LncRNA JHDM1D-AS1 promotes osteogenic differentiation of periodontal ligament cells by targeting miR-532-5p to activate IGF1R signaling.

OBJECTIVE: The aim of this study was to explore the mechanism underlying periodontal ligament cells (PDLCs) osteogenic differentiation. BACKGROUND: Periodontitis causes damage to tooth-supporting apparatus and eventually leads to tooth loss. PDLCs hold great promise in periodontal regeneration due to their osteogenic features. METHODS: The expression of osteogenic markers, lncRNA JHDM1D-AS1, miR-532-5p and IGF1R was examined. For osteogenic differentiation, primary human PDLCs (hPDLCs) were cultured in an osteogenic medium, and it was assessed by ALP activity and Alizarin Red staining. The interaction between JHDM1D-AS1, miR-532-5p and IGF1R was analyzed via dual luciferase, RIP and RNA pull-down assays. RESULTS: JHDM1D-AS1 was up-regulated during osteogenic differentiation and its silencing inhibited hPDLC osteogenic differentiation. JHDM1D-AS1 worked as a miR-532-5p sponge in hPDLCs. miR-532-5p directly targeted IGF1R to suppress its expression, and miR-532-5p knockdown facilitated osteogenic differentiation of hPDLCs. Overexpression of IGF1R promoted osteogenic differentiation of hPDLCs via activating Notch/HES1 signaling in hPDLCs. CONCLUSION: JHDM1D-AS1 promotes osteogenic differentiation of hPDLCs via sponging miR-532-5p to facilitate IGF1R expression and activate Notch/HES1 signaling.

Dentoperiodontal and skeletal changes induced by miniscrew-assisted rapid maxillary expansion (C-expander) treatment in adults: A retrospective clinical trial.

INTRODUCTION: The objective of this study was to evaluate the dental periodontal and skeletal response to ≥5 mm of expansion width achieved by C-expander treatment with posterior miniscrews placed between the first and second molars in adults. METHODS: A total of 28 patients aged 21.91 ± 3.20 years with maxillary transverse deficiency underwent C-expander treatment. Anterior miniscrews were positioned between the first and second premolars, whereas posterior miniscrews were positioned between the first and second molars. Cone-beam computed tomography records were obtained before expansion and 3 months after expansion. The dental periodontal and skeletal changes for all patients were recorded. RESULTS: The C-expander treatment expanded the palatal suture with slight buccal alveolar bone inclination. An increase in the nasal cavity width and a greater increase in the maxillary base bone width were observed after maxillary expansion. The expansion at the posterior nasal spine (3.78 mm) was approximately 85.7% of that at the anterior nasal spine (4.41 mm). No significant buccal dehiscence occurred after expansion, whereas the mesiobuccal alveolar bone thickness of the first molars was decreased at the 8 mm level with respect to the cementoenamel junction. The first molar showed decreased inclination (right, -0.45°; left, -0.38°, P >0.05), whereas the expansion at the apical level was less than that at the crown level. Age and the skeletal/dental expansion ratio had no discernible relationship. CONCLUSIONS: Miniscrew-assisted C-expander treatment can be effective for adults with maxillary transverse deficiency. Rearward placement of the miniscrews may create an approximately parallel expansion. Most maxillary expansion was derived from skeletal expansion with slight alveolar bone buccal inclination.

Induced oxidative stress and apoptosis by 1-bromopropane in SH-SY5Y cells correlates with inhibition of Nrf2 function.

