical post-translational modification (PTM) of cytoplasmic and nuclear proteins. O-GlcNAcylation levels are regulated by the activity of two enzymes, O-GlcNAc transferase (OGT) and O‑GlcNAcase (OGA). While OGT attaches O-GlcNAc to proteins, OGA removes O-GlcNAc from proteins. Since its discovery, researchers have demonstrated O-GlcNAcylation on thousands of proteins implicated in numerous different biological processes. Moreover, dysregulation of O-GlcNAcylation has been associated with several pathologies, including cancers, ischemia-reperfusion injury, and neurodegenerative diseases. In this review, we focus on progress in our understanding of the role of O-GlcNAcylation in bone pathophysiology, and we discuss the potential molecular mechanisms of O-GlcNAcylation modulation of bone-related diseases. In addition, we explore significant advances in the identification of O-GlcNAcylation-related regulators as potential therapeutic targets, providing novel therapeutic strategies for the treatment of bone-related disorders.

Runx2 and Polycystins in Bone Mechanotransduction: Challenges for Therapeutic Opportunities

Bone mechanotransduction is a critical process during skeletal development in embryogenesis and organogenesis. At the same time, the type and level of mechanical loading regulates bone remodeling throughout the adult life. The aberrant mechanosensing of bone cells has been implicated in the development and progression of bone loss disorders, but also in the bone-specific aspect of other clinical entities, such as the tumorigenesis of solid organs. Novel treatment options have come into sight that exploit the mechanosensitivity of osteoblasts, osteocytes, and chondrocytes to achieve efficient bone regeneration. In this regard, runt-related transcription factor 2 (Runx2) has emerged as a chief skeletal-specific molecule of differentiation, which is prominent to induction by mechanical stimuli. Polycystins represent a family of mechanosensitive proteins that interact with Runx2 in mechano-induced signaling cascades and foster the regulation of alternative effectors of mechanotransuction. In the present narrative review, we employed a PubMed search to extract the literature concerning Runx2, polycystins, and their association from 2000 to March 2024. The keywords stated below were used for the article search. We discuss recent advances regarding the implication of Runx2 and polycystins in bone remodeling and regeneration and elaborate on the targeting strategies that may potentially be applied for the treatment of patients with bone loss diseases.

Activation of CaMKII/HDAC4 by SDF1 contributes to pulmonary arterial hypertension via stabilization Runx2

Stromal derived factor 1 (SDF1) has been shown to be involved in the pathogenesis of pulmonary artery hypertension (PAH). However, the detailed molecular mechanisms remain unclear. To address this, we utilized primary cultured rat pulmonary artery smooth muscle cells (PASMCs) and monocrotaline (MCT)-induced PAH rat models to investigate the mechanisms of SDF1 driving PASMCs proliferation and pulmonary arterial remodeling. SDF1 increased runt-related transcription factor 2 (Runx2) acetylation by Calmodulin (CaM)-dependent protein kinase II (CaMKII)-dependent HDAC4 cytoplasmic translocation, elevation of Runx2 acetylation conferred its resistance to proteasome-mediated degradation. The accumulation of Runx2 further upregulated osteopontin (OPN) expression, finally leading to PASMCs proliferation. Blocking SDF1, suppression of CaMKII, inhibition the nuclear export of HDAC4 or silencing Runx2 attenuated pulmonary arterial remodeling and prevented PAH development in MCT-induced PAH rat models. Our study provides novel sights for SDF1 induction of PASMCs proliferation and suggests that targeting SDF1/CaMKII/HDAC4/Runx2 axis has potential value in the management of PAH.

Neferine alleviates ovariectomy-induced osteoporosis by enhancing osteogenic differentiation of bone marrow mesenchymal stem cells via regulation of the p38MAPK pathway

OBJECTIVE

Osteoporosis, a skeletal ailment marked by bone metabolism imbalance and disruption of bone microarchitecture, Neferine, a bisbenzylisoquinoline alkaloid with diverse pharmacological activities, has received limited attention in the context of osteoporosis treatment.

METHODS

We employed a bilateral ovariectomy (OVX) rat model to induce osteoporosis and subsequently administered Neferine treatment for four weeks following successful model establishment. Throughout the modeling and treatment phases, we closely monitored rat body weights. We assessed alterations in bone tissue microstructure through micro-CT, HE staining, and safranin O-fast green staining. Levels of bone formation and resorption markers in serum were evaluated using ELISA assay. Western blot analysis was employed to determine the expression levels of p38MAPK, p-p38MAPK, and bone formation-related genes in bone tissue. We isolated and cultured OVX rat BMSCs (OVX-BMSCs) and induced osteogenic differentiation while simultaneously introducing Neferine and the p38MAPK inhibitor SB203580 for intervention.

RESULTS

Neferine treatment effectively curbed the rapid weight gain in OVX rats, ameliorated bone loss, and decreased serum levels of TRAP, CTX-I, PINP, and BALP. Most notably, Neferine promoted the expression of bone formation-related factors in bone tissue of OVX rats, while concurrently activating the p38MAPK signaling pathway. In in vitro experiments, Neferine facilitated the expression of bone formation-related factors in OVX-BMSCs, increased the osteogenic differentiation potential of OVX-BMSCs, and activated the p38MAPK signaling pathway. Nevertheless, SB203580 partially reversed Neferine's promotive effect.

