Invasion Of Osteosarcoma Cells Research Articles

LncRNA GClnc1 promotes osteosarcoma progression by stabilizing NONO and blocking FBXW7-mediated ubiquitination

BackgroundLong non-coding RNA (lncRNA) plays a vital role in the occurrence and development of varieties of tumors. Previous studies have shown that lncRNA GClnc1 is highly expressed in osteosarcoma (OS). However, the mechanism of lncRNA GClnc1 in osteosarcoma has not been fully elucidated. In this study, we investigated the biological roles of lncRNA GClnc1 in osteosarcoma and unveiled its underlying mechanisms.MethodsThe expression of lncRNA GClnc1 in OS cells was detected by real-time quantitative PCR (qRT-PCR). The functional roles of lncRNA GClnc1 were examined by CCK8, trans-well, scratch wound healing assay, colony formation, and apoptosis assays in osteosarcoma cells upon silencing or overexpressing GClnc1. Western blot analysis, qRT-PCR, and RNA co-immunoprecipitation (RIP) assays were used to detect the interaction between lncRNA GClnc1 and NONO.ResultsThe expression of lncRNA GClnc1 was up-regulated in osteosarcoma cell lines. Knockdown of lncRNA GClnc1 suppressed the cell growth, migration, and invasion of OS cells, whereas the over-expression of GClnc1 improved the proliferation, migration, and invasion of OS cells. Mechanistically, we identified that lncRNA GClnc1 regulates the stability of NONO by blocking FBXW7-mediated ubiquitination degradation. Additionally, overexpression of NONO can reverse GClnc1 silencing exerted suppression of the cell proliferation, migration, and invasion, and vice versa.ConclusionsOur study elucidated that lncRNA GClnc1 participates in the progression of OS by regulating the NONO signal pathway. Targeting GClnc1 provides a potential target for future clinical treatment of OS.

SLC38A5 suppresses ferroptosis through glutamine-mediated activation of the PI3K/AKT/mTOR signaling in osteosarcoma

BackgroundSolute carrier family 38 member 5 (SLC38A5) is an amino acid transporter that plays a significant role in various cellular biological processes and may be involved in regulating the progression of tumors However, its function and underlying mechanism in osteosarcoma remain unexplored.MethodsUtilizing various database analyses and experiments, we have explored the dysregulation of SLC38A5 in osteosarcoma and its prognostic value. A series of in vitro functional experiments, including CCK-8, colony formation, wound healing, and transwell invasion assays, were conducted to evaluate the effects of SLC38A5 on the proliferation, migration, and invasion of osteosarcoma cells. Downstream pathways of SLC38A5 were explored through methods such as western blot and metabolic assays, followed by a series of validations. Finally, we constructed a subcutaneous xenograft tumor model in nude mice to explore SLC38A5 function in vivo.ResultsSLC38A5 is upregulated in osteosarcoma and is associated with poor prognosis in patients. Upregulation of SLC38A5 promotes proliferation, migration, and invasion of osteosarcoma cells, while the PI3K inhibitor BKM120 can counteract these effects. Additionally, silencing of SLC38A5 inhibits tumor growth in vivo. Mechanistically, SLC38A5 mediates the activation of the PI3K/AKT/mTOR signaling pathway by transporting glutamine, which subsequently enhances the SREBP1/SCD-1 signaling pathway, thereby suppressing ferroptosis in osteosarcoma cells.ConclusionSLC38A5 promotes osteosarcoma cell proliferation, migration, and invasion via the glutamine-mediated PI3K/AKT/mTOR signaling pathway and inhibits ferroptosis. Targeting SLC38A5 and the PI3K/AKT signaling axis may provide a meaningful therapeutic strategy for the future treatment of osteosarcoma.Graphical abstracts

A novel hypoxia- and lactate metabolism-related prognostic signature to characterize the immune landscape and predict immunotherapy response in osteosarcoma

