Molecular structure, expression, and the emerging role of Siglec-15 in skeletal biology and cancer.

Siglec-15, a Siglec family member and type-1 transmembrane protein, is expressed mainly in human macrophages and dendritic cells. It is comprised of a lysine-containing transmembrane domain, two extracellular immunoglobulin (Ig)-like domains and a short cytoplasmic domain. Siglec-15 is highly conserved in vertebrates and acts as an immunoreceptor. It exerts diverse functions on osteoclast physiology as well as the tumor microenvironment. Siglec-15 interacts with adapter protein DAP12 - Syk signaling pathway to regulate the RANKL/RANK-mediated PI3K, AKT, and ERK signaling pathways during osteoclast formation in vitro. Consistently, the lack of the Siglec-15 gene in mice leads to impaired osteoclast activity and osteopetrosis in vivo. In addition, Siglec-15 is expressed by tumor-associated macrophages (TAMs) and regulates the tumor microenvironment by activating the SYK/MAPK signaling pathway. Interestingly, Siglec-15 shares sequence homology to programmed death-ligand 1 (PD-L1) and has a potential immune-regulatory role in cancer immunology. Thus, Siglec-15 might also represent an alternative target for the treatment of cancers that do not respond to anti-PD-L1/PD-1 immunotherapy. Understanding the role of Siglec-15 in osteoclastogenesis and the tumor microenvironment will help us to develop new treatments for bone disorders and cancer.

Differential Proteomic and Genomic Comparison of Resistance Mechanism of Pseudomonas aeruginosa to Cefoperazone Sodium/Sulbactam Sodium.

The aim of this study was to determine the resistance mechanism of Pseudomonas aeruginosa to cefoperazone sodium/sulbactam sodium. We retrospectively analyzed the drug resistance of P.a isolated at the First Affiliated Hospital of Guangxi Medical University. Drug-resistant P.a strains were constructed, then wild-type (WT) and drug-resistant (DR) strains were compared using protein and gene microarrays to determine differences between DR and WT strains. The resistance rates of P. aeruginosa during 2013, 2014 and 2015 were 21.2%, 21.4%, and 24.6% respectively. Among 242 protein peaks of WT and DR bacteriophage proteins, 41 were differentially expressed between the two groups. The expression of 26 and 15 proteins were respectively upregulated and downregulated in the DR compared with the WT group. Gene microarray results revealed 679 mutant loci in the DR group, of which 42 with the top 50 Q values were found in the NCBI database. The rate of P.a resistance to cefoperazone sodium/sulbactam sodium remained high between 2013 and 2015. The numbers of different proteins and genetic variations in the DR strains suggested that the resistance mechanism of P.a to cefoperazone sodium/sulbactam sodium involves multiple genes and proteins that might be key to controlling P.a resistance to cefoperazone sodium/sulbactam sodium.

A missense mutation sheds light on a novel structure-function relationship of RANKL.

The tumor necrosis factor (TNF)-like core domain of receptor activator of nuclear factor-κB ligand (RANKL) is a functional domain critical for osteoclast differentiation. One of the missense mutations identified in patients with osteoclast-poor autosomal recessive osteopetrosis (ARO) is located in residue methionine 199 that is replaced with lysine (M199K) amid the TNF-like core domain. However, the structure-function relationship of this mutation is not clear. Sequence-based alignment revealed that the fragment containing human M199 is highly conserved and equivalent to M200 in rat. Using site-directed mutagenesis, we generated three recombinant RANKL mutants M200K/A/E (M200s) by replacing the methionine 200 with lysine (M200K), alanine (M200A), and glutamic acid (M200E), representative of distinct physical properties. TRAcP staining and bone pit assay showed that M200s failed to support osteoclast formation and bone resorption, accompanied by impaired osteoclast-related signal transduction. However, no antagonistic effect was found in M200s against wild-type rat RANKL. Analysis of the crystal structure of RANKL predicted that this methionine residue is located within the hydrophobic core of the protein, thus, likely to be crucial for protein folding and stability. Consistently, differential scanning fluorimetry analysis suggested that M200s were less stable. Western blot analysis analyses further revealed impaired RANKL trimerization by M200s. Furthermore, receptor-ligand binding assay displayed interrupted interaction of M200s to its intrinsic receptors. Collectively, our studies revealed the molecular basis of human M199-induced ARO and elucidated the indispensable role of rodent residue M200 (equivalent to human M199) for the RANKL function.

