Metastasis Of Osteosarcoma Cells Research Articles

Tetrahedral Framework Nucleic Acid-Loaded Retinoic Acid Promotes Osteosarcoma Stem Cell Clearance.

Metastatic osteosarcoma is a commonly seen malignant tumor in adolescents, with a five year survival rate of approximately 20% and a lack of treatment options. Osteosarcoma cancer stem cells are considered to be important drivers of the metastasis of osteosarcoma, and therefore their clearance is considered a promising strategy for treating metastatic osteosarcoma. In the relevant literature, retinoic acid (ATRA) is considered effective for eliminating osteosarcoma stem cells, but it has some inherent disadvantages, including poor solubility, difficulty in entering cells, and structural instability. Tetrahedral framework nucleic acids (tFNAs) are a type of nanoparticles that can carry small-molecule drugs into cells to exert therapeutic effects. Therefore, we designed and synthesized a nanoparticle named T-ATRA by using tFNAs to load ATRA and studied its effect in a nude mouse model. T-ATRA is more effective than ATRA in the clearance of osteosarcoma stem cells and in inhibiting osteosarcoma cell metastasis via the Wnt signaling pathway, thus prolonging the survival time of nude mice with osteosarcoma.

Retraction of: miR-627-3p inhibits osteosarcoma cell proliferation and metastasis by targeting PTN.

Retraction of: miR-627-3p inhibits osteosarcoma cell proliferation and metastasis by targeting PTN.

MTA2 knockdown suppresses human osteosarcoma metastasis by inhibiting uPA expression.

The relationship between metastasis-associated protein 2 (MTA2) overexpression and tumor growth and metastasis has been extensively studied in a variety of tumor cells but not in human osteosarcoma cells. This study aims to elucidate the clinical significance, underlying molecular mechanisms, and biological functions of MTA2 in human osteosarcoma in vitro and in vivo. Our results show that MTA2 was elevated in osteosarcoma cell lines and osteosarcoma tissues and was associated with tumor stage and overall survival of osteosarcoma patients. Knockdown of MTA2 inhibited osteosarcoma cell migration and invasion by reducing the expression of urokinase-type plasminogen activator (uPA). Bioinformatic analysis demonstrated that high levels of uPA in human osteosarcoma tissues correlated positively with MTA2 expression. Furthermore, treatment with recombinant human uPA (Rh-uPA) caused significant restoration of OS cell migration and invasion in MTA2 knockdown osteosarcoma cells. We found that ERK1/2 depletion increased the expression of uPA, facilitating osteosarcoma cell migration and invasion. Finally, MTA2 depletion significantly reduced tumor metastasis and the formation of lung nodules in vivo. Overall, our study suggests that MTA2 knockdown suppresses osteosarcoma cell metastasis by decreasing uPA expression via ERK signaling. This finding provides new insight into potential treatment strategies against osteosarcoma metastasis by targeting MTA2.

The sEVs miR-487a/Notch2/GATA3 axis promotes osteosarcoma lung metastasis by inducing macrophage polarization toward the M2-subtype

Small extracellular vesicles (sEVs) are important mediators of intercellular communication between tumor cells and their surrounding environment. Furthermore, the mechanisms by which miRNAs carried in tumor sEVs regulate macrophage polarization remain largely unknown. To concentrate sEVs, we used the traditional ultracentrifugation method. Western blot, NanoSight, and transmission electron microscopy were used to identify sEVs. To determine the function of sEVs-miR-487a, we conducted in vivo and in vitro investigations. The intercellular communication mechanism between osteosarcoma cells and M2 macrophages, mediated by sEVs carrying miR-487a, was validated using luciferase reporter assays, transwell assays, and Western blot analysis. In vitro, sEVs enriched in miR-487a and delivered miR-487a to macrophages, promoting macrophage polarization toward an M2-like type, which promotes proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of osteosarcoma cells. In vivo, sEVs enriched in miR-487a facilitate lung metastasis of osteosarcoma. Moreover, plasma miR-487a in sEVs was shown to be a potential biomarker applicable for osteosarcoma diagnosis. In summary, miR-487a derived from osteosarcoma cells can be transferred to macrophages via sEVs, then promote macrophage polarization towards an M2-like type by targeting Notch2 and activating the GATA3 pathway. In a feedback loop, the activation of macrophages accelerates epithelial-mesenchymal transition (EMT), which in turn promotes the migration, invasion, and lung metastasis of osteosarcoma cells. This reciprocal interaction between activated macrophages and osteosarcoma cells contributes to the progression of the disease. Our data demonstrate a new mechanism that osteosarcoma tumor cells derived exosomal-miR-487a which is involved in osteosarcoma development by regulating macrophage polarization in tumor microenvironment (TME).

