CircDOCK1 promotes the tumorigenesis and cisplatin resistance of osteogenic sarcoma via the miR-339-3p/IGF1R axis.

BACKGROUND: Circular RNAs (circRNAs), a class of noncoding RNAs (ncRNAs), may modulate gene expression by binding to miRNAs. Additionally, recent studies show that circRNAs participate in some pathological processes. However, there is a large gap in the knowledge about circDOCK1 expression and its biological functions in osteogenic sarcoma (OS). METHODS: Differentially expressed circRNAs in OS cell lines and tissues were identified by circRNA microarray analysis and quantitative real-time PCR (qRT-PCR). To explore the actions of circDOCK1 in vivo and in vitro, circDOCK1 was knocked down or overexpressed. To assess the binding and regulatory associations among miR-339-3p, circDOCK1 and IGF1R, we performed rescue experiments, RNA immunoprecipitation (RIP), RNA pulldown assays and dual-luciferase assays. Moreover, we performed apoptosis assays to reveal the regulatory effects of the circDOCK1/miR-339-3p/IGF1R axis on cisplatin sensitivity. RESULTS: CircDOCK1 expression remained stable in the cytoplasm and was higher in OS tissues and cells than in the corresponding controls. Overexpression of circDOCK1 increased oncogenicity in vivo and malignant transformation in vitro. In the U2OS and MG63 cell lines, circDOCK1 modulated tumor progression by regulating IGF1R through sponging of miR-339-3p. Additionally, in the U2OS/DDP and MG63/DDP cell lines, cisplatin sensitivity was regulated by circDOCK1 via the miR-339-3p/IGF1R axis. CONCLUSIONS: CircDOCK1 can promote progression and regulate cisplatin sensitivity in OS via the miR-339-3p/IGF1R axis. Thus, the circDOCK1/miR-339-3p/IGF1R axis may be a key mechanism and therapeutic target in OS.

Long non-coding RNA AFAP1-AS1 accelerates the progression of melanoma by targeting miR-653-5p/RAI14 axis.

BACKGROUND: Melanoma is the most aggressive skin cancer that derived from pigment cells, accounting for the majority of the skin-cancer-related deaths. Despite great development and evolution have been made in surgery, radiotherapy and adjuvant chemotherapy, the prognosis of melanoma patients exhibited no significant improvement. Long noncoding RNAs (lncRNAs) are frequently dysregulated and involved in the development of cancers. LncRNA AFAP1-AS1 has been explored in various cancers, whereas its role and regulatory mechanism in melanoma are not well understood. METHODS: The expression of AFAP1-AS1 was detected by qRT-PCR. CCK-8, colony formation, transwell and western blot assays were performed to investigate the biological role of AFAP1-AS1 in melanoma. Male BALB/c nude mice were applied for in vivo experiments. The interaction among AFAP1-AS1, miR-653-5p and RAI14 was investigated by RNA pull down, RIP and luciferase reporter assays. RESULTS: AFAP1-AS1 was highly expressed in melanoma cell lines. Suppression of AFAP1-AS1 impaired cell proliferation, migration, invasion and EMT in melanoma. Moreover, AFAP1-AS1 was a ceRNA of RAI14 by competitively binding with miR-653-5p. Besides, miR-653-5p overexpression or RAI14 inhibition could repress tumor growth. Eventually, rescue assays indicated that the function of AFAP1-AS1 in the cellular process of melanoma was dependent on miR-653-5p and RAI14. CONCLUSIONS: AFAP1-AS1 exerts its oncogenic function in melanoma by targeting miR-653-5p/RAI14 axis.

Interferon-α versus interleukin-2 in Chinese patients with malignant melanoma: a randomized, controlled, trial.

The US Food and Drug Association has approved interferon-α (IFN-α) and interleukin-2 (IL-2) as adjuvant therapy in malignant melanoma. The objective of the study was to compare efficacy and safety of subcutaneous interferon-α with continuous intravenous IL-2 in Chinese patients with malignant melanoma. A total of 250 patients with unresectable malignant melanoma were subjected to randomized in 1 : 1 ratio. Patients received subcutaneous 9×10 IU/m IFN-α (IFN-α group, n=125) or continuous intravenous 9×10 IU/m IL-2 (IL-2 group, n=125) at every 21 days for 4 months. The response, progression-free survival, overall survival, adverse effects, and cost were evaluated by experts in the field. IL-2 and IFN-α were effective in improvement of malignant melanoma after 4 months of intervention. IL-2 was effective in improving brain metastasis. Patients of the IL-2 group had a higher overall survival (P<0.0001) and a higher progression-free survival (P=0.002) than those of IFN-α group. The IL-2 group reported hypotension, kidney dysfunction, liver dysfunctions, flu-like symptoms, and capillary leak syndrome as adverse effects. IFN-α group reported thrombocytopenia and neutropenia as adverse effects. Healthcare management and expert charges lead to increase in the cost of treatment for IL-2 group patients than IFN-α group (P<0.0001). Continuous intravenous IL-2 should be recommended in relapse-free Chinese patients with malignant melanoma. Level of Evidence: I.

