Modulation of uPA, MMPs and their inhibitors by a novel nutrient mixture in human glioblastoma cell lines

Abstract

Brain tumors are highly aggressive tumors that are characterized by high levels of matrix metalloproteinase (MMP)-2 and -9 secretions that degrade the extracellular matrix (ECM) and basement membrane, allowing cancer cells to spread to distal organs. Proteases play a key role in tumor cell invasion and metastasis by digesting the basement membrane and ECM components. Strong clinical and experimental evidence demonstrates association of elevated levels of urokinase plasminogen activators (uPA) and MMPs with cancer progression, metastasis and shortened patient survival. MMP activities are regulated by specific tissue inhibitors of metalloproteinases (TIMPs). Our main objective was to study the effect of a nutrient mixture (NM) on the activity of uPA, MMPs and TIMPs in various human gliomas. Human glioblastoma (LN-18, T-98G and A-172) cell lines (ATCC) were cultured in their respective media and treated at confluence with NM at 0, 50, 100, 250, 500 and 1000 μg/ml. Analysis of uPA activity was carried out by fibrin zymography, MMPs by gelatinase zymography and TIMPs by reverse zymography. Glioblastoma cell lines LN-18 and T-98G expressed uPA, which was inhibited by NM in a dose-dependent manner. However, no bands corresponding to uPA were detected for the A-172 cell line. On gelatinase zymography, all three cell lines showed bands corresponding to MMP-2 and LN-18 and T-98G showed PMA (100 ng/ml)-induced MMP-9. NM inhibited their expression in a dose-dependent manner. Activity of TIMP-2 was upregulated by NM in all glioma cell lines in a dose-dependent manner. Analysis revealed a positive correlation between uPA and MMP-2 and a negative correlation between uPA/MMPs and TIMP-2. These findings suggest the therapeutic potential of NM in the treatment of gliomas.