Metastasis is driven by extensive cooperation between a tumor and its microenvironment, resulting in the adaptation of molecular mechanisms that evade the immune system and enable pre-metastatic niche (PMN) formation. Little is known of the tumor-intrinsic factors that regulate these mechanisms. Here we show that expression of the transcription factor interferon regulatory factor 5 (IRF5) in osteosarcoma (OS) and breast carcinoma (BC) clinically correlates with prolonged survival and decreased secretion of tumor-derived extracellular vesicles (t-dEVs). Conversely, loss of intra-tumoral IRF5 establishes a PMN that supports metastasis. Mechanistically, IRF5-positive tumor cells retain IRF5 transcripts within t-dEVs that contribute to altered composition, secretion, and trafficking of t-dEVs to sites of metastasis. Upon whole-body pre-conditioning with t-dEVs from IRF5-high or -low OS and BC cells, we found increased lung metastatic colonization that replicated findings from orthotopically implanted cancer cells. Collectively, our findings uncover a new role for IRF5 in cancer metastasis through its regulation of t-dEV programming of the PMN.

Previous studies have reported the correlation between gut microbiota (GM), GM-derived metabolites, and various intestinal and extra-intestinal cancers. However, limited studies have investigated the correlation between GM, GM-derived metabolites, and osteosarcoma (OS). This study successfully established a female BALB/c nude mouse model of OS. Mice (n = 14) were divided into the following two groups (n = 7/group): OS group named OG, injected with Saos-2 OS cells; normal control group named NCG, injected with Matrigel. The GM composition and metabolites were characterized using 16S rDNA sequencing and untargeted metabolomics, respectively. Bioinformatics analysis revealed that amino acid metabolism was dysregulated in OS. The abundances of bone metabolism-related genera Alloprevotella, Rikenellaceae_RC9_gut_group, and Muribaculum were correlated with amino acid metabolism, especially histidine metabolism. These findings suggest the correlation between GM, GM-derived metabolites, and OS pathogenesis. Clinical significance: The currently used standard therapeutic strategies for OS, including surgery, chemotherapy, and radiation, are not efficacious. The findings of this study provided novel insights for developing therapeutic, diagnostic, and prognostic strategies for OS.

BACKGROUND: Osteosarcoma is considered as the most prevalent form of primary malignant bone cancer, prompting a pressing need for novel therapeutic options. Arnicolide D, a sesquiterpene lactone derived from the traditional Chinese herbal medicine Centipeda minima (known as E Bu Shi Cao in Chinese), showed anticancer efficacy against several kinds of cancers. However, its effect on osteosarcoma remains unclear.
OBJECTIVE: This study aimed to investigate the anticancer activity of arnicolide D and the underlying molecular mechanism of its action in osteosarcoma cells, MG63 and U2OS.
METHODS: Cell viability and proliferation were evaluated through MTT assay and colony formation assay following 24 h and 48 h treatment with different concentrations of arnicolide D. Flow cytometry was employed to examine cell cycle progression and apoptosis after 24 h treatment of arnicolide D. Western blotting was performed to determine the expression of the PI3k, Akt and m-TOR and their phosphorylated forms.
RESULTS: Our findings revealed that arnicolide D treatment resulted in a significant reduction in cell viability, the inhibition of proliferation, and the induction of apoptosis and cell cycle arrest in the G2/M phase. Furthermore, arnicolide D could inhibit the activation of PI3K/Akt/mTOR pathway in osteosarcoma cells.
CONCLUSIONS: Based on our results, arnicolide D demonstrated significant anti-osteosarcoma activity and held the potential to be considered as a therapeutic candidate for osteosarcoma in the future.

Osteosarcoma is a form of bone cancer that predominantly impacts osteoblasts, the cells responsible for creating fresh bone tissue. Typical indications include bone pain, inflammation, sensitivity, mobility constraints, and fractures. Utilising imaging techniques such as X-rays, MRI scans, and CT scans can provide insights into the size and location of the tumour. Additionally, a biopsy is employed to confirm the diagnosis. Analysing genes with distinct expression patterns unique to osteosarcoma can be valuable for early detection and the development of effective treatment approaches. In this research, we comprehensively examined the entire transcriptome and pinpointed genes with altered expression profiles specific to osteosarcoma. The study mainly aimed to identify the molecular fingerprint of osteosarcoma. In this study, we processed 90 FFPE samples from PathWest with an almost equal number of osteosarcoma and healthy tissues. RNA was extracted from Paraffin-embedded tissue; RNA was sequenced, the sequencing data was analysed, and gene expression was compared to the healthy samples of the same patients. Differentially expressed genes in osteosarcoma-derived samples were identified, and the functions of those genes were explored. This result was combined with our previous studies based on FFPE and fresh samples to perform a meta-analysis. We identified 1,500 identical differentially expressed genes in PathWest osteosarcoma samples compared to normal tissue samples of the same patients. Meta-analysis with combined fresh tissue samples identified 530 differentially expressed genes. IFITM5, MMP13, PANX3, and MAGEA6 were some of the most overexpressed genes in osteosarcoma samples, while SLC4A1, HBA1, HBB, AQP7 genes were some of the top downregulated genes. Through the meta-analysis, 530 differentially expressed genes were identified to be identical among FFPE (105 FFPE samples) and 36 fresh bone samples. Deconvolution analysis with single-cell RNAseq data confirmed the presence of specific cell clusters in FFPE samples. We propose these 530 DEGs as a molecular fingerprint of osteosarcoma.