BackgroundImmunotherapy has shown considerable promise in cancer treatment, yet only a minority of osteosarcoma patients derive benefits from this approach. Hypoxia and lactate metabolism are two predominant characteristics of the tumor microenvironment. These features are crucial for molding the immune landscape and thus have the potential to act as predictive indicators for immunotherapy response.MethodsPrognostic modeled genes were identified through univariate and multivariate Cox regression as well as LASSO regression analyses. The tumor microenvironment was evaluated using ESTIMATE, CIBERSORT, and ImmuCellAI analyses. Tide prediction and expression of immune checkpoints, MHC molecules, chemokines, interleukins, interferons, receptors, and other cytokines were utilized to estimate immunotherapy efficacy. Single-cell analysis was performed to demonstrate the expression of modeled genes among various immune cell types. Experimental validation was carried out to verify the expression and functions of SFXN4 and SQOR.ResultsA potent signature was constructed with 8 genes related to hypoxia and lactate metabolism, including MAFF, COL5A2, FAM162A, SQOR, UQCRB, SFXN4, PFKFB2 and COX6A2. A nomogram incorporating risk scores and other clinical features demonstrated excellent predictive capacity. Osteosarcoma patients with high-risk scores exhibited poor prognosis and more “cold” tumor characteristics. According to the ESTIMATE algorithm, these patients displayed lower immune, stromal, and ESTIMATE scores, partially attributed to inadequate infiltration of key immunocytes. The Ciborsort analysis similarly indicated that high-risk individuals had diminished infiltration of critical anti-tumor immune cells such as Cytotoxic T cells, CD4+ T cells, and NK cells. The low expression levels of certain immune checkpoints, MHC molecules, chemokines, interleukins, interferons, receptors, and other cytokines in high-risk cases suggested their unsatisfactory responses to immune treatment. Tide prediction further demonstrated that fewer individuals classified as high risk may exhibit sensitivity to immune checkpoint inhibitor therapy. Notably, SFXN4 was found to be highly expressed in osteosarcoma tissues and cells; it promoted the growth, migration, and invasion of osteosarcoma cells, while SQOR had the opposite effect.ConclusionOur research has developed a robust hypoxia- and lactate metabolism-related gene signature, providing a solid theoretical foundation for prognosis prediction, classification of “cold” and “hot” tumors, accessing immunotherapy response, and directing personalized treatment for osteosarcoma.

Tanshinone II A Facilitates Chemosensitivity of Osteosarcoma Cells to Cisplatin via Activation of p38 MAPK Pathway.

To examine the mechanism of action of tanshinone II A (Tan II A) in promoting chemosensitization of osteosarcoma cells to cisplatin (DDP). The effects of different concentrations of Tan II A (0-80 µ mol/L) and DDP (0-2 µ mol/L) on the proliferation of osteosarcoma cell lines (U2R, U2OS, 143B, and HOS) at different times were examined using the cell counting kit-8 and colony formation assays. Migration and invasion of U2R and U2OS cells were detected after 24 h treatment with 30 µ mol/L Tan II A, 0.5 µ mol/L DDP alone, and a combination of 10 µ mol/L Tan II A and 0.25 µ mol/L DDP using the transwell assay. After 48 h of treatment of U2R and U2OS cells with predetermined concentrations of each group of drugs, the cell cycle was analyzed using a cell cycle detection kit and flow cytometry. After 48 h treatment, apoptosis of U2R and U2OS cells was detected using annexin V-FITC apoptosis detection kit and flow cytometry. U2R cells were inoculated into the unilateral axilla of nude mice and then the mice were randomly divided into 4 groups of 6 nude mice each. The 4 groups were treated with equal volume of Tan II A (15 mg/kg), DDP (3 mg/kg), Tan II A (7.5 mg/kg) + DDP (1.5 mg/kg), and normal saline, respectively. The body weight of the nude mice was weighed, and the tumor volume and weight were measured. Cell-related gene and signaling pathway expression were detected by RNA sequencing and Kyoto Encyclopedia of Genes and Genomes pathway analysis. p38 MAPK signaling pathway proteins and apoptotic protein expressions were detected by Western blot. In vitro studies have shown that Tan II A, DDP and the combination of Tan II A and DDP inhibit the proliferation, migration and invasion of osteosarcoma cells. The inhibitory effect was more pronounced in the Tan II A and DDP combined treatment group (P<0.05 or P<0.01). Osteosarcoma cells underwent significantly cell-cycle arrest and cell apoptosis by Tan II A-DDP combination treatment (P<0.05 or P<0.01). In vivo studies demonstrated that the Tan II A-DD combination treatment group significantly inhibited tumor growth compared to the Tan II A and DDP single drug group (P<0.01). Additionally, we found that the combination of Tan II A and DDP treatment enhanced the p38 MAPK signaling pathway. Western blot assays showed higher p-p38, cleaved caspase-3, and Bax and lower caspase-3, and Bcl-2 expressions with the combination of Tan II A and DDP treatment compared to the single drug treatment (P<0.01). Tan II A synergizes with DDP by activating the p38/MAPK pathway to upregulate cleaved caspase-3 and Bax pro-apoptotic gene expressions, and downregulate caspase-3 and Bcl-2 inhibitory apoptotic gene expressions, thereby enhancing the chemosensitivity of osteosarcoma cells to DDP.

