Excessive mechanical stretch­mediated osteoblasts promote the catabolism and apoptosis of chondrocytes via the Wnt/ß­catenin signaling pathway.

Excessive biomechanical loading is considered an important cause of osteoarthritis. Although the mechanical responses of chondrocytes and osteoblasts have been investigated, their communication during mechanical loading and the underlying molecular mechanisms are not yet fully known. The present study investigated the effects of excessive mechanically stretched osteoblasts on the metabolism and apoptosis of chondrocytes, and also assessed the involvement of the Wnt/ß­catenin signaling pathway. In the present study, rat chondrocytes and osteoblasts were subjected to mechanical tensile strain, and an indirect chondrocyte­osteoblast co­culture model was established. Reverse transcription­quantitative PCR and western blotting were performed to determine the expression levels of genes and proteins of interest. An ELISA was performed to investigate the levels of cytokines, including matrix metalloproteinase (MMP) 13, MMP 3, interleukin­6 (IL­6) and prostaglandin E2 (PG E2), released from osteoblasts. Flow cytometry was performed to detect the apoptosis of chondrocytes exposed to stretched osteoblast conditioned culture medium. The levels of MMP 13, IL­6 and PG E2 increased significantly in the supernatants of stretched osteoblasts compared with the un­stretched group. By contrast, the mRNA expression levels of Collagen 1a and alkaline phosphatase were significantly decreased in osteoblasts subjected to mechanical stretch compared with the un­stretched group. The mRNA expression level of Collagen 2a was significantly decreased, whereas the expression levels of MMP 13 and a disintegrin and metalloproteinase with thrombospondin­like motifs 5 were significantly increased in chondrocytes subjected to mechanical stretch compared with the un­stretched group. In the co­culture model, the results indicated that excessive mechanically stretched osteoblasts induced the catabolism and apoptosis of chondrocytes, which was partly inhibited by Wnt inhibitor XAV­939. The results of the present study demonstrated that excessive mechanical stretch led to chondrocyte degradation and inhibited osteoblast osteogenic differentiation; furthermore, excessive mechanically stretched osteoblasts induced the catabolism and apoptosis of chondrocytes via the Wnt/ß­catenin signaling pathway.

Post-menopausal oestrogen deficiency induces osteoblast apoptosis via regulating HOTAIR/miRNA-138 signalling and suppressing TIMP1 expression.

In this study, we aimed to explore the molecular mechanisms underlying the development of osteoporosis in post-menopausal females. Real-time PCR was conducted to measure the expression of potential lncRNAs involved in the osteoporosis of post-menopausal females. In addition, Western blot and IHC assays were used to study the possible correlation among HOTAIR, miR-138 and TIMP1, while a computational analysis was carried out to predict the 'seed sequence' responsible for the binding between miR-138 and HOTAIR/TIMP1. Furthermore, luciferase reporter assays were conducted to validate the negative regulatory relationship between miR-138 and TIMP1/HOTAIR. To evaluate the effect of oestrogen on the function of HOATIR and its downstream effectors, luciferase activity was measured in cells cotransfected with different vectors or treated with different doses of oestrogen. The results of the luciferase assay were further validated by real-time PCR, Western blot, MTT assay and flow cytometry. Among the candidate lncRNAs, HOTAIR was the only lncRNA down-regulated in post-menopausal females. HOTAIR bound to miR-138 and negatively regulated its expression. Meanwhile, miR-138 could also bind to TIMP1 mRNA and reduce its expression. Furthermore, a dose-dependent up-regulation of HOTAIR was observed in cells treated with oestrogen, and the elevated HOTAIR increased the level of TIMP1 by targeting miR-138. In addition, oestrogen promoted cell viability and suppressed cell apoptosis, and effects of oestrogen were blocked by the silencing of HOTAIR. Therefore, it can be concluded that oestrogen deficiency could induce the apoptosis of osteoblasts and lead to osteoporosis in post-menopausal females via modulation of the HOTAIR/miR-138/TIMP1 signalling axis.

MicroRNA-425-5p promotes breast cancer cell growth by inducing PI3K/AKT signaling.

MicroRNA-425-5p (miR-425-5p) has been reported to be involved in the tumorigenesis of several tumors, but its function in breast cancer is still unknown. In this study, miR-425-5p was found significantly upregulated in breast cancer cells, and predicted a poor prognosis for breast cancer patients. Overexpression of miR-425-5p could significantly promote breast cancer cell growth. Further studies showed that overexpression of miR-425-5p upregulated the protein levels of Cyclin D1, Cyclin D3, CDK4, and CDK6. However, inhibiting miR-425-5p downregulated their expression and induced cell cycle arrest at G0/G1 phase. In mechanism, overexpression of miR-425-5p increased the phosphorylation of PI3K p85 and AKT, but inhibiting miR-425-5p displayed opposite effects. Moreover, miR-425-5p bound to the 3'UTR of PTEN mRNA, and downregulated the expression levels of PTEN in both mRNA and protein levels in breast cancer cells. Collectively, the results above demonstrated that miR-425-5p was involved in the tumorigenesis of breast cancer by inducing PI3K/AKT signaling and indicated that miR-425-5p could be as a potential target for breast cancer therapy in the future.