In this study, we established SH-SY5Y human neuroblastoma cells as an in vitro model to investigate whether oxidative stress and the nuclear erythroid-2 related factor 2 (Nrf2) signaling pathway are associated with 1-bromopropane (1-BP) -induced nerve cell injury. We identified that 1-BP exhibited neurotoxicity mainly through oxidant-based processes in SH-SY5Y cells, as reactive oxygen species, malondialdehyde levels, and 8-hydroxy-2' -deoxyguanosine significantly increased, while superoxide dismutase activity decreased. Furthermore, Nrf2 translocation from the cytosol to the nucleus was inhibited, as was downstream protein expression of the Nrf2-regulated genes HO-1 and Bcl-2. Activation of caspase-9 and -3 increased, and apoptosis was observed. Vitamin C alleviated 1-BP-induced apoptosis by decreasing oxidative stress and activating the Nrf2 signaling pathway. Knockdown of Nrf2 in SH-SY5Y cells increased 1-BP-induced reactive oxygen species production and cell apoptosis, and inhibited HO-1 and Bcl-2 protein expression, while overexpression of Nrf2 alleviated these processes. These findings suggest that 1-BP-induced oxidative stress and apoptosis in SH-SY5Y cells are associated with Nrf2 function inhibition.

circSKIL promotes osteoblastic differentiation of periodontal ligament cells by sponging miR-532-5p to activate Notch signaling.

BACKGROUND AND OBJECTIVE: Periodontal ligament cells (PDLCs) possess the capacity to differentiate into a variety of cell types to benefit periodontal regeneration. In this study, we examined the circSKIL/miR-532-5p/Notch1 axis in controlling the osteoblastic differentiation of PDLCs. METHODS: Primary human PDLCs (hPDLCs) were isolated and induced to differentiate into osteoblasts. Osteogenic responses were assessed for the expressions of osteoblast-related marker proteins (including alkaline phosphatase (ALP), osteocalcin (OCN), bone morphogenetic protein-2 (BMP2), and runt-related transcription factor 2 (RUNX2) by RT-PCR. The formation of mineralized nodules was examined by Alizarin Red S (ARS) staining and ALP activity. Expressions of circSKIL, miR-532-5p, and Notch1 were measured by RT-PCR and western blotting, and their regulations by combining bioinformatic analysis and luciferase reporter assay. Notch signaling was assessed for the expressions of hairy and enhancer of split-1 (HES1) and Notch intracellular domain (NICD). RESULTS: During osteoblastic differentiation of hPDLCs, circSKIL, and Notch1 were up-regulated, while miR-532-5p down-regulated. By sponging miR-532-5p, circSKIL activated Notch signaling, increasing levels of Notch1, HES1, and NICD. Functionally, knocking down circSKIL or overexpressing miR-532-5p inhibited osteoblastic differentiation of PDLCs, down-regulating ALP, OCN, BMP2, and RUNX2, and reducing ARS staining or ALP activity. The impacts of circSKIL knockdown were rescued by miR-532-5p inhibitor or overexpressing Notch1, while those caused by up-regulating miR-532-5p were reversed by overexpressing Notch1. CONCLUSION: By targeting miR-532-5p and up-regulating Notch1, circSKIL critically controls osteoblastic differentiation of hPDLCs. Therefore, modulating this axis may maximize the differentiation of PDLCs into osteoblasts and benefit periodontal regeneration.

Oral microbiota alteration associated with oral cancer and areca chewing.

Oral cancer is among most common neoplasm of oral cavity; in many cases, it develops at the site of premalignant lesion. Areca nut has been identified as a carcinogen, which was proved to promote the inflammation level and contributes to oral malignancy. Chewing areca nut is the main cause of the premalignant disease oral submucous fibrosis (OSF). Bacterial alterations were suggested to be assonated with oral cancer progression. Therefore, the present study was carried out to determine the changes of microbiota in the mucosa along stage of development of oral cancer with areca nut chewing. 162 participants, reporting to department of oral medical center, were enrolled into the study which includes 45 patients each of OSF, 42 of oral cancer, 29 healthy controls (HC) with areca nut chewing, and 46 healthy controls (HC) never chewing areca nut. Oral swabbing of tongue dorsum, buccal mucosa, and gingiva was evaluated by MiSeq platform of the V3-V4 region of the 16S rRNA gene. These data revealed microbial changes that may mirror oral cancer progression and reflect clinical preconditions such as areca nut chewing. Consequently, revealing microbial changes in patients with oral squamous cell carcinomas and the premalignant disease oral submucous fibrosis (OSF) with areca nut chewing might improve our understanding of the pathobiology of the disease and help in the design of novel diagnostic and treatment strategies.