Effect of ac4C acetyltransferase NAT10 on tumor progression via ATF4/ASNS mediated asparagine biosynthesis in osteosarcoma.

234 Background: Osteosarcoma is the most common primary malignant bone tumor in children and adolescents, characterized by high malignancy, high mortality, and high disability rates. Investigating the mechanism of osteosarcoma progression, identifying new targets, and developing effective therapy are of great significance for improving patient clinical outcomes. NAT10-mediated ac4C modification is widely present in mRNA and plays important roles in multiple biological processes of mRNA. NAT10 and ac4C modification also play a crucial role in the occurrence and development of malignant tumors such as bladder cancer, esophageal cancer, and breast cancer. Methods: Through RNA-seq and functional screening, NAT10 was identified as the potential therapeutic target. The biological functions of NAT10 and ac4C modification in osteosarcoma were explored in vivo and in vitro. Downstream target of NAT10 was identified through acRIP-seq combined with RNA-seq. The ac4C modification of downstream target gene were detected using RIP-qPCR and its regulatory effect on mRNA stability was explored using RNA half-life analysis. Drug screening was performed using FDA-approved drugs and a small molecule compound library to identify NAT10 inhibitors. The efficacy of inhibitors in osteosarcoma treatment is validated through in vivo, in vitro experiments and patient-derived tumor xenograft (PDX) models. Results: Functional screening targeting RNA modification regulatory factors demonstrated that inhibiting NAT10 significantly reduced the proliferation, migration and invasion of osteosarcoma cells. NAT10 knockout significantly inhibited the proliferation and metastasis of osteosarcoma cells, as well as the malignant progression in vivo. The acRIP-seq and RNA-seq revealed that ATF4 is a downstream target gene regulated by NAT10 in osteosarcoma. NAT10 promoted ac4C modification of ATF4 mRNA, enhanced the stability of ATF4 mRNA, and ATF4 promoted the transcription and expression of ASNS. ASNS catalyzes the synthesis of asparagine (Asn), thereby promoting the malignant progression of osteosarcoma. Drug screening identified Paliperidone and AG-401 as potential inhibitors of NAT10. Through cell functional experiments, orthotopic osteosarcoma models, organoids model, and PDX models, it was demonstrated that Paliperidone and AG-401 can inhibit the malignant progression of osteosarcoma. Conclusions: NAT10 was highly expressed in osteosarcoma and associated with patient prognosis. Through ac4C modification, NAT10 regulated the synthesis of asparagine mediated by ATF4/ASNS, providing materials for protein and nucleotide synthesis in tumor cells, thus promoting the malignant progression of osteosarcoma. Paliperidone and AG-401 were identified as potential NAT10 inhibitors and targeting NAT10 could be a promosing strategy in osteosarcoma treatment.

Lycorine combined with cisplatin synergistically inhibited osteosarcoma cells growth and metastasis by suppressing Wnt/β-Catenin and STAT3 signaling pathways

Cisplatin is commonly used in treating osteosarcoma, however, chemoresistance reduces its efficacy and results in a poor prognosis. Lycorine, a Chinese herbal medicine component, possesses anti-tumor and anti-inflammatory properties. This study aims to investigate the combined impact of lycorine and cisplatin on osteosarcoma and its molecular mechanism. The combination of lycorine and cisplatin exhibited a synergistic effect evaluated by MTT and Zheng-Jun Jin’s method. Lycorine and cisplatin synergistically inhibit proliferation, migration, invasion, and induce apoptosis of osteosarcoma cells. Pharmacological analysis predicts 13 key targets, including Wnt/β-Catenin and STAT3. After treatment with this combination, key molecules in Wnt/β-Catenin and STAT3 pathways were significantly inhibited. In an orthotopic tumor model, the combination significantly reduces lung metastasis. The present work suggests that a combination of lycorine with cisplatin can effectively inhibit OS cells by suppressing the Wnt/β-Catenin and STAT3 signaling pathways synergistically. This is expected to enhance the therapeutic effect of OS.

