Combined SET7/9 and CDK4 inhibition act synergistically against osteosarcoma.

Osteosarcoma is the most common malignant bone tumor. It has a poor prognosis because of a lack of therapeutic targets and strategies. The SET domain-containing lysine-specific methyltransferase, SET7/9, has various functions in different cancer types in tissue-type and signaling context-dependent manners. The role of SET7/9 in osteosarcoma cells is currently controversial and its potential as a therapeutic candidate in osteosarcoma is unknown. In the present study, SET7/9 inhibition or ablation suppressed osteosarcoma cell proliferation by causing G1 arrest. Mechanistically, SET7/9 inhibition disrupted the interaction between cyclin-dependent kinase 4 (CDK4) and cyclin D1, which affected CDK4-cyclin D1 complex function, leading to decreased phosphorylation of retinoblastoma protein. CDK4 was overexpressed in osteosarcoma tissues and was closely related to a poor prognosis in patients with osteosarcoma. We therefore hypothesized that SET7/9 inhibition might increase the sensitivity of osteosarcoma cells to CDK4 inhibitors, potentially decreasing the risk of adverse effects of CDK4 inhibitors. The combination of SET7/9 and CDK4 inhibition enabled dose reductions of both inhibitors and had a synergistic effect against osteosarcoma growth in vivo. Collectively, these findings indicate that SET7/9 plays an oncogenic role in osteosarcoma by regulating CDK4-cyclin D1 complex interaction and function. The combination of SET7/9 and CDK4 inhibition may thus provide a novel effective therapeutic strategy for osteosarcoma with no significant toxicity.

Syndecan-4 is a Novel Therapeutic Target for Intervertebral Disc Degeneration via Suppressing JNK/p53 Pathway.

Syndecan-4 is a member of the polysaccharide syndecan family and plays a vital role in intervertebral disc development. Several studies have demonstrated the positive relationship between syndecan-4 expression and intervertebral disc degeneration. However, the detailed molecular mechanism by which syndecan-4 affects the degeneration of nucleus pulposus cells (NPCs) remains unclear. In this study, cell viability was determined by CCK-8 assay, mRNA level was determined by qPCR, and protein expression was determined by western blot. Molecular interaction was determined by chromatin immunoprecipitation assay. A rabbit intervertebral disc degeneration model was established to test for syndecan in vivo. We found that the morphology and viability of NPCs were not affected by the expression of syndecan-4 in the long term. While the NPC function were affected, which results in the degeneration of intervertebral disc. Syndecan-4 overexpression promoted the degeneration of NPCs. Syndecan-4 also activated the JNK signaling pathway and downstream p53 pathways, and promoted degeneration. Inhibition of the JNK pathway, which down-regulated p53 expression, alleviated the degeneration. In an in vivo study, syndecan-4 siRNA injection stopped the development of rabbit disc degeneration, and even created a reverse effect, in which JNK/p53 played a role. Syndecan-4 may be a novel therapeutic target for intervertebral disc degeneration via suppressing the JNK/p53 pathway.

The role of TGF-ß1/Smad2/3 pathway in platelet-rich plasma in retarding intervertebral disc degeneration.

Recent studies have suggested that platelet-rich plasma (PRP) injections are an effective way to retard intervertebral disc degeneration, but the mechanism of action is unclear. Activated platelets release some growth factors, such as transforming growth factor-ß1 (TGF-ß1), which positively modulate the extracellular matrix of nucleus pulposus cells. The purpose of this study was to explore the mechanism underlying the PRP-mediated inhibition of intervertebral disc degeneration. In an in vitro study, we found that the proliferation of nucleus pulposus cells was greatly enhanced with 2.5% PRP treatment. The TGF-ß1 concentration was much higher after PRP treatment. PRP administration effectively increased the collagen II, aggrecan and sox-9 mRNA levels and decreased collagen X levels. However, Western blotting demonstrated that specifically inhibiting TGF-ß1 signalling could significantly prevent nucleus pulpous cellular expression of Smad2/3 and matrix protein. In a rabbit study, magnetic resonance imaging revealed significant recovery signal intensity in the intervertebral discs of the PRP injection group compared with the very low signal intensity in the control groups. Histologically, the PRP plus inhibitor injection group had significantly lower expression levels of Smad2/3 and collagen II than the PRP group. These results demonstrated that a high TGF-ß1 content in the platelets retarded disc degeneration in vitro and in vivo. Inhibiting the TGF-ß1/Smad2/3 pathway could prevent this recovery by inactivating Smad2/3 and down-regulating the extracellular matrix. Therefore, the TGF-ß1/Smad2/3 pathway might play a critical role in the ability of PRP to retard intervertebral disc degeneration.