Intensity­dependent effect of treadmill running on differentiation of rat bone marrow stromal cells.

The effect of running on bone mass depends on its intensity. However, the underlying molecular mechanism that associates running intensity with bone mass is unclear. The current study examined the effects of treadmill running at different intensities on bone mass and osteogenic differentiation of bone marrow stromal cells (BMSCs) in a rat model. A total of 24 male Wistar rats were randomly divided into groups and subjected to no running (Con group), low­intensity running (LIR group), moderate­intensity running (MIR group), and high­intensity running (HIR group). Histological, immunohistochemistry and micro­CT examinations were performed on the femora harvested after 8 weeks of treadmill running. The study demonstrated that treadmill running affected trabecular bone mass in an intensity­dependent manner. In addition, such an intensity­dependent effect was also demonstrated on the osteogenic and adipogenic differentiation and proliferation of BMSCs. Furthermore, the Wnt/ß­catenin signaling pathway may be involved in the running­induced increase in bone mass in rats in the MIR group. There appears to be a biomechanical 'window', in which running­induced strain signals can increase the number of BMSCs and progenitor cells (specific to the osteoblast lineage) causing upregulation of osteogenesis and downregulation of adipogenesis of BMSCs. This finding may provide insight into the molecular and cellular mechanisms responsible for bone homeostasis.

Exercise affects biological characteristics of mesenchymal stromal cells derived from bone marrow and adipose tissue.

Both bone marrow mesenchymal stromal cells (BMSCs) and adipose-derived mesenchymal stromal cells (ADSCs) are good sources for tissue engineering. To maximize therapeutic efficacy of MSCs, an appropriate source of MSCs should be selected according to their own inherent characteristics for future clinical application. Hence, this study was conducted to compare proliferative, differential and antiapoptosis abilities of both MSCs derived from exercised and sedentary rats under normal and hypoxia/serum deprivation conditions (H/SD). Our results showed that exercise may enhance proliferative ability and decrease adipogenic ability of BMSCs and ADSCs. However, positive effect of exercise on osteogenesis was only observed for BMSCs in either environment. Little effect was observed on the antiapoptotic ability of both MSC types. It was also suggested that biological characteristics of both types were partly changed. It is therefore believed that BMSCs derived from exercised rat on early passage may be a good cell source for bone tissue engineering.

Periosteal osteosarcoma and Marfan's syndrome: A case report and literature review.

Periosteal osteosarcoma (POS) is a rare primary malignant bone tumor arising from the surface of long bones. In addition, Marfan's syndrome (MFS) is an infrequent hereditary autosomal dominant connective tissue disorder with high penetrance and variable phenotypes, which primarily affects the ocular, skeletal and cardiovascular systems. The present study reported a case of POS and MFS co-occurring in a child. A 6-year-old girl with MFS presented with pain, swelling and deformity in the right thigh following a fall. The patient was diagnosed with a right femoral shaft fracture and underwent open internal fixation surgery at a local hospital. At 2 weeks following surgery, the patient's parents observed increased swelling in the right thigh and thus, revisited the clinic. X-ray examination revealed extensive osteotylus around the fracture site and the clinician decided to remove the internal fixation. Following removal of the implant, aggravated swelling and superficial venous engorgement were observed. The patient was then admitted to Nanfang Hospital, where magnetic resonance imaging was performed, which identified symptoms of an abnormal periosteal reaction with bone erosion, indicating POS. The patient underwent a wide resection of the tumor and the histopathological examination confirmed the diagnosis of POS. No recurrence was identified at 9 months postoperatively. In conclusion, the present case report may result in increased awareness of the possibility of malignant bone tumors in a hereditary patient with osteotylus overgrowth following fracture surgery; in addition, the present case indicated a possible correlation between POS and MFS.

Hepatitis B surface antigen seroclearance in patients with chronic hepatitis B infection: a clinical study.

OBJECTIVE: To investigate the clinical characteristics of hepatitis B surface antigen (HBsAg) seroclearance in patients with chronic hepatitis B virus (HBV) infection. METHODS: Patients with chronic HBV infection who achieved sustained virological response (SVR) within 6 years of ceasing formal antiviral treatment were assessed for HBsAg seroclearance (defined as loss of serum HBsAg on repeated testing for a period of >6 months), using enzyme immunoassays. Phase of HBV infection and liver function (serum alanine aminotransferase [ALT] and aspartate aminotransferase [AST] levels) and HBV DNA levels were also assessed. RESULTS: In total, 272 patients with chronic HBV and SVR were included; HBsAg seroclearance was achieved in 42 patients and not achieved in 230 patients. Serum HBsAg and ALT levels, ratios of HBsAg to HBV DNA and ratios of AST to ALT were significantly different between patients achieving, and not achieving, HBsAg seroclearance. The area under the receiver operating characteristic (ROC) curve of HBsAg levels for predicting the likelihood of HBsAg seroclearance was 0.85; the cut-off value was 203.86 IU/ml. CONCLUSIONS: These data demonstrate that HBsAg seroclearance was independently associated with host immunity, serum HBsAg level, serum ALT level, serum HBsAg to HBV DNA ratio and timing of drug therapy within the course of chronic HBV infection.

