Role In Osteosarcoma Research Articles

HOTAIR promotes osteosarcoma development by sponging miR-217 and targeting ZEB1.

Long noncoding RNAs (lncRNAs) have drawn increasing attention because of the role which they play in various diseases, including osteosarcoma. So far, the function and mechanism of HOTAIR in osteosarcoma are unclear. In our study, we observed that HOTAIR was elevated accompanied with a decrease of miR-217 and an increase of ZEB1 in human osteosarcoma cells including U2OS, MG63, Saos-2, and SW1353 compared with human osteoblast cell line hFOB. In addition, the subsequent functional assay exhibited that silencing HOTAIR could significantly repress osteosarcoma cell growth, migration, invasion, and induce cell apoptosis capacity, which indicated that HOTAIR exerted an oncogenic role in osteosarcoma. Moreover, it was revealed by using bioinformatics analysis that HOTAIR can be targeted by microRNA-217 (miR-217). miR-217 has been recognized as a crucial tumor suppressive gene in cancers. We verified that mimics of miR-217 were able to suppress the osteosarcoma development. Furthermore, real-time quantitative PCR showed that HOTAIR siRNA increased miR-217 expression. Besides these, ZEB1 was identified as a downstream gene of miR-217 and we found that HOTAIR can mediate osteosarcoma progress by upregulating ZEB1 expression via acting as a competitive endogenous RNA (ceRNA) via miR-217. Taken these together, our findings in this study indicated that HOTAIR/miR-217/ZEB1 axis, as a novel research point can provide new insights into molecular mechanism of osteosarcoma development.

Long noncoding RNA APTR contributes to osteosarcoma progression through repression of miR-132-3p and upregulation of yes-associated protein 1.

A growing amount of evidence has shown that long noncoding RNAs (lncRNAs) play crucial roles in osteosarcoma (OS). However, little knowledge is available about the functional roles and molecular mechanisms of lncRNA Alu-mediated p21 transcriptional regulator (APTR) in OS. Herein, APTR expression was demonstrated to be significantly upregulated in OS tumor tissues and four OS cell lines (including MG63, 143B, Saos-2, and HOS) compared with the adjacent tissues and human osteoblast cell line hFOB1.19, respectively. We confirmed miR-132-3p to be a target for APTR, and its expression was demonstrated to be inhibited by APTR. In functional terms, knockdown of APTR and overexpression of miR-132-3p both, remarkably repressed human OS cell proliferation, invasion and migration, and induced apoptosis. Also, Yes-associated protein 1 (YAP1) was determined as an inhibitory target of miR-132-3p. Moreover, our findings demonstrated that the repression of YAP1 protein expression and the suppression of Ki-67, MMP9, and Bcl2 expression induced by APTR knockdown required increased miR-132-3p. Thus, APTR contributed to OS progression through repression of miR-132-3p and upregulation of YAP1 expression. Therefore, we have uncovered a novel regulatory mechanism by which the APTR/miR-132-3p/YAP1 axis can regulate OS progression.

MicroRNA‑944 targets vascular endothelial growth factor to inhibit cell proliferation and invasion in osteosarcoma

Emerging evidence has demonstrated that the dysregulation of microRNA (miRNA/miR) serves a crucial role in the tumorigenesis and tumor development of osteosarcoma (OS), primarily by affecting various pathological behaviors. Therefore, better knowledge of miRNA in OS may provide novel insights into the pathogenesis of OS, and may facilitate the development of promising therapeutics for patients with this disease. MiRNA‑944 is frequently dysregulated in human cancers. However, the expression levels, functions and underlying mechanisms of miR‑944 in OS remain largely elusive. In the present study, reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was performed to detect miR‑944 expression in OS tissues and cell lines. The regulatory influence of miR‑944 in OS proliferation and invasion was determined with MTT and Transwell invasion assays. In addition, the mechanisms underlying the action of miR‑944 in OS cells were elucidated through a series of experiments, including bioinformatics analysis, luciferase reporter assay, RT‑qPCR and western blot analysis. Spearman's correlation analysis was utilized to examine the relationship between miR‑944 and VEGF expression levels, and rescue experiments were applied to further verify whether VEGF mediates the role of miR‑944 in OS. The results demonstrated that miR‑944 was downregulated in cancer tissues and cell lines. Furthermore, exogenous miR‑944 expression inhibited cell proliferation and invasion in OS invitro. Vascular endothelial growth factor (VEGF) was identified as a direct target of miR‑944 in OS and was overexpressed in cancer tissues. VEGF expression was inversely correlated with miR‑944 expression in cancer tissues. Rescue experiments demonstrated that overexpression of VEGF partially prevented the miR‑944‑induced inhibition of OS cell proliferation and invasion. These results suggested that miR‑944 may serve a tumor suppressive role in OS by directly targeting VEGF. Therefore, miR‑944 may be a promising target in the treatment of OS.