CONCLUSION

Neferine can boost the osteoblastic differentiation of BMSCs and alleviate OVX-induced osteoporosis in rats by activating the p38MAPK signaling pathway.

Bioactive Self-Regulated Liquified Microcompartments to Bioengineer Bone-Like Microtissues

Designing a microenvironment that drives autonomous stromal cell differentiation toward osteogenesis while recapitulating the complexity of bone tissue remains challenging. In the current study, bone-like microtissues are created using electrohydrodynamic atomization to form two distinct liquefied microcapsules (mCAPs): i) hydroxypyridinone (HOPO)-modified gelatin (GH mCAPs, 7.5% w/v), and ii) HOPO-modified gelatin and dopamine-modified gelatin (GH+GD mCAPs, 7.5%+1.5% w/v). The ability of HOPO to coordinate with iron ions at physiological pH allows the formation of a semipermeable micro-hydrogel shell. In turn, the dopamine affinity for calcium ions sets a bioactive milieu for bone-like microtissues. After 21 days post encapsulation, GH and GH+GD mCAPs potentiate autonomous osteogenic differentiation of mesenchymal stem cells accompanied by collagen type-I gene upregulation, increased alkaline phosphatase (ALP) expression, and formation of mineralized extracellular matrix. However, the GH+GD mCAPs show higher levels of osteogenic markers starting on day 14, translating into a more advanced and organized mineralized matrix. The GH+GD system also shows upregulation of the receptor activator of nuclear factor kappa-B ligand (RANK-L) gene, enabling the autonomous osteoclastic differentiation of monocytes. These catechol-based mCAPs offer a promising approach to designing multifunctional and autonomous bone-like microtissues to study in vitro bone-related processes at the cell-tissue interface, angiogenesis, and osteoclastogenesis.

Circ_ST6GAL1-mediated competing endogenous RNA network regulates TGF-β1-stimulated matrix Metalloproteinase-13 expression via Runx2 acetylation in osteoblasts

Transforming growth factor-beta1 (TGF-β1) stimulates matrix metalloproteinase-13 (MMP-13, a bone-remodeling gene) expression, and this effect requires p300-mediated Runx2 (Runt-related transcription factor 2) acetylation in osteoblasts. p300 and Runx2 are transcriptional coactivator and bone transcription factor, respectively, which play key roles in the regulation of bone-remodeling genes. Non-coding ribonucleic acids (ncRNAs), such as long ncRNAs (lncRNAs) and microRNAs (miRNAs), have been linked to both physiological and pathological bone states. In this study, we proposed that TGF-β1-mediated stimulation of MMP-13 expression is due to the downregulation of p300 targeting miRNAs in osteoblasts. We identified miR-130b-5p as one of the miRNAs downregulated by TGF-β1 in osteoblasts. Forced expression of miR-130b-5p decreased p300 expression, Runx2 acetylation, and MMP-13 expression in these cells. Furthermore, TGF-β1 upregulated circ_ST6GAL1, (a circular lncRNA) in osteoblasts; circRNA directly targeted miR-130b-5p. Antisense-mediated knockdown of circ_ST6GAL1 restored the function of miR-130b-5p, resulting in downregulation of p300, Runx2, and MMP-13 in these cells. Hence, our results suggest that TGF-β1 influences circ_ST6GAL1 to sponge and degrade miR-130b-5p, thereby promoting p300-mediated Runx2 acetylation for MMP-13 expression in osteoblasts. Thus, the circ_ST6GAL1/miR-130b-5p/p300 axis has potential significance in the treatment of bone and bone-related disorders.

The role of zinc finger proteins in the fate determination of mesenchymal stem cells during osteogenic and adipogenic differentiation

Zinc finger proteins (ZFPs) constitute a crucial group of transcription factors widely present in various organisms. They act as transcription factors, nucleases, and RNA-binding proteins, playing significant roles in cell differentiation, growth, and development. With extensive research on ZFPs, their roles in the determination of mesenchymal stem cells (MSCs) fate during osteogenic and adipogenic differentiation processes have become increasingly clear. ZFP521, for instance, is identified as an inhibitor of the Wnt signaling pathway and RUNX2's transcriptional activity, effectively suppressing osteogenic differentiation. Moreover, ZFP217 contributes to the inhibition of adipogenic differentiation by reducing the M6A level of the cell cycle regulator cyclin D1 (CCND1). In addition, other ZFPs can also influence the fate of mesenchymal stem cells (MSCs) during osteogenic and adipogenic differentiation through various signaling pathways, transcription factors, and epigenetic controls, participating in the subsequent differentiation and maturation of precursor cells. Given the prevalent occurrence of osteoporosis, obesity, and related metabolic disorders, a comprehensive understanding of the regulatory mechanisms balancing bone and fat metabolism is essential, with a particular focus on the fate determination of MSCs in osteogenic and adipogenic differentiation. In this review, we provide a detailed summary of how zinc finger proteins influence the osteogenic and adipogenic differentiation of MSCs through different signaling pathways, transcription factors, and epigenetic mechanisms. Additionally, we outline the regulatory mechanisms of ZFPs in controlling osteogenic and adipogenic differentiation based on various stages of MSC differentiation.