Addition of Zoledronate to Chemotherapy in Patients with Osteosarcoma Treated with Limb-Sparing Surgery: A Phase III Clinical Trial.

BACKGROUND Zoledronate has anti-bone resorption activity and is reported to reduce skeletal-related events. The objective of this study was to test the hypothesis that addition of zoledronate in chemotherapy is safe and effective in osteosarcoma. MATERIAL AND METHODS A total of 798 patients, age 25 years and above, with newly diagnosed high-grade surgically salvageable malignant osteosarcoma, were included in the trial. All patients had received standard chemotherapies (n=399). In addition, in a standard chemotherapy regimen, patients enrolled in the zoledronate group also received 10 courses of 4 mg intravenous infusions of zoledronate (n=399). Limb-sparing surgery was performed by orthopedic surgeons (n=798). Clinical assessment, laboratory monitoring, overall survival, event-free survival, and treatment-emergent adverse effects were evaluated. The chi-square independence-samples test was used for statistical analysis at 95% confidence level. RESULTS The histopathological response was the same for both groups (p=0.12). Addition of zoledronate to chemotherapy improved skeletal event-free survival (p=0.04) but decreased overall survival (p=0.02). Zoledronate induced hypocalcemia (p<0.0001), hypophosphatemia (p<0.0001), cardiotoxicity (p<0.0001), lung metastases (p=0.03), flu-like syndrome (p<0.0001), and ototoxicity (p=0.02), and elevated serum aspartate aminotransferase (p<0.0001) and serum alanine aminotransferase (p<0.0001). CONCLUSIONS The addition of zoledronate to standard chemotherapy in high-grade resectable osteosarcoma is detrimental and is not advised.

PLGA-based drug delivery systems in treating bone tumors.

Bone tumor has become a common disease that endangers human health. Surgical resection of bone tumors not only causes biomechanical defects of bone but also destroys the continuity and integrity of bone and cannot completely remove the local tumor cells. The remaining tumor cells in the lesion bring a hidden danger of local recurrence. To improve the chemotherapeutic effect and effectively clear tumor cells, traditional systemic chemotherapy often requires higher doses, and high doses of chemotherapeutic drugs inevitably cause a series of systemic toxic side effects, often intolerable to patients. PLGA-based drug delivery systems, such as nano delivery systems and scaffold-based local delivery systems, can help eliminate tumors and promote bone regeneration and therefore have more significant potential for application in bone tumor treatment. In this review, we summarize the research progress of PLGA nano drug delivery systems and PLGA scaffold-based local delivery systems in bone tumor treatment applications, expecting to provide a theoretical basis for developing novel bone tumor treatment strategies.

[Retracted] Ursolic acid suppresses the biological function of osteosarcoma cells.

[This retracts the article DOI: 10.3892/ol.2019.10561.].

Phantom Limb Pain and Sensations in Chinese Malignant Tumor Amputees: A Retrospective Epidemiological Study.