1-Bromopropane-induced apoptosis in OVCAR-3 cells via oxidative stress and inactivation of Nrf2.

The bromoalkane, 1-bromopropane (1-BP), may damage the reproductive system though oxidative stress, while the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) plays an important role in regulating intracellular antioxidant levels against oxidative stress. This study explored the role of oxidative stress and the Nrf2 signaling pathway in mediating the reproductive toxicity of 1-BP using the ovarian carcinoma cell line OVCAR-3 as an in vitro model of the human ovary. OVCAR-3 cells were treated with 1, 5, 10 and 15 mM 1-BP. After 24 h, the cellular reactive oxygen species and malondialdehyde concentrations significantly increased, while the superoxide dismutase activity decreased; translocation of Nrf2 from the cytosol to the nucleus as well as downstream protein expression of Nrf2-regulated genes heme oxygenase-1 and Bcl-2 was inhibited. Apoptosis was also observed, accompanied by increased caspase-3 and caspase-9 activity. The antioxidant vitamin C alleviated 1-BP-induced apoptosis by inhibiting caspase activity activating the Nrf2 signaling pathway. These findings suggested that 1-BP induced oxidative stress and apoptosis in OVCAR-3 cells through inactivation of Nrf2 signaling.

Feasibility and safety of a self-developed sleeve for the endoscopic removal of refractory foreign body incarceration.

Objective: This study aimed to assess the feasibility and safety of a novel self-designed sleeve for the endoscopic removal of a refractory incarcerated foreign body in the upper gastrointestinal tract (UGIT). Methods: An interventional study was conducted between June and December 2022. A total of 60 patients who underwent an endoscopic removal of a refractory incarcerated foreign body from the UGIT were randomly allocated to the self-developed sleeve and the conventional transparent cap. The study evaluated and compared the operation time, successful removal rate, new injury length at the entrance of the esophagus, new injury length at the impaction site, visual field clarity, and postoperative complications between the two groups. Results: The success rates of the two cohorts in the foreign body removal display no significant discrepancy (100% vs. 93%, P = 0.529). Nevertheless, the methodology of the novel overtube-assisted endoscopic foreign body removal has culminated in a significant reduction in the removal duration [40 (10, 50) min vs. 80 (10, 90) min, P = 0.01], reduction in esophageal entrance traumas [0 (0, 0) mm vs. 4.0 (0, 6) mm, P < 0.001], mitigation of injuries at the location of the foreign body incarceration [0 (0, 2) mm vs. 6.0 (3, 8) mm, P < 0.001], an enhanced visual field (P < 0.001), and a decrement in postoperative mucosal bleeding (23% vs. 67%, P < 0.001). The self-developed sleeve effectively negated the advantages of incarceration exclusion during removal. Conclusion: The study findings support the feasibility and safety of the self-developed sleeve for the endoscopic removal of a refractory incarcerated foreign body in the UGIT, with advantages over the conventional transparent cap.

Involvement of miR-337 in high glucose-suppressed osteogenic differentiation in bone marrow mesenchymal stem cells via negative regulation of Rap1A.