Helvolic acid attenuates osteoclast formation and function via suppressing RANKL-induced NFATc1 activation.

Excessive osteoclast formation and function are considered as the main causes of bone lytic disorders such as osteoporosis and osteolysis. Therefore, the osteoclast is a potential therapeutic target for the treatment of osteoporosis or other osteoclast-related diseases. Helvolic acid (HA), a mycotoxin originally isolated from Aspergillus fumigatus , has been discovered as an effective broad-spectrum antibacterial agent and has a wide range of pharmacological properties. Herein, for the first time, HA was demonstrated to be capable of significantly inhibiting receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis and bone resorption in vitro by suppressing nuclear factor of activated T cells 1 (NFATc1) activation. This inhibition was followed by the dramatically decreased expression of NFATc1-targeted genes including Ctr (encoding calcitonin receptor), Acp5 (encoding tartrate-resistant acid phosphatase [TRAcP]), Ctsk (encoding cathepsin K), Atp6v0d2 (encoding the vacuolar H+ ATPase V0 subunit d2 [V-ATPase-d2]) and Mmp9 (encoding matrix metallopeptidase 9) which are osteoclastic-specific genes required for osteoclast formation and function. Mechanistically, HA was shown to greatly attenuate multiple upstream pathways including extracellular signal-regulated kinase (ERK) phosphorylation, c-Fos signaling, and intracellular Ca 2+ oscillation, but had little effect on nuclear factor-κB (NF-κB) activation. In addition, HA also diminished the RANKL-induced generation of intracellular reactive oxygen species. Taken together, our study indicated HA effectively suppressed RANKL-induced osteoclast formation and function. Thus, we propose that HA can be potentially used in the development of a novel drug for osteoclast-related bone diseases.

Cistanche deserticola polysaccharide attenuates osteoclastogenesis and bone resorption via inhibiting RANKL signaling and reactive oxygen species production.

Osteoporosis is a metabolic disease characterized by osteopenia and bone microstructural deterioration. Osteoclasts are the primary effector cells that degrade bone matrix and their abnormal function leads to the development of osteoporosis. Reactive oxygen species (ROS) accumulation during cellular metabolism promotes osteoclast proliferation and differentiation, therefore, playing an important role in osteoporosis. Cistanche deserticola polysaccharide (CDP) possesses antitumor, anti-inflammatory, and antioxidant activity. However, the impact of CDP on osteoclasts is unclear. In this study, tartrate-resistant acid phosphatase staining, immunofluorescence, reverse transcription-polymerase chain reaction, and western blot analysis were utilized to demonstrate that CDP inhibited osteoclastogenesis and hydroxyapatite resorption. In addition, CDP also inhibited the expression of osteoclast maker genes including Ctsk, Mmp9, and Acp5 and had no effect on receptor activator of nuclear factor κB (RANK) expression. Mechanistic analyses revealed that CDP increases the expression of antioxidant enzymes to attenuate RANKL-mediated ROS production in osteoclasts and inhibits nuclear factor of activated T cells and mitogen-activated protein kinase activation. These results suggest that CDP may represent a candidate drug for the treatment of osteoporosis caused by excessive osteoclast activity.

Achyranthes bidentata polysaccharide suppresses osteoclastogenesis and bone resorption via inhibiting RANKL signaling.