TGF-ßl Suppresses Inflammation in Cell Therapy for Intervertebral Disc Degeneration.

Recent studies suggest that cell therapy may be an effective way to repair intervertebral disc degeneration. As a strong immune suppressor, TGF-ß1 has been shown to inhibit inflammation respond effectively. The objective of this study was to explore the effects of TGF-ß1 during bone marrow mesenchymal stem cells-based therapy for disc degeneration. In vitro assays demonstrated that co-culturing of nucleus pulposus cells with bone marrow mesenchymal stem cells resulted in significantly higher levels of TGF-ßl secretion. This increase inhibited IκB phosphorylation and NF-κB activation, detected by western blot analysis. Meanwhile, in a rabbit model, MRI analysis revealed significant recovery of signal intensity in the degenerative discs of rabbits receiving cells transplantation, than receiving cells treated with a TGF-ß1 inhibitor or saline. These findings indicated that enhanced TGF-ß1 production recovered the degeneration of intervertebral disc. And also immunohistochemical staining detected enhanced collagen II expression in the rabbits treated with cell transplantation. However, the NF-κB positive cells were significantly less than other two control groups. Thus, cell therapy promoted TGF-ß1 expression in nucleus pulposus, leading to anti-inflammatory effects via the inhibition of NF-κB, and the amelioration of disc degradation due to increased expression of collagen II and aggrecan in degenerative intervertebral disc.

The effects of platelet-rich plasma on the osteogenic induction of bone marrow mesenchymal stem cells.

Bone marrow mesenchymal stem cells (BMSCs) are multipotent stem cells. Finding methods to improve the osteogenic potential of these cells is a key factor in bone tissue engineering. Platelet-rich plasma (PRP) contains powerful growth factors that produce changes in a variety of cell types. The purpose of this study was to explore the effects of PRP on the osteogenic differentiation of BMSCs in vitro. Rabbit BMSCs were harvested and cultured in vitro in control media or in media enhanced with PRP. BMSCs began to attach 12-24 hours after seeding. A MTT assay demonstrated that PRP-induced BMSCs grew rapidly compared with the control group. The PRP group also showed strongly positive staining of alkaline phosphatase and mineralized nodules whereas the control group showed negative staining. However, the alkaline phosphatase activity and the mRNA level of the osteogenic markers (osteocalcin and osteopontin) remained higher in the PRP group. These results confirmed that PRP could enhance the proliferation of BMSCs and effectively promote the osteogenic differentiation of BMSCs in vitro.

Expression of insulin-like growth factor II mRNA-binding protein 3 (IMP3) in sacral chordoma.

Sacral chordoma is a rare and aggressive tumor, with a high rate of local recurrence even when the tumor is radically resected. The fundamental knowledge of its biological behavior remains unknown. Insulin-like growth factor II mRNA-binding protein 3 (IMP3) is one of the RNA binding proteins and is expressed during embryogenesis and in various malignant tumors. This study evaluated expression of IMP3 in sacral chordoma for association with patient's clinicopathological factors. A total of 32 patients with sacral chordoma (17 male and 15 female) and 10 samples of distant normal tissues were collected for analysis of IMP3 expression using immunohistochemistry. Association between IMP3 expression and clinicopathological factors (such as patient's age, gender, tumor location, tumor size, surrounding muscle invasion, Ki-67 expression, and tumor recurrence) were statistically analyzed. IMP3 was expressed in 20 (62.5%) patients, whereas there was no expression in the 10 distant normal tissues. IMP3 expression was associated with tumor invasion into the surrounding muscle (P = 0.028), high levels of Ki-67 expression (P = 0.009), and tumor recurrence (P = 0.012). The log-rank test revealed that patients with positive IMP3 expression had a shorter continuous disease-free survival time than those with negative IMP3 expression (P = 0.016). IMP3 expression was independent of age, gender, tumor location and tumor size. These results indicate that IMP3 was overexpressed in sacral chordoma and this expression was associated with tumor invasion and recurrence; thus, IMP3 may play an important role in tumor progression and could serve as a prognostic biomarker for sacral chordoma and IMP3 could be used as a potential therapeutic target for the treatment of sacral chordoma.

Isolation and osteogenic differentiation of skeletal muscle­derived stem cells for bone tissue engineering.