This study aims to investigate the inhibitory effect of microRNA-337 (miR-337) on osteogenic differentiation in bone marrow mesenchymal stem cells and its action of mechanisms. Overexpression and knockdown of miR-337 were performed in bone marrow mesenchymal stem cells (BMSCs). Cell proliferation was assessed by using a cell counting kit-8 (CCK-8), mineralization assay was performed by alizarin red staining, and alkaline phosphatase activity was then measured. Luciferase reporter assay was applied to verify miR-337 binding to Ras-related protein 1A (Rap1A) mRNA. Reverse transcription and quantitative polymerase chain reaction (RT-qPCR) was applied to measure the expressions of runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), osteocalcin (OCN), osteopontin (OPN), bone morphogenetic protein (BMP2), and miR-337. Then the protein level of Rap1A was determined by western blot analysis. High glucose inhibited osteogenic differentiation but increased the level of miR-337. Overexpression of miR-337 inhibited osteogenic differentiation in high glucose-treated BMSCs, while the knockdown of miR-337 reversed this process. Luciferase reporter assay confirmed that the presumed pairing binding site of miRNA-337 was in the 3'-UTR of the Rap1A WT. In addition, the knockdown of Rap1A distinctly repressed osteogenic differentiation, which blocked the effect of miR-337-knockdown on osteogenic differentiation in high glucose-treated BMSCs. MiR-337 could repress osteogenic differentiation in high glucose-treated BMSCs directly targeting Rap1A, thus provide a potential therapeutic strategy for patients with diabetic osteoporosis in clinic.

Nomograms for Predicting Cancer-Specific Survival of Patients with Gingiva Squamous Cell Carcinoma: A Population-Based Study.

OBJECTIVE: The use of the traditional American Joint Committee on Cancer (AJCC) staging system alone has limitations in predicting the survival of gingiva squamous cell carcinoma (GSCC) patients. We aimed to establish a comprehensive prognostic nomogram with a prognostic value similar to the AJCC system. METHODS: Patients were identified from SEER database. Variables were selected by a backward stepwise selection method in a Cox regression model. A nomogram was used to predict cancer-specific survival rates for 3, 5 and 10 years in patients with GSCC. Several basic features of model validation were used to evaluate the performance of the survival model: consistency index (C-index), receiver operating characteristic (ROC) curve, calibration chart, net weight classification improvement (NRI), comprehensive discriminant improvement (IDI) and decision curve analysis (DCA). RESULTS: Multivariate analyses revealed that age, race, marital status, insurance, AJCC stage, pathology grade and surgery were risk factors for survival. In particular, the C-index, the area under the ROC curve (AUC) and the calibration plots showed good performance of the nomogram. Compared to the AJCC system, NRI and IDI showed that the nomogram has improved performance. Finally, the nomogram's 3-year and 5-year and 10-year DCA curves yield net benefits higher than traditional AJCC, whether training set or a validation set. CONCLUSION: We developed and validated the first GSCC prognosis nomogram, which has a better prognostic value than the separate AJCC staging system. Overall, the nomogram of this study is a valuable tool for clinical practice to consult patients and understand their risk for the next 3, 5 and 10 years.

Investigation of anthropometric measurements of anatomic structures of orbital soft tissue in 102 young han chinese adults.

PURPOSE: The aim is to measure and investigate the anatomic structures of orbital soft tissue and the relationships between the adjacent regions in 102 normal young Han Chinese adults using a computer-assisted photography system to provide reference data for periocular cosmetic and reconstructive surgery. METHODS: A random sample of 102 Han young Chinese adults (53 males and 49 females) aged from 18 to 25 years in Changsha, Hunan Province, was obtained. Standard digital images were taken and then processed using Image-Pro Plus 6.0 software. The linear and angular measurements, including intercanthal distance, outer canthal distance, palpebral fissure width (PFW), palpebral fissure height (PFH), orbit height (OH), upper lid height, lower lid height, nasal eyebrow height, central eyebrow height, temporal eyebrow height, reference line to lateral canthus'inclination of palpebral fissure, were measured. The proportional indices, including intercanthal distance/outer canthal distance, PFH/PFW, PFH/OH, OH/PFW, upper lid height/OH, lower lid height/OH, nasal eyebrow height/OH, central eyebrow height/OH, and temporal eyebrow height/OH, were investigated. RESULTS: Means and standard deviations of all the items had been obtained and differences between male and female subjects were assessed. CONCLUSIONS: The normal measurement values of anatomic structures of orbital soft tissue and the proportional indices for normal young Han Chinese adults provided reference data for periorbital cosmetic and reconstructive surgery.

