Osteosarcoma Tumor Growth Research Articles

Vaccine potential of dendritic cells

Cancer Immunology The ability of dendritic cells (DCs) to process and present antigens to the immune system makes them intriguing candidates for the development of cancer immunotherapies. Zhou et al. investigated whether the CD103+ tissue-resident conventional DC1 (cDC1) subset could control tumors in mouse models. DCs were grown and activated in cell culture using an immunostimulant called polyinosinic:polycytidylic acid (poly I:C). The cells were then loaded with tumor antigens and injected into mice to assess their vaccine potential. The authors found that in vitro–generated CD103+ cDC1s restrained melanoma and osteosarcoma tumor growth. Tumors could be further hindered if the in vitro–generated cDC1s were combined with immune checkpoint blockade treatment. J. Immunother. Cancer 8 , e000474 (2020).

LncRNA NR_136400 Suppresses Cell Proliferation and Invasion by Acting as a ceRNA of TUSC5 That Is Modulated by miR-8081 in Osteosarcoma.

Long non-coding RNAs (lncRNAs) are emerging as important regulators of the processes involved in cancer development and progression. The molecular mechanism by which lncRNAs regulate the progression of osteosarcoma has not been clearly elucidated. The role of NR_136400, which is an uncharacterized lncRNA, has not been previously reported in osteosarcoma (OS). In the present study, we demonstrated that NR_136400 was downregulated in OS cells and that its downregulation promoted OS cell proliferation, apoptosis, and invasion. NR_136400 downregulation facilitated EMT by inhibiting the expression of E-cadherin and elevating the expression of ZEB1, Snail, and fibronectin. In vivo experiments using a xenograft tumor mouse model revealed that NR_136400 downregulation promoted tumor growth in OS. Mechanistic investigations demonstrated that NR_136400 competitively bound to miR-8081 and then upregulated the protein expression of TUSC5. Taken together, a newly identified regulatory mechanism of the lncRNA NR_136400/miR-8081/TUSC5 axis was systematically studied in OS, providing a promising target for therapeutic treatment.

Knockdown of KRT17 decreases osteosarcoma cell proliferation and the Warburg effect via the AKT/mTOR/HIF1α pathway

Keratins are fibrous structural proteins that serve essential roles in forming the stratum corneum and protect the cells in this layer of skin from damage. Keratin 17 (KRT17) is a key member of the keratins, and dysregulated expression of KRT17 has been reported in various types of cancer, such as lung and gastric cancer. The present study aimed to identify the role of KRT17 in osteosarcoma and the underlying molecular mechanism. The expression of KRT17 in osteosarcoma tissues and cell lines was detected using reverse transcription-quantitative PCR (RT-qPCR) and western blotting. The effects of KRT17 on osteosarcoma cell proliferation and the Warburg effect in vitro were detected using CCK-8 and colony formation assays, cell cycle distribution analysis and metabolic measures. The effects of KRT17 on osteosarcoma cell proliferation in vivo were detected using a subcutaneous tumorigenesis model. The association between KRT17 and the AKT/mTOR/hypoxia-inducible factor 1α (HIF1α) pathway was detected using RT-qPCR and western blotting. The results demonstrated that KRT17 was highly expressed in osteosarcoma tissues and cell lines. Knockdown of KRT17 decreased osteosarcoma cell proliferation and colony formation, induced G1 phase arrest and inhibited glycolysis in vitro. Similarly, the suppression of KRT17 decreased osteosarcoma tumor growth in vivo. Knockdown of KRT17 decreased the expression of phosphorylated (p)-AKT, p-mTOR, HIF1α and the target gene of HIF1α glucose transporter 1. Restoring the expression of p-AKT, p-mTOR or HIF1α reversed the effect of KRT17 inhibition on cell proliferation and glycolysis. These results indicated that knockdown of KRT17 may be an effective method for treating osteosarcoma through inhibiting osteosarcoma cell proliferation and the Warburg effect by suppressing the AKT/mTOR/HIF1α pathway.

Long Non-Coding RNA OIP5-AS1 Knockdown Enhances CDDP Sensitivity in Osteosarcoma via miR-377-3p/FOSL2 Axis.