The osteogenic effects of sappanchalcone in vitro and in vivo

BACKGROUND AND OBJECTIVES

The utilization of natural products to enhance the function of periodontal ligament cells (PDLCs) has emerged as a popular area of research. Recent investigations have demonstrated that sappanchalcone (SC) possesses pharmacological properties such as anti-inflammatory and osteoprotective effects. This study aims to explore the impact of SC on the in vivo and in vitro osteogenic differentiation ability of PDLCs.

MATERIALS

Cell proliferation was quantified using the CCK-8 assay, while gene expression levels were assessed through qRT-PCR analysis. Osteoblast differentiation capacity was evaluated by employing Alizarin red staining (ARS), alkaline phosphatase (ALP) staining and western blot (WB) analysis. A rat model of periodontitis was established utilizing the tether-wire method. Micro-CT imaging and hematoxylin and eosin (HE) staining were employed to evaluate alveolar bone resorption. Masson's trichrome staining was utilized to observe fiber alignment, whereas immunohistochemistry (IHC) techniques were applied for detecting osteogenic and inflammatory factors.

RESULTS

The results from the CCK-8 assay indicate no observed cytotoxicity for concentrations of 1, 5, or 10 nM for SC treatment (p < .05), while qRT-PCR analysis demonstrates a significant decrease in inflammatory factors such as MMP-1 and IL-6 with treatment by SC (p < .05). Additionally, western blotting reveals an increase in protein expression levels of Runx2 and OPN within PDLCs treated with SC compared to control groups (p < .05), which is further supported by ARS and ALP staining indicating an increase in mineralized nodules formation along with elevated ALP content within these cells following treatment with this compound (p < .05). Finally, both HE staining as well as micro-CT imaging suggest potential benefits associated with using this compound including slowing alveolar bone resorption while simultaneously promoting junctional epithelium proliferation.

CONCLUSIONS

Our in vitro and in vivo findings suggest that SC can effectively enhance the inflammatory response of PDLCs and promote their osteogenic differentiation ability under inflammatory conditions, indicating its potential as a promising therapeutic agent for improving periodontal inflammation and bone formation.

Explorating the mechanism of Epimedii folium-Rhizoma drynariae herbal pair promoted bone defects healing through network pharmacology and experimental studies

ETHNOPHARMACOLOGICAL RELEVANCE

Bone defects are difficult to treat and have a high incidence of nonunion. The Epimedii folium-Rhizoma drynariae herbal pair (EDP) is a traditional Chinese medicine (TCM) used for treating bone diseases. However, the mechanisms by which EDP promotes osteogenesis or bone formation remain largely unclear.

AIM OF THE STUDY

This study aimed to investigate the mechanism of EDP promoted bone formation in bone defects using network pharmacology and experiments.

MATERIALS AND METHODS

The chemical components of EDP were analyzed by UHPLC-MS. The hub target and pathway enrichment analysis was conducted using molecular docking or network pharmacology. The pharmacological actions of EDP were determined by μCT and histopathology examination using a bone defect rat model. The effects of EDP on the mRNA expression of Bmp2, Smad2/5, Runx2, and Alp genes were measured by RT-PCR, while changes in the protein expressions of BMP2, COL1A1, SPP1, ALP, and RUNX2in the tibia tissues of the rats in response to EDP were analyzed by immunohistochemical staining or Western blot. We also performed cell viability assays, Alizarin Red and ALP staining assays, and RT-PCR to better understand how EDP affected osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs).

RESULTS

Identified 14 key compounds and 47 hub targets of EDP that may be involved in promoting osteogenesis to repair bone defects. And the BMP/Smad/Runx2 pathway was likely the key pathway through which EDP promoted bone defects repairing. The results of in vivo rat experiments indicated that EDP effectively promoted tibia repair in the model rats and activated the BMP/Smad/Runx2 pathway in the tibia tissue, with upregulating Bmp2, Bmpr1α, Smad2/5, Runx2, and Alp genes, and increased the protein expression of BMP2, COL1A1, RUNX2, and ALP. In vitro, EDP was found to increase the proliferation, differentiation, and mineralization in BMSCs- and also up-regulated the expression of key genes in the BMP/Smad/Runx2 pathway.

CONCLUSION

This study highlighted the ability of EDP to promote the osteogenic differentiation to enable bone repair by activating the BMP/Smad/Runx2 pathway.

Circ_0027885 sponges miR-203-3p to regulate RUNX2 expression and alleviates osteoporosis progression

BACKGROUND

Osteoporosis (OP) is a progressive metabolic disorder that is difficult to cure clinically. The molecular mechanisms of OP urgently need to be further examined. This study was designed to explore the potential function of circ_0027885 during osteogenic differentiation, as well as the systematic interactions among circ_0027885, miR-203-3p and runt-related transcription factor 2 (RUNX2).