Anthropometric measurement and analysis of the external nasal soft tissue in 119 young Han Chinese adults.

A random sample of 119 young, healthy Han Chinese adults (56 men and 63 women) between the age of 18 and 25 years (mean, 22.7 y) in PR China was obtained for this study. By the guidance of standard methods, based on Farkas's anthropometric measurements in craniofacial region, 12 nasal soft tissue landmarks and 12 linear and 3 angular measurements were chosen. The linear measurements were taken directly, whereas the angular measurements were taken by photogrammetric method. Eight nasal proportion indices were calculated according to the linear measurements. The application of the independent-samples t-test showed sex dimorphism in most parameters of the nasal region. All the linear measurements were larger in men than in women, whereas all the angular measurements were smaller in men than in women. The significant differences in partial parameters between men and women have been proved. Ten of 12 linear measurements, 1 of 3 angular measurements, and 3 of 8 nasal proportion indices showed significant sexual dimorphism (P < 0.01). Compared with other racial/ethnic groups, the nasal anthropometric measurements and proportion indices of Han Chinese adults were different, to some extent. This study could provide credible and objective reference material for plastic and maxillofacial surgeons for the external nasal soft tissue evaluation and planning of the cosmetic nasal surgery. Besides, these results could be a useful guidance for preoperative and postoperative evaluations of secondary rhinoplasty in nasal deformity associated with cleft lip and palate.

Discovery of novel biomarkers in oral submucous fibrosis by microarray analysis.

Oral submucous fibrosis (OSF) is a high-risk precancerous condition of the oral cavity. Areca nut chewing is its key etiologic factor, but the full pathogenesis is still obscure. In this study, microarray analysis was used to characterize the mRNA changes of 14,500 genes in four OSF and four normal buccal mucosa samples to identify novel biomarkers of OSF. Five candidate genes with the most differential changes were chosen for validation. The correlation between clinicopathologic variables of 66 OSF patients and the expression of each gene was assessed by immunohistochemistry. The microarray analysis showed that 661 genes were up-regulated (fold value >2) and 129 genes were down-regulated (fold value <0.5) in OSF (q < 0.01). The top three up-regulated genes [Loricrin, Cartilage oligomeric matrix protein (COMP), Cys-X-Cys ligand 9 (CXCL9)] with the largest fold changes and the top two down-regulated genes [keratin 19 (KRT19), cytochrome P450 3A5 (CYP 3A5)] with the most significantly differential changes in OSF were chosen as candidate biomarkers. In immunohistochemical results, the expression of Loricrin and COMP showed statistically significant association with histologic grade of OSF (P = 0.03 and 0.006, respectively). COMP was found to be overexpressed frequently in patients with the habit of areca nut chewing for more than 4 years (P = 0.002). CYP 3A5 was revealed an inverse correlation with histologic grade (P = 0.04). This pilot study showed that five novel genes might play important roles in the pathogenesis of OSF and may be clinically useful for early detection of OSF.

Insulin augments mechanical strain-induced ERK activation and cyclooxygenase-2 expression in MG63 cells through integrins.

Insulin has been proposed to be a positive regulator of osteoblast proliferation and bone formation. In vivo mechanical loading is essential for maintaining skeletal integrity and bone mass. Since insulin and mechanical force activate similar signaling pathways in osteoblasts, it was hypothesized that insulin may affect mechanical stimulation in osteoblasts. The present study tested the hypothesis that insulin augments mechanical strain-induced signaling and early gene expression in MG63 cells via activation of the extracellular signal-regulated kinase (ERK) pathway and cyclooxygenase-2 (Cox-2) expression. Western blot analysis and quantitative polymerase chain reaction demonstrated respectively that insulin enhanced mechanical strain-induced ERK phosphorylation and Cox-2 expression levels in a dose-dependent manner. The effect of insulin on mechanical strain-induced Cox-2 expression was inhibited by blockade of the ERK pathway. In addition, echistatin, an inhibitor of integrin function, prevented the effects of insulin on mechanical strain-induced ERK phosphorylation and Cox-2 expression. The data obtained from this study suggested that insulin augments mechanical strain-induced Cox-2 expression levels via integrin-dependent activation of the ERK pathway in osteoblasts.