BackgroundDrug resistance is one of big obstacles for the treatment of tumor. Long non-coding RNA Opa-interacting protein 5-antisense RNA 1 (OIP5-AS1) was identified to involve in drug resistance. In this research, the effects of OIP5-AS1 on cisplatin (CDDP) resistance in osteosarcoma (OS) were mainly investigated.MethodsThe levels of OIP5-AS1, microRNA-377-3p (miR-377-3p), and FOS like 2 (FOSL2) were measured by quantitative real-time polymerase chain reaction. The inhibitory concentration 50 (IC50) value of CDDP, cell viability and apoptotic rate was evaluated through Cell Counting Kit-8 and flow cytometry assays, respectively. The levels of multidrug resistance-associated protein 1 (MRP1), P-glycoprotein, B-cell lymphoma 2, Bcl2-associated X, cleaved-caspase-3, and FOSL2 were detected by Western blot assay. The interaction between miR-377-3p and OIP5-AS1 or FOSL2 was verified by Dual-Luciferase Reporter and RNA Immunoprecipitation assays. The function of OIP5-AS1 was detected by a xenograft tumor model in vivo.ResultsOIP5-AS1 and FOSL2 were up-regulated, while miR-377-3p was down-regulated in CDDP-resistant OS tissues and cells. OIP5-AS1 silencing inhibited cell viability and the IC50 value of CDDP, and promoted apoptotic rate in CDDP-resistant OS cells. Mechanically, OIP5-AS1 was verified as a sponge to miR-377-3p and FOSL2 was a target of miR-377-3p. Moreover, OIP5-AS1 knockdown repressed OS tumor growth and enhanced CDDP sensitivity of OS in vivo.ConclusionOIP5-AS1 positively modulated FOSL2 expression to decrease CDDP sensitivity in OS by sponging miR-377-3p.

LINC00514 drives osteosarcoma progression through sponging microRNA-708 and consequently increases URGCP expression.

Long intergenic nonprotein-coding RNA 00514 (LINC00514) is upregulated in papillary thyroid cancer and contributes to its aggressiveness. In this study, we thoroughly explored the expression profile, specific functions, and relevant molecular mechanism of LINC00514 in osteosarcoma (OS). Herein, LINC00514 was significantly upregulated in OS tissues and cells, and increased LINC00514 expression was closely correlated with tumor size, TNM stage, and distant metastasis. OS patients with high LINC00514 expression had shorter overall survival than those with low LINC00514 expression. LINC00514 interference inhibited OS cell proliferation, colony formation, migration, and invasion in vitro but promoted cell apoptosis and G0/G1 cell cycle arrest. LINC00514 downregulation hindered OS tumor growth in vivo. Mechanistically, LINC00514 functioned as a competing endogenous RNA by directly interacting with microRNA-708-5p (miR-708) and consequently increasing the expression of upregulator of cell proliferation (URGCP). Both miR-708 knockdown and URGCP restoration partially neutralized anticancer activities of LINC00514 silencing in OS cells. LINC00514 increases URGCP expression by acting as a competing endogenous RNA for miR-708, thus exerting oncogenic roles in OS progression. In conclusion, the LINC00514/miR-708/URGCP pathway may be a promising target for drug discovery in the future.

MiR‑95 promotes osteosarcoma growth by targeting SCNN1A.

Osteosarcoma (OS) is a common malignant bone tumor, presenting particularly in children and young adults, and accounts for approximately 19% of all malignant bone cancers. Despite advances in OS treatment, long-term prognosis remains poor. miRNAs are non-coding single-stranded RNAs ~22 nucleotides in length. Increasing evidence suggests that numerous miRNAs may play critical roles in tumorigenesis and tumor progression; however, the role of miR-95 in OS has not been examined. In the present study, we investigated the role of miR-95 in OS using in vitro and in vivo models and publicly available expression data. Our findings indicate that abnormal miR-95 expression occurs in OS, according to the Gene Expression Omnibus (GEO) database. The miR-95 inhibitor reduced cell proliferation and promoted apoptosis in OS cell lines as detected by EdU staining, TUNEL staining and flow cytometry. Furthermore, a dual luciferase reporter assay revealed that miR-95 regulates the cell cycle of OS cells and apoptosis by targeting sodium channel epithelial 1α subunit (SCNN1A). Additionally, miR-95 antagomir suppressed the growth of U2OS xenograft tumors in a mouse model. In summary, our results suggest that miR-95 induces OS growth in vitro and in vivo by targeting SCNN1A. Our results help clarify the mechanism underlying the miR-95-mediated effects on OS tumor growth, thus potentially establishing it as a diagnostic target.

