The role of circRNA derived from RUNX2 in the serum of osteoarthritis and its clinical value.

BACKGROUND: Circular RNA (circRNA) has been shown to affect the pathological process of osteoarthritis (OA) and is expected to become a potential marker for disease diagnosis. This study aimed to investigate the association between circRNA derived from the gene of runt-related transcription factor 2 (RUNX2) and OA risk. METHODS: The expression profile of RUNX2-derived circRNAs in serum of OA patients was detected. Then, the cytological localization of screened differential circRNAs was studied. Luciferase (LUC) reporter assay was used to identify the microRNA (miRNA) sponge capacity of the circRNAs. Bioinformatics analysis was used to construct the functional pathway of this circRNA-miRNAs network. And then, the diagnostic value of RUNX2-derived circRNAs in OA was evaluated. RESULTS: RUNX2-derived hsa_circ_0005526 (circ_RUNX2) is significantly highly expressed in OA serum and mainly located in the cytoplasm within the cartilage cell by sponging multiple miRNAs (miR-498, miR-924, miR-361-3p, and miR-665). Bioinformatics analysis showed ECM-receptor interaction pathway ranked the most significant pathway of circ_RUNX2-miRNAs regulatory network in KEGG database. The ROC curve showed that there may be good diagnostic value of serum circ_RUNX2 in OA. CONCLUSION: RUNX2-derived circ_RUNX2 may be involved in OA development via ECM-receptor interaction pathways and may be used as potential clinical indicator of OA.

Icariin Prevents Diabetes-Induced Bone Loss in Rats by Reducing Blood Glucose and Suppressing Bone Turnover.

Diabetic Osteoporosis (DOP) is a common metabolic bone disease, characterized by decreased bone mineral density (BMD) and destruction of bone microstructure. It has been reported that icariin is beneficial for estrogen deficiency-induced osteoporosis, and alcohol-induced osteoporosis; whether icariin has protective effects on diabetes-induced osteoporosis has not been reported. In this study, a rat model of diabetic osteoporosis was established by streptozotocin injection, the bone protective effects and potential mechanism of icariin on diabetes-induced bone loss was observed. Thirty 8-week-old female Sprague Dawley rats were divided into control group (vehicle treatment), T1DM (diabetic) group and T1DM-icariin (ICA) group (diabetic rats treated with icariin), 10 rats in each group. The bone histomorphometry parameters, bone mineral density (BMD), serum bone turnover markers, and bone marrow adipogenesis were analyzed after 8 weeks of icariin administration. The results showed consumption of icariin at a doses of 100 mg kg-1 decreased blood glucose, and increased the BMD of diabetic rats. Icariin effectively decreased serum bone turnover marker levels, including CTX-1, ALP, TRACP 5b, osteocalcin, and PINP. Meanwhile, the bone histomorphometry parameters, the number of osteoclasts per bone perimeter were turned to be normal level, and the icariin treatment suppressed bone marrow adipogenesis. The runt-related transcription factor 2 (RUNX 2), as well as the osteoprotegerin (OPG)/receptor activator of nuclear factor-κ B ligand (RANKL) ratio in serum and bone tissues were increased significantly after icariin treatment in diabetic rats. All of the above indicate that oral administration of icariin can prevent diabetic osteoporosis; the effect is mainly related to its ability to reduce blood glucose, inhibit bone turnover and bone marrow adipogenesis, as well as up-regulate bone RUNX 2, and OPG expression.

Circ-VANGL1 promotes the progression of osteoporosis by absorbing miRNA-217 to regulate RUNX2 expression.