Inhibition of mitochondrial OMA1 ameliorates osteosarcoma tumorigenesis

OMA1 is an ATP-independent zinc metalloprotease essential for maintaining mitochondrial homeostasis and plays a vital role in tumorigenesis. Depending on the type of cancer, a decrease in OMA1 expression has been linked to a varying prognosis for patients. The role of OMA1 in human osteosarcoma (OS), one of the most prevalent malignant bone tumors, remains elusive. Here, we observed elevated OMA1 expression in OS tumor tissues from four patients with advanced OS. Knockout of OMA1 in OS cells significantly reduces OS tumor weight and size, and lung metastatic nodules in BALB/c nude mice. Immunohistochemistry analysis showed a significant decrease in Ki67 and an increase in Cleaved-caspase 3 in OMA1 knockout tumor samples. Mechanistically, we found that OMA1 deficiency increases the levels of PINK1 and Parkin and consequently induces excessive mitophagy, leading to increased apoptosis and reduced cell proliferation and invasion in OS cells. Specifically, OMA1 deficiency reduces the amount of cytosolic p53 and p53-associated cytosolic Parkin but increases mitochondrial p53, which may lead to enhanced apoptosis. Regarding the effect on cell proliferation and invasion, loss of OMA1 reduces mitochondrial ROS levels and increases cytosolic glycogen synthase kinase 3β (GSK3β) levels, thereby increasing interaction between GSK3β and β-catenin and then reducing cytosolic and nuclear β-catenin. This contributes to reduced cell proliferation and migration in OMA1-deficient cells. Moreover, we found that ciclopirox (CPX), an antifungal drug, induces OMA1 self-cleavage and L-OMA1 degradation in cultured OS cells. CPX also reduces tumor development of control OS cells but not OMA1-deficient OS cells in mice. These findings strongly support the important role of OMA1 in OS tumorigenesis and suggest that OMA1 may be a valuable prognostic marker and a promising therapeutic target for OS.

Curcumin and Methotrexate: A Promising Combination for Osteosarcoma Treatment via Hedgehog Pathway Inhibition