MiR-210-5p promotes epithelial\u2013mesenchymal transition by inhibiting PIK3R5 thereby activating oncogenic autophagy in osteosarcoma cells

Osteosarcoma (OS) is a malignant bone tumor which occurs mainly in adolescents with frequent pulmonary metastasis and a high mortality rate. Accumulating evidence has indicated that microRNAs (miRNAs) play a vital role in various tumors by modulating target genes as well as signal pathways, and aberrant expression of miRNAs may contribute to OS progression. This study aimed to determine the association between miR-210-5p expression and OS progression and to investigate its potential underlying mechanism. Using reverse transcription-polymerase chain reaction (RT-PCR), miR-210-5p was found to be upregulated in clinical OS specimens and cell lines. Further functional analysis demonstrated that miR-210-5p promoted epithelial–mesenchymal transition (EMT) and induced oncogenic autophagy. Luciferase reporter assay, RNA-ChIP, and western blot analysis confirmed that PIK3R5, an essential regulator in the AKT/mTOR signaling pathway, is a target downstream gene of miR-210-5p. Overexpression or knockdown of PIK3R5 reversed the functional role of overexpression or knockdown of miR-210-5p, respectively. Silencing autophagy-related gene 5 (ATG5) abolished the functional effects of miR-210-5p upregulation or PIK3R5 knockdown in OS cells. In vivo, miR-210-5p overexpression promoted OS tumor growth and pulmonary metastasis. Taken together, our results demonstrated that miR-210-5p promoted EMT and oncogenic autophagy by suppressing the expression of PIK3R5 and regulating the AKT/mTOR signaling pathway. Therefore, inhibition of miR-210-5p may represent a promising treatment for OS.

Long non-coding RNA CDKN2B-AS1 promotes osteosarcoma by increasing the expression of MAP3K3 via sponging miR-4458.

Osteosarcoma (OS) is the most common primary malignant bone tumor worldwide. Recently, several studies have shown that the long non-coding RNA (lncRNA) CDKN2B-AS1 plays a critical role in several cancers. However, the function and underlying mechanism of CDKN2B-AS1 in OS development remains elusive. In this study, we firstly assessed the expression of CDKN2B-AS1 in OS tissues and cells, showing that CDKN2B-AS1 expression were remarkably upregulated in OS tissues and cells. Moreover, CDKN2B-AS1 knockdown suppressed cell proliferation, migration, and EMT progress in OS. Interestingly, we found and proved that CDKN2B-AS1 could sponge miR-4458 in OS cells. Moreover, MAP3K3 was certified as a downstream target of miR-4458 in OS. Besides, MAP3K3 was negatively regulated by miR-4458 and positively regulated by CDKN2B-AS1. More importantly, overexpression of MAP3K3 could partly counteract the effect of CDKN2B-AS1 suppression on the biological behavior of OS cells. Also, the in vivo experiments further testified that CDKN2B-AS1 accelerated tumor growth in OS. Our results suggested that CDKN2B-AS1 facilitated OS progression by sponging miR-4458 to enhance MAP3K3 expression, which provides a novel insight into improving diagnostic and therapeutic strategies for patients with OS.

MiR-497 inhibits tumor growth and migration of osteosarcoma by targeting plexinA4 and CDK6.

MicroRNAs are small non-coding RNAs that regulate gene expression at the post-transcriptional level which have been reported to be involved in the pathogenesis of various cancers. In the present study, we found that miR-497 was downregulated in osteosarcoma tissues. Gain and loss of function studies were carried out to investigate the effect of miR-497 on the growth of osteosarcoma cells. The results indicated that miR-497 inhibited the growth of osteosarcoma cells. Furthermore, bioinformatics analysis predicted plexinA4 and CDK6 as targets of miR-497, which was afterward confirmed by luciferase activity assay and rescue experiments. These findings suggested that miR-497, plexinA4 and CDK6 may serve as novel potential makers for osteosarcoma diagnostics and therapy.

Mycophenolic acid is a drug with the potential to be repurposed for suppressing tumor growth and metastasis in osteosarcoma treatment.