METHODS

Relative levels of circ_0027885, miR-203-3p and RUNX2 were analyzed with RT-qPCR and western blotting. Alizarin red staining was performed to detect the mineralization ability under the control of circ_0027885 and miR-203-3p. Dual-luciferase reporter gene assay was conducted to examine the combination among circ_0027885, miR-203-3p and RUNX2.

RESULTS

Our research demonstrated that circ_0027885 was significantly increased during hBMSCs differentiation. Overexpression of circ_0027885 notably facilitated osteogenic differentiation and upregulated RUNX2 expression, while knockdown of circ_0027885 reversed the above results. Through prediction on bioinformatics analysis, miR-203-3p was the target binding circ_0027885, and RUNX2 was the potential target of miR-203-3p. Subsequently, these changes induced by the overexpression of circ_0027885 were reversed upon addition of miR-203-3p mimic.

CONCLUSIONS

Circ_0027885 could sponge miR-203-3p to regulate RUNX2 expression and alleviate osteoporosis progression.

An osteoporosis bone defect regeneration strategy via three-dimension short fibers loaded with alendronate modified hydroxyapatite

Osteoporotic bone defect has become clinic challenge due to its morbid bone microenvironment. Overactive bone resorption and limited bone formation lead to unstable combination between bone tissue and scaffolds. Electrospinning has been widely used in guide tissue membrane, but its barrier property results in limited application. In order to optimize the structure and add anti-bone resorption function of electrospinning fibers, we exploited the application of short fibers generated by homogenization at osteoporotic tibial bone defect. The modified nano-hydroxyapatite (m-HA) was loaded with alendronate. It overcame the problem that hydrophilic drugs were difficult to distribute uniformly in hydrophobic fibers. We confirmed that m-HA was loaded into polycaprolactone (PCL) short fibers. PCL short fibers with m-HA (PCL/m-HA) continuously released ALN, provided stable structure and showed good cytocompatibility. In vitro, PCL/m-HA increased the activity of alkaline phosphatase (ALP), promoted extracellular matrix mineralization and upregulated the expression of osteogenesis-related genes, Col 1, Alp, osteopontin (Opn) and runt-related transcription factor 2 (Runx2). In vivo, PCL/m-HA short fibers accelerated the new bone formation, inhibited the bone resorption and rebalanced the bone microenvironment through regulating osteoprotegerin (OPG) /receptor activator of NF-kB (RANKL) ratio. The above results confirmed that the PCL/m-HA short fibers achieved the application of three-dimension osteoporotic bone defect and had potential prospects in bone tissue scaffolds.

Prevention and treatment of osteoporosis with natural products: Regulatory mechanism based on cell ferroptosis

CONTEXT

With the development of society, the number of patients with osteoporosis is increasing. The prevention and control of osteoporosis has become a serious and urgent issue. With the continuous progress of biomedical research, ferroptosis has attracted increased attention. However, the pathophysiology and mechanisms of ferroptosis and osteoporosis still need further study. Natural products are widely used in East Asian countries for osteoporosis prevention and treatment.

OBJECTIVE

In this paper, we will discuss the basic mechanisms of ferroptosis, the relationship between ferroptosis and osteoclasts and osteoblasts, and in vitro and in vivo studies of natural products to prevent osteoporosis by interfering with ferroptosis.

METHODS

This article takes ferroptosis, natural products, osteoporosis, osteoblasts and osteoclast as key words. Retrieve literature from 2012 to 2023 indexed in databases such as PubMed Central, PubMed, Web of Science, Scopus and ISI.

RESULTS

Ferroptosis has many regulatory mechanisms, including the system XC -/GSH/GPX4, p62/Keap1/Nrf2, FSP1/NAD (P) H/CoQ10, P53/SAT1/ALOX15 axes etc. Interestingly, we found that natural products, such as Artemisinin, Biochanin A and Quercetin, can play a role in treating osteoporosis by promoting ferroptosis of osteoclast and inhibiting ferroptosis of osteoblasts.

CONCLUSIONS

Natural products have great potential to regulate OBs and OCs by mediating ferroptosis to prevent and treat osteoporosis, and it is worthwhile to explore and discover more natural products that can prevent and treat osteoporosis.

Injectable platelet-rich fibrin positively regulates osteogenic differentiation of stem cells from implant hole via the ERK1/2 pathway

Bone regeneration in dentistry is a dynamic approach for treating critical size bone defects that are unlikely to self-heal. Human bone marrow stem cell (hBMSCs) therapies are being tested clinically for various disorders and have remarkable clinical advancements in bone regeneration. Injectable platelet-rich fibrin (i-PRF), which is obtained from autologous blood centrifuged at 700 rpm (60 G) for 3 min can promote osteogenic differentiation of this cell, but the mechanism remains unclear. The objectives of this study were to explore the contents of i-PRF further and investigate its effect on the cell behavior of hBMSCs and the underlying molecular mechanisms. The results showed that i-PRF contained 41 cytokines, including macrophage colony-stimulating factor (M-CSF) and β-nerve growth factor (β-NGF), which had not been reported before. The Cell Counting Kit-8 and wound healing assay showed that 10% and 20% i-PRF improved the proliferation rate and the migration capacity of hBMSCs without toxicity to cells. Besides, the expression of osteogenic markers and the capacity to form mineralized nodules of hBMSCs were promoted by 20% i-PRF. Furthermore, i-PRF activated the ERK pathway, and the ERK inhibitor attenuated its effects. In summary, i-PRF promotes hBMSCs proliferation and migration and facilitates cell osteogenesis through the ERK pathway, which has promising potential in bone regeneration.