MiRNA-708/CUL4B axis contributes into cell proliferation and apoptosis of osteosarcoma.

The functions of miRNA-708 for various diseases have been confirmed. However, its roles in osteosarcoma are unclear. In this study, we aimed to explore the role of miRNA-708 in osteosarcoma. Detection of the expression of miRNA-708 and CUL4B was used by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Cells were transfected with miRNA-708 mimics (mimics group) and miRNA negative control (NC group). Detection of cell growth curve at 24 h, 48 h, 72 h, and 96 h was made by cell counting kit-8 (CCK-8). Examination of the apoptosis rate was made by flow cytometry. The identification of the regulatory function was made by the luciferase reporter assay. The expression level of CUL4B was detected by Western blot. MiRNA-708 expression was reduced in the tumor cell lines. Compared with NC group, miRNA-708 expression was up-regulated by transfecting with mimics. Lower proliferation efficiency and higher cell apoptosis were showed in miRNA-708 mimics group relative to NC group. MiRNA-708 could regulate the expression of CUL4B by binding to its 3'UTR area. Furthermore, lower miRNA-708 and higher CUL4B were expressed in tumor tissues. MiRNA-708 expression was lower in tissues with IIB-III stage than that in IA-IIA stage. MiRNA-708/CUL4B axis contributes into cell proliferation and apoptosis of osteosarcoma.

Elevated Expression of Transforming Acidic Coiled-Coil Containing Protein 3 (TACC3) Is Associated With a Poor Prognosis in Osteosarcoma.

Transforming acidic coiled-coil containing protein 3 (TACC3) is expressed during the mitotic phase of nuclear division and regulates microtubules. Recently, high TACC3 expression in tumor cells of various cancers including soft tissue sarcoma has been reported. However, its role in osteosarcoma remains unknown. Because we have few prognostic markers for survival in osteosarcoma, we wanted to investigate the potential role of TACC3 in human osteosarcoma and determine if it is associated with survival. (1) Is there a relationship between TACC3 expression and clinicopathologic characteristics such as sex, age (< 20 or ≥ 20 years), histologic type (osteoblastic or others), tumor location (femur or others), American Joint Committee on Cancer staging system (AJCC stage IIA or IIB), tumor necrosis percentage after chemotherapy (< 90% or ≥ 90%), p53 expression (low or high), and Ki-67 expression (low or high)? (2) Is TACC3 expression associated with event-free and overall survival in patients with osteosarcoma? Forty-six conventional patients with osteosarcoma were treated at our institution from 1989 to 2013. Patients were excluded because of unresectable primary site (two patients) and no chemotherapy (two patients). Patients with metastasis at the initial visit (five patients), without pretreatment biopsy samples (two patients), or clinical charts (two patients) were also excluded. The left 33 patients who received neoadjuvant and adjuvant chemotherapy, which consisted of cisplatin/doxorubicin/methotrexate or cisplatin/doxorubicin/methotrexate/ifosfamide, and completed surgical resection with histologic wide tumor margins. Primary tumor samples before chemotherapy were used in this study. We investigated TACC3 expression using immunohistochemical staining and statistically analyzed the TACC3 expression, clinicopathologic characteristics, and event-free and overall survival in patients with osteosarcoma. High TACC3 expression was observed in 19 of 33 osteosarcoma specimens (58%), and this was associated with larger tumor size (ie, AJCC stage IIB in this study; p = 0.002), higher p53 expression (p = 0.007), and higher Ki-67 expression (p = 0.002). The estimated metastasis-free survival at 5 years was 21% (95% confidence interval [CI], 7%-41%) in patients with high TACC3 expression and 79% (95% CI, 47%-93%) in patients with low TACC3 expression (p < 0.001), and the estimated overall survival at 5 years was 34% (95% CI, 13%-56%) in patients with high TACC3 expression and 86% (95% CI, 54%-96%) in patients with low TACC3 expression (p < 0.001). Furthermore, high TACC3 expression was an independent poor prognostic factor for metastasis-free survival with a hazard ratio of 3.89 (95% CI, 1.07-19.78; p = 0.039) as well as overall survival with 4.41 (95% CI, 1.01-32.97; p = 0.049). High TACC3 expression was associated with aggressive clinicopathologic features and unfavorable prognosis in these patients with osteosarcoma. Our preliminary results suggest that further analysis about mutation or an inactive form of TACC3 would be useful to understand the mechanism of abnormal TACC3 expression in patients with osteosarcoma. If these findings are substantiated in larger studies, TACC3 might be useful for predicting survival and a potential therapeutic target for osteosarcoma. Level III, therapeutic study.