Osteoclasts are highly differentiated multinucleated giant cells that play fundamental roles in bone resorption and in the pathogenesis of osteolytic conditions, such as osteoporosis and cancer-induced bone loss. Achyranthes bidentata polysaccharide (ABP) is a hydrophilic compound with anti-oxidation and anti-aging characteristics. The impact of ABP on RANKL-induced osteoclast formation and bone resorption has not been assessed, hence, in this study we investigated the effect of ABP on osteoclast formation and resorption in murine bone marrow derived osteoclasts. We found that ABP was able to suppress RANKL-induced osteoclast differentiation and bone resorption activity at concentrations above 6.5 µM, while demonstrating no cytotoxicity at concentrations up to 10 µM. The actions of ABP were mediated through inhibition of RANKL-induced c-Fos and NFATc1 gene and protein expression. Furthermore, we found that ABP suppressed NFATc1 transcriptional activity, and the phosphorylation of MAPK pathways induced by RANKL. Collectively, ABP attenuates RANKL-mediated osteoclast activity and signaling, and might serve as a potential therapeutic candidate for preventing bone loss related diseases.

Poria cocos polysaccharide attenuates RANKL-induced osteoclastogenesis by suppressing NFATc1 activity and phosphorylation of ERK and STAT3.

Pathological fractures caused by osteolytic lesions seriously threaten the health of patients. Osteoclasts play important roles in bone resorption whose hyperfunction are closely related to osteolytic lesions. Studies on osteoclast differentiation and function assist in the prevention of excessive bone loss associated diseases. We screened a variety of natural compounds with anti-inflammatory effect and found that poria cocos polysaccharide (PCP) inhibited RANKL-induced osteoclast formation and bone resorption via TRAcP staining, immunofluorescence, RT-PCR and western blot. PCP down-regulated phosphorylation of STAT3, P38, ERK and JNK, and thus repressed the expression of NFAcT1 and c-Fos during RANKL-induced osteoclastogenesis. Besides, the expression of bone resorption related genes such as TRAcP and CTSK was suppressed by PCP. The results suggest that PCP can be invoked as a candidate for the treatment of osteolytic diseases by inhibiting osteoclastogenesis.

Mechanisms of Protective Effect of Ramulus Mori Polysaccharides on Renal Injury in High-Fat Diet/Streptozotocin-Induced Diabetic Rats.

BACKGROUND: Diabetic nephropathy (DN) is the most important complication of diabetes and the most common cause of end-stage renal disease (ESRD). AIMS: A recent study established that the Ramulus mori polysaccharides (RMP) exert antioxidant effects on DN in rats. METHODS: The diabetic rats which induced by high-fat diet and streptozotocin injection were orally administered RMP by doses of 250, 500 and 1000 mg/kg daily for 8 weeks. The effects of RMP on hyperglycemia and other biochemical changes were examined in the sera and kidney tissues. Additionally, the pathological and ultrastructural changes and expressions of nuclear-factor kappa B (NF-x03BA;B) and transforming growth factor-ß1 (TGF-ß1) were assessed. RESULTS: The results revealed that the serum levels of blood glucose, total cholesterol (TC) and triglycerides (TG) were significantly decreased by RMP. Furthermore, the blood urea nitrogen (BUN), serum creatinine (SCr) and 24-hour urine protein levels in the RMP-medicated rats were lower than those in untreated diabetic rats. Moreover, treatment of the DN rats with RMP normalized all biochemical changes, including the malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels in the serum and kidney tissues. In contrast, the protein expression levels of NF-x03BA;B and TGF-ß1, which were enhanced in the kidneys of DN rats, were reduced by RMP. CONCLUSION: These results suggest that RMP improving the renal function of diabeitc rats possibly via its ameliorating antioxidant activities.

A Novel Extensible Continuum Robot with Growing Motion Capability Inspired by Plant Growth for Path-Following in Transoral Laryngeal Surgery.

This article presents a novel extensible continuum robot (ECR) with growing motion capability for improved flexible access in transoral laryngeal procedures. The robot uses an extensible continuum joint with a staggered V-shaped notched structure as the backbone, driven by the pushing and pulling of superelastic Nitinol rods. The notched structure is optimized to achieve a wide range of extension/contraction and bending motion for the continuum joint. The successive and uniform deflection of the notches provides the continuum joint with excellent constant curvature bending characteristics. The bidirectional rod-driven approach expands the robot's extension capabilities with both pushing and pulling operations, and the superelasticity of the driving rods preserves the robot's bending performance. The ECR significantly increases motion dexterity and reachability through its variable length, which facilitates collision-free access to deep lesions by following the anatomy. To further exploit the advantages of the ECR in path-following for flexible access, a growing motion approach inspired by the plant growth process has been proposed to minimize the path deviation error. Characterization experiments are conducted to verify the performances of the proposed ECR. The extension ratio achieves up to 225.92%, and the average distal positioning error and hysteresis error values are 2.87% and 0.51% within the ±120° bending range. Compared with the typical continuum robot with a fixed length, the path-following deviation of this robot is reduced by more than 58.30%, effectively reducing the risk of collision during access. Phantom experiments validate the feasibility of the proposed concept in flexible access procedures.