Expression of matrix metalloproteinases-8 and -9 and their tissue inhibitor in the condyles of diabetic rats with mandibular advancement.

The present study aimed to evaluate the effects of type 1 diabetes mellitus on the condylar response during treatment with a functional appliance. Sprague-Dawley rats were divided into 3 groups, normal (NG), diabetes (DG) and diabetes with insulin-treatment (TG). Bite-jumping appliances were fitted to the rats in the experimental groups. At 7, 14, 21 and 28 days following fitting, animals were sacrificed and condyles were excised and processed using routine histological techniques. The expression of matrix metalloproteinase (MMP)-8, MMP-9 and tissue inhibitor of metalloproteinase-1 (TIMP-1) was detected using immunohistochemical analysis. Mandibular advancement increased the expression levels of MMP-8 (peaked on day 28), MMP-9 (peaked on day 21), TIMP-1 (peaked on days 21 and 28) and the ratio of MMP-8 to TIMP-1 and MMP-9 to TIMP-1. In the DG, diabetes decreased the expression levels of MMP-8 and MMP-9 induced by mandibular advancement and increased the expression levels of TIMP-1 compared with that of the NG. The ratio of MMP-8 to TIMP-1 and MMP-9 to TIMP-1 also showed a significant decrease in the DG compared with that of the NG. A recovery of these parameters was observed in the TG. Diabetes significantly altered the condylar response, which was triggered by mandibular advancement, and weakened subsequent bone deposition. The results from the TG were not significantly different from that of the NG.

Endothelin-1 induces interleukin-18 expression in human osteoblasts.

OBJECTIVE: Both endothelin-1 (ET-1) and interleukin (IL)-18 induce osteoblast proliferation under normal and pathophysiological conditions. In the present study, we explored the interaction between the two proteins by examining the effect of ET-1 on IL-18 expression in cultured human osteoblasts. METHODS: Human osteoblasts were treated with ET-1 in different concentrations (1, 10, 20, 40, or 50 nM) for different length of time (1, 6, 12, 18, or 24 h) in the presence or absence of ET A receptor (ETAR) blocker BQ123, ET B receptor (ETBR) blocker BQ788, p38 mitogen-activated protein kinase (MAPK) siRNA, or different kinase inhibitors. RESULTS: ET-1 increased the IL-18 mRNA level in a statistically significant dose- and time-dependent manner within 18 h, which was reflected in dose-dependent induction of the human IL-18 gene promoter activity and IL-18 protein/secreted protein expression. BQ123 (1µ M) and p38 MAPK siRNA and inhibitor PD169316 (25 µM) completely abolished the promoting effect of ET-1 on IL-18 expression. [(3)H]thymidine incorporation assays showed that ET-1 lost a major part (57%) of its promoting effect on osteoblast proliferation when the endogenous IL-18 expression in osteoblasts was knocked down by 75%. CONCLUSIONS: ET-1 induces IL-18 expression in human osteoblasts at the gene promoter/transcription level via ETAR by a p38 MAPK-dependent mechanism, and that IL-18 mediates a major part of ET-1 induced osteoblast proliferation. This study provides the first evidence of interaction between ET-1 and IL-18 in osteoblast and adds new insights into bone physiology and pathophysiology.

[Effect of compressive stress on the expression of DNAX-activating protein 12 and tartrate-resistant acid phosphatase in mouse monocyte RAW264.7].