Downregulation of B4GALNT1 inhibits proliferation and metastasis of osteosarcoma cells.

Osteosarcoma is the most common malignant bone tumor in children and adolescents, characterized by a high potential for proliferation and metastasis. Patients with osteosarcoma who have distant metastases generally have a poor prognosis. Challenges in treatment include incomplete resection of tumor and chemotherapy resistance, with no effective cure currently available. Recent studies suggest that β-1,4-N-acetyl-galactosaminyltransferase 1 (B4GALNT1) plays a role in the progression of various malignant tumors. However, the function of B4GALNT1 in osteosarcoma cells has not been reported. This study aims to investigate the expression of B4GALNT1 in osteosarcoma tissues compared to normal tissues and to explore its effects on the proliferation, migration, and invasion of osteosarcoma cells, thereby providing new theoretical foundations and directions for the treatment of osteosarcoma patients. Tumor tissues and corresponding normal tissue samples were collected from 16 osteosarcoma patients who underwent tumor resection at the Second Xiangya Hospital of Central South University. The patients' ages ranged from 8 to 17 years (median age 12 years). The expression of B4GALNT1 mRNA in osteosarcoma tissues, corresponding normal tissues, 3 osteosarcoma cell lines (MG63, Saos-2, and U2OS), and human fetal osteoblastic cells (hFOB) was detected using real-time reverse transcription PCR (real-time RT-PCR). The effects of B4GALNT1 knockdown on the proliferation of osteosarcoma cells Saos-2 and U2OS were analyzed using cell counting kit-8 (CCK-8) assays and colony formation assays. The effects of B4GALNT1 knockdown on the migration and invasion abilities of Saos-2 and U2OS cells were evaluated using Transwell migration and invasion assays. Western blotting analysis was performed to assess the impact of B4GALNT1 knockdown on the expression of epithelial-mesenchymal transition (EMT) and invasion-related proteins in Saos-2 and U2OS cells. Real-time RT-PCR results showed that B4GALNT1 mRNA expression levels were significantly higher in osteosarcoma tissues and the 3 osteosarcoma cell lines compared to normal tissues and hFOB cells (all P<0.01). CCK-8 and colony formation assays indicated that B4GALNT1 knockdown significantly reduced the proliferation rate of osteosarcoma cells compared to the control group (all P<0.05). Transwell migration and invasion assays demonstrated that B4GALNT1 knockdown significantly decreased the number of migrating and invading osteosarcoma cells (all P<0.01). Western blotting analysis revealed that B4GALNT1 knockdown inhibited the expression of N-cadherin, Snail, Vimentin, and matrix metalloproteinase 9 (MMP9) compared to the control group (all P<0.01). B4GALNT1 is upregulated in osteosarcoma tissues and cell lines, and its knockdown suppresses the malignant phenotype of osteosarcoma cells. B4GALNT1 may function as an oncogene in the proliferation and metastasis of osteosarcoma cells.

Multi-omic validation of the cuproptosis-sphingolipid metabolism network: modulating the immune landscape in osteosarcoma.