LncRNA FAL1 is a negative prognostic biomarker and exhibits pro-oncogenic function in osteosarcoma.

Long noncoding RNA focally amplified lncRNA on chromosome 1 (FAL1) plays an important role in the development of several human malignancy entities. However, the expression and function of FAL1 in the carcinogenesis and development of osteosarcoma remain unknown. In this study, we detected the FAL1 levels in human osteosarcoma tissues and cell lines by quantitative real-time polymerase chain reaction and investigated its role in osteosarcoma using in vitro assays. Our results showed that FAL1 expression was significantly upregulated in human osteosarcoma tissues and cell lines compared with their normal controls. FAL1 expression level was positively correlated with the distance metastasis (P = .008) and tumor stage ( P = .013). Higher expression of FAL1 conferred a significantly poorer survival, as determined by the Kaplan-Meier method with the log-rank test. Multivariate Cox proportional hazards analysis revealed that FAL1 was probably an independent risk of overall survival. Additionally, the serum FAL1 expression level was associated with osteosarcoma status in patients. Receiver operating characteristic curve analysis demonstrated that FAL1 expression was different between patients with osteosarcoma and healthy cohorts (area under the curve, 0.839; P < .001). Furthermore, knockdown of FAL1 by small interfering RNA significantly inhibited cell proliferation via inducing G2/M arrest in osteosarcoma cells. Depletion of FAL1 also suppressed osteosarcoma cell migration and invasion, which might be mediated by inhibiting the epithelial-mesenchymal transition (EMT) program. Taken together, our study showed that lncRNA FAL1 exhibits an important pro-oncogenic effect on osteosarcoma progression by targeting EMT, which may serve as a potential therapeutic target for osteosarcoma.

CXCR4-mediated osteosarcoma growth and pulmonary metastasis is suppressed by MicroRNA-613.

Osteosarcoma is the most common primary bone malignancy. Recently, studies showed chemokine receptor 4 (CXCR4) played a critical role in osteosarcoma. However, the regulation of CXCR4 is not fully understood. microRNAs are short, non‐coding RNAs that play an important roles in post‐transcriptional regulation of gene expression in a variety of diseases including osteosarcoma. miR‐613 is a newly discovered miRNA and has been reported to function as a tumor suppressor in many cancers. In this study, we confirmed that both Stromal Cell‐Derived Factor (SDF‐1) and CXCR4 could be prognostic markers for osteosarcoma. Meanwhile this study found that SDF‐1/CXCR4 pathway regulated osteosarcoma cells proliferation, migration and reduced apoptosis. Besides, we demonstrated that miR‐613 was significantly downregulated in osteosarcoma patients. Elevated expression of miR‐613 directly suppressed CXCR4 expression and then decreased the proliferation, migration and induced apoptosis of osteosarcoma cells. Moreover, our study found that CXCR4 promoted the development of lung metastases and inhibition of CXCR4 by miR‐613 reduced lung metastases. These data indicated that CXCR4 mediated osteosarcoma cell growth and lung metastases and this effect can be suppressed by miR‐613 through directly downregulating CXCR4.