Alkaline shear-thinning micro-nanocomposite hydrogels initiate endogenous TGFβ signaling for in situ bone regeneration

Recruiting endogenous stem cells to bone defects without stem cell transplantation and exogenous factor delivery represents a promising strategy for bone regeneration. Herein, we develop an alkaline shear-thinning micro-nanocomposite hydrogel (10-MmN), aiming to alkaline-activate endogenous TGFβ1 and achieve in situ bone regeneration. It contains polyethyleneimine (PEI)-modified gelatin, laponite nanoplatelets (LAP), a bicarbonate buffer with a pH of 10, and gelatin microspheres (MSs). PEI-modified gelatin plays a pivotal role in hydrogel fabrication. It endows the system with sufficient positive charges, and forms a shear-thinning nanocomposite matrix in the pH 10 buffer (10-mN) with negatively charged LAP via electrostatic gelation. For biological functions, the pH 10 buffer dominates alkaline activation of endogenous serum TGFβ1 to recruit rat bone marrow stem cells through the Smad pathway, followed by improved osteogenic differentiation. In addition, MSs are incorporated into 10-mN to form 10-MmN, and function as substrates to provide good attachment sites for the recruited stem cells and facilitate further their osteogenic differentiation. In a rat critical-sized calvarial defect model, 10-MmN exhibits excellent biocompatibility, biodegradability, hydrogel infusion and retention in bone defects with flexible shapes and active bleeding. Importantly, it repairs ~95% of the defect areas in 3 months by recruiting TGFβR2+ and CD90+CD146+ stem cells, and promoting cell proliferation, osteogenic differentiation and bone formation. The present study provides a biomaterial-based strategy to regulate alkalinity in bone defects for the initiation of endogenous TGFβ signaling, which can be extended to treat other diseases.

Systemic and local inflammatory response after implantation of biomaterial in critical bone injuries

PURPOSE

To evaluate inflammatory response in critical bone injuries after implantation of the biomaterial composed of hydroxyapatite (HA)/poly (lactic-coglycolic acid) (PLGA)/BLEED.

METHODS

Forty-eight male Wistar rats (280 ± 20 grams) were divided into two groups: control group (CG), in which the animals do not receive any type of treatment; and biomaterial group (BG), in which the animals received the HA/PLGA/BLEED scaffold. Critical bone injury was induced in the medial region of the skull calotte with the aid of a trephine drill 8 mm in diameter. The biomaterial was implanted in the form of 1.5-mm thick scaffolds. Serum and calotte were collected at one, three and seven days.

RESULTS

Biomaterial had a significant effect on the morphological structure of the bone, accelerating osteoblast activation within three days, without causing exacerbated systemic inflammation. In addition, quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that BG induced upregulation of osteogenic genes such as runt-related transcription factor 2, and stimulated genes of inflammatory pathways such as tumor necrosis factor-α, on the first day without overexpressing genes related to bone matrix degradation, such as tissue inhibitor of metalloproteinases-1 and matrix metalloproteinase-9.

CONCLUSIONS

The HA/PLGA/BLEED® association can be used as a bone graft to aid bone repair, as it is capable of modulating expression of important genes at this stage of the repair process.

Melatonin and bone-related diseases: an updated mechanistic overview of current evidence and future prospects

PURPOSE

Bone diseases account for an enormous cost burden on health systems. Bone disorders are considered as age-dependent diseases. The aging of world population has encouraged scientists to further explore the most effective preventive modalities and therapeutic strategies to overcome and reduce the high cost of bone disorders. Herein, we review the current evidence of melatonin's therapeutic effects on bone-related diseases.

METHODS

This review summarized evidences from in vitro, in vivo, and clinical studies regarding the effects of melatonin on bone-related diseases, with a focus on the molecular mechanisms. Electronically, Scopus and MEDLINE®/PubMed databases were searched for articles published on melatonin and bone-related diseases from inception to June 2023.

RESULTS

The findings demonstrated that melatonin has beneficial effect in bone- and cartilage-related disorders such as osteoporosis, bone fracture healing, osteoarthritis, and rheumatoid arthritis, in addition to the control of sleep and circadian rhythms.

CONCLUSION

A number of animal and clinical studies have indicated that various biological effects of melatonin may suggest this molecule as an effective therapeutic agent for controlling, diminishing, or suppressing bone-related disorders. Therefore, further clinical studies are required to clarify whether melatonin can be effective in patients with bone-related diseases.