A Novel Electromagnetic Driving System for 5-DOF Manipulation in Intraocular Microsurgery.

This work presents a novel electromagnetic driving system that consists of eight optimized electromagnets arranged in an optimal configuration and employs a control framework based on an active disturbance rejection controller (ADRC) and virtual boundary. The optimal system configuration enhances the system's compatibility with other ophthalmic surgical instruments, while also improving its capacity to generate magnetic force in the vertical direction. Besides, the optimal electromagnet parameters provide a superior comprehensive performance on magnetic field generation capacity and thermal power. Hence, the presented design achieves a stronger capacity for sustained work. Furthermore, the ADRC controller effectively monitors and further compensates the total disturbance as well as gravity to enhance the system's robustness. Meanwhile, the implementation of virtual boundaries substantially enhances interactive security via collision avoidance. The magnetic and thermal performance tests have been performed on the electromagnet to verify the design optimization. The proposed electromagnet can generate a superior magnetic field of 2.071 mT at a distance of 65 mm with an applied current of 1 A. Moreover, it demonstrates minimal temperature elevation from room temperature (25 °C) to 46 °C through natural heat dissipation in 3 h, thereby effectively supporting prolonged magnetic manipulation of intraocular microsurgery. Furthermore, trajectory tracking experiments with disturbances have been performed in a liquid environment similar to the practical ophthalmic surgery scenarios, to verify the robustness and security of the presented control framework. The maximum root mean square (RMS) error of performance tests in different operation modes remains 35.8 µm, providing stable support for intraocular microsurgery.

Advances in SEMA3F regulation of clinically high-incidence cancers.

Cancer has become a leading cause of morbidity and mortality in recent years. Its high prevalence has had a severe impact on society. Researchers have achieved fruitful results in the causative factors, pathogenesis, treatment strategies, and cancer prevention. Semaphorin 3F (SEMA3F), a member of the signaling family, was initially reported in the literature to inhibit the growth, invasion, and metastasis of cancer cells in lung cancer. Later studies showed it has cancer-inhibiting effects in malignant tumors such as breast, colorectal, ovarian, oral squamous cell carcinoma, melanoma, and head and neck squamous carcinoma. In contrast, recent studies have reported that SEMA3F is expressed more in hepatocellular carcinoma than in normal tissue and promotes metastasis of hepatocellular carcinoma. We chose lung, breast, colorectal, and hepatocellular carcinomas with high clinical prevalence to review the roles and molecular mechanisms of SEMA3F in these four carcinomas. We concluded with an outlook on clinical interventions for patients targeting SEMA3F.

Pharmacology-based molecular docking of 4-methylcatechol and its role in RANKL-mediated ROS/Keap1/Nrf2 signalling axis and osteoclastogenesis.

4-Methylcatechol (4-MC) is an agonist of various neurotrophic factors, which can upregulate the expression of Heme oxygenase 1 (HO-1) protein by activating nuclear factor erythroid 2-related factor 2 (Nrf2), thereby inhibiting oxidative stress-induced neural stem cell death. During RANKL-stimulated osteoclast differentiation, intracellular reactive oxygen species (ROS) levels were increased. Nonetheless, the effect of 4-MC on osteoclast formation and bone resorption function has not been researched. In this study, we investigated the effect of HO-1 upregulation by 4-MC on RANKL-induced osteoclastogenesis and explored the molecular mechanism of HO-1 upregulation by 4-MC. We found that the small molecule compound 4-MC could bind to Keap1 amino acid residue of glycine GLY 367, isoleucine ILE 559 and valine VAL 606, with a predicted binding energy of -4.99 kcal/mol. 4-MC was found to inhibit osteoclast differentiation in vitro by activating Nrf2 to scavenge ROS, inhibiting NF-κB phosphorylation, and alleviating osteoporosis in ovariectomized (OVX) mice. Taken together, 4-MC reduces ROS by inhibiting Keap1, thereby preventing OVX-induced bone loss.