Downregulation of microRNA‑660 inhibits cell proliferation and invasion in osteosarcoma by directly targeting forkhead box O1.

The abnormal expression of microRNAs (miRNAs/miRs) has been observed in osteosarcoma (OS), and these differently expressed miRNAs contribute to the occurrence and development of OS by regulating various biological behaviours. Therefore, a comprehensive understanding of the detailed roles of aberrantly expressed miRNAs in OS progression may be favourable to the identification of promising therapeutic strategies for the treatment of patients with this malignancy. The present study demonstrated that miR‑660‑5p (miR‑660) expression was significantly upregulated in OS tissues and cell lines compared with that in normal adjacent tissues and normal human osteoblast hFOB1.19, respectively. miR‑660 downregulation led to a significant decrease in the proliferation and invasion of OS cells. Forkhead box O1 (FOXO1) was predicted as a potential target of miR‑660. The subsequent luciferase reporter assay indicated that miR‑660 directly binds to the 3'‑untranslated region of FOXO1. Furthermore, miR‑660 inhibition increased the FOXO1 expression in OS cells at mRNA and protein levels. Moreover, FOXO1 was downregulated in OS tissues and this downregulation was negatively correlated with miR‑660 levels. Besides, rescue experiments demonstrated that FOXO1 knockdown abolished the effects of miR‑660 knockdown on OS cell proliferation and invasion. These results suggest that miR‑660 may serve oncogenic roles in OS by directly targeting FOXO1. Targeting miR‑660 may be an effective candidate for the treatment of patients with OS.

MiR-299-5p targets cell cycle to promote cell proliferation and progression of osteosarcoma.

Osteosarcoma is a common primary bone tumor with high mortality. MicroRNA (miRNA, miR) is a small RNA with 20-25 nucleotides, which could regulate diverse biological processes by targeting 3'-UTR of gene to degrade it. MiR-299-5p has been reported to participate in the progression of many diseases, but the role in osteosarcoma is still uncertain. The aim of this work was to investigate the expression of miR-299-5p in osteosarcoma and its clinical significance. The datasets of osteosarcoma miRNA was searched in Gene Expression Omnibus (GEO) datasets, including GSE65071, GSE39040, and GSE39055. Osteosarcoma U2 and MG-63 cells were cultured in our study. Cell proliferation level after transfection was detected by using Cell Counting Kit-8 (CCK8) and colon formation assay. Cell cycles were explored using flow cytometer and cell protein expression levels after that the transfection was detected by Western blotting. We found that ROC curve analysis showed that miR-299-5p was a sensitivity diagnostic criteria and GSEA indicated that miRNA-299-5p may regulate cell cycle. Gain of function assay showed that miR-299-5p promotes cell cycle transition and proliferation. Reversely, the opposite results were observed with loss of function assay. At last, Western blotting assay showed that miR-299-5p may promote cell cycle transition by regulating CDK family.

A Review of Osteosarcoma Therapeutics

Osteosarcoma is a rare but deadly cancer, predominantly affecting both adolescent and young adult populations. Osteosarcoma occurs when an aggressive malignant neoplasm arises from transformed cells of mesenchymal origin, which eventually produce a malignancy in the osteoid. Diagnosis of osteosarcoma typically results from symptoms of pain or swelling in the bone, which can be confirmed through laboratory testing of alkaline phosphatase and lactate dehydrogenase levels as well the detection of microscopic and macroscopic lesions. Pathogenesis of osteosarcoma is caused by a diverse set of factors including physical agents, radiation, chromosomal aberrations and viral infection which dysregulate cellular functions. Current research focuses on understanding how microRNAs play a role in osteosarcoma and other aggressive cancers. In this review, we discuss current treatments options including chemoresistant strategies and immunotherapies that show promise at combating osteosarcoma and other cancers.