Osteosarcoma (OS) is the most severe bone tumor in children. A chemotherapy regimen includes a combination of high-dose Methotrexate (MTX), doxorubicin, and cisplatin. These drugs cause acute and chronic side effects, such as infections, thrombocytopenia, neutropenia, DNA damage, and inflammation. Therefore, to identify new therapeutic strategies, effective and with a safety profile, is necessary. The Hedgehog (Hh) signaling pathway involved in tumorigenesis is active in OS. Hh components Patched receptor 1 (PTCH1), Smoothened (SMO), and glioma-associated oncogene homolog transcription factors (GLI1 and GLI2) are overexpressed in OS cell lines and patient samples. Curcumin (CUR)—with antioxidant and anti-cancer properties—downregulates Hh components in cancer, inhibiting progression. This study investigates CUR effects on the MG-63 OS cell line, alone and combined with MTX, to propose a novel therapeutic approach. Our study suggests CUR as a novel therapeutic agent in OS, particularly when combined with MTX. Targeting the Hh signaling pathway, CUR and MTX showed significant pro-apoptotic effects, increasing the BAX/Bcl-2 ratio and total apoptotic cell percentage. They reduced the expression of Hh pathway components (PTCH1, SMO, GLI1, and GLI2), inhibiting OS cell proliferation, survival, and invasion. CUR and MTX combined determined a β-Catenin decrease and a trend toward reducing NF-kB and matrix metalloproteinases (MMP-2 and MMP-9). Our findings suggest CUR as a support to OS treatment, improving outcomes and reducing the adverse effects of current therapies.

Adaptor protein CIN85 promotes collagen adhesion and invasion of osteosarcoma cells

Adaptor protein CIN85 promotes collagen adhesion and invasion of osteosarcoma cells

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).

Ezetimibe Inhibits Cell Viability and Invasion by Suppressing PI3K/AKT Signaling Pathway in Human Osteosarcoma Cells

Introduction: Osteosarcoma is one of the most prevalent malignant bone tumors with a poor overall prognosis and mainly happens in children and adolescents. Current therapy strategies still possess a lot of limitations, and new and efficient strategies are required. Ezetimibe was previously reported to have its anti-tumor effect in various tumors, but the investigation of Ezetimibe on osteosarcoma is still limited. Aims: This study explores whether ezetimibe could exert an anti-tumor effect on human osteosarcoma cell lines, U2OS, and Saos-2. Methods: The effect of ezetimibe on the proliferation of osteosarcoma was explored by CCK-8 and colony formation assay. The role of ezetimibe on osteosarcoma cell migration and invasion was explored by wound healing assay and transwell assay. The role of ezetimibe on osteosarcoma cell apoptosis was explored by PI/Annexin V analysis. In addition, a western blot was performed to verify the phenotype. Results: The flow cytometry assay indicated that ezetimibe could promote osteosarcoma apoptosis. Western blot assay further demonstrated the effect of ezetimibe on proliferation, migration, invasion and apoptosis- related proteins. Finally, the deep anti-tumor effect of ezetimibe contributed to suppressing the PI3K/AKT signaling pathway. Conclusion: Present data indicated that ezetimibe has an antitumor effect on osteosarcoma and could be considered a future osteosarcoma treatment.

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.

MTF2 facilitates the advancement of osteosarcoma through mediating EZH2/SFRP1/Wnt signaling

BackgroundOsteosarcoma is a soft tissue neoplasm with elevated recurrence risk and highly metastatic potential. Metal response element binding transcriptional factor 2 (MTF2) has been revealed to exert multiple activities in human tissues. The present research was conducted to explore the functions and related response mechanism of MTF2 in osteosarcoma which have not been introduced yet.MethodsBioinformatics tools identified the differential MTF2 expression in osteosarcoma tissues. MTF2 expression in osteosarcoma cells was examined with Western blot. Cell Counting Kit-8 (CCK-8) assay, 5-Ethynyl-2’-deoxyuridine (EDU) staining, wound healing as well as transwell assays measured cell proliferation, migration and invasion, respectively. Flow cytometry assay detected the cellular apoptotic level. Western blot also measured the expressions of proteins associated with epithelial mesenchymal transition (EMT), apoptosis and enhancer of zeste homolog 2 (EZH2)/secreted frizzled-related protein 1 (SFRP1)/Wnt signaling. Co-immunoprecipitation (Co-IP) assay confirmed MTF2-EZH2 interaction.ResultsMTF2 expression was increased in osteosarcoma tissues and cells. MTF2 interference effectively inhibited the proliferation, migration and invasion of osteosarcoma cells and promoted the cellular apoptotic rate. MTF2 directly bound to EZH2 and MTF2 silence reduced EZH2 expression, activated SFRP1 expression and blocked Wnt signaling in osteosarcoma cells. EZH2 upregulation or SFRP1 antagonist WAY-316606 partly counteracted the impacts of MTF2 down-regulation on the SFRP1/Wnt signaling and the biological phenotypes of osteosarcoma cells.ConclusionsMTF2 might down-regulate SFRP1 to activate Wnt signaling and drive the progression of osteosarcoma via interaction with EZH2 protein.

