Osteosarcoma (OS) is a malignant tumor mainly occurring in young people. Due to the limited effective therapeutic strategies, OS patients cannot achieve further survival improvement. G-protein-coupled receptors (GPCRs) constitute the largest family of cell membrane receptors and consequently hold the significant promise for tumor imaging and targeted therapy. We aimed to explore the biological functions of Sphingosine 1-phosphate receptor 3 (S1PR3), one of the members of GPCRs family, in OS and the possibility of S1PR3 as an effective target for the treatment of osteosarcoma. The quantitative real time PCR (qRT-PCR) and western blotting were used to analyze the mRNA and protein expressions. Cell counting kit-8 (CCK8), colony formation assay and cell apoptosis assay were performed to test the cellular proliferation in vitro. Subcutaneous xenograft mouse model was generated to evaluate the functions of S1PR3 in vivo. RNA sequencing was used to compare gene expression patterns between S1PR3-knockdown and control MNNG-HOS cells. In addition, metabolic alternations in OS cells were monitored by XF96 metabolic flux analyzer. Co-immunoprecipitation (Co-IP) assay was used to explore the interaction between Yes-associated protein (YAP) and c-MYC. Chromatin immunoprecipitation was used to investigate the binding capability of PGAM1 and YAP or c-MYC. Moreover, the activities of promoter were determined by the luciferase reporter assay. S1PR3 and its specific ligand Sphingosine 1-phosphate (S1P) were found elevated in OS, and the higher expression of S1PR3 was correlated with the poor survival rate. Moreover, our study has proved that the S1P/S1PR3 axis play roles in proliferation promotion, apoptosis inhibition, and aerobic glycolysis promotion of osteosarcoma cells. Mechanistically, the S1P/S1PR3 axis inhibited the phosphorylation of YAP and promoted the nuclear translocation of YAP, which contributed to the formation of the YAP-c-MYC complex and enhanced transcription of the important glycolysis enzyme PGAM1. Moreover, the S1PR3 antagonist TY52156 exhibited in vitro and in vivo synergistic inhibitory effects with methotrexate on OS cell growth. Our study unveiled a role of S1P, a bioactive phospholipid, in glucose metabolism reprogram through interaction with its receptor S1PR3. Targeting S1P/S1PR3 axis might serve as a potential therapeutic target for patients with OS. FUND: This research was supported by National Natural Science Foundation of China (81472445 and 81672587).

Metabolic switch from oxidative phosphorylation to aerobic glycolysis, which is also called the Warburg effect, is a hallmark of osteosarcoma (OS) and leads to the enhancement of cell chemoresistance, growth, metastasis, and invasion. Emerging evidence indicates that long non-coding RNA (lncRNA) plays a crucial role in the Warburg effect of cancer cells. Here, we report that lncRNA KCNQ1OT1 was upregulated in OS. Meanwhile, functional experiments demonstrated that the KCNQ1OT1 facilitated proliferation and suppressed apoptosis of OS cells. In addition, KCNQ1OT1 contributed to the Warburg effect by stimulating aldolase A (ALDOA) expression. Furthermore, using bioinformatics analysis, luciferase reporter, RNA immunoprecipitation, and RNA pull-down assay, we identified that KCNQ1OT1 functions as a competing endogenous RNA (ceRNA) by sponging miR-34c-5p, which inhibited ALDOA expression by directly targeting its 3ʹUTR. Taken together, these data identified a key role of KCNQ1OT1 in glucose metabolism reprogramming of OS. Targeting the KCNQ1OT1/miR-34c-5p/ALDOA axis may be a potential therapeutic target in OS treatment.

Background: Electrospinning is a widely used technology that can produce scaffolds with high porosity and surface area for bone regeneration. However, the small pore sizes in electrospun scaffolds constrain cell growth and tissue-ingrowth. In this study, novel drug-loading core-shell scaffolds were fabricated via electrospinning and freeze drying to facilitate the repair of tibia bone defects in rabbit models. Materials and Methods: The collagen core scaffolds were freeze-dried containing icariin (ICA)-loaded chitosan microspheres. The shell scaffolds were electrospun using collagen, polycaprolactone and hydroxyapatite materials to form CPH composite scaffolds with the ones containing ICA microspheres named CPHI. The core-shell scaffolds were then cross-linked by genipin. The morphology, microstructure, physical and mechanical properties of the scaffolds were assessed. Rat marrow mesenchymal stem cells from the wistar rat were cultured with the scaffolds. The cell adhesion and proliferation were analysed. Adult rabbit models with tibial plateau defects were used to evaluate the performance of these scaffolds in repairing the bone defects over 4 to 12 weeks. Results: The results reveal that the novel drug-loading core-shell scaffolds were successfully fabricated, which showed good physical and chemical properties and appropriate mechanical properties. Furthermore, excellent cells attachment was observed on the CPHI scaffolds. The results from radiography, micro-computed tomography, histological and immunohistochemical analysis demonstrated that abundant new bones were formed on the CPHI scaffolds. Conclusion: These new core-shell composite scaffolds have great potential for bone tissue engineering applications and may lead to effective bone regeneration and repair.

The lncRNA LINC01123 has been reported to act as an oncogene in many human cancers. Nevertheless, the function and underlying mechanism of LINC01123 in osteosarcoma (OS) remain unclear. This study aimed to explore the roles and mechanisms of LINC01123 in OS progression. In this study, the expression of LINC01123 was significantly upregulated in OS cell lines than in a human osteoblast cell line. Furthermore, in vitro and in vivo experiments confirmed that knockdown of LINC01123 suppressed cell progression. Mechanistically, LINC01123 acted as a competing endogenous RNA by sponging miR‐516b‐5p, thus, increasing Gli1 expression by directly targeting its 3ʹUTR. Taken together, LINC01123 enhances OS proliferation and metastasis via the miR‐516b‐5p/Gli1 axis. Therefore, LINC01123 may be a potential therapeutic target for OS treatment.

Osteosarcoma (OS), which is a common and aggressive primary bone malignancy, occurs mainly in children and adolescent. Long noncoding RNAs (lncRNAs) are reported to play a pivotal role in various cancers. Here, we found that the lncRNA HOTAIRM1 is upregulated in OS cells and tissues. A set of functional experiments suggested that HOTAIRM1 knockdown attenuated the proliferation and stimulated the apoptosis of OS cells. A subsequent mechanistic study revealed that HOTAIRM1 functions as a competing endogenous RNA to elevate ras homologue enriched in brain (Rheb) expression by sponging miR‐664b‐3p. Immediately afterward, upregulated Rheb facilitates proliferation and suppresses apoptosis by promoting the mTOR pathway‐mediated Warburg effect in OS. In summary, our findings demonstrated that HOTAIRM1 promotes the proliferation and suppresses the apoptosis of OS cells by enhancing the Warburg effect via the miR‐664b‐3p/Rheb/mTOR axis. Understanding the underlying mechanisms and targeting the HOTAIRM1/miR‐664b‐3p/Rheb/mTOR axis are essential for OS clinical treatment.