Our previous review of proteomics data showed that in osteosarcoma, some overexpressed proteins were targets of FDA-approved immunosuppressive and anti-arrhythmic drugs, including mycophenolate mofetil (MMF), ribavirin, leflunomide, azathioprine and digoxin. Here, these drugs were screened for growth inhibitory effects in human osteosarcoma cell lines, including MNNG/HOS, U2OS, SaOS-2, MG-63 and 143B cells. Only mycophenolic acid (MPA), an active metabolite of MMF, efficiently inhibited osteosarcoma cell growth with IC50 values of 0.46-7.3 μM; these values are in the therapeutic range for organ transplant patients. At a therapeutic dose (10 μM), MPA significantly inhibited colony formation, caused cell cycle arrest in the S phase, and induced apoptosis. Moreover, the in vitro invasion of osteosarcoma cells was reduced by MPA by inhibiting cell migration capability. The in vivo antitumor effect of MMF was determined in nude mice harboring 143B cell xenografts. Daily oral administration of 200 mg/kg/day MMF for 2 weeks significantly suppressed tumor growth in treated mice, achieving 57.4 ± 11.1% tumor growth inhibition. Compared with the vehicle group, the MMF group treated with 50-200 mg/kg/day for 3 weeks had a significant reduction in the number of lung metastatic nodules in a tail vein-lung metastasis model of 143B cells. MMF doses of 50, 100 and 200 mg/kg/day are approximately equivalent to the non-toxic doses of 0.25, 0.5 and 1 g/day in humans, respectively. These findings indicate that MPA/MMF can effectively control osteosarcoma tumor growth and metastasis. Thus, the potential to repurpose MPA/MMF for use in osteosarcoma chemotherapy is of great interest.

Gankyrin promotes osteosarcoma tumorigenesis by forming a positive feedback loop with YAP

BackgroundAlthough gankyrin has been identified as a vital regulator of tumorigenesis, its role and regulatory mechanism in osteosarcoma (OS) remain unclear. MethodsQRT-PCR, western blot and IHC staining were conducted to detect the expression of gankyrin in OS. Pearson’s χ² test was adopted to examine the associations between gankyrin expression and clinicopathologic characteristics. Kaplan-Meier method was used to investigate the relationship between gankyrin expression and overall survival of patients with OS. Next, a series of in vitro and in vivo assays were performed to determine the positive feedback loop between gankyrin and YAP in OS. ResultsWe first reported that gankyrin is upregulated in human OS specimens and cell lines and predicts OS progression and poor prognosis. Furthermore, we demonstrated that gankyrin protects miR-200a-mediated yes-associated protein (YAP) downregulation through p53 and establishes a positive feedback loop to regulate YAP signaling in U2OS and MG63 cells. Intriguingly, gankyrin interacts with YAP to promote OS cell growth in vitro. In addition, our results showed that gankyrin promotes OS tumor growth and regulates YAP levels in vivo. Notably, we also observed a positive correlation between gankyrin and YAP expression in human OS tissues, and co-upregulation of gankyrin and YAP indicated a poor prognosis. ConclusionsOur results identify that gankyrin acts as an oncogene in OS by forming a positive feedback loop with YAP, and disrupting the gankyrin-YAP regulation may be beneficial for controlling OS tumorigenesis.

Long noncoding RNA HIF1A-AS2 facilitates cell survival and migration by sponging miR-33b-5p to modulate SIRT6 expression in osteosarcoma.

Long noncoding RNAs (lncRNAs) are emerging as vital regulators in various physiological and pathological processes. It was recently found that lncRNA HIF1A-AS2 could play oncogenic roles in several cancers. However, the function and regulatory mechanism of lncRNA HIF1A-AS2 in osteosarcoma (OS) remain largely unclear. In this study, we demonstrated that HIF1A-AS2 was overexpressed in OS tissues and cells. Downregulation of HIF1A-AS2 significantly affects multiple biological functions in OS cells, including cell proliferation, cell cycle progression, cell apoptosis, cell migration, and cell invasiveness. Mechanistic investigations demonstrated that HIF1A-AS2 can interact with miR-33b-5p and negatively regulate its expression, thereby upregulating the protein expression of miR-33b-5p's target SIRT6. Additionally, in vivo experiments using a xenograft tumor mouse model revealed that downregulation of HIF1A-AS2 suppresses tumor growth in OS. Taken together, a newly identified regulatory mechanism for the lncRNA HIF1A-AS2-miR-33b-5p-SIRT6 axis was systematically studied in OS, which could be a promising target for the treatment of OS.

PTEN loss activates a functional AKT/CXCR4 signaling axis to potentiate tumor growth and lung metastasis in human osteosarcoma cells.