The current understanding of the mechanisms by which metal ion metabolism promotes the progression and drug resistance of osteosarcoma remains incomplete. This study aims to elucidate the key roles and mechanisms of genes involved in cuproptosis-related sphingolipid metabolism (cuproptosis-SPGs) in regulating the immune landscape, tumor metastasis, and drug resistance in osteosarcoma cells. This study employed multi-omics approaches to assess the impact of cuproptosis-SPGs on the prognosis of osteosarcoma patients. Lasso regression analysis was utilized to construct a prognostic model, while multivariate regression analysis was applied to identify key core genes and generate risk coefficients for these genes, thereby calculating a risk score for each osteosarcoma patient. Patients were then stratified into high-risk and low-risk groups based on their risk scores. The ESTIMATE and CIBERSORT algorithms were used to analyze the level of immune cell infiltration within these risk groups to construct the immune landscape. Single-cell analysis was conducted to provide a more precise depiction of the expression patterns of cuproptosis-SPGs among immune cell subtypes. Finally, experiments on osteosarcoma cells were performed to validate the role of the cuproptosis-sphingolipid signaling network in regulating cell migration and apoptosis. In this study, seven cuproptosis-SPGs were identified and used to construct a prognostic model for osteosarcoma patients. In addition to predicting survival, the model also demonstrated reliability in forecasting the response to chemotherapy drugs. The results showed that a high cuproptosis-sphingolipid metabolism score was closely associated with reduced CD8 T cell infiltration and indicated poor prognosis in osteosarcoma patients. Cellular functional assays revealed that cuproptosis-SPGs regulated the LC3B/ERK signaling pathway, thereby triggering cell death and impairing migration capabilities in osteosarcoma cells. The impact of cuproptosis-related sphingolipid metabolism on the survival and migration of osteosarcoma cells, as well as on CD8 T cell infiltration, highlights the potential of targeting copper ion metabolism as a promising strategy for osteosarcoma patients.

Targeting nerve growth factor-mediated osteosarcoma metastasis: mechanistic insights and therapeutic opportunities using larotrectinib

Osteosarcoma (OS) therapy presents numerous challenges, due largely to a low survival rate following metastasis onset. Nerve growth factor (NGF) has been implicated in the metastasis and progression of various cancers; however, the mechanism by which NGF promotes metastasis in osteosarcoma has yet to be elucidated. This study investigated the influence of NGF on the migration and metastasis of osteosarcoma patients (88 cases) as well as the underlying molecular mechanisms, based on RNA-sequencing and gene expression data from a public database (TARGET-OS). In osteosarcoma patients, the expression of NGF was significantly higher than that of other growth factors. This observation was confirmed in bone tissue arrays from 91 osteosarcoma patients, in which the expression levels of NGF and matrix metallopeptidase-2 (MMP-2) protein were significantly higher than in normal bone, and strongly correlated with tumor stage. In summary, NGF is positively correlated with MMP-2 in human osteosarcoma tissue and NGF promotes osteosarcoma cell metastasis by upregulating MMP-2 expression. In cellular experiments using human osteosarcoma cells (143B and MG63), NGF upregulated MMP-2 expression and promoted wound healing, cell migration, and cell invasion. Pre-treatment with MEK and ERK inhibitors or siRNA attenuated the effects of NGF on cell migration and invasion. Stimulation with NGF was shown to promote phosphorylation along the MEK/ERK signaling pathway and decrease the expression of microRNA-92a-1-5p (miR-92a-1-5p). In in vivo experiments involving an orthotopic mouse model, the overexpression of NGF enhanced the effects of NGF on lung metastasis. Note that larotrectinib (a tropomyosin kinase receptor) strongly inhibited the effect of NGF on lung metastasis. In conclusion, it appears that NGF promotes MMP-2-dependent cell migration by inhibiting the effects of miR-92a-1-5p via the MEK/ERK signaling cascade. Larotrectinib emerged as a potential drug for the treatment of NGF-mediated metastasis in osteosarcoma.

KAT7 serves as an oncogenic gene and regulates CCL3 expression via STAT1 signaling in osteosarcoma

Osteosarcoma, considered as the primary cause of malignant bone tumors in children, necessitates novel therapeutic strategies to enhance overall survival rates. KAT7, a histone acetyltransferase, exerts pivotal functions in gene transcription and immune modulation. In light of this, our study identified a significant upregulation of KAT7 in the mRNA and protein levels in human osteosarcoma, boosting cell proliferation in vivo and in vitro. In addition, KAT7-mediated H3K14ac activation induced MMP14 transcription, leading to increased expression and facilitation of osteosarcoma cell metastasis. Subsequent bioinformatics analyses highlighted a correlation between KAT7 and adaptive immune responses, indicating CCL3 as a downstream target of KAT7. Mechanistically, STAT1 was found to transcriptionally upregulate CCL3 expression. Furthermore, overexpression of KAT7 suppressed CCL3 secretions, whereas knockdown of KAT7 enhanced its release. Overall, these findings underscore the oncogenic role of KAT7 in regulating immune responses for osteosarcoma treatment.