Ethyl caffeate inhibits macrophage polarization via SIRT1/NF-κB to attenuate traumatic heterotopic ossification in mice.

Heterotopic ossification (HO) denotes the presence of mature bone tissue in soft tissues or around joints. Inflammation is a key driver of traumatic HO, and macrophages play an important role in this process. Ethyl caffeate (ECF), a critical active compound found in Petunia, exerts significant anti-inflammatory effects. Herein, we established a mouse model of HO by transection of the Achilles tendon and back burn and found abundant macrophage infiltration in the early stage of HO, which decreased with time. In vitro and in vivo experiments indicated that ECF inhibited macrophage polarization, and mechanistic studies showed that it inhibited the SIRT1/NF-κB signalling pathway, thereby suppressing the release of downstream inflammatory cytokines. ECF reduced HO in mice, and its effect was comparable to indomethacin (INDO). In vitro studies revealed that ECF did not directly affect the mineralization of mesenchymal stem cells (MSCs) or osteogenic differentiation but inhibited these processes by reducing the level of inflammatory cytokines in the conditioned medium (CM). Thus, M1 macrophages may play a crucial role in the pathogenesis of HO, and ECF is a prospective candidate for the prevention of trauma-induced HO. DATA AVAILABILITY: Data will be made available on request.

Corylifol A protects against ovariectomized-induced bone loss and attenuates RANKL-induced osteoclastogenesis via ROS reduction, ERK inhibition, and NFATc1 activation.

Osteoclast differentiation and function are critical targets for anti-osteoporosis treatment. Oxidative stress also plays an important regulatory role in the differentiation of osteoclasts. Corylifol A (CA) is a flavonoid extracted from the Psoralea fruit. It has anti-inflammatory and antioxidant properties despite its unknown effect on osteoporosis. This study found that CA prevented estrogen-deficiency-induced bone loss and suppressed osteoclastogenesis in ovariectomized (OVX) mice by inhibiting intracellular reactive oxygen species (ROS) levels. In vivo, CA effectively prevented trabecular bone loss and reduced osteoclasts' number on the bone surface in OVX mice, as demonstrated in micro-CT, osteometry, and immunohistochemical data. However, CA did not affect cortical bone. In vitro, CA inhibited RANKL-induced podosome belt formation, osteoclastogenesis, and bone resorption functions. CA suppressed RANKL-induced ROS by boosting antioxidant enzymes (Catalase and NQO1) and NFATc1 signaling pathway related protein expression, including integrin αvß3, NFATc1 and CTSK. Moreover, CA inhibited osteoclast-specific genes, including Ctsk, Acp5, and Mmp9. CA also attenuated the MAPK/ERK pathway, but did not affect the NF-κB signaling pathway. In terms of osteogenesis, CA did not inhibit or promote osteogenic differentiation and mineralization in vitro. These results reveal that CA could be a new replacement therapy for treating estrogen-deficiency osteoporosis via suppressing osteoclastogenesis and intracellular ROS.

RNA-seq and Single-Cell Transcriptome Analyses of TRAIL Receptors Gene Expression in Human Osteosarcoma Cells and Tissues.