Osteosarcoma (OS) is the most common primary malignant bone tumor in children and adolescents. Loss of the tumor suppressor PTEN or activation of chemokine receptor CXCR4 has been demonstrated to associate with OS respectively. However, the signaling mechanism underlying PTEN-mediated antitumor effect remains largely unknown, and the crosstalk between PTEN and CXCR4 in OS has not been investigated. Here, we uncover a PTEN/AKT/CXCR4 pathway nexus in highly tumorigenic and metastatic human 143B OS cells. Loss of PTEN activates AKT/CXCR4 signaling axis and regulates a series of tumor cell behaviors. Notably, ERK is inversely regulated by PTEN and its activation occurs downstream of AKT but upstream of CXCR4, suggesting this kinase to be an important mediator between AKT and CXCR4. In vivo studies show that overexpression of PTEN dramatically attenuates bone destruction, and this inhibition is associated with reduced CXCR4 expression in tumors. CXCR4 inhibitor AMD3100 also markedly suppresses tumor growth in the bone. In addition, PTEN overexpression or AMD3100 substantially inhibits tumor expansion in the lung. Our studies highlight a novel PTEN/AKT/CXCR4 signaling nexus in OS tumor growth and lung metastasis, and provide a strong rationale to consider PTEN restoration or CXCR4 blockade for the treatment of aggressive OS in humans.

Dynasore suppresses cell proliferation, migration, and invasion and enhances the antitumor capacity of cisplatin via STAT3 pathway in osteosarcoma

Osteosarcoma (OS) is the most common malignant bone tumor. The prognosis of metastatic and recurrent OS patients still remains unsatisfactory. Cisplatin reveals undeniable anti-tumor effect while induces severe side effects that threatening patients’ health. Dynasore, a cell-permeable small molecule that inhibits dynamin activity, has been widely studied in endocytosis and phagocytosis. However, the anti-tumor effect of dynasore on OS has not yet been ascertained. In the present study, we suggested that dynasore inhibited cell proliferation, migration, invasion, and induced G0/G1 arrest of OS cells. Besides, dynasore repressed tumorigenesis of OS in xenograft mouse model. In addition, we demonstrated that dynasore improved the anti-tumor effect of cisplatin in vitro and in vivo without inducing nephrotoxicity and hepatotoxicity. Mechanistically, dynasore repressed the expression of CCND1, CDK4, p-Rb, and MMP-2. Furthermore, we found that dynasore exerts anti-tumor effects in OS partially via inhibiting STAT3 signaling pathway but not ERK-MAPK, PI3K-Akt or SAPK/JNK pathways. P38 MAPK pathway served as a negative regulatory mechanism in dynasore induced anti-OS effects. Taken together, our study indicated that dynasore does suppress cell proliferation, migration, and invasion via STAT3 signaling pathway, and enhances the antitumor capacity of cisplatin in OS. Our results suggest that dynasore is a novel candidate drug to inhibit the tumor growth of OS and enhance the anti-tumor effects of cisplatin.

LncRNA AFAP1-AS1 promotes tumorigenesis and epithelial-mesenchymal transition of osteosarcoma through RhoC/ROCK1/p38MAPK/Twist1 signaling pathway

BackgroundAn increasing number of studies have demonstrated that long non-coding RNAs (lncRNAs) play pivotal roles in cancer onset and development. LncRNA AFAP1-AS1 has been validated to be abnormally upregulated and play oncogenic roles in various malignant tumors. The biological role and mechanism of AFAP1-AS1 in OS (osteosarcoma) remains unclear.MethodsQuantitative reverse transcription PCR (qRT-PCR) is applied to examine AFAP1-AS1 expression in OS tissues and OS cell lines. The function of AFAP1-AS1 in OS cells is investigated via in-vitro and in-vivo assays. Western bolt and rescue experiments are applied to detect the expression changes of key molecules including epithelial-mesenchymal transition markers and identify the underlying molecular mechanism. RNA immunoprecipitation is performed to reveal the interaction between AFAP1-AS1 and RhoC.ResultsAFAP1-AS1 expression is upregulated in human OS tissues and cell lines. AFAP1-AS1 knockdown induces OS cell apoptosis and cell cycle G0/G1 arrest, suppresses OS cells growth, migration, invasion, vasculogenic mimicry formation and epithelial-mesenchymal transition (EMT), and affects actin filament integrity. AFAP1-AS1 knockdown suppresses OS tumor formation and growth in nude mice. AFAP1-AS1 knockdown elicits a signaling inhibition including decreased levels of RhoC, ROCK1, p38MAPK and Twist1. Moreover, AFAP1-AS1 interacts with RhoC. Overexpression of RhoC can partly reverse AFAP1-AS1 downregulation-induced cell EMT inhibition.ConclusionsAFAP1-AS1 is overexpressed in osteosarcoma and plays an oncogenic role in osteosarcoma through RhoC/ROCK1/p38MAPK/Twist1 signaling pathway, in which RhoC acts as the interaction target of AFAP1-AS1. Our findings indicated a novel molecular mechanism underlying the tumorigenesis and progression of osteosarcoma. AFAP1-AS1 could serve as a promising therapeutic target in OS treatment.