A diagnostic signature developed based on the necroptosis-related genes and its association with immune infiltration in osteosarcoma

IntroductionOsteosarcoma is a bone-derived malignancy that often leads to lung metastasis and death. Material and methodsThe RNA-seq data of TARGET-osteosarcoma were collected from TARGET database. GSE16088 and GSE12865 datasets of osteosarcoma x from Gene Expression Database (GEO) were donwloaded. ConsensusClusterPlus was used for molecular subtype classification. Univariate Cox and Lasso regression was employed to develop a risk model. To analyze the regulatory effects of model feature genes on the malignant phenotype of osteosarcoma cell lines, qRT-PCR, Transwell and wound healing assays were performed. The abundance of immune cell infiltration was assessed using MCP-Counter, Gene Set Enrichment Analysis (GSEA), and ESTIMATE. The Tumor Immune Dysfunction and Exclusion (TIDE) software was employed to evaluate immunotherapy and response to conventional chemotherapy drugs. ResultsThree clusters (C1, C2 and C3) were classified using 39 necroptosis score-associated genes. In general, C1 and C2 showed better prognosis outcome and lower death rate than C3. Specifically, C2 could benefit more from immunotherapy, while C3 was more sensitive to traditional medicines, and C1 had higher immune cell infiltration. Next, an 8-gene signature and a risk score model were developed, with a low risk score indicating better survival and immune cell infiltration. ROC analysis showed that 1-, 3-, and 5-year overall survival of osteosarcoma could be correctly predicted by the risk score model. Cellular experiments revealed that the model feature gene IFITM3 promoted the osteosarcoma cell migration and invasion. Furthermore, the overall survival of osteosarcoma patients from TARGET and validation datasets can be accurately evaluated using the nomogram model. ConclusionsOur prognostic model developed using necroptosis genes could facilitate the prognostic prediction for patients suffering from osteosarcoma, offering potential osteosarcoma targets.

Identification of a pro-protein synthesis osteosarcoma subtype for predicting prognosis and treatment

Osteosarcoma (OS) is a heterogeneous malignant spindle cell tumor that is aggressive and has a poor prognosis. Although combining surgery and chemotherapy has significantly improved patient outcomes, the prognosis for OS patients with metastatic or recurrent OS has remained unsatisfactory. Therefore, it is imperative to gain a fresh perspective on OS development mechanisms and treatment strategies. After studying single-cell RNA sequencing (scRNA-seq) data in public databases, we identified seven OS subclonal types based on intra-tumor heterogeneity. Subsequently, we constructed a prognostic model based on pro-protein synthesis osteosarcoma (PPS-OS)-associated genes. Correlation analysis showed that the prognostic model performs extremely well in predicting OS patient prognosis. We also demonstrated that the independent risk factors for the prognosis of OS patients were tumor primary site, metastatic status, and risk score. Based on these factors, nomograms were constructed for predicting the 3- and 5-year survival rates. Afterward, the investigation of the tumor immune microenvironment (TIME) revealed the vital roles of γδ T-cell and B-cell activation. Drug sensitivity analysis and immune checkpoint analysis identified drugs that have potential application value in OS. Finally, the jumping translocation breakpoint (JTB) gene was selected for experimental validation. JTB silencing suppressed the proliferation, migration, and invasion of OS cells. Therefore, our research suggests that PPS-OS-related genes facilitate the malignant progression of OS and may be employed as prognostic indicators and therapeutic targets in OS.