OBJECTIVE: This study aims to investigate whether circ-VANGL1 can promote the progression of osteoporosis (OP) by absorbing miRNA-217 to regulate RUNX2 expression. PATIENTS AND METHODS: The serum levels of circ-VANGL1, miRNA-217 and RUNX2 in OP patients and non-OP patients were detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Their expression levels in human bone marrow mesenchymal stem cells (hBMSCs) at different time points of osteogenesis differentiation were determined as well. The expression levels of RUNX2 and osteogenic proteins (BSP, OCN, OPN) in hBMSCs were detected by Western blot. Dual-Luciferase reporter gene assay was performed to verify the relationship among circ-VANGL1, miRNA-217 and RUNX2. Alkaline phosphatase (ALP) staining was conducted to evaluate the degree of osteogenic differentiation influenced by circ-VANGL1 and miRNA-217. RESULTS: OP patients presented a higher serum level of miRNA-217 and lower serum levels of circ-VANGL1 and RUNX2 relative to non-OP patients. Circ-VANGL1 accelerated osteogenic differentiation by absorbing miRNA-217 to regulate RUNX2 expression. Moreover, miRNA-217 inhibited osteogenic differentiation by degrading RUNX2 by targeting to RUNX2 3'UTR. The overexpression of circ-VANGL1 upregulated expressions of RUNX2, BSP, OCN, and OPN. Meanwhile, ALP activity increased in hBMSCs overexpressing circ-VANGL1. However, co-overexpression of circ-VANGL1 and miRNA-217 did not alter RUNX2 expression. ALP activity in hBMSCs co-overexpressing circ-VANGL1 and miRNA-217 slightly increased, but had no difference with controls. CONCLUSIONS: Circ-VANGL1 promotes the development of OP via binding to miRNA-217 to downregulate RUNX2 expression.

CircRUNX2 through has-miR-203 regulates RUNX2 to prevent osteoporosis.

OBJECTIVE: We aimed to discover the molecular mechanism of hsa_circ_0076694 (circRUNX2) on osteogenic differentiation. We also explored the interaction between circRUNX2, miR-203 and RUNX2. METHODS: Clinical samples obtained from femoral neck fracture patients' bone tissues were used to collect circRUNX2, miR-203, and RUNX2 expression data, while their expression changes were observed in human bone mesenchymal stem cells (hBMSCs) during osteogenic differentiation. QRT-PCR and Western blot were used to analyse levels of RNAs and proteins. Biotin pull down, RIP, RNA FISH, and Dual-Luciferase Reporter assays demonstrated the relationship between circRUNX2, miR-203, and RUNX2. ALP and ARS staining were used to measure the degree of osteogenic differentiation under the control of circRUNX2, miR-203. RESULTS: CircRUNX2 were down-regulated in osteoporotic patients' bone tissues. CircRUNX2 could inhibit miR-203 expression by sponging miR-203. MiR-203 inhibited osteogenic differentiation by targeting the 3'-UTR of RUNX2 and down-regulate RUNX2 expression. Overexpression of circRUNX2 promoted the expression of osteogenic differentiation-related proteins such as RUNX2, OCN, OPN, BSP, and prevented osteoporosis. CONCLUSION: circRUNX2 could sponge miR-203 and enhance RUNX2 expression, thus circRUNX2 prevents osteoporosis and may provide a novel therapeutic strategy for it.

The intervention effect of zuogui pill on chronic kidney disease-mineral and bone disorder regulatory factor.

Chronic kidney disease-mineral and bone disorder (CKD-MBD) play a critical role in the pathogenesis of cardiovascular complications in patients with chronic kidney disease (CKD). Zuogui pill as a traditional Chinese herbal drug has been used for nourish kidney essence improve bone malnutrition of renal bone disease by regulating the metabolism of calcium and phosphorus and participating in osteoblast metabolism. In the present study, 5/6 nephrectomy rat model was used to reveal the mechanism of zuogui pill in treatment of CKD-MBD. Compared with sham rats, the levels of serum phosphorus, PTH, iPTH and creatinine were significantly decreased, while the serum calcium level was significantly increased, and the Cbfa1 protein level was significantly decreased and FGF23 protein level was significantly increased by Zuogui pill treatment. Compared with model rats, the BMD of rat was significantly increased by Zuogui pill treatment. Histological analysis revealed that the kidney injury of rats with CKD was significantly reduced by zuogui pill treatment. Compared with model rats, the CYP27B1 mRNA level was significantly increased, and the PTH mRNA level and NaPiIIa protein level were significantly decreased in the kidney by zuogui pill treatment. We inferred that zuogui pill exhibited potential therapeutic effects on CKD-MBD in the rats by regulating bone metabolism and nourish kidney.

Changes of Circulating MicroRNAs in Response to Treatment With Teriparatide or Denosumab in Postmenopausal Osteoporosis.

