IL-6 Deficiency Attenuates Skeletal Muscle Atrophy by Inhibiting Mitochondrial ROS Production through the Upregulation of PGC-1α in Septic Mice.

Current evidences indicate that both inflammation and oxidative stress contribute to the pathogenesis of sepsis-associated skeletal muscle atrophy. However, the interaction between inflammation and oxidative stress has not been completely understood in sepsis-associated skeletal muscle atrophy. Here in the present study, a murine model of sepsis has been established by cecal ligation and puncture (CLP) with wild-type and interleukin- (IL-) 6 knockout (KO) mice. Our results suggested that IL-6 KO largely attenuated skeletal muscle atrophy as reflected by reduced protein degradation, increased cross-sectional area (CSA) of myofibers, and improved muscle contractile function (all P < 0.05). In addition, we observed that IL-6 KO promoted the expression of peroxisome proliferator-activated receptor γ coactivator-1alpha (PGC-1α) and inhibited CLP-induced mitochondrial reactive oxygen species (ROS) production in skeletal muscles (all P < 0.05). However, the knockdown of PGC-1α abolished the protective effects of IL-6 KO in CLP-induced skeletal muscle atrophy and reversed the changes in mitochondrial ROS production (all P < 0.05). Ex vivo experiments found that exogenous IL-6 inhibited PGC-1α expression, promoted mitochondrial ROS production, and induced proteolysis in C2C12 cells (all P < 0.05). Together, these results suggested that IL-6 deficiency attenuated skeletal muscle atrophy by inhibiting mitochondrial ROS production through the upregulation of PGC-1α expression in septic mice.

Silencing circOMA1 Inhibits Osteosarcoma Progression by Sponging miR-1294 to Regulate c-Myc Expression.

Background: Several studies have reported that circRNAs have a crucial function in the tumorigenesis of various cancers. However, the expression and function of circOMA1 in osteosarcoma is unknown. Methods: circOMA1 was identified through bioinformatics analysis. qRT-PCR was used to assess the expressions of circOMA1, miR-1294, and c-Myc in osteosarcoma tissues. Further, we performed functional experiments to explore the biological function of circOMA1 in osteosarcoma. Moreover, a luciferase reporter assay, RNA immunoprecipitation (RIP), and fluorescence in situ hybridisation (FISH) assay were performed to demonstrate the association between circOMA1 and miR-1294. Results: circOMA1 exhibited considerable upregulation in osteosarcoma tissues compared with adjacent normal tissues. Silencing circOMA1 suppressed osteosarcoma progression in vitro and in vivo. Mechanically, circOMA1 functioned as a sponge of miR-1294 to upregulate c-Myc expression. Conclusion: circOMA1 played the role of an oncogene in osteosarcoma and promoted osteosarcoma progression by mediating the miR-1294/c-Myc pathway, which might be a new target for treating osteosarcoma.

Comprehensive Analysis of a Zinc Finger Protein Gene-Based Signature with Regard to Prognosis and Tumor Immune Microenvironment in Osteosarcoma.

Osteosarcoma is the most common malignant bone tumor that seriously threatens the lives of teenagers and children. Zinc finger (ZNF) protein genes encode the largest transcription factor family in the human genome. Aberrant expressions of ZNF protein genes widely occur in osteosarcoma, and these genes are therefore attractive biomarker candidates for prognosis prediction. In this study, we conducted a comprehensive analysis of ZNF protein genes in osteosarcoma and identified prognosis-related ZNF protein genes. Then, we constructed a prognostic signature based on seven prognosis-related ZNF protein genes and stratified patients into high- and low-risk groups. The seven genes included MKRN3, ZNF71, ZNF438, ZNF597, ATMIN, ZNF692, and ZNF525. After validation of the prognostic signature in internal and external cohorts, we constructed a nomogram including clinical features such as sex and age and the relative risk score based on the risk signature. Functional enrichment analysis of the risk-related differentially expressed genes revealed that the prognostic signature was closely associated with immune-related biological processes and signaling pathways. Moreover, we found significant differences between the high- and low-risk groups for the scores of diverse immune cell subpopulations, including CD8+ T cells, neutrophils, Th1 cells, and TILs. Regarding immune function, APC co-inhibition, HLA, inflammation promotion, para-inflammation, T-cell co-inhibition, and the type I IFN response were significantly different between the high- and low-risk groups. Of the seven ZNF protein genes, lower expressions of ATMIN, MKRN3, ZNF71, ZNF438, and ZNF597 were correlated with a high risk, while higher expressions of ZNF525 and ZNF692 were associated with a high risk. The Kaplan-Meier survival analysis suggested that lower expressions of ATMIN, ZNF438, and ZNF597 and the higher expression of ZNF692 were associated with worse overall survival in osteosarcoma. In conclusion, our ZNF protein gene-based signature was a novel and clinically useful prognostic biomarker for osteosarcoma patients.