Effect of p27mt gene on apoptosis of the colorectal cancer cell line Lovo.

AIM: To construct p27mt recombinant adenovirus, transfect the colorectal cell line Lovo and observe the effects of p27mt on Lovo cell apoptosis and cell cycle inhibition. METHODS: We constructed recombinant adenovirus containing p27mt by homologous recombination in bacteria. The colorectal cancer cell line Lovo was infected with recombinant replication-defective adenovirus Ad-p27mt, and expression of p27mt was determined by Western blotting; the inhibitory effect of p27mt on Lovo cells was detected by cytometry. Cell cycle was determined by flow cytometry. DNA fragment analysis identified the occurrence of apoptosis. RESULTS: The recombinant adenovirus which already contained p27mt target gene was successfully constructed. When multiplicity of infection was >or= 50, the infection efficiency was 100%. After transfection of Lovo cells with Ad-p27mt the cells had high p27 expression which was identified by immunoblotting assay. PI staining and flow cytometry showed that 77.96% of colorectal cancer cells were inhibited in phase G(0)/G(1), while in the Ad-LacZ group and blank control group, 27.57% and 25.29% cells were inhibited in the same phase, respectively. DNA fragment analysis, flow cytometry and TUNEL assay demonstrated that p27mt is able to induce apoptosis in colorectal cancer cells. CONCLUSION: p27mt has an obvious blocking effect on colorectal cancer cell cycle, and most cells were inhibited in phase G(0)/G(1). Therefore, p27mt can induce apoptosis in colorectal cells.

Impact of p27mt gene on transplantation model of human colorectal cancer in nude mice.

AIM: To investigate the inhibitory and anti-metastatic effect of mutant p27 gene (p27mt) on the growth of colorectal cancer xenografts in nude mice and its underlying mechanism. METHODS: Inhibitory effect of p27mt gene on the growth of colorectal cancer xenografts was determined by measurement of tumor size before and after direct intra-tumoral injection of Ad-p27mt in a pre-established transplantation model of human colorectal cancer in nude mice. Cell cycle and apoptosis were detected by flow cytometry performed on single-cell suspension from an isolated tumor. Expression of MMP-9 in tumor tissue was detected by immunohistochemistry. RESULTS: The average sizes of transplantation tumors were 1.94 +/- 0.67 cm(3), 2.75 +/- 0.83 cm(3) and 3.01 +/- 0.76 cm(3) in the Ad-p27mt, Ad-LacZ and control groups, respectively (P < 0.05). The average proliferation rates were 37.34% +/- 1.45%, 53.16% +/- 3.27% and 54.48% +/- 2.43%, in the Ad-p27mt, Ad-LacZ and control groups, respectively (P < 0.05). The average apoptosis rates were 19.79% +/- 3.32%, 6.38% +/- 4.91% and 7.25% +/- 5.20% in the Ad-p27mt, Ad-LacZ and control groups, respectively (P < 0.01). The average MMP-9 expression rates were 20%, 75% and 66.7% in the Ad-p27mt, Ad-LacZ and control groups, respectively (P < 0.01). CONCLUSION: p27mt inhibits the growth of transplanted tumor by blocking the proliferation of cancer xenografts and by promoting apoptosis of transplantated tumor cells, as well as decrease transpl-anted tumor metastasis.

Antitumor bioactivity of adenovirus-mediated p27mt in colorectal cancer cell line SW480.

AIM: To explore the antitumor bioactivity of adenovirus-mediated mutant type p27(kip1) gene in a colorectal cancer cell line SW480. METHODS: We constructed recombinant adenovirus vector expressing a mutant type p27(kip1) gene (ad-p27mt), with mutation of Thr-187/Pro-188 (ACGCCC) to Met-187/Ile-188 (ATGATC), and transduced into SW480 cells. Then we detected expression of p27, Bcl-2 and Bax protein in the transductants by Western blotting, cell cycle of transductants by a digital flow cytometric system, migrating potential with Boyden Chamber and SW480 tumor cell growth inhibition in vitro and in vivo. RESULTS: We found that a recombinant adenovirus vector of expressing ad-p27mt, with mutation of Thr-187/Pro-188 (ACGCCC) to Met-187/Ile-188 (ATGATC) has potent inhibition of SW480 tumor cell growth in vitro and in vivo. Furthermore, ad-p27mt induced cell apoptosis via regulating bax and bcl-2 expressions, and G(1)/S arrest in SW480 cells and inhibited cell migration. CONCLUSION: ad-p27mt has a strong anti-tumor bioactivity and has the potential to develop into new therapeutic agents for colorectal cancer.