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The aim of this study is to investigate the role of tumor necrosis factor-α (TNF-α) in apoptosis and autophagy of mouse osteoblast MC3T3-E1 cells, as well as the crosstalk between autophagy and apoptosis. Mouse osteoblast MC3T3-E1 cells were cultured in vitro and treated with 5-fluorouracil (5-FU), rapamycin, 3-methyl adenine (3-MA) and TNF-α either alone or in combination, respectively. MTT assays were used to monitor the cell viability upon different treatments. Annexin-V-FITC/propidium iodide (PI) staining was used to detect the apoptotic rate of osteoblasts. Autophagic structure and apoptotic bodies were visualized by transmission electron microscopy (TEM). Western blot analysis was performed to detect the autophagic marker LC3-II/I, p62 and apoptotic marker cleaved caspase-3. TNF-α inhibits MC3T3-E1 cell viability in a dose-dependent and time-dependent manner. Annexin-V-FITC/PI staining, coupled with TEM, showed that TNF-α induced cell apoptosis and autophagy in MC3T3-E1 cells. The autophagy inducer rapamycin ameliorated TNF-α-induced apoptosis. In contrast, 3-MA, which is an autophagy inhibitor, caused an exaggerated induction of TNF-α-induced apoptosis. TNF-α upregulated autophagy marker LC3-II/I, but downregulated p62 in osteoblasts. Combined treatment of rapamycin and TNF-α further exaggerated this effect, whereas co-treatment of 3-MA and TNF-α decreased LC3-II/I, but increased p62 compared with TNF-α alone. In addition, TNF-α caused an induction of apoptotic marker cleaved caspase-3. TNF-α-mediated induction of cleaved caspase-3 was downregulated by rapamycin, but upregulated by 3-MA, respectively. TNF-α induced both autophagy and apoptosis in osteoblasts, and upregulated autophagy protects the cell by reducing TNF-α-induced apoptosis. [ABSTRACT FROM AUTHOR]

Objectives: Pauwels III fracture is a kind of femoral neck fractures, in which the angle of the fracture line in the coronal plane and the upper edge of the acetabulum is more than 50°. Internal fixation for the treatment of femoral neck fractures is largely performed by cannulated compression screw (CCS), dynamic hip screw, or locking plate. This study aims to compare the biomechanical properties of parallel CCS combined with medial buttress plate fixation and F-type CCS fixation in the treatment of Pauwels III femoral neck fracture by finite element modeling and to determinate the most suitable procedure for such fractures., Methods: A 52-year-old male volunteer, 176 cm in height and 72 kg in weight, with no history of hip joint, was selected. X-ray and CT examination confirmed that the morphology and bone condition of the right hip of the volunteer were normal. A simulation model of Pauwels III femoral neck fracture was established from the collected CT data of the right proximal femur of the volunteer by the finite element method. Four internal fixations were developed to treat the finite element model: Three CCSs in an inverted triangular parallel configuration combined with medial buttress plate model served as Group A, 2 CCSs in a vertical parallel configuration combined with medial buttress plate model served as Group B, 2 CCSs in a horizontal parallel configuration combined with medial buttress model served as Group C, and the "F" shaped CCS model served as Group D. The distribution of stress, the peak stress, the distribution and maximum of displacement of internal fixations and fracture ends in different models were evaluated., Results: For Groups A, B, C, and D, the peak stresses on the internal fixation were 362.74, 586.84, 558.25, and 208.66 mPa, respectively, all of which occurred near the fractures and the stress distribution in Group D was the most uniform. The maximum displacements of internal fixations in Groups A, B, C, and D were 0.39, 0.45, 0.44, and 0.41 mm, respectively; the peak stresses on the fracture ends were 70.62, 98.48, 55.84, and 65.39 mPa, respectively, all of which were concentrated on the base of femoral neck and lateral cortex of the femoral shaft, and the stresses of Groups C and D were more evenly distributed than those of Groups A and B. The maximum displacements of fracture ends in Groups A, B, C, and D were 0.44, 0.52, 0.50, and 0.44 mm, respectively., Conclusions: The biomechanical stability of F-type CCS fixation is similar to that of 3 CCSs in an inverted triangular parallel configuration combined with medial buttress plate, with a better dispersion of stress. F-type CCS fixation may be a well option for the treatment of femoral neck fracture of Pauwels III.