Osteosarcoma (OS) is a common primary bone tumor in children and adolescents. Circular RNA (circRNA)-IARS acts as an oncogene in multiple human tumors. However, the circ-IARS function in OS is unclear. This research aimed to elucidate the roles and mechanisms of circ-IARS in OS. In this study, circ-IARS expressions were raised in OS tissues and cells. circ-IARS expressions were closely related to clinical stage and distant metastasis. Furthermore, overall survival rates were reduced in OS patients with high circ-IARS levels. Also, silencing circ-IARS weakened OS cell proliferation and invasion, yet enhanced cell ferroptosis. Mechanistically, circ-IARS targeted miR-188-5p to regulate RAB14 expressions in OS cells. Moreover, circ-IARS knockdown repressed OS cell proliferation, invasion, and induced ferroptosis, yet these impacts were abolished by co-transfection with anti-miR-188-5p or pcDNA-RAB14. Meanwhile, interference with circ-IARS reduced OS cell proliferation, and decreased RAB14 (a member of the RAS oncogene family), GPX4, and xCT (crucial ferroptosis regulators) expressions in vivo. In conclusion, circ-IARS facilitated OS progression via miR-188-5p/RAB14.

Despite advances in treating osteosarcoma, postoperative tumor recurrence, periprosthetic infection, and critical bone defects remain critical concerns. Herein, the growth of selenium nanoparticles (SeNPs) onto MgFe-LDH nanosheets (LDH) is reported to develop a multifunctional nanocomposite (LDH/Se) and further modification of the nanocomposite on a bioactive glass scaffold (BGS) to obtain a versatile platform (BGS@LDH/Se) for comprehensive postoperative osteosarcoma management. The uniform dispersion of negatively charged SeNPs on the LDH surface restrains toxicity-inducing aggregation and inactivation, thus enhancing superoxide dismutase (SOD) activation and superoxide anion radical (·O2 -)-H2O2 conversion. Meanwhile, Fe3+ within the LDH nanosheets can be reduced to Fe2+ by depleting glutathione (GSH) in the tumor microenvironments (TME), which can catalyze H2O2 into highly toxic reactive oxygen species. More importantly, incorporating SeNPs significantly promotes the anti-bacterial and osteogenic properties of BGS@LDH/Se. Thus, the developed BGS@LDH/Se platform can simultaneously inhibit tumor recurrence and periprosthetic infection as well as promote bone regeneration, thus holding great potential for postoperative \"one-stop-shop\" management of patients who need osteosarcoma resection and scaffold implantation.

UNASSIGNED: Osteosarcoma (OS) is highly malignant and prone to local infiltration and distant metastasis. Due to the poor outcomes of OS patients, the study aimed to identify differentially expressed genes (DEGs) in OS and explore their role in the carcinogenesis and progression of OS.
UNASSIGNED: RNA sequencing was performed to identify DEGs in OS. The functions of the DEGs in OS were investigated using bioinformatics analysis, and DEG expression was verified using RT-qPCR and Western blotting. The role of SLC25A4 was evaluated using gene set enrichment analysis (GSEA) and then investigated using functional assays in OS cells.
UNASSIGNED: In all, 8353 DEGs were screened. GO and KEGG enrichment analyses indicated these DEGs showed strong enrichment in the calcium signaling pathway and pathways in cancer. Moreover, the Kaplan-Meier survival analysis showed ten hub genes were related to the outcomes of OS patients. Both SLC25A4 transcript and protein expression were significantly reduced in OS, and GSEA suggested that SLC25A4 was associated with cell cycle, apoptosis and inflammation. SLC25A4-overexpressing OS cells exhibited suppressed proliferation, migration, invasion and enhanced apoptosis.
UNASSIGNED: SLC25A4 was found to be significantly downregulated in OS patients, which was associated with poor prognosis. Modulation of SLC25A4 expression levels may be beneficial in OS treatment.