Human umbilical vein endothelial cells derived-exosomes promote osteosarcoma cell stemness by activating Notch signaling pathway.

Osteosarcoma is one of the most common primary malignant tumors of bone in adolescents. Human umbilical vein endothelial cells (HUVECs) derived exosomes are associated with osteosarcoma cell stemness. Little is known about the function of HUVECs-exosomes in osteosarcoma cell stemness. This work aimed to investigate the mechanism of action of HUVECs-exosomes in regulating stem cell-like phenotypes of osteosarcoma cells. HUVECs were treated with GW4869 (exosome inhibitor). Human osteosarcoma cells (U2OS and 143B) were treated with HUVECs supernatant, HUVECs-exosomes with or without RO4929097 (γ secretase inhibitor, used to block Notch signaling pathway). We found that HUVECs supernatant and HUVECs-exosomes enhanced the proportions of STRO-1+CD117+ cells and the expression of stem cell-related proteins Oct4 and Sox2. Both HUVECs supernatant and HUVECs-exosomes promoted the sarcosphere formation efficiency of U2OS and 143B cells. These stem-like phenotypes of U2OS and 143B cells conferred by HUVECs-exosomes were repressed by GW4869. Moreover, HUVECs-exosomes promoted the expression of Notch1, Hes1 and Hey1 in the U2OS and 143B cells. RO4929097 treatment reversed the impact of HUVECs-exosomes on Notch1, Hes1, and Hey1 expression by inhibiting Notch1 signaling pathway. In conclusion, this work demonstrated that HUVECs-exosomes promoted cell stemness in osteosarcoma through activating Notch signaling pathway. Thus, our data reveal the mechanism of HUVECs-exosomes in regulating cell stemness of osteosarcoma, and provide a theoretical basis for osteosarcoma treatment by exosomes.

LncRNA PLAC 2 Is Downregulated in Osteosarcoma and Regulates Cancer Cell Proliferation Through miR-93.

INTRODUCTION: PLAC 2 is a tumor-suppressive lncRNA in glioma, while its roles in other types of cancer remain unclear. This study was carried out to explore the potential involvement of PLAC 2 in osteosarcoma (OS). METHODS: Expression levels of PLAC 2 in OS and paired non-tumor tissues from OS patients were determined by RT-qPCR. A follow-up study was performed to analyze the prognostic value of PLAC 2 for OS. Interactions between PLAC 2 and miR-93 were assessed by cell transfection, followed by RT-qPCR. Cell proliferation assay was performed to analyze cell proliferation. RESULTS: Our results showed that PLAC 2 was downregulated in OS tissues, and the high expression levels of PLAC 2 were associated with favorable overall survival of OS patients. MiR-93 was upregulated in OS tissues and its expression was inversely correlated with the expression of PLAC 2. In OS cells, overexpression of PLAC 2 resulted in downregulated miR-93, while overexpression of miR-93 did not affect the expression of PLAC 2. Overexpression of PLAC 2 led to decreased proliferation rate of OS cells, while overexpression of miR-93 showed opposite roles and reduced the overexpressing effects of PLAC 2. CONCLUSION: PLAC 2 is downregulated in OS and regulates cancer cell proliferation through miR-93.

The Notch Pathway Promotes Osteosarcoma Progression through Activation of Ephrin Reverse Signaling.

Despite significant advancements in the diagnosis and treatment of osteosarcoma, the molecular mechanisms underpinning disease progression remain unclear. This work presents strong clinical and experimental evidence demonstrating that Notch signaling contributes to osteosarcoma progression. First, using a cohort of 12 patients, Notch genes were upregulated in tumors compared with adjacent normal tissue, and high tumor expression of Notch1 intercellular domain (NICD1) and the Notch target gene Hes1 correlated with poor chemotherapy response. Data mining of publicly available datasets confirmed that expression of Notch pathway genes is related to poor prognosis in osteosarcoma. On the basis of in vitro analysis, Notch signaling promoted osteosarcoma proliferation, enhanced chemoresistance, facilitated both migration and invasion, and upregulated stem cell-like characteristics. Xenograft models demonstrated that Notch signaling promotes primary tumor growth and pulmonary metastasis, and Notch inhibition is effective in reducing tumor size and preventing metastasis. Mechanistically, activated Notch signaling induces the expression of ephrinB1 and enhances the tumor-promoting ephrin reverse signaling. Overall, these findings provide functional evidence for Notch pathway genes as candidate biomarkers to predict prognosis in patients with osteosarcoma, and suggest a mechanistic rationale for the use of Notch inhibitors to treat osteosarcoma. IMPLICATIONS: The study provides preclinical evidence for Notch pathway as a molecular marker to predict osteosarcoma prognosis and as a therapeutic target against osteosarcoma. In addition, we identified a novel mechanism that ephrin reverse signaling acts as a key mediator of Notch pathway.