Construction of a 5-Gene super-enhancer-related signature for osteosarcoma prognosis and the regulatory role of TNFRSF11B in osteosarcoma

Osteosarcoma, one of the most common primary malignancies in children and adolescents, has the primary characteristics of a poor prognosis and high rate of metastasis. This study used super-enhancer-related genes derived from two different cell lines to construct five novel super-enhancer-related gene prognostic models for patients with osteosarcoma. The training and testing datasets were used to confirm the prognostic models of the five super-enhancer-related genes, which resulted in an impartial predictive element for osteosarcoma. The immunotherapy and prediction of the response to anticancer drugs have shown that the risk signature of the five super-enhancer-related genes positively correlate with chemosensitivity. Furthermore, functional analysis of the risk signature genes revealed a significant relationship between gene groups and the malignant characteristics of tumours. TNF Receptor Superfamily Member 11b (TNFRSF11B) was selected for functional verification. Silencing of TNFRSF11B suppressed the proliferation, migration, and invasion of osteosarcoma cells in vitro and suppressed osteosarcoma growth in vivo. Moreover, transcriptome sequencing was performed on MG-63 cells to study the regulatory mechanism of TNFRSF11B in osteosarcoma cells, and it was discovered that TNFRSF11B is involved in the development of osteosarcoma via the phosphoinositide 3-kinase signalling pathway. Following the identification of TNFRSF11B as a key gene, we selected an inhibitor that specifically targeted this gene and performed molecular docking simulations. In addition, risedronic acid inhibited osteosarcoma growth at both cellular and molecular levels. In conclusion, the super-enhancer-related gene signature is a viable therapeutic tool for osteosarcoma prognosis and treatment.

Downregulation of PRKCI inhibits osteosarcoma cell growth by inactivating the Akt/mTOR signaling pathway.

PRKCI is abnormally expressed in various cancers, but its role in osteosarcoma is unknown. This study aimed to explore the biological function of PRKCI in osteosarcoma and its potential molecular mechanism. PRKCI expression was evaluated in osteosarcoma cell lines using Western blot analysis and reverse transcription PCR. The CCK-8 assay, colony formation assay, flow cytometry, Transwell assay, and wound-healing assay were used to detect the proliferation, colony-forming capacity, cell cycle, migration, and invasion of osteosarcoma cells when PRKCI was overexpressed or knocked down. The interaction between PRKCI and SQSTM1 was explored using immunoprecipitation. Finally, the protein molecule expression of the Akt/mTOR signaling pathway in osteosarcoma was detected when PRKCI was knocked down. Our study found that PRKCI was overexpressed in osteosarcoma cell lines. The overexpression of PRKCI promoted the proliferation and colony-forming capacity of osteosarcoma cells, while silencing PRKCI inhibited the proliferation, colony-forming capacity, migration, and invasion of osteosarcoma cells and arrested the cell cycle at the G2/M phase. Both PRKCI and SQSTM1 were overexpressed in osteosarcoma. The expression of PRKCI was only related to histological type, while that of SQSTM1 was not related to clinical characteristics. The expression of PRKCI and SQSTM1 in osteosarcoma was higher than that in chondrosarcoma. Knockdown of PRKCI inhibited the proliferation of osteosarcoma cells by inactivating the Akt/mTOR signaling pathway, suggesting that PRKCI was a potential target for osteosarcoma therapy.

Circ_0049271 targets the miR-1197/PTRF axis to attenuate the malignancy of osteosarcoma.

Circular RNAs (circRNAs) perform key regulatory functions in osteosarcoma (OS) tumorigenesis. In this study, we aimed to explore the detailed action mechanisms of circ_0049271 in OS progression. Cell colony formation, cell counting kit-8, and transwell assays were performed to assess the proliferation and invasion of OS cells. Quantitative reverse transcription-polymerase chain reaction and western blotting were used to determine the expression levels of polymerase 1 and transcript release factor (PTRF), microRNA (miR)-1197, and circ_0049271 in OS cells. Furthermore, RNA immunoprecipitation and dual luciferase assays were conducted to explore the targeted relationships among PTRF, miR-1197, and circ_0049271. Finally, a tumor formation assay was conducted to determine the effects of circ_0049271 on in vivo tumor growth in mice. High expression levels of miR-1197 and low levels of circ_0049271 and PTRF were observed in OS cells. circ _0049271 targeted miR-1197 to mediate PTRF expression. Moreover, the proliferation and invasion of OS cells were repressed by circ_0049271 or PTRF overexpression and increased by miR-1197 upregulation. Enforced circ_0049271 also impeded tumor growth in vivo. Upregulation of miR-1197 reversed the antitumor effects of circ_0049271 on OS progression in vitro; however, PTRF overexpression attenuated the cancer-promoting effects of miR-1197 on OS in vitro. Our findings revealed that circ_0049271 targeted the miR-1197/PTRF axis to attenuate the malignancy of OS, suggesting a potential target for its clinical treatment.