HOXB5 promotes the progression and metastasis of osteosarcoma cells by activating the JAK2/STAT3 signalling pathway

ObjectiveTo investigate the involvement of the homeobox gene B5 (HOXB5) in the progression and metastasis of osteosarcoma. MethodsThe expression of HOXB5 in human osteosarcoma tissues and its correlation with clinical indicators were investigated using bioinformatics analysis and immunohistochemical labelling. Human osteosarcoma cells (HOS, MG63, U2OS, and Saos-2) and normal human osteoblasts (hFOB1.19) were cultivated. The expression of HOXB5 in these cells was detected using western blotting (WB) and RT‒PCR. Two cell lines exhibiting elevated HOXB5 expression were chosen and divided into three groups: the blank group (mock), control group (control) and transfection group (shHOXB5). The transfection group was infected with lentivirus expressing shRNAs targeting HOXB5. The transfection efficiency was detected by WB. Cell proliferation suppression was measured by CCK-8 and 5-ethynyl-2′-deoxyuridine (EdU) assays; the percentage of apoptotic cells was determined by flow cytometry; and cell migration and invasion were detected via the Transwell chamber test. WB was utilized to determine the protein expression of genes linked to metastasis (MMP2, MMP9), apoptosis (Bax, Bcl-2), and the JAK2/STAT3 pathway (JAK2, p-JAK2, STAT3, p-STAT3). ResultsIn osteosarcoma tissues, HOXB5 expression was elevated and strongly correlated with distant metastasis. Silencing HOXB5 reduced the proliferation, migration and invasion of osteosarcoma cells; prevented the progression and metastasis of tumours in tumour-bearing nude mice; and reduced the activation of key proteins in the JAK2/STAT3 signalling pathway. ConclusionThrough the JAK2/STAT3 signalling pathway, HOXB5 plays a crucial role in the malignant progression of osteosarcoma and is a promising target for osteosarcoma treatment.

Proteomic Analyses Reveal the Role of Alpha-2-Macroglobulin in Canine Osteosarcoma Cell Migration.

Canine osteosarcoma (OSA) is an aggressive bone neoplasia with high metastatic potential. Metastasis is the main cause of death associated with OSA, and there is no current treatment available for metastatic disease. Proteomic analyses, including matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI TOF/TOF MS), are widely used to select molecular targets and identify proteins that may play a key role in primary tumours and at various steps of the metastatic cascade. The main aim of this study was to identify proteins differently expressed in canine OSA cell lines with different malignancy phenotypes (OSCA-8 and OSCA-32) compared to canine osteoblasts (CnOb). The intermediate aim of the study was to compare canine OSA cell migration capacity and assess its correlation with the malignancy phenotypes of each cell line. Using MALDI-TOF/TOF MS analyses, we identified eight proteins that were significantly differentially expressed (p ≤ 0.05) in canine OSA cell lines compared to CnOb: cilia- and flagella-associated protein 298 (CFAP298), general transcription factor II-I (GTF2I), mirror-image polydactyly gene 1 protein (MIPOL1), alpha-2 macroglobulin (A2M), phosphoglycerate mutase 1 (PGAM1), ubiquitin (UB2L6), ectodysplasin-A receptor-associated adapter protein (EDARADD), and leucine-rich-repeat-containing protein 72 (LRRC72). Using the Simple Western technique, we confirmed high A2M expression in CnOb compared to OSCA-8 and OSCA-32 cell lines (with intermediate and low A2M expression, respectively). Then, we confirmed the role of A2M in cancer cell migration by demonstrating significantly inhibited OSA cell migration by treatment with A2M (both at 10 and 30 mM concentrations after 12 and 24 h) in a wound-healing assay. This study may be the first report indicating A2M's role in OSA cell metastasis; however, further in vitro and in vivo studies are needed to confirm its possible role as an anti-metastatic agent in this malignancy.

METTL3 Promotes Osteosarcoma Metastasis via an m6A-dependent Epigenetic Activity of CBX4.