P300 Acetylates JHDM1A to inhibit osteosarcoma carcinogenesis

JHDM1A participates in cancer development via demethylate dimethyl histone H3 lysine 36 (H3K36me2). p300 is an intrinsic acetyltransferase. This study explored the acetyltransferase activity of p300 on JHDM1A and analyzed the JHDM1A acetylation on H3K36me2 demethylation in osteosarcoma. Co-immunoprecipitation (CoIP) and immunoblotting assay found that p300 directly acetylated JHDM1A at K409 residue in osteosarcoma MG-63 and HOS cells. Nucleosomes and mononucleosomes were prepared and found that acetylation of JHDMIA disrupted its association with nucleosomes and thereby impaired its capability to induce H3K36me2 demethylation. Moreover, chromatin immunoprecipitation (ChIP) assay discovered that the input levels of H3K36me2 in the promoter regions of p21 and puma were increased after acetylation of JHDM1A, which raised the p21 and puma mRNA levels in the cells. Finally, the analysis of JHDM1A acetylation on osteosarcoma cell proliferation and invasion, along with tumor growth pointed out that acetylation of JHDMIA inhibited the proliferation and invasion of osteosarcoma HOS cells, as well as suppressed the tumor growth of osteosarcoma. In conclusion, the outcomes of our research verified that p300 could directly acetylate JHDM1A at K409 site, which reduces the demethylation of H3K36me2, enhanced the transcription of p21 and puma, and thereby inhibited the growth and metastasis of osteosarcoma.

FGF5 promotes osteosarcoma cells proliferation via activating MAPK signaling pathway.

Objective: This study aimed to investigate the role of fibroblast growth factor-5 (FGF5) in osteosarcoma (OS) and explore the potential mechanisms.Methods: OS gene expression data was downloaded from the Gene Expression Omnibus (GEO; GSE12865) and analyzed by R software. OS tissues and cell lines were collected. The expression level of FGF5 in tumor tissues and cell lines was detected using qRT-PCR. Knockout of FGF5 was performed using CRISPR/Cas9 system. The effects of FGF5 knockout on OS cell proliferation and tumor growth were determined through cell counting kit-8 assay and xenograft nude mice, respectively. Additionally, recombinant FGF5 (rFGF5) was added into OS cell and the effects of rFGF5 on the proliferation and apoptosis of OS cell lines were assayed. Furthermore, the protein expression levels of mitogen-activated protein kinase (MAPK) signaling pathway were detected through Western blot.Results: FGF5 was significantly upregulated in OS tissues and cells, and closely associated with poor differentiation, larger tumor size, lymph node metastasis, and advanced TNM stage. FGF5 knockout could inhibit proliferation of OS cells and tumor growth in nude mouse model. Addition of exogenous rFGF5 promoted OS cell proliferation while inhibited OS cell apoptosis. The expression levels of MAPK signaling pathway proteins in FGF5 knockout group were significantly lower than that in control when there was no rFGF5. Additionally, their expression level in rFGF5 addition group was higher than that in without rFGF5 group.Conclusion: We demonstrated for the first time that FGF5 was overexpressed in OS cell lines and clinical tissue samples and promotes OS cell proliferation by activating MAPK signaling pathway, which indicated that FGF5 was a potential therapeutic target for OS.

MicroRNA-377 exerts a potent suppressive role in osteosarcoma through the involvement of the histone acetyltransferase 1-mediated Wnt axis.