Fucosterol exerts antiproliferative effects on human lung cancer cells by inducing apoptosis, cell cycle arrest and targeting of Raf/MEK/ERK signalling pathway.

BACKGROUND: Phytochemicals have attained tremendous attention as the chemo-preventive and chemotheruptic agents. Fucosterol is a phytosterol that in prevalently found in marine algae and many other plant species. Previous studies have indicated the potential of fucosterol as an anticancer agent. However, the information on the anticancer activity of fucosterol against lung cancer as well as several other types of cancers is scantly. PURPOSE: The present study was designed to investigate the anticancer activity of fucosterol against a panel of lung cancer cell lines. METHODS: MTT and colony formation assays were used to determine the cell viability. DAPI and annexin V/PI staining assays were used for the detection of apoptosis. Cell cycle analysis was performed by flow cytometery. Boyden chamber assay was used to monitor cell migration and western blot analysis was used to determine the protein expression. In vivo evaluation was carried out in xenografted mice models. RESULTS: The results indicated that fucosterol inhibits the growth of the lung cancer cell lines. However, the anticancer effects were more profound against the A549 and SK-LU-1 cancer cells (IC50, 15 µM). In contrast, the anticancer effects of fucosterol on the non-cancerous lung cell lines were minimal. Further investigation revealed that the anticancer effects of fucosterol on the A549 and SK-LU-1 cells are due to the induction of apoptosis. Fucosterol significantly enhanced the expression of Bax and cleaved caspase-3 which was concomitant with decline in the expression of Bcl-2. Fucosterol also triggered G2/M cell cycle arrest of the A549 and SK-LU-1 cells which was associated with decrease in the expression of Cdc2, Cyclin A, Cyclin B1 and upregulation of the negative regulators of cell cycle progression (p21Cip1, and p27Kip1). Moreover, fucosterol could also inhibit the invasion of A549 and SK-LU-1 cells. Finally fucosterol could also inhibit the growth of xenografted tumours in mice. CONCLUSION: Taken together, fucosterol inhibits the growth of lung cancer cells and may prove to be a lead molecule for the treatment of lung cancer.

miR-143-3p inhibits the proliferation, migration and invasion in osteosarcoma by targeting FOSL2.

Osteosarcoma (OS) is the most common type of primary malignant bone tumor and mainly occurs in children and adolescent. Because of its early migration and invasion, OS has a poor prognosis. It has been reported that mircoRNAs (miRNAs) play a crucial role in the occurrence and development of multiple tumors. In this study, we identified the aberrant-expression of miR-143-3p in osteosarcoma and examined the role of miR-143-3p in OS development. Further, we searched the miR-143-3p target gene and verified its accuracy by luciferase experiments. Finally, we explored the relationship between miR-143-3p and FOS-Like antigen 2 (FOSL2). Our data indicated that miR-143-3p expression was substantially lower in OS tissues and cell-line compared with normal tissues, and was lower in patients with poor prognosis. In addition miR-143-3p inhibited OS cell proliferation and metastasis while promoting apoptosis. We next showed that FOSL2 was directly targeted by miR-143-3p and could reverse the inhibition caused by miR-143-3p. Finally, we found FOSL2 expression in OS cells was significantly higher compared with normal cells and negatively correlated with miR-143-3p. Thus, miR-143-3p directly and negatively targets FOSL2 to affect OS characteristics. This provides a new target for the treatment of OS and deserves further study.

Baicalein inhibits progression of osteosarcoma cells through inactivation of the Wnt/ß-catenin signaling pathway.

Osteosarcoma is a very common type of malignant bone tumor in children and young adults and aberrant activation of Wnt/ß-catenin signaling pathway has been discovered in osteosarcoma. The traditional Chinese medicine baicalein was proved to have anti-proliferative and anti-metastatic properties in osteosarcoma, but the mechanism remained poorly understood. In the present study, we assessed the effects of baicalein on osteosarcoma and detected the potential molecular mechanism. We found that baicalein significantly suppressed the proliferation of osteosarcoma cells in a concentration- and time-dependent manner. In additional, baicalein could induce apoptosis and cell cycle arrest and reduce cell motility. Moreover, the level of ß-catenin and its target genes, including c-myc, cyclinD1, and survivin significantly decreased in baicalein-treated osteosarcoma cells, whereas exogenous expression of ß-catenin could reverse the anti-proliferative and anti-metastatic effects of baicalein. Subsequently, we established a 143B xenograft tumor model and found that baicalein treatment significantly inhibited tumor growth accompanied with inhibiting Wnt/ß-catenin pathway. Thus, these findings suggest that baicalein may be a potentially effective Chinese herbal medicine for therapeutics of osteosarcoma and Wnt/ß-catenin signaling pathway may serve as an efficient molecular marker or predictive target for osteosarcoma.