Osteosarcoma cells are prone to metastasis, and the mechanism of N6-methyladenosine (m6A) methylation modification in this process is still unclear. Methylation modification of m6A plays an important role in the development of osteosarcoma, which is mainly due to abnormal expression of enzymes related to methylation modification of m6A, which in turn leads to changes in the methylation level of downstream target genes messenger RNA (mRNA) leading to tumor development. We analyzed the expression levels of m6A methylation modification-related enzyme genes in GSE12865 whole-genome sequencing data. And we used shRNA (short hairpin RNA) lentiviral interference to interfere with METTL3 (Methyltransferase 3) expression in osteosarcoma cells. We studied the cytological function of METTL3 by Cell Counting Kit-8 (CCK8), flow cytometry, migration and other experiments, and the molecular mechanism of METTL3 by RIP (RNA binding protein immunoprecipitation), Western blot and other experiments. We found that METTL3 is abnormally highly expressed in osteosarcoma and interferes with METTL3 expression in osteosarcoma cells to inhibit metastasis, proliferation, and apoptosis of osteosarcoma cells. We subsequently found that METTL3 binds to the mRNA of CBX4 (chromobox homolog 4), a very important regulatory protein in osteosarcoma metastasis, and METTL3 regulates the mRNA and protein expression of CBX4. Further studies revealed that METTL3 inhibited metastasis of osteosarcoma cells by regulating CBX4. METTL3 has been found to be involved in osteosarcoma cells metastasis by CBX4 affecting the protein expression of matrix metalloproteinase 2 (MMP2), MMP9, E-Cadherin and N-Cadherin associated with osteosarcoma cells metastasis. These results suggest that the combined action of METTL3 and CBX4 plays an important role in the regulation of metastasis of osteosarcoma, and therefore, the METTL3-CBX4 axis pathway may be a new potential therapeutic target for osteosarcoma.

A tumor suppressor protein encoded by circKEAP1 inhibits osteosarcoma cell stemness and metastasis by promoting vimentin proteasome degradation and activating anti-tumor immunity.

Osteosarcoma (OS) is one of most commonly diagnosed bone cancer. Circular RNAs (circRNAs) are a class of highly stable non-coding RNA, the majority of which have not been characterized functionally. The underlying function and molecular mechanisms of circRNAs in OS have not been fully demonstrated. Microarray analysis was performed to identify circRNAs that are differentially-expressed between OS and corresponding normal tissues. The biological function of circKEAP1 was confirmed in vitro and in vivo. Mass spectrometry and western blot assays were used to identify the circKEAP1-encoded protein KEAP1-259aa. The molecular mechanism of circKEAP1 was investigated by RNA sequencing and RNA immunoprecipitation analyses. Here, we identified a tumor suppressor circKEAP1, originating from the back-splicing of exon2 of the KEAP1 gene. Clinically, circKEAP1 is downregulated in OS tumors and associated with better survival in cancer patients. N6-methyladenosine (m6A) at a specific adenosine leads to low expression of circKEAP1. Further analysis revealed that circKEAP1 contained a 777 nt long ORF and encoded a truncated protein KEAP1-259aa that reduces cell proliferation, invasion and tumorsphere formation of OS cells. Mechanistically, KEAP1-259aa bound to vimentin in the cytoplasm to promote vimentin proteasome degradation by interacting with the E3 ligase ARIH1. Moreover, circKEAP1 interacted with RIG-I to activate anti-tumor immunity via the IFN-γ pathway. Taken together, our findings characterize a tumor suppressor circKEAP1 as a key tumor suppressor regulating of OS cell stemness, proliferation and migration, providing potential therapeutic targets for treatment of OS.

RANK/RANKL axis promotes migration, invasion, and metastasis of osteosarcoma via activating NF-κB pathway

Osteosarcoma (OS) is one of the most prevalent primary bone tumors with a high degree of metastasis and poor prognosis. Epithelial-to-mesenchymal transition (EMT) is a cellular mechanism that contributes to the invasion and metastasis of cancer cells, and OS cells have been reported to exhibit EMT-like characteristics. Our previous studies have shown that the interaction between tumor necrosis factor superfamily member 11 (TNFRSF11A; also known as RANK) and its ligand TNFSF11 (also known as RANKL) promotes the EMT process in breast cancer cells. However, whether the interaction between RANK and RANKL enhances aggressive behavior by inducing EMT in OS cells has not yet been elucidated. In this study, we showed that the interaction between RANK and RANKL increased the migration, invasion, and metastasis of OS cells by promoting EMT. Importantly, we clarified that the RANK/RANKL axis induces EMT by activating the nuclear factor-kappa B (NF-κB) pathway. Furthermore, the NF-κB inhibitor dimethyl fumarate (DMF) suppressed migration, invasion, and EMT in OS cells. Our results suggest that the RANK/RANKL axis may serve as a potential tumor marker and promising therapeutic target for OS metastasis. Furthermore, DMF may have clinical applications in the treatment of lung metastasis in patients with OS.