Osteoarthritis (OA) is the most common skeletal disease and the leading cause of pain and disability in the aged population (>65 years). However, the underlying factors involved in OA pathogenesis remain elusive which has resulted in failure to identify disease-modifying OA drugs. Altered metabolism has been shown to be a prominent pathological change in OA. As a critical bioenergy sensor, AMP-activated protein kinase (AMPK) mediates not only energy homeostasis but also redox balance in chondrocytes to counter various cell stress. Dysfunction of AMPK activity has been associated with reduced autophagy, impaired mitochondrial function, excessive reactive oxygen species generation, and inflammation in joint tissue. These abnormalities ultimately trigger articular cartilage degeneration, synovial inflammation, and abnormal subchondral bone remodeling. This review focuses on recent findings describing the central role of AMPK in joint homeostasis and OA development. We also highlight current advances that target AMPK as a novel therapeutic strategy for OA prevention., Competing Interests: None., (AJTR Copyright © 2020.)

Previous studies have shown that protein inhibitor of activated STAT (PIAs)xα is crucial in protein sumoylation and is associated with cancer cell progression. However, the mechanism underlying the inhibitory effect on cancer cells, which may assist in developing novel treatment strategies in cancer remains to be elucidated. In present study, the expression levels of PIAsxα from tissue samples of osteosarcoma and adjacent tissues from 25 patients were analyzed using reverse transcription-quantitative polymerase chain reaction, western blot and immunohistochemical analyses. In addition, techniques using an overexpression vector and small interfering (si)RNAs were used to examine the effect of PIAsxα on osteosarcoma cells. Finally, using xenograft U2-OS osteosarcoma cells overexpressing PIAsxα, the effect of PIAsxα on osteosarcoma formation was determined. The results revealed low expression of PIAsxα in osteosarcoma tissues. In addition, following overexpression of PIAsxα, the apoptotic rates were significantly increased. The rate of G2/M arrest was at the highest level in the overexpression group, compared with other groups assessed. Furthermore, the expression levels of cyclin D1 and cyclin D3 were inhibited following PIAsxα increase, indicating the repressive effects of PIAsxα on cell cycle. Accordingly, cyclin D kinase (CDK) genes, including CDK4, CDK6 and CDK8, increased markedly following treatment with PIAsxα siRNAs. The expression levels of CDK4, CDK6 and CDK8 decreased significantly in the overexpression group, compared to the other groups. Furthermore, high expression levels of PIAsxα inhibited tumor formation in a nude mouse model. Taken together, these findings provide evidence for the effects of PIAsxα and its mechanism on osteosarcoma progression, which offers novel insight into sumoylation and the cell cycle in osteosarcoma.

The aim of this study was to uncover that unfolded protein response (UPR) contributed to the development of cisplatin resistance in osteosarcoma. MG-63 cells and SaOS-2 cells were exposed to cisplatin at presence or absence of 4-phenylbutyrayte (4-pba) and then analyzed by MTT assay and flow cytometry to determine the cell survival rates and apoptosis. Levels of glucose regulated protein 78KD (GRP78), C/EBP homologus protein (CHOP), cytoplasmic and nuclear NF-κB were detected by Western blot. Further, MG-63 cells and SaOS-2 cells were subjected to cisplatin with or without Bay 11-7082, a well-known inhibitor of NF-κB. After that, MTT assay and flow cytometry were used to determine the cell survival rates and apoptosis. Cisplatin and 4-PBA co-treatment significantly enhanced the cell apoptosis. Administration of cisplatin substantially increased the levels of GRP78 and CHOP. Moreover, mechanistic investigation uncovered that cisplatin promoted the levels of nuclear NF-κB whereas 4-PBA administration suppressed the cisplatin-induced accumulation of nuclear NF-κB level in osteosarcoma cells. Cisplatin combined with Bay 11-7082 obviously augmented MG-63 cells and SaOS-2 cells apoptosis when compared to that in osteosarcoma cells treated by cisplatin alone. Taken together, our data show that UPR protects osteosarcoma from cisplatin-mediated apoptosis through activation of NF-κB pathway. Therefore, targeting UPR may be a potential strategy to improve the osteosarcoma therapy.