OBJECTIVE: To investigate the expression of DNAX-activating protein 12 (DAP12) and tartrate-resistant acid phosphatase (TRAP) in mouse monocyte RAW264.7 subjected to compressive stress. METHODS: Mouse monocyte RAW264.7 was subjected to four-point bending system. The expression of DAP12 and TRAP mRNA were examined by reverse transcription-polymerase chain reaction (RT-PCR) and the expression of DAP12 protein by Western Blotting after 0, 3, 6 and 12h's compressive stress. RESULTS: After RAW264.7 cells were cultured by osteoclast cell culture fluid, the amount of the cells increased, and the volume enlarged, and the number of nuclei per osteoclast increased in vitro. The expression of DAP12 and TRAP mRNA and DAP12 protein of RAW264.7 cells subjected to compressive stress increased along with the time (P < 0.05). CONCLUSION: The mouse monocyte RAW264.7 can differentiate into osteoclast in vitro, and high expression of DAP12 exists in the process of osteoclast differentiation.

[Effects of DNAX-associated protein 12 signal pathways on differentiation of mouse monocytes RAW264.7 into osteoclasts by tensile strain].

OBJECTIVE: To explore the effect of DNAX-associated protein 12 (DAP12) pathway on the transformation from mouse monocytes RAW264.7 to osteoclasts induced by tensile strain. METHODS: DAP12shRNA plasmid was constructed and introduced to RAW264.7 cells. Then we supplied tensile strain to RAW264.7 cells by four-point bending system. The mRNA or protein expression of DAP12, tartrate-resistant acid phosphatase (TRAP), tyrosine kinases Btk and Tec and nuclear facior of activated T cells 1 (NFATc1) was measured by reverse transcription PCR (RT-PCR) and Western blotting respectively. RESULTS: The expression of DAP12 mRNA (0.112 ± 0.025) and protein (0.193 ± 0.015) both declined sharply after plasmid being introduced into monocytes RAW264.7 (P < 0.05). After silencing DAP12 expression in RAW264.7 cells by RNA interference, tensile strain-induced TRAP mRNA expression of RAW264.7 cells increased at 6 h (0.671 ± 0.031) and 12 h (0.800 ± 0.043) (P < 0.05), but it was weaker than non-RNA-interference-groups at each time point (P < 0.05). After silencing DAP12 expression in RAW264.7 cells by RNA interference, the expressions of Btk, Tec, NFATc1 increased as time passed (6, 12 h) (P < 0.05), but the expressions on corresponding time decreased sharply compared with those in control groups (P < 0.05). CONCLUSIONS: DAP12 pathway play an important role in regulating osteoclast differentiation induced by tensile strain.

[Effect of parathyroid hormone related protein on proliferation of human osteoblast-like cell under tension force].

OBJECTIVE: To investigate the effect of parathyroid hormone related protein (PTHrP) on proliferation of human osteoblasts (MG-63) under the circumstance of tension force in vitro. METHODS: An apparatus was designed and fabricated by which force was loaded onto the cultured cells in vitro. Reverse transcription-polymerase chain reaction (RT-PCR) was used for measuring the expression of PTHrP mRNA and c-fos mRNA. The effect of tension force and different PTHrP dose(0, 0.01, 0.1, 1 nmol/L) on the proliferation of human osteoblasts were examined using flow cytometry. RESULTS: Various forces of the mechanical stretching exerted different influences on the intensities of the mRNA' expression. The strain of 12% induced the most remarkable mRNA' expression. The mitogenesis happened in the group with tension force (12%) combined with PTHrP was more active than that in the group with PTHrP or tension' force only. Tension force combined with PTHrP induced significantly more c-fos mRNA than that of tension force only. CONCLUSION: The mechanical stretching can inevitably influence the expression of PTHrP mRNA. The most active mitogenesis happened in the group with tension force combined with PTHrP. The effect may be related with the signaling pathways of c-fos.