Hypoxia inducible factor-1ɑ as a potential therapeutic target for osteosarcoma metastasis.

Osteosarcoma (OS) is a malignant tumor originating from mesenchymal tissue. Pulmonary metastasis is usually present upon initial diagnosis, and metastasis is the primary factor affecting the poor prognosis of patients with OS. Current research shows that the ability to regulate the cellular microenvironment is essential for preventing the distant metastasis of OS, and anoxic microenvironments are important features of solid tumors. During hypoxia, hypoxia-inducible factor-1α (HIF-1α) expression levels and stability increase. Increased HIF-1α promotes tumor vascular remodeling, epithelial-mesenchymal transformation (EMT), and OS cells invasiveness; this leads to distant metastasis of OS cells. HIF-1α plays an essential role in the mechanisms of OS metastasis. In order to develop precise prognostic indicators and potential therapeutic targets for OS treatment, this review examines the molecular mechanisms of HIF-1α in the distant metastasis of OS cells; the signal transduction pathways mediated by HIF-1α are also discussed.

MiR-150-5p inhibits cell proliferation and metastasis by targeting FTO in osteosarcoma.

Osteosarcoma (OS), recognized as the predominant malignant tumor originating from bones, necessitates an in-depth comprehension of its intrinsic mechanisms to pinpoint novel therapeutic targets and enhance treatment methodologies. The role of fat mass and obesity-associated (FTO) in OS, particularly its correlation with malignant traits, and the fundamental mechanism, remains to be elucidated. 1. The FTO expression and survival rate in tumors were analyzed. 2. FTO in OS cell lines was quantified utilizing western blot and PCR. 3. FTO was upregulated and downregulated separately in MG63. 4. The impact of FTO on the proliferation and migration of OS cells was evaluated using CCK-8, colony formation, wound healing, and Transwell assays. 5. The expression of miR-150-5p in OS cells-derived exosomes was identified. 6. The binding of miR-150-5p to FTO was predicted by TargetScan and confirmed by luciferase reporter assay. 7. The impact of exosome miR-150-5p on the proliferation and migration of OS cells was investigated. The expression of FTO was higher in OS tissues compared to normal tissues correlating with a worse survival rate. Furthermore, the downregulation of FTO significantly impeded the growth and metastasis of OS cells. Additionally, miR-150-5p, which was downregulated in both OS cells and their derived exosomes, was found to bind to the 3'-UTR of FTO through dual luciferase experiments. Exosomal miR-150-5p was found to decrease the expression of FTO and inhibit cell viability. We identified elevated levels of FTO in OS, which may be attributed to insufficient miR-150-5p levels in both the cells and exosomes. It suggests that the dysregulation of miR-150-5p and its interaction with FTO could potentially promote the development of OS.

(S)-10-Hydroxycamptothecin Inhibits EMT-evoked Osteosarcoma Cell Growth and Metastasis by Activating the HIPPO Signaling Pathway.

Osteosarcoma is the most common primary bone cancer in children and adolescents with high metastatic ability. This study aimed to explore the inhibitory effects of (S)-10-hydroxycamptothecin (HCPT) on osteosarcoma cell growth and metastasis as well as the underlying mechanism. The osteosarcoma cells of 143B and U-2 OS (U-2), treated with HCPT (20, 100, or 300 nM), underwent detections, such as CCK-8, flow cytometry, Transwell, wound healing, and immunoblotting. EMT-related key proteins, like N-cadherin, Snail, and Vimentin, were found to be down-regulated, while E-cadherin was up-regulated dose-dependently in HCPT-exposed 143B and U-2 cells. Additionally, incubation of 143B and U-2 cells with HCPT for 3 hours dosedependently reduced the expression ratios of p-LATS1/LATS1, p-MST1/MST1, p-YAP/YAP, and p-TAZ/TAZ. Taken together, our study has demonstrated HCPT to inhibit osteosarcoma growth and metastasis potentially by activating the HIPPO signaling pathway and reversing EMT. HCPT might be a candidate agent for the prevention and treatment of osteosarcoma.