Sarcomas are malignant tumors that may metastasize and the course of the disease is highly aggressive in children and young adults. Because of the rare incidence of sarcomas and the heterogeneity of tumors, there is a need for non-invasive diagnostic and prognostic biomarkers in sarcomas. The aim of the study was to investigate the level of miR-218-5p in peripheral blood and tumor tissue samples of Ewing\'s sarcoma, osteosarcoma, spindle cell sarcoma patients, and healthy controls, and assessed whether the corresponding molecule was a diagnostic and prognostic biomarker. The study was performed patients (n = 22) diagnosed and treated with Ewing\'s sarcoma and osteosarcoma and in a control group of 22 healthy children who were matched for age, gender, and ethnicity with the patient group. The expression level of miR-218-5p in RNA samples from peripheral blood and tissue samples were analyzed using the RT-PCR and the expression level of miR-218-5p was evaluated by comparison with the levels in patients and healthy controls. The expression level of miR-218-5p was found to be statistically higher (3.33-fold, p = 0.006) in pediatric patients with sarcomas and when the target genes of miR-218-5p were investigated using the bioinformatics tools, the miR-218-5p was found as an important miRNA in cancer. In this study, the miR-218-5p was shown for the first time to have been highly expressed in the peripheral blood and tumor tissue of sarcoma patients. The results suggest that miR-218-5p can be used as a diagnostic and prognostic biomarker in sarcomas and will be evaluated as an important therapeutic target.

UNASSIGNED: Osteosarcoma is the most common malignant primary bone tumor. The prognosis for patients with disseminated disease remains very poor despite recent advancements in chemotherapy. Moreover, current treatment regimens bear a significant risk of serious side effects. Thus, there is an unmet clinical need for effective therapies with improved safety profiles. Taurolidine is an antibacterial agent that has been shown to induce cell death in different types of cancer cell lines.
UNASSIGNED: In this study, we examined both the antineoplastic and antiangiogenic effects of taurolidine in animal models of osteosarcoma. K7M2 murine osteosarcoma cells were injected, both intramuscular and intraperitoneal, into 60 BALB/c mice on day zero. Animals were then randomized to receive treatment with taurolidine 2% (800 mg/kg), taurolidine 1% (400 mg/kg), or NaCl 0.9% control for seven days by intravenous or intraperitoneal administration.
UNASSIGNED: After 35 days, mice were euthanized, and the tumors were harvested for analysis. Eighteen mice were excluded from the analysis due to complications. Body weight was significantly lower in the 2% taurolidine intraperitoneal treatment group from day 9 to 21, consistent with elevated mortality in this group. Intraperitoneal tumor weight was significantly lower in the 1% (p = 0.003) and 2% (p = 0.006) intraperitoneal taurolidine treatment groups compared to the control. No antineoplastic effects were observed on intramuscular tumors or for intravenous administration of taurolidine. There were no significant differences in microvessel density or mitotic rate between treatment groups. Reduced body weight and elevated mortality in the 2% taurolidine intraperitoneal group suggest that the lower 1% dose is preferable.
UNASSIGNED: In conclusion, there is no evidence of antiangiogenic activity, and the antitumor effects of taurolidine on osteosarcoma observed in this study are limited. Moreover, its toxic profile grants further evaluation. Given these observations, further research is necessary to refine the use of taurolidine in osteosarcoma treatment.

UNASSIGNED: To analyze the effect of allicin on the immunoreactivity of osteosarcoma (OS) cells and further explore whether its mechanism is related to the long non-coding Ribonucleic Acid (lncRNA) CBR3-AS1/miR-145-5p/GRP78 axis, so as to provide clinical evidence.
UNASSIGNED: The human OS cell line Saos-2 was treated with allicin at 25, 50, and 100 μmol/L, respectively, to observe changes in cell biological behaviors. Subsequently, CBR3-AS1 abnormal expression vectors were constructed and transfected into Saos-2 to discuss their influence on OS. Furthermore, the regulatory relationship between allicin and the CBR3-AS1/miR-145-5p/GRP78 axis was validated by rescue experiments. Finally, a nude mice tumorigenesis experiment was carried out to analyze the effects of allicin and CBR3-AS1/miR-145-5p/GRP78 axis on the growth of living tumors. Alterations in T-lymphocyte subsets were also detected to assess the effect of allicin on OS immunoreactivity.
UNASSIGNED: With the increase of allicin concentration, Saos-2 activity decreased and apoptosis increased (P < 0.05). In addition, the expression of CBR3-AS1 and GRP78 decreased after allicin intervention, while miR-145-5p increased (P < 0.05). Silencing CBR3-AS1 led to reduced Saos-2 activity, enhanced apoptosis, and activated mitophagy and endoplasmic reticulum stress (P < 0.05). In the rescue experiment, the effect of CBR3-AS1 on OS cells was reversed by silencing miR-145-5p, while the impact of miR-145-5p was reversed by GRP78. Finally, the tumorigenesis experiment in nude mice confirmed the regulatory effects of allicin and CBR3-AS1/miR-145-5p/GRP78 on tumor growth in vivo. Meanwhile, it was seen that allicin activated CD4+CD8+ in OS mice, confirming that allicin has the effect of activating OS immunoreactivity.
UNASSIGNED: Allicin activates OS immunoreactivity and induces apoptosis through the CBR3-AS1/miR-145-5p/GRP78 molecular axis.