Abstract
Lung cancer, the most prevalent cancer worldwide and malignant mesothelioma are highly aggressive tumors that are characterized by high levels of matrix metalloproteinase (MMP)-2 and -9 secretion. 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 u-PA 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 u-PA, MMPs and TIMPs on human lung and malignant mesothelioma (MM) cell lines. Human lung cancer (A-549 and Calu-3) and malignant mesothelioma (MSTO-211H) cell lines were cultured in their respective media and treated at confluence with NM at 0, 50, 100, 250, 500 and 1000 µg/ml. Analysis of u-PA activity was carried out by fibrin zymography, MMPs by gelatinase zymography and TIMPs by reverse zymography. Both lung cancer cell lines expressed u-PA, which was inhibited by NM in a dose-dependent manner. However, no bands corresponding to u-PA were detected for the MSTO-211H MM cell line. On gelatinase zymography, A-549 cells showed one band corresponding to MMP-2 and induction of MMP-9 with PMA (100 ng/ml) treatment. MSTO-211H showed two bands, an intense band corresponding to MMP-2 and a faint band corresponding to MMP-9; MMP-9 was enhanced significantly with PMA treatment. NM inhibited their expression in both cell lines in a dose-dependent manner. Calu-3 showed no MMP-2 or MMP-9 expression. Activity of TIMPs was upregulated by NM in all cancer cell lines in a dose-dependent manner. Analysis revealed a positive correlation between u-PA and MMPs and a negative correlation between u-PA/MMPs and TIMPs. These findings suggest the therapeutic potential of NM in the treatment of lung and mesothelioma cancers.