CircPVT1 promotes the tumorigenesis and metastasis of osteosarcoma via mediation of miR-26b-5p/CCNB1 axis.

INTRODUCTION: Osteosarcoma (OS) is the most aggressive malignancy among the bone tumors in the world. Circular RNAs (circRNAs) have been reported to be participated in multiple cancers, including OS. Meanwhile, circPVT1 has been proved to be upregulated in OS. However, the mechanism by which circPVT1 mediates the tumorigenesis of OS remains to be further explored. MATERIALS AND METHODS: Protein and gene expressions in OS cells were measured by western blot and RT-qPCR, respectively. Cell growth was assessed by flow cytometry and colony formation, respectively. In addition, cell migration was assessed by wound healing, and invasion was evaluated by Transwell assay. Meanwhile, the correlation among circPVT1, miR-26b-5p and CCNB1 was explored by RNA pull-down and dual luciferase assay. Finally, in vivo model was established to explore the role of circPVT1 in OS in vivo. RESULTS: CircPVT1 and CCNB1 were significantly upregulated in OS cells, while miR-26b-5p was downregulated. Knockdown of circPVT1 notably inhibited proliferation and induced apoptosis of OS cells. CircPVT1 shRNA significantly suppressed the OS cell invasion and migration. Meanwhile, circPVT1 sponged miR-26b-5p and CCNB1 was found to be the direct target of miR-26b-5p. Furthermore, silencing of circPVT1 inhibited the growth and metastasis of OS in vivo. CONCLUSION: Silencing of circPVT1 notably suppressed the tumorigenesis and metastasis of OS via miR-26b-5p/CCNB1 axis. Therefore, circPVT1 might be used as a target for OS treatment.

The neurofibromatosis type I gene promotes autophagy via mTORC1 signalling pathway to enhance new bone formation after fracture.

Bone fracture is one of the most common injuries. Despite the high regenerative capacity of bones, failure of healing still occurs to near 10% of the patients. Herein, we aim to investigate the modulatory role of neurofibromatosis type I gene (NF1) to osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) and new bone formation after fracture in a rat model. We studied the NF1 gene expression in normal and non-union bone fracture models. Then, we evaluated how NF1 overexpression modulated osteogenic differentiation of BMSCs, autophagy activity, mTORC1 signalling and osteoclastic bone resorption by qRT-PCR, Western blot and immunostaining assays. Finally, we injected lentivirus-NF1 (Lv-NF1) to rat non-union bone fracture model and analysed the bone formation process. The NF1 gene expression was significantly down-regulated in non-union bone fracture group, indicating NF1 is critical in bone healing process. In the NF1 overexpressing BMSCs, autophagy activity and osteogenic differentiation were significantly enhanced. Meanwhile, the NF1 overexpression inhibited mTORC1 signalling and osteoclastic bone resorption. In rat non-union bone fracture model, the NF1 overexpression significantly promoted bone formation during fracture healing. In summary, we proved the NF1 gene is critical in non-union bone healing, and NF1 overexpression promoted new bone formation after fracture by enhancing autophagy and inhibiting mTORC1 signalling. Our results may provide a novel therapeutic clue of promoting bone fracture healing.

Combination of intramedullary rod, wrapping bone grafting and Ilizarov's fixator for the treatment of Crawford type IV congenital pseudarthrosis of the tibia: mid-term follow up of 56 cases.