Non-Specific Inhibition of Dipeptidyl Peptidases 8/9 by Dipeptidyl Peptidase 4 Inhibitors Negatively Affects Mesenchymal Stem Cell Differentiation

DPP4 may play a relevant role in MSC differentiation into osteoblasts or adipocytes. Dipeptidyl peptidase 4 (DPP4) inhibitors (DPP4i), such as sitagliptin and vildagliptin, are used as antidiabetic drugs. However, vildagliptin is not a specific DPP4i and also inhibits DPP8/9, which is involved in energy metabolism and immune regulation. The aim of this study is to evaluate how sitagliptin, vildagliptin or 1G244 (a DPP8/9 specific inhibitor) may influence cell viability, as well as osteogenic and adipogenic differentiation in human mesenchymal stem cells (MSC). Viability, apoptosis, osteoblastogenesis and adipogenesis markers, as well as protein synthesis of β-catenin, were studied in MSC cultures induced to differentiate into osteoblasts or adipocytes in the presence or absence of sitagliptin, vildagliptin or 1G244. The two tested DPP4i did not affect MSC viability, but 1G244 significantly decreased it in MSC and osteoblast-induced cells. Additionally, 1G244 and vildagliptin inhibited osteogenesis and adipogenesis, unlike sitagliptin. Therefore, inhibition of DPP4 did not affect MSC viability and differentiation, whereas inhibition of DPP8/9 negatively affected MSC. To the best of our knowledge, these results show for the first time that DPP8/9 have an important role in the viability and differentiation of human MSC. This data can be considered for human clinical use of drugs affecting DPP8/9 activity.

Epigenetic regulation of bone remodeling and its role in the pathogenesis of primary osteoporosis

Discovery of molecular mechanisms of primary osteoporosis development is fundamental to understand the pathogenesis of musculoskeletal diseases in general and for identifying key links in the genetic and epigenetic regulation of bone remodelling genes. The number of identified molecular genetic markers for osteoporosis is increasing but there is a need to describe their functional interactions. These interactions have been determined to be associated with the control of expression of a number of transcription factors and the differentiation of mesenchymal stem cells through the pathway of osteoblastogenesis or adipogenesis, and monocytic precursors through the pathway of osteoclastogenesis. The results of epigenetic studies have significantly increased the understanding of the role of post-translational modifications of histones, DNA methylation and RNA interference in the osteoporosis pathogenesis and in bone remodelling. However, the knowledge should be systematised and generalised according to the results of research on the role of epigenetic modifiers in the development of osteoporosis, and the influence of each epigenetic mechanism on the individual links of bone remodelling during ontogenesis of humans in general, including the elderly, should be described. Understanding which mechanisms and systems are involved in the development of this nosology is of interest for the development of targeted therapies, as the possibility of using microRNAs to regulate genes is now being considered. Systematisation of these data is important to investigate the differences in epigenetic marker arrays by race and ethnicity. The review article analyses references to relevant reviews and original articles, classifies information on current advances in the study of epigenetic mechanisms in osteoporosis and reviews the results of studies of epigenetic mechanisms on individual links of bone remodelling.

The Osteogenesis Mechanisms of Dental Alveolar Bone Socket Post Induction with Hydroxyapatite Bovine Tooth Graft: An Animal Experimental in Rattus norvegicus Strain Wistar

OBJECTIVES

 Surgical endodontics (hemisection) commonly involves the alveolar bone socket and the periradicular tissue. In today's era, optimizing the bone healing process is updated by using bone graft induction. This study explores the mechanisms of bone healing of the alveolar bone socket post-dental extraction of Wistar rats after administration of a bovine tooth graft (hydroxyapatite bovine tooth graft [HAp-BTG]).

MATERIALS AND METHODS

 Fifty Wistar rats were randomly selected into two groups, control and treatment, and into five subgroups on days 3, 7, 14, 21, and 28. The postextraction socket was filled with polyethylene glycol (PEG) as the control and PEG + HAp-BTG as the treatment group. On days 3, 7, 14, 21, and 28, Wistar rats were sacrificed, mandibles were taken, paraffin blocks were made, cut 4 µm thick, and made into glass preparations for microscopic examination. The variable analysis was performed by staining hematoxylin-eosin for osteoblasts (OBs) and osteoclasts (OCs) and immunohistochemistry for runt-related transcription factor 2 (RUNX2), osterix (OSX), osteocalcin (OCN), bone morphogenic protein (BMP) 2. We analyzed the expressed cell count per microscope field.

RESULTS

 In general, the number of cell expressions in the treatment group was significantly higher and faster, except for significantly lower OC. The high variables peak occurred on day 14 for RUNX2 and OCN, on day 7 for OSX, while OB significantly increased on day 21 and remained until day 28. The decrease of OC cells occurred on day 7 and remained low until 28 days. BMP2 was first dominantly induced by HAp-BTG, then the others.

CONCLUSION

 HAp-BTG can induce higher and faster bone healing biomarkers. BMP2 is the dominant first impacted. On the 28th day, it did not significantly express the suppression of OC by OB, which entered the bone formation and remodeling step.