Delphinidin induces apoptosis and inhibits epithelial-to-mesenchymal transition via the ERK/p38 MAPK-signaling pathway in human osteosarcoma cell lines.

Delphinidin is major anthocyanidin that is extracted from many pigmented fruits and vegetables. This substance has anti‐oxidant, anti‐inflammatory, anti‐angiogenic, and anti‐cancer properties. In addition, delphinidin strongly suppresses the migration and invasion of various cancer cells during tumorigenesis. Although delphinidin has anti‐cancer effects, little is known about its functional roles in osteosarcoma (OS). For these reasons, we have demonstrated the effects of delphinidin on OS cell lines. The effects of delphinidin on cell viability and growth of OS cells were assessed using the MTT assay and colony formation assays. Hoechst staining indicated that the delphinidin‐treated OS cells were undergoing apoptosis. Flow cytometry, confocal microscopy, and a western blot analysis also indicated evidence of apoptosis. Inhibition of cell migration and invasion was found to be associated with epithelial‐to‐mesenchymal transition (EMT), observed by using a wound healing assay, an invasion assay, and a western blot analysis. Furthermore, delphinidin treatment resulted in a profound reduction of phosphorylated forms of ERK and p38. These findings demonstrate that delphinidin treatment suppressed EMT through the mitogen‐activated protein kinase (MAPK) signaling pathway in OS cell lines. Taken together, our results suggest that delphinidin strongly inhibits cell proliferation and induces apoptosis. Delphinidin treatment also suppresses cell migration and prevents EMT via the MAPK‐signaling pathway in OS cell lines. For these reasons, delphinidin has anti‐cancer effects and can suppress metastasis in OS cell lines, and it might be worth using as an OS therapeutic agent.

Long non-coding RNA ANRIL is associated with a poor prognosis of osteosarcoma and promotes tumorigenesis via PI3K/Akt pathway

AimIncreasing evidence has shown that long noncoding RNAs (lncRNAs) ANRIL may function as oncogenes in various types of malignancies. However, there is still a lack of knowledge concerning its role in osteosarcoma (OS). In this study, we aimed to investigate the influence of ANRIL on cell proliferation and invasion of OS and to determine its association with clinicopathological features of the patients. MethodsThe tumor specimens and the adjacent normal tissues were collected from 57 OS patients and the expression level of ANRIL was quantified by RT-qPCR. High expression of ANRIL was defined as a relative mRNA expression of > 1.5 fold (tumor/normal). Knockdown of ANRIL was performed in human OS cell lines to investigate its influence on cell proliferation, apoptosis and invasion. In addition, expression of downstream genes in the transfected cells were determined by Western blot. ResultsThe expression level of ANRIL was significantly increased in OS tissues than in the adjacent normal tissues. 33 patients were included in the high expression group and the other 24 patients were included in the normal expression group. ANRIL expression was significantly associated with tumor size (5.7 cm ± 2.4 cm vs. 4.3 cm ± 1.7 cm, p = 0.02) and the 5-year survival rate (51.5% vs. 79.1%, p = 0.03). Knockdown of ANRIL could significantly induce cell apoptosis and inhibit cell proliferation and invasion. Moreover, knockdown of ANRIL could significantly decrease the expression level of phosphorylated PI3K and AKT in OS cells. ConclusionsUpregulated expression of ANRIL is associated with the tumor development and prognosis of OS. ANRIL may regulate the function of OS cells through the AKT pathway.

SPOP suppresses osteosarcoma invasion via PI3K/AKT/NF-κB signaling pathway.