BACKGROUND: The purpose of this study was to investigate the initial union rate, refracture rate and residual deformities of congenital pseudarthrosis of the tibia (CPT), using combined surgery including pseudarthrosis resection, intramedullary rodding, autogenous iliac bone grafting and Ilizarov's fixator, with a mean 5.2 years follow-up. METHODS: We retrospectively reviewed the records and diagrams of patients with Crawford type IV congenital pseudarthrosis of the tibia between February 2007 and March 2010. Patients managed by pseudarthrosis resection, intramedullary rod of the tibia, wrapping autogenous iliac bone grafting and Ilizarov's fixator were enrolled. We evaluated the bone union rate, tibial alignment, limb length discrepancy (LLD), valgus deformity of the ankle and the frequencies of refracture during period of follow-up. RESULTS: There were 56 cases enrolled in the study, with a mean follow-up 5.2 years (range, 3 to 6.7 years). The mean age of the patients at surgery was 3.5 years (range, 1.5 to 12.4 years). Fifty (89.2 %) of the 56 patients had primary bone union at site of pseudarthrosis, while 5 obtained union after second surgery and 1 failed. The average time spent to obtain pseudarthrosis initial union was 4.5 months (range, 3.0 to 10.0 months) and mean duration of Ilizarov treatment was 4.7 months (range, 3.2 to 10.4 months). Eleven (19.6 %) patients had proximal tibial valgus with a mean angle of 9.5° (range, 5 to 24°), while 10 (17.9 %) patients had ankle valgus deformities with a mean of 12.3° (range, 6 to 21°). Sixteen (28.6 %) patients had an average 2.2 cm LLD (range, 1.5-4.2 cm). Of the 50 cases who obtained initial bone union of pseudarthrosis, 13 (26.0 %) had refracture which need cast immobilization or secondary surgery. CONCLUSIONS: This combined surgery obtained initial union rate of 89.2 % at primary surgery while the refracture rate is 26.0 %. However, residual deformities such as proximal tibial valgus, LLD and ankle valgus were also existed which should be pay more attention to and dealt with. TRIAL REGISTRATION: This study was registered in ClinicalTrials.gov under the name "The Effect of Combined Surgery in Management of Congenital Pseudarthrosis of Tibia" ( NCT02640040 ), which was released on August 31, 2015.

Effect of distraction osteogenesis in patient with tibial shortening after initial union of Congenital Pseudarthrosis of the Tibia (CPT): a preliminary study.

BACKGROUND: The purpose of our retrospective study was to evaluate the preliminary result of distraction osteogenesis in patient with tibial shortening after initial union of Congenital Pseudarthrosis of the Tibia (CPT). METHODS: All the CPT cases with tibial shortening after initial union managed by proximal tibial lengthening using Ilizarov technique were identified. All the patient charts and radiograms were reviewed. RESULTS: Between March 2007 and January 2012, 11 CPT cases were included with an average follow-up of 41 months (range, 34-51 months). The mean age at surgery was 8.5 years (range, 3.9-14.5y). The average length of discrepancy was 5.6 cm (range, 2.0-8.2 cm). Eight (8) cases had radiological findings of proximal tibial dysplasia, while the other 3 cases had not. The average distraction length gained was 5.3 cm (range, 3.5-8.0 cm) with a mean elongation rate of 21.4% (range, 15-30%). The Healing Index (HI) was 63.1 d/cm (range, 47-77 d/cm). In the 8 patients with proximal tibial dysplasia, 5 cases had lateral callus, 3 had central callus, and poor bone regeneration was observed in all of them with an average HI of 67 d/cm. In the other 3 patients without proximal tibial dysplasia, concave shaped callus was identified with an average HI of 52.7 d/cm. None of the patients had re-fracture, nonunion, axis deviation or angulation of the distraction area. Ankle joint stiffness was found in 2 of the patients. No evidence of knee contracture was detected. There were 5 cases with pin-tract infection which was managed by pin-tract nurse and oral administration of antibiotics. CONCLUSIONS: We concluded that proximal tibial lengthening after initial union of CPT was effective for management of tibial shortening, however it was characterized by poor bone regeneration with different types of callus from normal, greater healing index and prolonged fixator wearing. We recommended that tibial lengthening could be considered when the limb length discrepancy (LLD) was more than 4 cm in younger children after primary union of CPT.

[Diagnostic value of high mobility group box 1 for acute appendicitis in children].

OBJECTIVE: To evaluate the value of high mobility group box 1(HMGB1) in the diagnosis of pediatric acute appendicitis. METHODS: The children with acute abdomen who had a diagnosis of suspected acute appendicitis between January and July 2013 and 25 healthy children were enrolled in this study. Serum HMGB1 levels were measured using ELISA on admission. The patients were classified into 2 groups according to surgery confirmation or pathological results: appendicitis (n=28) and non-appendicitis (n=35). RESULTS: Serum HMGB1 levels and WBC in the appendicitis and non-appendicitis groups were significantly higher than in the healthy children group (P<0.01). The appendicitis group showed more increased serum HMGB1 levels compared with the non-appendicitis group (median: 32.9 ng/mL vs 22.0 ng/mL; P<0.01). For a diagnosis of acute appendicitis, the sensitivity and specificity of serum HMGB1 was 71.4% and 82.9% respectively at the best cutoff of 28.0 ng/mL, with the accuracy of 77.8% and the area under the curve of 0.765 (95%CI 0.638-0.893). CONCLUSIONS: HMGB1 may play a role in the diagnosis of pediatric acute appendicitis.