Osteosarcoma (OS) is the most common primary cancer in the skeletal system, characterized by a high incidence of lung metastasis, local recurrence and death. Systemic treatment of this aggressive cancer has not improved significantly since the introduction of chemotherapy regimens, underscoring a critical need for new treatment strategies. TRAIL receptors have long been proposed to be therapeutic targets for cancer treatment, but their role in osteosarcoma remains unclear. In this study, we investigated the expression profile of four TRAIL receptors in human OS cells using total RNA-seq and single-cell RNA-seq (scRNA-seq). The results revealed that TNFRSF10B and TNFRSF10D but not TNFRSF10A and TNFRSF10C are differentially expressed in human OS cells as compared to normal cells. At the single cell level by scRNA-seq analyses, TNFRSF10B, TNFRSF10D, TNFRSF10A and TNFRSF10C are most abundantly expressed in endothelial cells of OS tissues among nine distinct cell clusters. Notably, in osteoblastic OS cells, TNFRSF10B is most abundantly expressed, followed by TNFRSF10D, TNFRSF10A and TNFRSF10C. Similarly, in an OS cell line U2-OS using RNA-seq, TNFRSF10B is most abundantly expressed, followed by TNFRSF10D, TNFRSF10A and TNFRSF10C. According to the TARGET online database, poor patient outcomes were associated with low expression of TNFRSF10C. These results could provide a new perspective to design novel therapeutic targets of TRAIL receptors for the diagnosis, prognosis and treatment of OS and other cancers.

CGK733 alleviates ovariectomy-induced bone loss through blocking RANKL-mediated Ca2+ oscillations and NF-κB/MAPK signaling pathways.

Osteoporosis is a prevalent systemic metabolic disease in modern society, in which patients often suffer from bone loss due to over-activation of osteoclasts. Currently, amelioration of bone loss through modulation of osteoclast activity is a major therapeutic strategy. Ataxia telangiectasia mutated (ATM) inhibitor CGK733 (CG) was reported to have a sensitizing impact in treating malignancies. However, its effect on osteoporosis remains unclear. In this study, we investigated the effects of CG on osteoclast differentiation and function, as well as the therapeutic effects of CG on osteoporosis. Our study found that CG inhibits osteoclast differentiation and function. We further found that CG inhibits the activation of NFATc1 and ultimately osteoclast formation by inhibiting RANKL-mediated Ca2+ oscillation and the NF-κB/MAPK signaling pathway. Next, we constructed an ovariectomized mouse model and demonstrated that CG improved bone loss in ovariectomized mice. Therefore, CG may be a potential drug for the prevention and treatment of osteoporosis.

Three-year experience with combined complex skin repair in patients with extensive burns: a retrospective study.

INTRODUCTION: The Meek micrografting technique used in STSG expansion is effective in achieving wide and rapid coverage of burn wounds. Certain growth factors have also been shown to modulate or mediate wound healing. OBJECTIVE: In this study, a combined treatment approach for severe burns involving the Meek micrografting technique, systemic application of rhGH, and topical application of rhEGF was evaluated. MATERIALS AND METHODS: A retrospective study was conducted of 7 extensively burned patients who were treated with the Meek technique, systemic application of rhGH, and topical application of rhEGF between January 2017 and December 2019. RESULTS: The mean percent TBSA burned was 89%. An average of 9.5 surgical procedures were performed to obtain skin cover, with an average of 5.8 Meek micrograft procedures performed in the 6 surviving patients. Complete wound healing was achieved at an average of 120 days in the 6 surviving patients. The mean graft take rate was 81%. Infection was the main reason for graft failure. Donor sites were used for up to 5 re-harvestings without additional morbidity. CONCLUSIONS: A multipronged treatment approach that combines the Meek micrografting technique, systemic application of rhGH, and topical application of rhEGF is a promising tool for the management of severe and extensive burns.

Isosinensetin alleviates estrogen deficiency-induced osteoporosis via suppressing ROS-mediated NF-κB/MAPK signaling pathways.

