Expression of Matrix Metalloproteinase-9 and CD34 in Giant Cell Tumor of Bone

Human Chorionic Gonadotropin Regulates the Smad Signaling Pathway by Antagonizing TGF-β in Giant Cell Tumor of Bone

BACKGROUND

Giant cell tumor of bone (GCTB) is a locally aggressive bone tumour aggravated by stromal cell proliferation and metastasis.

OBJECTIVE

We investigated the mechanism of action of human chorionic gonadotropin (HCG) in mediating GCTB proliferation and invasion.

METHODS

The expression of HCG was quantified using quantitative real-time PCR. After the primary stromal cells were isolated and identified, the function of HCG in GCTB was estimated using the cell counting kit-8, flow cytometry, scratch experiment, transwell assay, Western blot, and immunofluorescence. Moreover, the mechanism of HCG was assessed through western blotting.

RESULTS

HCG expression was decreased in clinical tissue samples from patients with GCTB. We validated that HCG repressed stromal cell proliferation, migration, invasion, autophagy, and epithelial- mesenchymal transition (EMT) and promoted cell apoptosis in GCTB. We also verified that HCG repressed the autophagy and EMT of stromal cells through the Smad signaling axis in GCTB. HCG inhibited the transduction of the Smad signaling pathway by restraining the binding of the TGF-β II receptor to ligand Activin A.

CONCLUSION

HCG restrained the Smad signaling pathway by antagonizing TGF-β signaling in GCTB. HCG may serve as a useful patent to treat GCTB.

Up-regulation of matrix metalloproteinase-9 in primary bone tumors and its association with tumor aggressiveness

BACKGROUND

Understanding the molecular mechanism underlying the pathophysiology of primary skeletal tumors is crucial due to the tumor-related complications, incidence at a young age, and tumor recurrence.

METHODS AND RESULTS

The local expression pattern of MMP-9 as an active matrix-degrading protease was detected in 180 bone tissues, including 90 tumors and 90 noncancerous tissues, utilizing real-time qRT-PCR at the mRNA level and immunohistochemistry at the protein level. The correlation of the MMP-9 expression level with the patient's clinical pathological characteristics and the aggressiveness of the tumor was evaluated. The diagnostic significance of MMP-9 and the model of association of variables and MMP-9 expression and their predictive values were determined. Mean mRNA expression was higher in all types of primary bone tumors than their paired non-cancerous tissues. Osteosarcoma and Ewing's sarcoma expressed higher levels of MMP-9 compared to benign giant cell tumors, and the MMP-9 expression level was significantly correlated with the size, metastasis, and recurrence of the malignant tumor. A consistent expression pattern was demonstrated for MMP-9 protein levels in tissues. In addition, the MMP-9 gene and protein levels significantly discriminate between bone tumors and normal tissue, as well as benign and malignant tumors, and could predict potentially malignant traits such as tumor grade and metastasis.

CONCLUSIONS

The data propose that MMP-9 may be involved in the proliferation and invasion of primary bone tumors and has the potential to monitor and treat the progression of malignant tumors.

Induction of autophagy by salidroside through the AMPK-mTOR pathway protects vascular endothelial cells from oxidative stress-induced apoptosis

Vascular endothelial cells are highly sensitive to oxidative stress, and this is one of the mechanisms by which widespread endothelial dysfunction is induced in most cardiovascular diseases and disorders. However, how these cells can survive in oxidative stress environments remains unclear. Salidroside, a traditional Chinese medicine, has been shown to confer vascular protective effects. We aimed to understand the role of autophagy and its regulatory mechanisms by treating human umbilical vein endothelial cells (HUVECs) with salidroside under oxidative stress. HUVECs were treated with salidroside and exposed to hydrogen peroxide (H₂O₂). The results indicated that salidroside exerted cytoprotective effects in an H₂O₂-induced HUVEC injury model and suppressed H₂O₂-induced apoptosis of HUVECs. Pretreatment with 3-methyladenine (3-MA), an autophagy inhibitor, increased oxidative stress-induced HUVEC apoptosis, while the autophagy activator rapamycin induced anti-apoptosis effects in HUVECs. Salidroside increased autophagy and decreased apoptosis of HUVECs in a dose-dependent manner under oxidative stress. Moreover, 3-MA attenuated salidroside-induced HUVEC autophagy and promoted apoptosis, whereas rapamycin had no additional effects compared with salidroside alone. Salidroside upregulated AMPK phosphorylation but downregulated mTOR phosphorylation under oxidative stress; however, administration of compound C, an AMPK inhibitor, abrogated AMPK phosphorylation and increased mTOR phosphorylation and apoptosis compared with salidroside alone. These results suggest that autophagy is a protective mechanism in HUVECs under oxidative stress and that salidroside might promote autophagy through activation of the AMPK pathway and downregulation of mTOR pathway.