Context: Expression of microRNAs (miRs) related to bone metabolism in the serum may be affected by antiosteoporotic treatment. Objective: To investigate the effect of two antiosteoporotic agents with opposite effects on bone metabolism on miR expression profile in the serum. Design: Observational, open label, nonrandomized clinical trial. Setting: The outpatient clinics for Metabolic Bone Diseases of 424 General Military Hospital, Thessaloniki, Greece. Patients and Interventions: Postmenopausal women with low bone mass were treated with either teriparatide (TPTD; n = 30) or denosumab (n = 30) for 12 months. Main Outcome Measures: Changes in the serum expression of selected miRs linked to bone metabolism at 3 and 12 months of treatment. Secondary measurements: associations of measured miRs with changes in bone mineral density (BMD) at 12 months and the bone turnover markers (BTMs) C-terminal cross-linking telopeptide of type I collagen and procollagen type I N-terminal propeptide at 3 and 12 months. Results: We found significantly decreased relative expression of miR-33-3p at 3 months (P = 0.03) and of miR-133a at 12 months (P = 0.042) of TPTD treatment. BMD values at 12 months of TPTD treatment were significantly and inversely correlated with miR-124-3p expression at 3 months (P = 0.008). Relative expression of miR-24-3p and miR-27a was correlated with changes in BTMs during TPTD treatment and of miR-21-5p, miR-23a-3p, miR-26a-5p, miR-27a, miR-222-5p, and miR-335-5p with changes in BTMs during denosumab treatment. Conclusions: Circulating miRs are differentially affected by treatment with TPTD and denosumab. TPTD affects the relative expression of miRs related to the expression of RUNX-2 (miR-33) and DKK-1 gene (miR-133).

Increased baseline RUNX2, caspase 3 and p21 gene expressions in the peripheral blood of disease-modifying anti-rheumatic drug-naïve rheumatoid arthritis patients are associated with improved clinical response to methotrexate therapy.

OBJECTIVE: To investigate the potential of the baseline gene expression in the whole blood of disease-modifying anti-rheumatic drug-naïve rheumatoid arthritis (RA) patients for predicting the response to methotrexate (MTX) treatment. METHODS: Twenty-six control subjects and 40 RA patients were examined. Clinical, immunological and radiographic parameters were assessed before and after 24 months of follow-up. The gene expressions in the whole blood were measured using real-time reverse transcription polymerase chain reaction. The protein concentrations in peripheral blood mononuclear cells were quantified using enzyme-linked immunosorbent assay. Receiver operating characteristic curve analyses were used to suggest thresholds that were associated with the prediction of the response. RESULTS: Decreases in the disease activity at the end of the study were accompanied by significant increases in joint space narrowing score (JSN). Positive correlations between the expressions of the Unc-51-like kinase 1 (ULK1) and matrix metalloproteinase 9 (MMP-9) genes with the level of C-reactive protein and MMP-9 expression with Disease Activity Score of 28 joints (DAS28) and swollen joint count were noted at baseline. The baseline tumor necrosis factor (TNF)α gene expression was positively correlated with JSN at the end of the follow-up, whereas p21, caspase 3, and runt-related transcription factor (RUNX)2 were correlated with the ΔDAS28 values. CONCLUSIONS: Our results suggest that the expressions of MMP-9 and ULK1 might be associated with disease activity. Increased baseline gene expressions of RUNX2, p21 and caspase 3 in the peripheral blood might predict better responses to MTX therapy.

Dried Plum Ingestion Increases the Osteoblastogenic Capacity of Human Serum.

In cell culture studies, dried plum (Prunus domestica L.) polyphenols increased osteoblast alkaline phosphatase (ALP) activity, mineralized nodule formation, and the expression of the bone marker genes runt-related transcription factor 2 (RUNX2) and osterix. The purpose of this study was to determine whether human serum collected 1 and 2 h after dried plum ingestion influenced osteoblast cell activity and gene expression. Five healthy women ingested 100 g of dried plum, and serum samples were collected at baseline (before dried plum ingestion) and 1 and 2 h postingestion of dried plum. MC3T3-E1 osteoblast cells were treated (2% of medium) with these serum samples for 3 or 9 days. Intracellular and extracellular ALP activities were significantly increased after 3 or 9 days of treatment with serum both postingestion time points, with no effect seen in baseline samples. Also, serum obtained 1 and 2 h postingestion significantly increased the mRNA expression of bone markers RUNX2 and connexin43 (CX43) after both 3 and 9 days of incubation periods. Finally, serum obtained 1 and 2 h postingestion increased the mRNA expression of ß-catenin after 9 days of incubation. We conclude that osteoblast activity and function are increased by dried plum ingestion, which may, in part, explain its beneficial effects on bone health.