It has been demonstrated that microRNAs (miRNAs) may contribute to tumorigenesis and tumor growth in osteosarcoma (OS), which is a primary malignant tumor of bone frequently diagnosed in adolescents and young people. The purpose of our investigation was to evaluate the functional relevance of miR-377 in OS and to investigate whether the mechanism was related to the histone acetyltransferase 1 (HAT1)-mediated Wnt signaling pathway. By screening differentially expressed genes in microarray GSE47572, HAT1 was found to be a candidate gene of interest. Besides, the regulatory miRNA (miR-377) of HAT1 was also selected. The interaction among miR-377, HAT1, and the Wnt signaling pathway was evaluated. In addition, the miR-377 expression was altered in OS cells (U-2OS and SOSP-9607) to assess the in vitro cell apoptosis and the in vivo tumor growth. OS tissues presented elevated HAT1 expression and decreased miR-377 expression. A putative miR-377 binding site in HAT1 3'-UTR HAT1 was verified. Cells with miR-377 overexpression or HAT1 silencing were observed to exhibit reduced HAT1 expression and promoted apoptosis, accompanied by blockade of Wnt signaling. Moreover, the in vivo experiment revealed that miR-377 overexpression or HAT1 silencing inhibited tumor growth and reduced tumor size in nude mice. Taken together, our results conclude that miR-377 may promote OS cell apoptosis through inactivation of the HAT1-mediated Wnt signaling pathway, highlighting the potential therapeutic effect of miR-377 on OS treatment.

Downregulation of Cdc6 inhibits tumorigenesis of osteosarcoma in vivo and in vitro

BackgroundOsteosarcoma is the most frequent malignant bone cancer in teenagers. In this study, cell division cycle 6 (Cdc6) was upregulated in the tumor tissues from patients with osteosarcoma according to the results of RNA sequencing. Cdc6 has been considered as a candidate prognostic marker, which was associated with cell apoptosis and cell cycle. However, the mechanisms by which Cdc6 regulates the apoptosis and cell cycle arrest in osteosarcoma remain unclear. MethodsFirstly, 3 pairs of osteosarcoma and adjacent normal tissues were subjected to RNA sequencing. In addition, the levels of Cdc6 in 30 pairs of patients’ tissues and in osteosarcoma cell lines were detected by western blotting and RT-qPCR. Moreover, the effects of Cdc6 on cell proliferation, apoptosis, cell cycle and invasion were evaluated by cell counting kit-8 (CCK-8), flow cytometric and transwell assay, respectively. ResultsCdc6 was significantly upregulated in patients with osteosarcoma and in osteosarcoma cell lines. Downregulation of Cdc6 inhibited the proliferation and invasion of MG63 cells by promoting apoptosis. In addition, downregulation of Cdc6 induced G1 phase cell cycle arrest. Moreover, inhibition of Cdc6 downregulated the expression of Cyclin D1 and Cyclin A2, and upregulated the level of p21 in MG63 cells. In vivo study confirmed downregulation of Cdc6 inhibited osteosarcoma tumor growth by inducing apoptosis. ConclusionOur findings indicated that Cdc6 may serve as an oncogene in osteosarcoma. Thus, inhibiting Cdc6 may be a therapeutic approach for the treatment of osteosarcoma.

MiR-425-5p decreases LncRNA MALAT1 and TUG1 expressions and suppresses tumorigenesis in osteosarcoma via Wnt/β-catenin signaling pathway.

Multiple miRNAs have been recognized as critical regulators in osteosarcoma (OS) carcinogenesis. miR-425-5p was demonstrated to be downregulated in the serum of OS patients. However, the detailed roles of miR-425-5p in OS progression and its underlying molecular mechanism are far from being addressed. In our study, the reduced expression of miR-425-5p was observed in OS tissues and cells. Functional analyses showed that miR-425-5p overexpression suppressed OS cell proliferation, invasion and migration in vitro. Moreover, miR-425-5p upregulation decreased the expressions of MALAT1 and TUG1 in OS cells via directly binding them. miR-425-5p upregulation strikingly abrogated the activation of Wnt/β-catenin signaling pathway induced by MALAT1 and TUG1 overexpression in OS cells. Finally, we validated that miR-425-5p hindered OS tumor growth, and suppressed MALAT1 and TUG1 expressions and the Wnt/β-catenin signaling pathway in vivo. Our findings concluded that miR-425-5p suppressed the tumorigenesis of OS via decreasing MALAT1 and TUG1 expressions through inactivation of the Wnt/β-catenin signaling pathway, contributing to a better understanding of the molecular mechanism of the tumorigenesis of OS.