The formation of osteoclasts and their hyperactive bone resorption are related to the aggregation of intracellular reactive oxygen species (ROS). Flavonoids, derived from plant active ingredients, can alleviate the symptoms of osteoporosis (OP). Isosinensetin (Iss) is a flavonoid with antioxidant effects obtained mainly from citrus fruits, and its effect on osteoclastogenesis has not been reported. In this study, we investigated the antioxidant activity of Iss on osteoclast differentiation and function, as well as the therapeutic impact of Iss on OP. We found that Iss inhibited osteoclastogenesis and suppressed the bone resorption function of osteoclasts. Additionally, Iss reduced receptor activator of nuclear factor-κB ligand (RANKL)-induced intracellular ROS. Using quantitative real-time polymerase chain reaction and western blot, we further found that Iss inhibited osteoclast-specific genes and related proteins, while promoting the expression of antioxidant enzyme-related genes and proteins. Mechanistically, Iss reduces intracellular ROS by activating nuclear factor-erythroid 2-related factor 2 (Nrf2) and its related antioxidant enzymes and inhibits the downstream nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways of ROS, which in turn inhibits nuclear factor of activated T cells 1 (NFATc1), and ultimately inhibits osteoclastogenesis. In vivo, by micro-computed tomography (Micro-CT) assay and histological analyses, we found that Iss could reduce bone loss in ovariectomized (OVX) mice. Therefore, Iss has the potential as an OP preventative and therapeutic drug option.

Single-cell RNA sequencing reveals differential expression of EGFL7 and VEGF in giant-cell tumor of bone and osteosarcoma.

Dysregulation of angiogenesis is associated with tumor development and is accompanied by altered expression of pro-angiogenic factors. EGFL7 is a newly identified antigenic factor that plays a role in various cancers such as breast cancer, lung cancer, and acute myeloid leukemia. We have recently found that EGFL7 is expressed in the bone microenvironment, but its role in giant-cell tumor of bone (GCTB) and osteosarcoma (OS) is unknown. The aims of this study are to examine the gene expression profile of EGFL7 in GCTB and OS and compare with that of VEGF-A-D and TNFSF11 using single-cell RNA sequencing data. In-depth differential expression analyses were employed to characterize their expression in the constituent cell types of GCTB and OS. Notably, EGFL7 in GCTB was expressed at highest levels in the endothelial cell (EC) cluster followed by osteoblasts, myeloid cells, and chondrocytes, respectively. In OS, EGFL7 exhibited highest expression in EC cell cluster followed by osteoblastic OS cells, myeloid cells 1, and carcinoma associated fibroblasts (CAFs), respectively. In comparison, VEGF-A is expressed at highest levels in myeloid cells followed by OCs in GCTB, and in myeloid cells, and OCs in OS. VEGF-B is expressed at highest levels in chondrocytes in GCTB and in OCs in OS. VEGF-C is strongly enriched in ECs and VEGF-D is expressed at weak levels in all cell types in both GCTB and OS. TNFSF11 (or RANKL) shows high expression in CAFs and osteoblastic OS cells in OS, and osteoblasts in GCTB. This study investigates pro-angiogenic genes in GCTB and OS and suggests that these genes and their expression patterns are cell-type specific and could provide potential prognostic biomarkers and cell type target treatment for GCTB and OS.

Single-cell RNA-seq identification of four differentially expressed survival-related genes by a TARGET: Osteosarcoma database analysis.

Osteosarcoma (OS) differentially expressed genes (DEGs) have been predicted using the data portal of the Therapeutically Applicable Research to Generate Effective Treatments (TARGET). In this study, we sought to identify cell types that specially express key DEGs (MUC1, COL13A1, JAG2, and KAZALD1) in each of the nine identified cell populations derived from tissues of OS tumors with single-cell RNA-sequencing data. Gene expression levels were pairwise compared between cell clusters and a p value < 0.05 was considered differentially expressed. It was revealed that MUC1 is expressed at high levels in osteoblastic OS cells followed by carcinoma-associated fibroblasts (CAFs) and plasmocytes, respectively. COL13A1 is highly expressed in osteoblastic OS cells, CAFs, and endothelial cells (ECs), respectively. The KAZALD1 gene is expressed in CAFs and osteoblastic OS cells at high levels, but at very low levels in plasmocytes, osteoclasts, NK/T, myeloid cells 1, myeloid cells 2, ECs, and B cells. JAG2 is expressed at significantly high levels in ECs and osteoblastic OS cells, and at relatively lower levels in all other cell types. Interestingly, LSAMP, as an established gene in the development of OS shows high expression in osteoblastic OS cells and CAFs but low in other cells such as osteoclasts. Our findings here highlight the heterogeneity of OS cells and cell-type-dependent DEGs which have potential as therapeutic targets in OS.