Ubiquitin-specific proteases: Vital regulatory molecules in bone and bone-related diseases

Stabilization of bone structure and function involves multiple cell-to-cell and molecular interactions, in which the regulatory functions of post-translational modifications such as ubiquitination and deubiquitination shouldn't be underestimated. As the largest family of deubiquitinating enzymes, the ubiquitin-specific proteases (USPs) participate in the development of bone homeostasis and bone-related diseases through multiple classical osteogenic and osteolytic signaling pathways, such as BMP/TGF-β pathway, NF-κB/p65 pathway, EGFR-MAPK pathway and Wnt/β-catenin pathway. Meanwhile, USPs may also broadly regulate regulate hormone expression level, cell proliferation and differentiation, and may further influence bone homeostasis from gene fusion and nuclear translocation of transcription factors. The number of patients with bone-related diseases is currently enormous, making exploration of their pathogenesis and targeted therapy a hot topic. Pathological increases in the levels of inflammatory mediators such as IL-1β and TNF-α lead to inflammatory bone diseases such as osteoarthritis, rheumatoid arthritis and periodontitis. While impaired body metabolism greatly increases the probability of osteoporosis. Abnormal physiological activity of bone-associated cells results in a variety of bone tumors. The regulatory role of USPs in bone-related disease has received particular attention from academics in recent studies. In this review, we focuse on the roles and mechanisms of USPs in bone homeostasis and bone-related diseases, with the expectation of informing targeted therapies in the clinic.

Role of RUNX2 in breast cancer development and drug resistance (Review)

Breast cancer is the most common malignancy and ranks second among the causes of tumor-associated death in females. The recurrence and drug resistance of breast cancer are intractable due to the presence of breast cancer stem cells (BCSCs), which are adequate to initiate tumor formation and refractory to conventional remedies. Runt-related transcription factor 2 (RUNX2), a pivotal transcription factor in mammary gland and bone development, has also been related to metastatic cancer and BCSCs. State-of-the-art research has indicated the retention of RUNX2 expression in a more invasive subtype of breast cancer, and in particular, triple-negative breast cancer development and drug resistance are associated with estrogen receptor signaling pathways. The present review mainly focused on the latest updates on RUNX2 in BCSCs and their roles in breast cancer progression and drug resistance, providing insight that may aid the development of RUNX2-based diagnostics and treatments for breast cancer in clinical practice.

Drug-Delivery Nanoplatform with Synergistic Regulation of Angiogenesis-Osteogenesis Coupling for Promoting Vascularized Bone Regeneration

It has been confirmed that substantial vascularization is an effective strategy to heal large-scale bone defects in the field of bone tissue engineering. The local application of deferoxamine (DFO) is among the most common and effective methods for promoting the formation of blood vessels, although its short half-life in plasma, rapid clearance, and poor biocompatibility limit its therapeutic suitability. Herein, zeolitic imidazolate framework-8 (ZIF-8) was selected as a vehicle to extend the half-life of DFO. In the present study, a nano DFO-loaded ZIF-8 (DFO@ZIF-8) drug delivery system was established to promote angiogenesis-osteogenesis coupling. The nanoparticles were characterized, and their drug loading efficiency was examined to confirm the successful synthesis of nano DFO@ZIF-8. Additionally, due to the sustained release of DFO and Zn²⁺, DFO@ZIF-8 NPs were able to promote angiogenesis in human umbilical vein endothelial cells (HUVECs) culture and osteogenesis in bone marrow stem cells (BMSCs) in vitro. Furthermore, the DFO@ZIF-8 NPs promoted vascularization by enhancing the expression of type H vessels and a vascular network. The DFO@ZIF-8 NPs promoted bone regeneration in vivo by increasing the expression of OCN and BMP-2. RNA sequencing analysis revealed that the PI3K-AKT-MMP-2/9 and HIF-1α pathways were upregulated by DFO@ZIF-8 NPs in HUVECs, ultimately leading to the formation of new blood vessels. In addition, the mechanism by which DFO@ZIF-8 NPs promoted bone regeneration was potentially related to the synergistic effect of angiogenesis-osteogenesis coupling and Zn²⁺-mediation of the MAPK pathway. Taken together, DFO@ZIF-8 NPs, which were demonstrated to have low cytotoxicity and excellent coupling of angiogenesis and osteogenesis, represent a promising strategy for the reconstruction of critical-sized bone defects.

Promoting lacunar bone regeneration with an injectable hydrogel adaptive to the microenvironment

Injectable hydrogel is suitable for the repair of lacunar bone deficiency. This study fabricated an injectable, self-adaptive silk fibroin/mesoporous bioglass/sodium alginate (SMS) composite hydrogel system. With controllable and adjustable physical and chemical properties, the SMS hydrogel could be easily optimized adaptively to different clinical applications. The SMS hydrogel effectively showed great injectability and shapeability, allowing defect filling with no gap. Moreover, the SMS hydrogel displayed self-adaptability in mechanical reinforcement and degradation, responsive to the concentration of Ca²⁺ and inflammatory-like pH value in the microenvironment of bone deficiency, respectively. In vitro biological studies indicated that SMS hydrogel could promote osteogenic differentiation of bone marrow mesenchymal stem cells by activation of the MAPK signaling pathway. The SMS hydrogel also could improve migration and tube formation of human umbilical vein endothelial cells. Investigations of the crosstalk between osteoblasts and macrophages confirmed that SMS hydrogel could regulate macrophage polarization from M1 to M2, which could create a specific favorable environment to induce new bone formation and angiogenesis. Meanwhile, SMS hydrogel was proved to be antibacterial, especially for gram-negative bacteria. Furthermore, in vivo study indicated that SMS could be easily applied for maxillary sinus elevation, inducing sufficient new bone formation. Thus, it is convincing that SMS hydrogel could be potent in a simple, minimally invasive and efficient treatment for the repair of lacunar bone deficiency.