OBJECTIVE: Phantom limb pain (PLP) was a common problem in malignant tumor amputees that can cause considerable suffering. The purposes of this study were to determine the incidence and factors associated with the occurrence of post-operation PLP, stump limb pain (SLP), and phantom limb sensations (PLS) in tumor amputees within the first month after surgery. Additionally, differences in phantom phenomena between upper and lower extremities were investigated. METHODS: In total, 162 amputees participated in this retrospective study who underwent malignant limb amputation between 2012 and 2019. Clinical characteristics were collected from medical records and reconfirmed by telephone interviews. A numerical rating scale (NRS) was used to quantitate phantom phenomena. We used analysis of variance and non-parametric statistics for categorical variables and ordinal variables separately. RESULTS: In the first month after malignant amputation, the incidence of PLP was 54.3%, that of PLS was 65.4%, and that of SLP was 32.7%. The duration of preoperative pain and amputation level was significantly different for the incidence of acute PLP. Further subgroup analysis of amputation level showed that patients whose amputation level was below the wrist and ankle joints had a significantly reduced incidence of PLP (p<0.0083 in Bonferroni test). Binary logistics regression analysis determined that amputation level was the primary risk factor for the incidence of PLP. Factors related to the severity of postoperative PLP also included amputation level, preoperative pain, and amputation times. By comparing the differences between upper and lower limbs after amputation, we found that the incidence of PLS was higher after lower limb amputation, but there was no significant difference in the incidence of PLP and SLP. Preoperative experience of chemotherapy was not a risk factor for PLP. CONCLUSION: Proximal amputation and long-term preoperative pain seemed to count more for PLP incidence. Further research may be required to individually determine factors associated with the occurrence and chronicity of phantom phenomena.

Upregulation of cell division cycle 20 in cisplatin resistance-induced epithelial-mesenchymal transition in osteosarcoma cells.

Cell division cycle 20 homologue (Cdc20) is characterized as an oncoprotein that is involved in carcinogenesis. Accumulated evidence reveals that Cdc20 plays an oncogenic role by governing cell growth, apoptosis, motility, and metastasis. The role of Cdc20 in drug resistance is elusive. In the present study, we exploited whether Cdc20 is involved in the cisplatin (DDP) resistance-induced epithelial-mesenchymal transition (EMT) of osteosarcoma cells. We found that DDP resistant U2OS and MG63 cells underwent EMT. Moreover, DDP-resistant cells exhibit the mesenchymal features such as enhanced attachment and detachment and increased invasion activity and migration. Mechanistically, Cdc20 was highly expressed in DDP-resistant osteosarcoma cells compared to parental cells. Consistently, downregulation of CdcC20 in DDP-resistant cells reversed the EMT phenotypes and changed the expression of EMT biomarkers. Our studies provide evidence for targeting Cdc20 as a promising approach to enhancing drug sensitivity for the treatment of osteosarcoma.

Magnoflorine inhibits the malignant phenotypes and increases cisplatin sensitivity of osteosarcoma cells via regulating miR-410-3p/HMGB1/NF-κB pathway.

AIMS: Magnoflorine is an essential type of alkaloid and possesses anti-tumor activity in multiple cancers. Recent studies have demonstrated that magnoflorine plays tumor-suppressive roles in gastric and breast cancers. However, its role in osteosarcoma (OS) tumorigenesis is enigmatic. This study aimed to investigate the role and mechanism of magnoflorine in OS. MATERIALS AND METHODS: Two human OS cells (MG-63 and U-2 OS) were treated with different concentrations of magnoflorine. Cell viability and invasion were then detected by Cell Counting Kit-8 and Transwell assay, respectively. And the effects of magnoflorine on the epithelial-mesenchymal transition (EMT) and cisplatin sensitivity were also measured. To explore the potential mechanism, we assayed the influence of magnoflorine on the miR-410-3p/HMGB1/NF-κB signaling pathway. Additionally, rescue experiments were performed to further confirm the regulation mechanism of magnoflorine. KEY FINDINGS: Magnoflorine inhibited the viability, invasion, and EMT of OS cells in a dose-dependent manner. And it increased the sensitivity of OS cells to cisplatin. Magnoflorine significantly suppressed HMGB1 expression and NF-κB activation, but upregulated miR-410-3p level. Overexpression of HMGB1 promoted NF-κB activation and reversed the effects of magnoflorine on the viability, invasion, EMT and cisplatin sensitivity of OS cells. miR-410-3p mimic inhibited the EMT of OS cells, which was restored by HMGB1 upregulation. And miR-410-3p inhibitor abrogated the influence of magnoflorine on HMGB1 expression in OS cells. SIGNIFICANCE: Magnoflorine inhibited the malignant phenotypes and increased cisplatin sensitivity of OS cells via modulating miR-410-3p/HMGB1/NF-κB pathway. These results indicated that magnoflorine might be a novel drug for the treatment of OS.

PTHR1 May Be Involved in Progression of Osteosarcoma by Regulating miR-124-3p-AR-Tgfb1i1, miR-27a-3p-PPARG-Abca1, and miR-103/590-3p-AXIN2 Axes.