The purpose of this study was to investigate the isolation and culture of muscle­derived stem cells (MDSCs) and their capability to differentiate into osteoblasts in vitro. Skeletal muscle tissue was obtained from double hind limbs of New Zealand white rabbits under sterile conditions and isolated by collagenase digestion. Following passages in basic medium, the primary cells were desmin (+), myosin (+) and CD105 (+). Differentiation of MDSCs was induced by osteogenic medium. Using a 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyl tetrazolium bromide assay, the differentiated cell population was found to proliferate faster than the undifferentiated. Alkaline phosphatase staining and alizarin red staining revealed that the differentiated cells were mineralized in vitro. Quantitative polymerase chain reaction assays also showed increased mRNA expression of osteogenic genes in differentiated cells. In conclusion, stem cells were successfully isolated and cultured from rabbit skeletal muscle tissue and were able to differentiate into osteoblasts following induction. These observations may indicate an ideal stem cell source for tissue engineering.

Bone transport combined with locking plate and bone grafting for treatment of nonunion of the ulna: a case report.

STUDY DESIGN: Nonunion complicating ulna fracture surgery in one patient. OBJECTIVE: To treat nonunion of the ulna using bone transport combined with locking plate and bone grafting. METHODS: A 54-year-old male patient developing nonunion of the ulna 3 years after left ulna fracture surgery was included in this study. Bone transport combined with locking plate and bone grafting was applied to treat the patient, with the purpose of achieving the goal of bone healing at the site where nonunion occurred. RESULTS: Postoperative imaging data of the patient suggested bone healing at the site where nonunion and bone transport (by osteotomy) occurred. The patient had no special chief complaints and his forearm rotation functions were normal. CONCLUSION: Bone transport combined with locking plate and bone grafting can provide a new option for treatment of nonunion of the ulna.

Surgical treatment of giant cell tumors of the sacrum and spine combined with pre-operative transarterial embolization.

The pre-operative embolization of hypervascular spinal tumors is often performed to decrease intraoperative blood loss and facilitate tumor resection; however, few studies have been published on its effectiveness in giant cell tumors (GCT) of the sacrum and spine. The purpose of the present study was to investigate the value of surgical excision with pre-operative transarterial embolization for GCTs of the sacrum and spine, and to evaluate the follow-up outcomes. A retrospective study was performed on 28 patients with GCTs of the sacrum and spine, who underwent surgical treatment combined with pre-operative transarterial embolization between June 1995 and August 2011. The intraoperative blood loss, transfusion, duration of surgery, treatment, local recurrence, complications, follow-up status and functional outcome were reviewed. The average follow-up period was 86.3 months (range, 12-193 months). All the patients were treated with intralesional resection without any intraoperative shock or fatalities. The average intraoperative level of blood loss was 1,528.6 ml (range, 400-5,800 ml), the average transfusion volume was 1,514.3 ml (range, 400-6,000 ml) and the average duration of surgery was 225.4 min (range, 120-470 min). In total, eight (28.6%) patients developed recurrence and two patients succumbed. A total of eight (28.6%) patients experienced complications and 24 (85.7%) retained normal neurological function. Pre-operative embolization significantly decreases intraoperative blood loss and facilitates the maximal removal of the tumor. Pre-operative embolization followed by intralesional resection is able to achieve satisfactory local control and clinical outcomes. It is an effective technique for excising GCTs of the sacrum and spine.

Wide local excision and reconstructive surgery of desmoid tumour of the crus (Case report).

Extra-abdominal desmoid tumour is a rare type of tumour which is conventionally treated with wide local excision. However, wide local excision usually causes irreparable damage to the limbs. Nevertheless, few patients have been subjected to wide local excision and reconstructive surgery in a single procedure. A 52-year-old female reported a slow-growing lump in the right crus which had been growing for two years. The patient complained of persistent pain, especially at night, and was first subjected to lump resection in another hospital. The postoperative histopathological examination indicated muscle fibroma. Three months later, the lump recurred in the same position. The persistent pain induced by the tumour hampered her ability to walk. Wide local excision was conducted on the major parts of the gastrocnemius and soleus. After the pathological examination confirmed that the resection margin was negative, we performed reconstructive surgery on the Achilles tendon. The patient recovered plantarflexion function following the surgery and did not report any recurrence in the 6-year follow-up period. The desmoid tumour is a low-grade malignant tumour. Thus, the main focus of the treatment is to restore the function of the limbs to optimal capacity, such that the incidence of tumour recurrence is minimised.