Speckle-type POZ protein (SPOP), is an E3 ubiquitin ligase adaptor that is frequently mutated in prostate and endometrial cancers. SPOP has been shown to be responsible for oncogene SRC-3 ubiquitination and proteolysisin prostate cancers. However, whether SPOP plays a role in osteosarcoma (OS) is unknown. In this study, we investigated the inhibitory effect of SPOP on invasion and migration of OS cells. Real-time PCR and Western blot were used to detect the expression of SPOP in human OS samples and cell lines. Short hairpin RNA (shRNA) was used to silencing the expression of SPOP. Small scale Real-time PCR screen was used to identify the matrix metalloproteases (MMP) family members responsible for the phenotype caused by SPOP depletion. Matrigel-coated invasion chambers were used to detect the invasion ability of SPOP in OS cells. We found that SPOP was down-regulated in clinic OS samples and cultured OS cells. Furthermore, we showed that silencing of SPOP promoted cell migratory and invasive ability of OS cells in vitro, whereas restored the expression of SPOP achieved the opposite effects. At the molecular level, we found that SPOP regulated the activity of "PI3K/Akt/NF-κB" signaling pathway in OS cells. Our results suggested that down-regulation of SPOP promoted OS cells migratory and invasive ability via modulating the "PI3K/Akt/NF-κB" signaling pathway. Thus, SPOP could be a promising drug target for the treatment of OS invasion.

MiR-183 inhibits osteosarcoma cell growth and invasion by regulating LRP6-Wnt/β-catenin signaling pathway

Recent studies have demonstrated that microRNA-183 (miR-183) deregulates and plays major roles in many tumors. However, the role of miR-183 in osteosarcoma (OS) pathogenesis is still largely unknown. In this study, we first over-expressed and knocked down miR-183 in MG63 and U20S cells, respectively. Functional analyses showed that ectopic expression of miR-183 suppressed MG63 cell growth, migration, and invasion in vitro and in vivo, whereas knockdown of endogenous miR-183 in U20S cells significantly enhanced these abilities. Next, we characterized low density lipoprotein receptor-related protein 6 (LRP6) as a direct target of miR-183 that interacted with the 3′-untranslated region of LRP6. Furthermore, ectopic expression of LRP6 significantly abrogated the tumor-suppressive effect induced by miR-183. Finally, miR-183 regulated the tumor-suppressive functions in MG63 cells by suppressing the LRP6-Wnt/β-catenin signaling pathway. Therefore, our study demonstrates that miR-183 is a tumor suppressor microRNA that plays a major role in OS.

Long Noncoding RNA FER1L4 Suppresses Tumorigenesis by Regulating the Expression of PTEN Targeting miR-18a-5p in Osteosarcoma

Background/Aims: Novel long non-coding RNA Fer-1-like protein 4 (FER1L4) has been reported to play crucial regulatory roles in tumor progression. However, its clinical significance and biological role in osteosarcoma (OS) is completely unknown. The aim of the present study was to investigate the role of FER1L4 in OS progression and the underlying mechanism. Methods: We analyzed the expression levels of FER1L4 in tissues of OS patients and cell lines via quantitative RT-PCR (qRT-PCR). The effect of FER1L4 on cell proliferation, colony formation, migration and invasion was analyzed by cell counting kit-8 (CCK-8), colony formation, wound healing and transwell invasion assay, respectively. Novel targets of FER1L4 were selected through a bioinformatics soft and confirmed using a dual-luciferase reporter system and qRT-PCR. To detect the role of FER1L4 in vivo tumorigenesis, tumor xenografts were created. Results: We found that the expression of FER1L4 was significantly downregulated in OS tissues and cell lines; moreover, low expression of FER1L4 was associated with advanced tumor-nude-metastasis (TNM) stage, lymph node metastases, and poor overall survival. Functional assays showed that upregulation of FER1L4 significantly inhibited OS cell proliferation, colony formation, migration, and invasion in vitro, as well as suppressed tumor growth in vivo. Assays performed to determine the underlying mechanism, indicated that FER1L4 interacted directly with miR-18a-5p. Subsequently, we found that FER1L4 significantly increased PTEN expression, a known target of miR-18a-5p, in OS cells. Furthermore, PTEN was found to be down-regulated, and positively correlated with FER1L4 in OS tissues. Conclusion: These findings suggest that FER1L4, acting as a competing endogenous RNA (ceRNA) of miR-18a-5p, exerts its anti-cancer role by modulating the expression of PTEN. Thus, FER1L4 may be a novel target for the prevention and treatment of OS.