Our previous study has indicated that the parathyroid hormone type 1 receptor (PTHR1) may play important roles in development and progression of osteosarcoma (OS) by regulating Wnt, angiogenesis, and inflammation pathway genes. The goal of this study was to further illuminate the roles of PTHR1 in OS by investigating upstream regulation mechanisms (including microRNA [miRNA] and transcription factors [TFs]) of crucial genes. The microarray dataset GSE46861 was downloaded from the Gene Expression Omnibus database, in which six tumors with short hairpin RNA (shRNA) PTHR1 knockdown (PTHR1.358) and six tumors with shRNA control knockdown (Ren.1309) were collected from mice. Differentially expressed genes (DEGs) between PTHR1.358 and Ren.1309 were identified using the linear models for microarray data (LIMMA) method, and then the miRNA-TF-mRNA regulatory network was constructed using data from corresponding databases, followed by module analysis, to screen crucial regulatory relationships. OS-related human miRNAs were extracted from the curated Osteosarcoma Database. Gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were enriched using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) tool. As a result, the miRNA-TF-mRNA regulatory network, including 1049 nodes (516 miRNA, 25 TFs, and 508 DEGs) and 15942 edges (interaction relationships, such as Pparg-Abca1 and miR-590-3p-AXIN2), was constructed, from which three significant modules were extracted and modules 2 and 3 contained interactions between miRNAs/TFs and DEGs such as miR-103-3p-AXIN2, miR-124-3p-AR-Tgfb1i1, and miR-27a-3p-PPARG-Abca1. miR-27a-3p was a known miRNA associated with OS. Abca1, AR, and miR-124-3p were hub genes in the miRNA-TF-mRNA network. Tgfb1i1 was involved in cell proliferation, Abca1 participated in the cholesterol metabolic process, and AXIN2 was associated with the canonical Wnt signaling pathway. Furthermore, we also confirmed upregulation of miR-590-3p and downregulation of AXIN2 in the mouse OS cell line K7M2-WT transfected with PTHR1 shRNA. In conclusion, PTHR1 may play important roles in progression of OS by activating miR-124-3p-AR-Tgfb1i1, miR-27a-3p-PPARG-Abca1, and miR-103/590-3p-AXIN2 axes.

Therapeutic Effect of Strontium Ranelate on Bone in Chemotherapy-Induced Osteopenic Rats via Increased Bone Volume and Reduced Bone Loss.

The purpose of this study was to determine whether treatment with strontium ranelate (SrR) can restore bone mass and strength at a skeletal site with established osteopenia in chemotherapy-induced rats. Forty-five Sprague-Dawley male rats were randomly assigned to three study groups (n = 15 rats per group): normal rats (control group), osteopenic rats (chemo group), and osteopenic rats with SrR (chemo-SrR group). We chose a male rat model that mimicked a clinical setting by weekly intravenous injection of cyclophosphamide at 20 mg/kg. The control and chemo groups were maintained without treatment, and the chemo-SrR group was intragastrically administered strontium ranelate at a dosage of 900 mg/kg/day. All animals were fed a standard laboratory diet, and blood samples were collected for biochemical analysis. After 12 weeks of treatment, micro-CT, biomechanical testing, and histomorphometry were examined. In addition, bone samples were obtained to evaluate the content of mineral substances in bones. SrR treatment of chemo rats significantly increased tibial trabecular bone volume, trabecular thickness, and BV/TV. Serum levels of the bone formation marker alkaline phosphatase (ALP) in the SrR group were significantly higher than those in the chemo animals, which was accompanied by an increase in the bone mineral content, bone calcium and phosphate, as well as reduced serum Ca and P concentrations. The serum level of tartrate-resistant acid phosphatase (TRAP) in the SrR treatment group showed no obvious changes. Histomorphological analyses revealed that chemotherapy resulted in decreased osteoclast number, which may be due to the inhibition of bone turnover. However, SrR treatment enhanced the number of osteoblasts while restoring bone mass and improving bone strength in chemo rats. Therefore, the results of this study indicate that SrR treatment has a positive effect on bone in chemotherapy-induced osteoporosis.

Ilex hainanensis Merr targets ITGAV to suppress the proliferation and metastasis of osteosarcoma cells.

