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Osteosarcoma (OS) is associated with a high incidence of lung metastasis, which leads to a high risk of cancer death. Circular RNA (circRNA), a novel class of noncoding RNA, is emerging as a key player in human cancer. Herein, we explored the role of circMGEA5 in OS metastasis by conducting circRNA expression microarray. CircMGEA5 was significantly upregulated in metastatic OS tissues compared to primary tissues. High circMGEA5 was positively related with shorter overall and disease-free survival time. Knockdown of circMGEA5 suppressed OS cell migration, invasion, and epithelial-mesenchymal transition (EMT). Mechanistically, circMGEA5 acted as a competing endogenous RNA (ceRNA) to directly sponge miR-153-3p and miR-8084, resulting in increasing ZEB1 and Snail expression, respectively, thereby inducing EMT and metastasis. In turn, ZEB1 and Snail were capable to bind to circMGEA5 promoter, activating circMGEA5 transcription, thus forming a positive feedback loop. Furthermore, we established the tail vein injection model and found that circMGEA5 depletion remarkably reduced lung metastasis nodules generated by OS cells. In sum, our findings, for the first time, reveal the metastasis-promoting role of circMGEA5 in OS. Targeting of this newly identified ceRNA axis may be crucial in the development of novel therapies for metastatic OS patients.

Background: Enhanced infiltration of M2-polarized tumor-associated macrophages (TAMs) is linked to osteosarcoma (OS) metastasis and growth. Here, we aim to explore a novel miR-221-3p shuttled by M2-TAM exosomes in the growth and metastasis of OS cells. Methods: THP-1 monocytes-derived M2-TAMs were induced by PMA/interleukin (IL)-4/IL-13 and then co-cultured with OS 143B and Saos2 cells. Overexpression or downregulation models of miR-221-3p were conducted to probe the impacts of exosome-derived M2-TAMs in OS cells. OS cell proliferative ability, colony formation, invasion, migration and apoptotic level were measured by the cell counting kit-8 (CCK-8) assay, colony formation, Transwell assay, and flow cytometry. Moreover, the SOCS3/JAK2/STAT3 axis in OS cells was testified by western blot, and a dual-luciferase reporter assay was conducted to confirm the link between miR-221-3p and SOCS3. Results: OS cells enhanced M2 polarization of TAMs, which significantly promoted OS cells’ viability, colony formation, migration, invasion, and reduced apoptosis. Moreover, the exosomes enriched by miR-221-3p from M2-polarized TAMs (M2-TAMs) also aggravated the malignant behaviors of OS cells. However, down-regulation of miR-221-3p brought about contrary results. Further, in-vivo tests uncovered that overexpressing miR-221-3p enhanced OS cells’ growth. Mechanistically, SOCS3 was a downstream target of miR-221-3p, and up-regulation of miR-221-3p choked SOCS3 and activated JAK2/STAT3. However, the pharmacological intervention of the JAK2/STAT3 pathway obviously inhibited the malignant behaviors of OS cells, which were significantly reversed by miR-221-3p up-regulation. Conclusion: The exosomal miR-221-3p derived from M2-TAMs aggravates OS progression via modulating the SOCS3/JAK2/STAT3 axis.

Background: This study investigated the association between post-traumatic chronic osteomyelitis (COM) and peripheral leukocyte telomere length (PLTL) and explored factors associated with PLTL in C...

Introduction. The effects of erythropoietin (EPO) on the behaviors of bone marrow mesenchymal stem cells (BMSCs) subjected to mechanical stretch remain unclear. This study was therefore aimed at establishing the dose-response effect of EPO stimulation on rat BMSCs and investigating the effects of mechanical stretch combined with EPO on the proliferation and osteogenic differentiation of BMSCs. Material and Methods. The proliferation and osteogenic differentiation of rat BMSCs were examined and compared using EPO with different concentrations. Thereafter, BMSCs were subjected to 10% elongation using a Flexcell strain unit, combined with 20 IU/ml EPO. The proliferation of BMSCs was detected by Cell Counting Kit-8, colony formation assay, and cell cycle assay; meanwhile, the mRNA expression levels of Ets-1, C-myc, Ccnd1, and C-fos were detected by reverse transcription and real-time quantitative PCR (qPCR). The osteogenic differentiation of BMSCs was detected by alkaline phosphatase (ALP) staining, and the mRNA expression levels of ALP, OCN, COL, and Runx2 were detected by qPCR. The role of the extracellular signal-regulated kinases 1/2 (ERK1/2) in the osteogenesis of BMSCs stimulated by mechanical stretch combined with 20 IU/ml EPO was examined by Western blot. Results. Our results showed that effects of EPO on BMSCs included a dose-response relationship, with the 20 IU/ml EPO yielding the largest. Mechanical stretch combined with 20 IU/ml EPO promoted proliferation and osteogenic differentiation of BMSCs. The increase in ALP, mineral deposition, and osteoblastic genes induced by the mechanical stretch–EPO combination was inhibited by U0126, an ERK1/2 inhibitor. Conclusion. EPO was able to promote the proliferation and osteogenic differentiation of BMSCs, and these effects were enhanced when combined with mechanical stretch. The underlying mechanism may be related to the activation of the ERK1/2 signaling pathway.