Serine/Threonine Kinase 35, a Target Gene of STAT3, Regulates the Proliferation and Apoptosis of Osteosarcoma Cells

Background/Aims: Serine/threonine kinase 35 (STK35) may be associated with Parkinson disease and human colorectal cancer, but there have been no reports on the expression levels or roles of STK35 in osteosarcoma. Methods: STK35 mRNA expression was determined in osteosarcoma and bone cyst tissues by real-time PCR. Cell proliferation and apoptosis were assessed by Cell Counting Kit-8 (CCK-8) assay and flow cytometry analysis, respectively. Results: STK35 was up-regulated in osteosarcoma tissues as indicated by analyzing publicly available expression data (GEO dataset E-MEXP-3628) and real-time PCR analysis on our own cohort. We subsequently investigated the effects of STK35 knockdown on two osteosarcoma cell lines, MG63 and U2OS. STK35 knockdown inhibited the growth of osteosarcoma cells in vitro and in xenograft tumors. Meanwhile, STK35 knockdown enhanced apoptosis. Expression of the active forms and the activity of two major executioner caspases, caspase 3 and caspase 7, were also increased in osteosarcoma cells with STK35 silenced. Additionally, Gene Set Enrichment Analysis (GSEA) identified that the JAK/STAT signaling pathway was positively correlated with STK35 expression. The mRNA expression of STK35 was repressed by STAT3 small interfering RNA (siRNA), but not by siRNA of STAT4, STAT5A or STAT6. A luciferase reporter assay further demonstrated that STAT3 transcriptionally regulated STK35 expression. A chromatin immunoprecipitation (ChIP) assay confirmed the direct recruitment of STAT3 to the STK35 promoter. The promotion effects of STAT3 knockdown on cell apoptosis were partially abolished by STK35 overexpression. Furthermore, STK35 mRNA expression was positively correlated with STAT3 mRNA expression in osteosarcoma tissues by Pearson correlation analysis. Conclusions: These results collectively reveal that STAT3 regulates the transcription of STK35 in osteosarcoma. STK35 may exert an oncogenic role in osteosarcoma.

Identification and functional characterization of circRNA-0008717 as an oncogene in osteosarcoma through sponging miR-203.

Circular RNA (circRNA) is a key regulator in the development and progression of human cancers, however its role in osteosarcoma tumorigenesis is not well understood. The present study aims to investigate the expression profiles and potential modulation of circRNA on osteosarcoma carcinogenesis. Human circRNA microarray was performed to screen for abnormally expressed circRNA in osteosarcoma tissue and circRNA-0008717 was identified as one circRNA significantly upregulated in osteosarcoma tissue. Osteosarcoma patients with high circRNA-0008717 expression had shortened survival. Gain and loss functional assays suggested that knockdown of circRNA-0008717 suppressed cell proliferation, migration and invasion, but promoted cell apoptosis. By using biotin-labeled circRNA-0008717 probe to perform RNA precipitation in osteosarcoma cells, we identified miR-203 as the circ0008717-associated microRNA. Subsequently, Bmi-1 was identified as the functional target of miR-203. In addition, overexpression of circRNA-0008717 in osteosarcoma could elevate Bmi-1 expression, resulting in the promotion of osteosarcoma cell proliferation and invasion. Furthermore, the tumor promoting effect of circRNA-0008717 was abolished by miR-203 mimics or Bmi-1 silencing vector. In conclusion, circRNA-0008717 plays an oncogenic role in osteosarcoma and may serve as a promising prognostic biomarker for osteosarcoma patients. Therefore, silence of circRNA-0008717 could be a future direction to develop a novel treatment strategy.

MicroRNA-497-5p Suppresses Tumor Cell Growth of Osteosarcoma by Targeting ADP Ribosylation Factor-Like Protein 2.