Background: Osteosarcoma (OS) is the most common primary malignant bone tumor. Hence, there is an urgent need to identify effective and safe therapeutic agents against OS. It has been reported that Ilex hainanensis Merr (IME) possesses antitumor properties. Integrin subunit alpha V (ITGAV) is important for the diagnosis, treatment, and prognosis of tumors. Purpose: The objective of this study was to whether IME can play a role in the treatment of osteosarcoma by regulating ITGAV. Methods: Western blot and real-time PCR were used to detect the expression of ITGAV in non-tumorous tissues, osteosarcoma tissues, and metastatic tumors. The expression of ITGAV in MG63, U2OS, and hFOB1. A total of 19 cells was determined through Western blotting and real-time PCR. The expression of ITGAV in OS cells treated with different concentrations of DDP was determined through Western blotting. Agter transfecting with control or si-ITGAV, and subsequently treated with control or 5 µmol/L DDP, MTT assay and transwell assay were used to detect the proliferaion and migration of cells. Western blot was used to detect the expression of ITGAV in cells treated with different concentrations of IME and MTT assay and transwell assay were used to detect the proliferaion and migration of cells. MG63 and U2OS cells were treated with control, 5 µmol/L DDP, 25 µmol/L IME, or 5 µmol/L DDP combined with 25 µmol/L IME, the expression of ITGAV was determined through Western blotting and real-time PCR. MTT assay and transwell assay were used to detect the proliferation and migration of cells. Inhibitory effect of IME on lung metastasis of osteosarcoma in vivo. Results: ITGAV was highly expressed in tumors, with the highest expression found in metastatic tumors and higher in OS cells. A low concentration of DDP (5 µmol/L) inhibited the expression of ITGAV. However, ITGAV may be related to the development of resistance to DDP. Silencing of ITGAV downregulates the proliferation and migration of OS cells as the effect of low-concentration DDP (5 µmol/L). IME inhibited the proliferation and migration of MG63 and U2OS cells in a concentration-dependent manner and decreased the expression of ITGAV. MTT and Transwell assays showed that 25 µmol/L IME and 5 µmol/L DDP exhibited similar inhibitory effects on the proliferation and migration of OS cells. The combination of IME with DDP resulted in the amplification of these inhibitory effects. Both DDP and IME downregulated the expression of ITGAV, and the inhibition of ITGAV was amplified by the combination of IME with DDP. In-vivo studies have shown that IME and DDP, independently or in combination, may significantly inhibit the metastasis of OS to the lungs. Conclusion: IME may reduce the resistance of OS cells to DDP to some extent.

Ursolic acid suppresses the biological function of osteosarcoma cells.

Osteosarcoma is a highly malignant tumour that occurs in adolescents. Upregulation or the constitutive activation of epidermal growth factor receptor (EGFR) is a hallmark of osteosarcoma. To investigate the effect of ursolic acid on the biological function of osteosarcoma, MTT assay was used to detect the effect of ursolic acid on the proliferation of HOS and MG63 cells, while flow cytometry was used to analyse the effect on the cell cycle and apoptosis. Transwell and Matrigel assays were used to detect the effect of ursolic acid on cell migration and invasion, respectively. Western blot analysis and reverse transcription-quantitative polymerase chain reaction were used to detect the effects of different concentrations of ursolic acid on EGFR signaling pathway-related proteins, cell cycle, apoptosis and cell migration-related proteins. After overexpression or silencing of EGFR, the effects of ursolic acid on EGFR pathway and cell biological function were subsequently detected, using the same methods. The present study identified that ursolic acid had inhibitory effects on the growth and metastatic ability of osteosarcoma cells by suppressing EGFR.

ß-Alanine mediated inhibition of PTHR1suppresses the proliferation, invasion and tumorigenesis in metastatic human osteosarcoma U2OS cells.

The present study was aimed to investigate the effect of ß-alanine mediated inhibition of parathyroid hormone 1 receptor (PTHR1), suppresses the proliferation, invasion, and tumorigenesis in metastatic human osteosarcoma U2OS cells. Cell survival rate was reduced 96.54, 91.23, 84.62, 76.42 and 69.72% following incubation of ß-alanine at 50-250 mM respectively. Annexin-V/propidium iodide (PI) staining showed a reduced level of viable cells (71.37%) at 250 mM of ß-alanine. U2OS cell proliferation, adhesion, invasion, and migration were decreased following incubation with ß-alanine. Matrix metalloproteinases-2/9 (MMP-2/9) mRNA expression was reduced, whereas tissue inhibitors of metalloproteinases-1/2 (TIMP-1/2) mRNA expression was increased remarkably. The mRNA and protein of PTHR1 were reduced in the cells following incubation with ß-alanine. Vacuole membrane protein 1 (Vmp1) mRNA and protein were increased in the cells following incubation with ß-alanine. In tunel assay, the number of PTHR1 positive cells was 67, 34 and 17 following incubation with ß-alanine at 150, 200 and 250 mM respectively. Taking all these data together, it is concluded that ß-alanine mediated inhibition of PTHR1 reduced the U2OS cell proliferation, invasion, migration, and tumorigenesis. Furthermore, the results indicated that the ß-alanine induced expression of PTHR1 has a positive relationship with invasion and metastasis of osteosarcoma cells.