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.

Quercetin induces senolysis of doxorubicin-induced senescent fibroblasts by reducing autophagy, preventing their pro-tumour effect on osteosarcoma cells

Cellular senescence contributes to ageing and age-related diseases, and multiple therapeutic strategies are being developed to counteract it. Senolytic drugs are being tested in clinical trials to eliminate senescent cells selectively, but their effects and mechanisms are still unclear. Several studies reveal that the upregulation of senescence-associated secretory phenotype (SASP) factors in senescent cells is accompanied by increased autophagic activity to counteract the endoplasmic reticulum (ER) stress. Our study shows that Doxo-induced senescent fibroblasts yield several SASP factors and exhibit increased autophagy. Interestingly, Quercetin, a bioactive flavonoid, reduces autophagy, increases ER stress, and partially triggers senescent fibroblast death. Given the role of senescent cells in cancer progression, we tested the effect of conditioned media from untreated and quercetin-treated senescent fibroblasts on osteosarcoma cells to determine whether senolytic treatment affected tumour cell behaviour. We report that the partial senescent fibroblast clearance, achieved by quercetin, reduced osteosarcoma cell invasiveness, curbing the pro-tumour effects of senescent cells. The reduction of cell autophagic activity and increased ER stress, an undescribed effect of quercetin, emerges as a new vulnerability of Doxo-induced senescent fibroblasts and may provide a potential therapeutic target for cancer treatment, suggesting novel drug combinations as a promising strategy against the tumour.

MATN4 as a target gene of HIF-1α promotes the proliferation and metastasis of osteosarcoma.

Osteosarcoma is a highly malignant bone tumor that exhibits rapid growth and early metastasis. Hypoxia plays a pivotal role in promoting the proliferation and metastasis of osteosarcoma through a series of molecular events, which are partially mediated and regulated by HIF-1α. However, the regulatory network associated with HIF-1α in osteosarcoma remains limited. Therefore, the objective of this study was to identify critical hypoxia-associated genes and investigate their effects and molecular mechanisms in osteosarcoma cells. Through bioinformatics analysis, matrilin-4 (MATN4) was identified as a crucial gene associated with hypoxia. The expression of MATN4 and HIF-1α was assessed using immunohistochemistry, RT-qPCR, and western blotting. The proliferative capacity of osteosarcoma cells was assessed through the utilization of CCK-8, EDU staining, and colony formation assays. The effects of MATN4 on the mobility of OS cells were evaluated using wound-healing assays and transwell assays. The interaction between MATN4 and HIF-1α was detected through chromatin immunoprecipitation. MATN4 is overexpressed in osteosarcoma tissue and cells, particularly in osteosarcoma cells with high metastatic potential. Knockdown of MATN4 inhibits the proliferation, migration, and invasion abilities of osteosarcoma cells and reverses the promoting effects of hypoxia on these functions. Additionally, HIF-1α binds to MATN4 and upregulates its expression. Interestingly, knockdown of HIF-1α reduces the stimulatory effects of MATN4 overexpression on the proliferation, migration, and invasion of osteosarcoma cells under hypoxic conditions. Taken together, our results suggest that MATN4 is regulated by HIF-1α and confers a more aggressive phenotype on OS cells. This evidence suggests that MATN4 may act as a potential target for OS diagnosis and treatment.