Evidence for Altered Canonical Wnt Signaling in the Trabecular Bone of Elderly Postmenopausal Women with Fragility Femoral Fracture.

Wnt signaling, a major regulator of bone formation and homeostasis, might be involved in the bone loss of osteoporotic patients and the consequent impaired response to fracture. Therefore we analyzed Wnt-related, osteogenic, and adipogenic genes in bone tissue of elderly postmenopausal women undergoing hip replacement for either femoral fracture or osteoarthritis. Bone specimens derived from the intertrochanteric region of the femurs of 25 women with fracture (F) and 29 with osteoarthritis without fracture (OA) were analyzed. Specific miRNAs were analyzed in bone and in matched blood samples. RUNX2, BGP, and OPG showed lower expression in F than in OA samples, while OSX, OPN, BSP, and RANKL were not different. Inhibitory genes of Wnt pathway were lower in F versus OA. ß-Catenin protein levels were higher in F versus OA, whereas its cotranscriptional regulator (Lef1) was lower in F group. miR-204, which targets RUNX2, and miR-130a, which inhibits PPARγ, were lower and higher, respectively, in F versus OA serum samples. The present study showed an inefficient Wnt signal transduction in F group despite higher ß-catenin protein levels, consistent with the expected overall postfracture systemic activation towards osteogenesis. This transcriptional inefficiency could contribute to the osteoporotic bone fragility.

Decreased local and systematic matrix Gla protein (MGP) expression and its link to radiographic progression in ankylosing spondylitis patients.

BACKGROUND: Decreased serum levels of uncarboxylated matrix Gla-protein (ucMGP) have been detected in Ankylosing Spondylitis (AS) patients. The current study was to investigate the expression of MGP in AS tissues as well as the relationship between serum ucMGP (an inactive form of MGP) levels and radiographic severity in AS patients. METHODS: Local MGP expression were assessed by Western blot and RT-PCR in hip synovial tissues from patients with AS and control subjects. In addition, the serum level of ucMGP was assessed by enzyme-linked immunosorbent assay in 68 healthy subjects and 62 patients with AS. The radiographic progression of AS was classified according to the radiographic events of modified New York Criteria for sacroiliac joint evaluation and modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) system for spine assessment. RESULTS: MGP expression was downregulated in AS patients compared to controls in hip tissues. Decreased levels of ucMGP in serum were found in AS patients compared with healthy controls. ucMGP levels in serum of AS patients were significantly negatively correlated with the disease radiographic severity evaluated by modified New York grading criteria (r = -0.293, p = 0.045) and mSASSS system (r = -0.361, p = 0.03). CONCLUSIONS: MGP expression is impaired in patients with AS. A low serum level of ucMGP in the setting of AS is linked to increased structural damage, emphasizing the role of MGP in the suppression of new bone formation.

Runx2 mRNA expression in the tissue, serum, and circulating non-hematopoietic cells of patients with thyroid cancer.

CONTEXT: Runx2, a master gene of osteogenic differentiation, is also expressed in nonosseous cancer cells. Microcalcifications are characteristic of papillary thyroid carcinoma and represent a useful find for diagnosis. However, the molecular expression of osteogenic differentiation transcription factor Runx2 has been poorly investigated in this tumor. OBJECTIVE: The aim of this study was to investigate Runx2 mRNA expression in normal and pathological thyroid tissue, serum, and circulating non-hematopoietic cells. SETTING: The study was performed in the Endocrine Unit of Internal Medicine of "Azienda Ospedaliera Universitaria Integrata of Verona" (Verona, Italy). PATIENTS: We enrolled 12 patients with a papillary thyroid carcinoma (PTC), who had undergone total thyroidectomy performed by the same surgeon. The results, obtained by real-time RT-PCR, were compared with biological samples obtained from 13 sex- and age-matched normal donors. RESULTS: Our data demonstrated that Runx2 mRNA is overexpressed (7.81-fold expression) in pathological thyroid tissue than in normal tissue (P < 0.05). Runx2 mRNA overexpression was also observed in serum and circulating non-hematopoietic cells of PTC patients with respect to normal donors (5.91-fold expression, P < 0.001; 3.82-fold expression, P < 0.05, respectively). We also observed that patients with microcalcifications expressed significantly higher levels of Runx2 mRNA in serum with respect to patients without microcalcifications (P < 0.05). CONCLUSION: This study can open up new research perspectives in the diagnosis and follow-up of PTC, even if further and larger cohort studies will be necessary to validate the Runx2 expression as biomarkers in thyroid cancer.