SPOCK1 promotes the growth of Osteosarcoma cells through mTOR-S6K signaling pathway.

SPOCK1 belongs to the SPARC family, which plays an important role in proliferation, invasion and migration of various tumour cells. However, the functions of SPOCK1 in osteosarcoma cell growth and proliferation have not been fully elucidated. In the present study, we found that SPOCK1 is significantly upregulated in osteosarcoma tissue. Moreover, overexpression of SPOCK1 was associated with tumour size, metastasis, Enneking stage and pathological degree. Furthermore, knockdown of SPOCK1 expression suppressed the growth of osteosarcoma cells in vitro and reduced tumourigenicity in nude mice in vivo. Additionally, our data suggest that inactivation of the mTOR-S6K signaling pathway participated in inhibition of SPOCK1-mediated suppression of osteosarcoma cell growth. These findings represent a novel pathogenetic mechanism of osteosarcoma development that provides a potential target for therapeutic strategies for osteosarcoma.

Protection of oxidative stress induced apoptosis in osteosarcoma cells by dihydromyricetin through down-regulation of caspase activation and up-regulation of BcL-2.

Current study was aimed to investigate the effect of dihydromyricetin on hydrogen peroxide induced oxidative stress in the osteosarcoma cells. MTT assay showed that hydrogen peroxide treatment at a concentration of 100 µM caused a significant (p < 0.005) reduction in the viability of MG63 cells. However, reduction in cell viability caused by 100 µM concentration of hydrogen peroxide was completely prevented on incubation with 30 µM dose of dihydromyricetin. Treatment with 100 µM concentration of hydrogen peroxide for 24 h led to condensation of chromatin material, rounding of cell shape and detachment of cells. The results from flow cytometry using annexin V-FITC and PI double staining showed apoptosis induction in 47.84 ± 5.21% cells on treatment with 100 µM concentration of hydrogen peroxide compared to 2.32 ± 0.54% in controlcells. The apoptotic alterations in MG63 cell morphology were prevented significantly on pre-treatment with 30 µM doses of dihydromyricetin for 48 h. Annexin V-FITC and PI staining showed reduction of hydrogen peroxide induced apoptotic cell percentage to 3.07 ± 0.86% on pre-treatment of MG63 cells with 30 µM dose of dihydromyricetin. Western blot analysis showed a significant increase in the activation of caspase-3 and -9 on treatment of MG63 cells for 24 h with 100 µM concentration of hydrogen peroxide. The expression level of Bcl-2 was decreased significantly by 100 µM concentration of hydrogen peroxide in MG63 cells. However, pre-treatment of MG63 cells with 30 µM dose of dihydromyricetin for 48 h significantly prevented hydrogen peroxide induced increase in caspase-3 and -9 levels and reduction in Bcl-2 level. Thus dihydromyricetin prevents hydrogen peroxide induced reduction in viability and induction of apoptosis in MG63 cells through down-regulation of caspase activation and up-regulation of Bcl-2 levels.

Osteosarcoma cells induce differentiation of mesenchymal stem cells into cancer associated fibroblasts through Notch and Akt signaling pathway.

Cancer-associated fibroblasts plays an important role in tumor progession, growth and metastasis. However, the mechanisms of mesenchymal stem cells differentiation to cancer-associated fibroblasts induced by tumor cells remains unclear. This study aimed to explore whether osteosarcoma cells can also induce BMSCs into CAFs through cells co-culture system, and identify the probably signailing pathway that mediates differentiation of BMSCs to CAFs. The results showed that osteosarcoma cells can induce BMSCs to exhibit the typical characteristics of CAFs, with increased expression of α-SMA, the most reliable marker for CAFs. Morever, we also reveals that Notch signaling acts upstream of Akt signaling in HBMSCs-TAFs differentiation.