Long non-coding RNA PRR7-AS1 promotes osteosarcoma progression via binding RNF2 to transcriptionally suppress MTUS1.

Osteosarcoma is a common bone malignant tumor in adolescents with high mortality and poor prognosis. At present, the progress of osteosarcoma and effective treatment strategies are not clear. This study provides a new potential target for the progression and treatment of osteosarcoma. The relationship between lncRNA PRR7-AS1 and osteosarcoma was analyzed using the osteosarcoma databases and clinical sample testing. Cell function assays and tumor lung metastasis were employed to study the effects of PRR7-AS1 on tumorigenesis in vivo and in vitro. Potential downstream RNF2 of PRR7-AS1 was identified and explored using RNA pulldown and RIP. The GTRD and KnockTF database were used to predict the downstream target gene, MTUS1, and ChIP-qPCR experiments were used to verify the working mechanismy. Rescue experiments were utilized to confirm the role of MTUS1 in the pathway. Deep mining of osteosarcoma databases combined with clinical sample testing revealed a positive correlation between lncRNA PRR7-AS1 and osteosarcoma progression. Knockdown of PRR7-AS1 inhibited osteosarcoma cell proliferation and metastasis in vitro and in vivo. Mechanistically, RNA pulldown and RIP revealed that PRR7-AS1 may bind RNF2 to play a cancer-promoting role. ChIP-qPCR experiments were utilized to validate the working mechanism of the downstream target gene MTUS1. RNF2 inhibited the transcription of MTUS1 through histone H2A lysine 119 monoubiquitin. Rescue experiments confirmed MTUS1 as a downstream direct target of PRR7-AS1 and RNF2. We identified lncRNA PRR7-AS1 as an important oncogene in osteosarcoma progression, indicating that it may be a potential target for diagnosis and prognosis of osteosarcoma.

METTL3 Mediated MALAT1 m6A Modification Promotes Proliferation and Metastasis in Osteosarcoma Cells.

As one of the most ubiquitous types of posttranscriptional modification, N6-methyladenosine (m6A) is extensively implicated in almost all types of cancers, including osteosarcoma. Our previous research partially uncovered the role of Metastasis Associated Lung Adenocarcinoma Transcript 1 (MALAT1) in osteosarcoma. However, the relationships between methyltransferase-like 3 (METTL3) and noncoding RNAs modified by METTL3, especially MALAT1, in osteosarcoma remain obscure. The expression of METTL3 in osteosarcoma was evaluated by online bioinformatics analysis, immunohistochemical (IHC) staining, western blotting (WB), and reverse transcription-quantitative PCR (RT‒qPCR). Cell Counting Kit 8 (CCK-8) and Transwell assays were used to evaluate the cell proliferation and invasion abilities. The expression of MALAT1 in osteosarcoma was evaluated by online bioinformatics analysis and RT‒qPCR analysis. m6A methylated RNA immunoprecipitation-qPCR (MeRIP-qPCR) was used to detect m6A modification changes in MALAT1. An actinomycin D assay was used to study changes in the stability of MALAT1. METTL3 was upregulated in osteosarcoma tissues and cell lines. Functionally, METTL3 promoted the proliferation and migration of osteosarcoma cells. Moreover, a clear positive correlation was found between METTL3 and MALAT1 expression, and MALAT1 was upregulated in osteosarcoma tissues and cells. Mechanistically, the presence of m6A modification sites in MALAT1 and METTL3-mediated m6A modification increased the stability of MALAT1 in osteosarcoma cells and promoted their proliferation and migration. In this study, it was concluded that in osteosarcoma cells, METTL3, acting as an oncogene, promoted m6A modification of MALAT1, increased the stability of MALAT, and enhanced MALAT1-mediated oncogenic function.