Excessive biomechanical loading is considered an important cause of osteoarthritis. Although the mechanical responses of chondrocytes and osteoblasts have been investigated, their communication during mechanical loading and the underlying molecular mechanisms are not yet fully known. The present study investigated the effects of excessive mechanically stretched osteoblasts on the metabolism and apoptosis of chondrocytes, and also assessed the involvement of the Wnt/β‑catenin signaling pathway. In the present study, rat chondrocytes and osteoblasts were subjected to mechanical tensile strain, and an indirect chondrocyte‑osteoblast co‑culture model was established. Reverse transcription‑quantitative PCR and western blotting were performed to determine the expression levels of genes and proteins of interest. An ELISA was performed to investigate the levels of cytokines, including matrix metalloproteinase (MMP) 13, MMP 3, interleukin‑6 (IL‑6) and prostaglandin E2 (PG E2), released from osteoblasts. Flow cytometry was performed to detect the apoptosis of chondrocytes exposed to stretched osteoblast conditioned culture medium. The levels of MMP 13, IL‑6 and PG E2 increased significantly in the supernatants of stretched osteoblasts compared with the un‑stretched group. By contrast, the mRNA expression levels of Collagen 1a and alkaline phosphatase were significantly decreased in osteoblasts subjected to mechanical stretch compared with the un‑stretched group. The mRNA expression level of Collagen 2a was significantly decreased, whereas the expression levels of MMP 13 and a disintegrin and metalloproteinase with thrombospondin‑like motifs 5 were significantly increased in chondrocytes subjected to mechanical stretch compared with the un‑stretched group. In the co‑culture model, the results indicated that excessive mechanically stretched osteoblasts induced the catabolism and apoptosis of chondrocytes, which was partly inhibited by Wnt inhibitor XAV‑939. The results of the present study demonstrated that excessive mechanical stretch led to chondrocyte degradation and inhibited osteoblast osteogenic differentiation; furthermore, excessive mechanically stretched osteoblasts induced the catabolism and apoptosis of chondrocytes via the Wnt/β‑catenin signaling pathway.

Background As a common malignant bone sarcoma, osteosarcoma (OS) affects the health and lives of many people. Here, we probed the effects of long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) and microRNA-758 (miR-758) on OS metastasis, and examined possible downstream effector. Methods Quantitative reverse transcription PCR (qRT-PCR) was performed to detect the expressions of XIST and miR-758 in OS tissues and cells. Cell transfection was carried out to alter the levels of XIST and miR-758 in OS cells, and cell viability, migration, and invasion were assessed. Subsequently, qRT-PCR and a dual-luciferase reporter assay were conducted to analyze the regulatory effects of XIST on miR-758 and miR-758 on Rab16. Finally, we investigated whether Rab16 was the downstream effector of XIST/miR-758 axis. Results XIST was highly expressed in OS tissues and cells, but the opposite was seen for miR-758. In OS cells, migration, invasion, and epithelial-mesenchymal transformation (EMT) was promoted by overexpression of XIST and miR-758 inhibitor, but were inhibited by XIST knockdown and miR-758 mimics. XIST regulated miR-758 expression, and miR-758 regulated Rab16 expression in OS cells. Overexpression of Rab16 reversed the effects of miR-758 mimics on OS cell migration and invasion. Conclusions XIST contributed to OS cell migration, invasion, and EMT via regulation of miR-758/Rab16.

Osteosarcoma is an aggressive malignancy with rapid development and poor prognosis. microRNA-19 (miR-19) plays an important role in several biological processes. Sprouty-related EVH1 domain protein 2 (SPRED2) is a suppressor of extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) signaling to inhibit tumor development and progression by promoting autophagy. In this study, we investigated the roles of miR-19, SPRED2, and autophagy in osteosarcoma. We detected the expression of miR-19, SPRED2, epithelial–mesenchymal transition (EMT) markers, and autophagy-related proteins via quantitative real-time polymerase chain reaction or western blot. To evaluate the function of miR-19 and SPRED2, we used MTT and colony formation assays to detect cell proliferation, Transwell, and wound-healing assays to detect cell invasion and migration. Targetscan and luciferase reporter assays confirmed the relationship between SPRED2 and miR-19. The expression of miR-19 was significantly upregulated in osteosarcoma, while SPRED2 was downregulated. miR-19 inhibitor reduced cell proliferation, invasion, migration, and EMT, while its cell biological effects were partially reversed by addition of autophagy inhibitor 3-methyladenine (3-MA) or SPRED2 siRNA in osteosarcoma. SPRED2, a suppressor of ERK/MAPK pathway that is known to trigger autophagy, was identified as a direct target of miR-19. SPRED2 overexpression increased cell proliferation, invasion, migration, and EMT by promoting autophagy, and the effects could be inhibited by 3-MA. Collectively, these findings reveal an underlying mechanism for development of osteosarcoma. miR-19 was upregulated in osteosarcoma cells, and negatively regulated SPRED2, thus promoting the malignant transformation of osteosarcoma cells via inhibiting SPRED2-induced autophagy. Therefore, miR-19/SPRED2 may be a potential target for the treatment of osteosarcoma.