Poncirin prevents bone loss in glucocorticoid-induced osteoporosis in vivo and in vitro.

Poncirin, a flavonoid isolated from the fruit of Poncirus trifoliata, possesses anti-bacterial and anti-inflammatory activities. However, the action of poncirin in bone biology is unclear. In this study, the in vivo and in vitro effects of poncirin in a glucocorticoid-induced osteoporosis (GIO) mouse model were investigated. Seven-month-old male mice were assigned to the following five groups: (1) sham-implantation (sham), (2) prednisolone 2.1 mg/kg/day (GC), (3) GC treated with 10 mg/kg/day of genistein, (4) GC treated with 3 mg/kg/day of poncirin, (5) and GC treated with 10 mg/kg/day of strontium (GC + SrCl(2)). After 8 weeks, bone loss was measured by microcomputed tomography. Osteocalcin (OC) and C-terminal telopeptides of type I collagen (CTX) were evaluated in sera. Runx2 protein, OC and osteoprotegerin (OPG) mRNA expression, alkaline phosphatase (ALP) activity, and mineral nodule assay were performed in C3H10T1/2 or primary bone marrow stromal cells. Poncirin significantly increased the bone mineral density and improved the microarchitecture. Poncirin increased serum OC, Runx2 protein production, expression of OC and OPG mRNA, ALP activity, and mineral nodule formation; and decreased serum CTX. These effects were more prominent in the poncirin group compared to the other positive control groups (genistein and strontium). The poncirin-mediated restoration of biochemical bone markers, increased bone mineral density, and improved trabecular microarchitecture likely reflect increased bone formation and decreased bone resorption in GIO mice.

Changes in serum runt-related transcription factor 2 levels after a 6-month treatment with recombinant human parathyroid hormone in patients with osteoporosis.

BACKGROUND: The mechanisms regulating the anabolic response of the skeleton for recombinant human PTH (1- 34) [rhPTH (1-34)] administration has not been fully elucidated. AIM: The aim of this study was to evaluate the effect of rhPTH (1-34) on serum levels of runt-related transcription factor 2 (Runx2) in women with osteoporosis. METHODS: Sixty post-menopausal women with osteoporosis (EO group) and 45 control subjects (NC group) were enrolled in this study. The EO group received daily injection of 20 µg rhPTH (1-34) plus oral 500 mg elemental calcium and 400 IU vitamin D3 for 6 months. Runx2 and Matrix metalloproteinase 13 (MMP-13) were measured with commercially available enzyme-linked immunosorbent assay kits. Bone mineral density (BMD) was also measured before and 6 months after rhPTH (1-34) treatment. RESULTS: Serum total Ca2+, phosphate, and bone-specific alkaline phosphatase were significantly increased (p<0.05 or p<0.01), and the lumbar spine BMD (LS-BMD) was also increased by 4% in patients with osteoporosis after treatment with rhPTH (1-34) (p<0.05). On the contrary, serum Runx2 and MMP-13 were significantly decreased at post treatment (13.1% and 36.6%, respectively, p<0.05 and p<0.01). At baseline, serum Runx2 positively correlated with MMP-13 (r=0.74, p<0.01), the correction remained after adjusting for age and body mass index. CONCLUSION: The daily injection of rhPTH (1-34) was able to stimulate bone formation. The therapy of 20 µg rhPTH (1- 34) for 6 months resulted in decrease of serum Runx2 and MMP-13. These changes might reflect the increase of active osteoblasts and the better bone homeostasis.