Although the 5-year survival rate of osteosarcoma (OS) has risen to ~60-70%, a substantial portion of patients still respond poorly to chemotherapy and have a high risk of relapse or metastasis even after curative resection. In this study, we found that the expression of miR-142 was significantly reduced in OS tissues and OS cell lines, while Ras-related C3 botulinum toxin substrate 1 (Rac1) expression was increased in the OS tissues and OS cell lines compared with expression in the controls. We then demonstrated that miR-142 regulated Rac1 expression at the transcriptional and translational levels by directly targeting its 3'-untranslated region (3'UTR). In addition, by loss- and gain-of function experiments, we investigated the role of miR-142 in OS cell lines and found that miR-142 acted as a tumor suppressor in the OS cell lines and inhibited cell proliferation and cell invasion and arrested cell cycle in the S phase. Furthermore, miR-142 inhibited osteosarcoma cell invasion by inducing E-cadherin expression and reducing expression of matrix metalloproteinase 2 (MMP2) and MMP9. Thus, overexpression of miR-142 and/or knockdown of Rac1 would be a novel target for OS therapy in the future.

Objective: To determine the effect of bone cement, with different amounts of alendronate on osteoblast, and determine the cytotoxicity of alendronate-integrated bone cement from the viewpoint of cell biology., Methods: According to different additions (0, 10, 50, 100, 500, 1 000 mg) of alendronate in 50 g Cemex®XL bone cement powder, the experiments were divided into 6 groups, namely G0-G5 groups. In all groups, the adhesive capacity of osteoblast-like cells MG-63 was evaluated by electron microscope, the optical density (OD) value of cells by MTT colorimetry method, the alkaline phosphatase activity (AKP) by AKP assay kit, the apoptosis rates by Annexin-V-FITC apoptosis detection kit, and the bone mineralization potentiality by phase contrast microscope., Results: The adhesive capacity of MG-63 was good in all groups. Compared with the G0 group, the cell apoptosis was inhibited in G1-G4 groups while in G5 group the cell apoptosis was promoted and cell proliferation was inhibited (P<0.05). In all groups, no significant difference was found in alkaline phosphatase activity and bone mineralization potentiality (P>0.05)., Conclusion: Less than 500 mg alendronate added in Cemex®XL 50 g bone cement powder has no cytotoxicity on osteoblasts.

Objective: To determine the effect of alendronate amount on the static mechanical properties of bone cement before elution and 4 weeks after elution, and determine suitable amount of alendronate in cement from the perspective of biomechanics., Methods: Samples of compression strength and bending strength (modulus) were prepared with bone cement adding 0, 10, 50, 100, 500 and 1000 mg alendronate in 50 g Cemex®XL bone cement powders respectively (named as G0-G5 groups). The compression strength, bending strength, and bending modulus of bone cement were examinated by INSTRON 8032 tester before the elution and 4 weeks after the elution. Some broken samples of 4-point bending test were examinated by scanning electronic microscopy (SEM), and some other samples of bending strength (modulus) tests by micro-CT., Results: No significant difference was found in the compression strength before the elution,4 weeks after elution in the 6 groups, and before and after the elution in the respective groups (P>0.05). Compared with G0 group, G1-G4 groups had no obvious difference in the bending strength before the elution and 4 weeks after the elution (P>0.05), while G5 group had difference (P<0.05). There was no significant difference in the bending strength before and after the elution in the respective groups (P>0.05). Taken G0 group as the control group, G1-G4 groups had no visible effects on the bending modulus 4 weeks after the elution (P>0.05), while G5 group decreased it significantly (P<0.05). Bending modulus before the elution in the 6 groups didn't show obvious difference (P>0.05), while bending modulus before and after the elution in the respective groups displayed a marked difference (P<0.05)., Conclusion: Less than 500 mg alendronate added in Cemex?XL 50 g bone cement powder does not decrease the compressive strength, flexural strength and flexural modulus before the elution and 4 weeks after the elution.

Objective: To explore the clinical effect of particulate bone grafting on reconstruction of femoral defects in revision total hip arthroplasty., Methods: Fifteen patients (20 hips) with femoral defects were treated by revision total hips arthroplasty with particulate bone grafting. After the operations, 14 patients (19 hips) were evaluated by X-rays and the Harris score., Results: During a follow-up of 43.6 months (11 approximately 65 months), 17 hips (89.5%) were cured, without obvious bone absorption or prosthesis sinking. Harris scores improved from 34.18 pre-operation to 86.6 post-operation., Conclusion: Reconstruction of femoral defects with particulate bone grafting is an effective method for bone defects in revision total hip arthroplasty.