Background It has been widely reported that curcumin (CUR) exhibits anticancer activity and triggers the apoptosis of human A549 non-small-cell lung cancer (NSCLC) cells. However, its application is limited owing to its poor solubility and bioavailability. Therefore, there is an urgent need to develop a new CUR formulation with higher water solubility and better biocompatibility for clinical application in the future. Materials and methods In this study, CUR-loaded methoxy polyethylene glycol–polylactide (CUR/mPEG–PLA) polymeric micelles were prepared by a thin-film hydration method. Their characteristics and antitumor effects were evaluated subsequently. Results The average size of CUR/mPEG–PLA micelles was 34.9±2.1 nm with its polydispersity index (PDI) in the range of 0.067–0.168. The encapsulation efficiency and drug loading were 90.2%±0.78% and 9.1%±0.07%, respectively. CUR was constantly released from the CUR/mPEG–PLA micelles, and its cellular uptake in A549 cells was significantly increased. It was also found that CUR/mPEG–PLA micelles inhibited A549 cell proliferation, increased the cell cytotoxicity, induced G2/M stage arrest and promoted cell apoptosis. Moreover, the CUR/mPEG–PLA micelles suppressed the migration and invasion of A549 cells more obviously than free CUR. Additionally, CUR/mPEG–PLA micelles inhibited human umbilical vein endothelial cells migration, invasion and corresponding tube formation, implying the antiangiogenesis ability. Its enhanced antitumor mechanism may be related to the reduced expression of vascular endothelial growth factor, matrix metalloproteinase (MMP)-2, MMP-9 and Bcl-2 as well as the increased expression of Bax. Conclusion The mPEG–PLA copolymer micelles can serve as an efficient carrier for CUR. The CUR/mPEG–PLA micelles have promising clinical potential in treating NSCLC.

The practices with low clippings production to save time, money, or landfill space, were favored by turf managers. Understanding the responses of Kentucky bluegrass (Poa pratensis L.) to Trinexapac-ethyl (TE) would facilitate recommendations regarding its safe and effective use in Northern China. The objectives of this study are (1) to investigate the effects of TE on vertical growth, clipping yield, leaf width, and chlorophyll content of Kentucky bluegrass, and (2) to compare the seasonal application impacts of TE. Both spring and autumn experiment results demonstrated that Trinexapac-ethyl applied to Kentucky bluegrass, suppressed the vertical grass growth and significantly reduced the Kentucky bluegrass clippings production within a few weeks after initial treatment. Applied trinexapac-ethyl enhanced Kentucky bluegrass leaf width in both spring and autumn experimental periods. Discoloration on leaf tips was observed and lasted for four weeks when the same TE rate of 0.191 mL$m-2 was applied in early autumn. Darker leaves with higher chlorophyll content compared with non-TE-treatments appeared after the initial four weeks of the treatment in autumn and the treatment for the entire spring.

A new tap-delay-line (TDL) channel model based on indoor radio wave propagation characteristics and measurement data is developed in this paper. It can estimate the mean power delay profile (PDP) simply and effectively for the LOS and NLOS routes. The model is proven to be consistent with the measurement results. Under the assumption of the WSSUS channels, the tap frequency correlations, tap amplitude distributions, tap Doppler spectrum and the tap space correlations are analyzed as well to find new ways to evaluate a TDL model. The channel models and parameters studied in this paper are important for indoor MIMO channel modeling and simulations for new radio system at 5GHz.

In this paper, based on experimental channel measurements performed at 60 GHz in a typical indoor environment for both LOS and NLOS scenarios, the interdependencies of different channel parameters are investigated for different antenna configurations. Specifically, the channel characteristic interdependencies are examined by calculating correlation coefficients between number of paths, rms delay spread, Rice K-factor, and shadow fading. The results show that parameters in the LOS environment are highly correlated compared with the correlation coefficients in the NLOS case generally. In the LOS case, correlation coefficients are higher for horn-omni than horn-horn antenna configurations. It is found that negative correlation relationship exists between K-factor with parameters of number of paths, delay spread and shadow fading. A linear model of number of paths with delay spread, K-factor and shadow fading is established for predicting channel parameters from one another. The presented results can be used for design of wireless machine-to-machine (M2M) networks.