Abstract. Human gliomas are a heterogeneous group of primary malignant brain tumors, which most commonly occur in the central nervous system of children and adults. Previous studies have suggested a prognostic role of matrix metalloproteinase 9 (MMP9) in glioma, however, the frequency and significance of the protein expression of MMP9 in glioma remain to be fully elucidated. In the present study, the expression of MMP9 was detected by reverse transcription-quantitative polymerase chain reaction (qPCR), western blotting and immunohistochemical staining. MTT and colony-forming assays were used to detect the role of MMP9 in the proliferation of glioma cells. MMP9 copy numbers in glioma were examined using qPCR. The results indicated that the expression level of MMP9 was significantly increased in glioma and was associated with World Health Organization (WHO) glioma grades. The high expression of MMP9 in tissues was an independent predictor of survival rates in patients with WHO grade III tumors. The overexpression of MMP9 promoted cell growth and induced a significant increase in clonogenic potential in U87 glioblastoma cell lines. These experimental data suggested that the overexpression of MMP9 in glioblastoma cells may occur primarily through an increase in gene copy number. The results of the present study suggested that the overexpression of MMP9 may be necessary for the transition to the more aggressive phenotype typical of WHO grade III gliomas, suggesting the likely involvement of the MMP9 gene in gliomagenesis and disease progression.
IntroductionHuman gliomas are a heterogeneous group of primary malignant brain tumors, which most commonly occur in the central nervous system of children and adults (1). Glioblastoma multiforme (GBM), the most aggressive form of glioma, exhibits advanced features of malignancy, including rapid tumor cell proliferation, apoptosis resistance, florid necrosis and angiogenesis (2). These tumor properties are associated with poor clinical outcome by conferring resistance to chemotherapy and radiotherapy, and by promoting neurological debilitation leading to individuals succumbing to mortality within 12-18 months of diagnosis (3).Gliomas can be categorized based on the type of glial cell, which they are most histologically similar to, the location of the tumor and the aggressiveness of the cancer cells. Tumors, which are most similar to astrocytes are specifically termed astrocytomas and can be further classified into grades I-IV based on the criteria set by the World Health Organization (WHO) (4), with higher grades corresponding to more aggressive tumors. Grade I and II astrocytomas correspond to low-grade tumors, which are predominantly non-malignant. Grade III and IV astrocytomas are high-grade, malignant tumors. Grade III astrocytomas are also known as anaplastic astrocytomas, whereas grade IV astrocytomas, commonly referred to as glioblastoma, are the most aggressive of all gliomas. GBMs are also the most common type of glioma with an annual incident rate of 3.19/100,000 in ...