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.