Osteosarcoma (OS) is a frequent primary bone malignancy. MicroRNA-497-5p (miR-497-5p) has been recently reported to be downregulated in angiosarcoma, but its potential role in OS remains unclear. Quantitative real-time polymerase chain reaction was used to determine miR-497-5p expression in OS tissues and cell lines. The effect of miR-497-5p on cell growth, cell cycle progression and apoptosis were measured using CCK-8 and flow cytometry assays, respectively. The effect of miR-497-5p on ADP-ribosylation factor-like protein 2 (ARL2) was determined by luciferase reporter assay and western blot. We found miR-497-5p was significantly downregulated in OS tissues and cells. Overexpression of miR-497-5p in OS cells inhibited tumor cell proliferation and induced a significant G0/G1 cell cycle arrest and apoptosis in vitro. Additionally, we found ARL2 was a new target of miR-497-5p. Moreover, ARL2 and P-p53 protein levels were significantly downregulated by treatment with miR-497-5p mimics in OS cells. Taken together, our findings revealed miR-497-5p may be a tumor suppressor in OS and serve as a promising therapeutic target for OS.

Long non-coding RNA ZFAS1 sponges miR-486 to promote osteosarcoma cells progression and metastasis in vitro and vivo.

Long noncoding RNAs (lncRNAs) have been wildly demonstrated to participate in the osteosarcoma tumorigenesis. ZFAS1 is a novel identified lncRNA, however, its role in osteosarcoma is still unclear. In present study, we utilize lncRNA microarray assay to screen the lncRNA expression profile in osteosarcoma tissue, and investigate the regulatory function of ZFAS1 in osteosarcoma. LncRNA microarray assay revealed that lncRNA ZFAS1 was significantly up-regulated in 3 pairs of osteosarcoma and adjacent non-tumor tissue, which was confirmed by RT-PCR. Furthermore, in 53 pairs of osteosarcoma patient samples, the up-regulated expression of ZFAS1 was closely related to poor prognosis. In vitro, loss-of-function experiments showed that ZFAS1 knockdown significantly suppressed the proliferation, induced cycle arrest at G0/G1 phase and enhance apoptosis. In vivo, ZFAS1 knockdown inhibited the tumor growth. Bioinformatics online programs predicted that ZFAS1 sponge miR-486 at 3’-UTR with complementary binding sites, which was validated using luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Rescue experiments confirmed that miR-486 could reverse the functions of ZFAS1 on osteosarcoma genesis. In conclusion, our results demonstrate that ZFAS1 act as competing endogenous RNA (ceRNA) for miR-486, and act as oncogene in osteosarcoma tumorigenesis, and discover the functional regulatory pathway of ZFAS1 sponging miR-486.

Increased SNAT1 is a marker of human osteosarcoma and potential therapeutic target

BackgroundSLC38A1/SNAT1 has been found to play an essential role in human development, but its role in osteosarcoma (OS) has yet to be evaluated. The purpose of this study was to assess the expression of SLC38A1/SNAT1 in patients with OS, and further investigate the mechanisms by which it affects tumor growth and metastasis.MethodsTissue microarray blocks and immunohistochemical studies were carried out to assess the expression of SNAT1 in 165 OS specimens. Its correlation with clinicopathological characteristics was then analyzed. The function of SNAT1 in OS cells was investigated by silencing SNAT1 using SNAT1-shRNA in vitro and in vivo.ResultsSNAT1 was highly expressed in 85% OS and significantly closely associated with pulmonary metastasis. Patients with high SNAT1 expression survived for shorter periods than those with low SNAT1 expression. Suppression of endogenous SNAT1 led to inhibition of cell proliferation, cell colony formation, and cell migration in vitro, and retarded tumor growth in xenograft models. Silencing SNAT1 reduced expression of MMP9, vimentin, fibronectin, p-Akt, p-mTOR, and VEGF.ConclusionsOur results indicated that increased expression of SNAT1 is a common event in OS. SNAT1 played an essential role in the development and progression of osteosarcoma, which may serve as a prognostic and therapeutic marker of OS.