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Mesoporous bioglass was used as the crosslinking agent and in-situ porogen to form a porous injectable hydrogel.

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The composite hydrogel had suitable injectability and self-adaptability for lacunar bone regeneration.

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The composite hydrogel can simultaneously regulate macrophage polarization and osteogenic differentiation.

Modulation of Osteogenic Gene Expression by Human Osteoblasts Cultured in the Presence of Bisphenols BPF, BPS, or BPAF

Bone effects attributed to bisphenols (BPs) include the inhibition of growth and differentiation. This study analyzes the effect of BPA analogs (BPS, BPF, and BPAF) on the gene expression of the osteogenic markers RUNX2, osterix (OSX), bone morphogenetic protein-2 (BMP-2), BMP-7, alkaline phosphatase (ALP), collagen-1 (COL-1), and osteocalcin (OSC). Human osteoblasts were obtained by primary culture from bone chips harvested during routine dental work in healthy volunteers and were treated with BPF, BPS, or BPAF for 24 h at doses of 10^-5, 10^-6, and 10^-7 M. Untreated cells were used as controls. Real-time PCR was used to determine the expression of the osteogenic marker genes RUNX2, OSX, BMP-2, BMP-7, ALP, COL-1, and OSC. The expression of all studied markers was inhibited in the presence of each analog; some markers (COL-1; OSC, BMP2) were inhibited at all three doses and others only at the highest doses (10^-5 and 10^-6 M). Results obtained for the gene expression of osteogenic markers reveal an adverse effect of BPA analogs (BPF, BPS, and BPAF) on the physiology of human osteoblasts. The impact on ALP, COL-1, and OSC synthesis and therefore on bone matrix formation and mineralization is similar to that observed after exposure to BPA. Further research is warranted to determine the possible contribution of BP exposure to the development of bone diseases such as osteoporosis.

Regulon active landscape reveals cell development and functional state changes of human primary osteoblasts in vivo

BACKGROUND

While transcription factor (TF) regulation is known to play an important role in osteoblast development, differentiation, and bone metabolism, the molecular features of TFs in human osteoblasts at the single-cell resolution level have not yet been characterized. Here, we identified modules (regulons) of co-regulated genes by applying single-cell regulatory network inference and clustering to the single-cell RNA sequencing profiles of human osteoblasts. We also performed cell-specific network (CSN) analysis, reconstructed regulon activity-based osteoblast development trajectories, and validated the functions of important regulons both in vivo and in vitro.

RESULTS

We identified four cell clusters: preosteoblast-S1, preosteoblast-S2, intermediate osteoblasts, and mature osteoblasts. CSN analysis results and regulon activity-based osteoblast development trajectories revealed cell development and functional state changes of osteoblasts. CREM and FOSL2 regulons were mainly active in preosteoblast-S1, FOXC2 regulons were mainly active in intermediate osteoblast, and RUNX2 and CREB3L1 regulons were most active in mature osteoblasts.

CONCLUSIONS

This is the first study to describe the unique features of human osteoblasts in vivo based on cellular regulon active landscapes. Functional state changes of CREM, FOSL2, FOXC2, RUNX2, and CREB3L1 regulons regarding immunity, cell proliferation, and differentiation identified the important cell stages or subtypes that may be predominantly affected by bone metabolism disorders. These findings may lead to a deeper understanding of the mechanisms underlying bone metabolism and associated diseases.

Astragalus Polysaccharides Alleviate Lung Adenocarcinoma Bone Metastases by Inhibiting the CaSR/PTHrP Signaling Pathway

Bone metastasis is one of the common complications of lung cancer and can lead to bone-related adverse events, such as pathological fractures, spinal cord defects, and nerve compression syndrome. As an effective medicinal component of Astragalus membranaceus, Astragalus polysaccharide (APS) has antitumor activity and alleviates osteoporosis to a certain extent. In this study, we explored the possible role and mechanism underlying APS inhibition of lung adenocarcinoma bone metastases by constructing a mouse model of lung adenocarcinoma bone metastases. First, we constructed osteoclast (OC) and osteoblast (OB) culture systems in vitro to confirm that APS affected the differentiation and function of OCs and OBs. Then, using the mouse bone metastasis model, microCT, and bone histopathology, we confirmed that APS inhibited osteolytic metastasis and tumor cell proliferation in mice, and the effect was mainly realized by inhibiting the CaSR/PTHrP signal pathway. The results showed that APS had a protective effect on lung adenocarcinoma bone metastases.