Matrix metalloproteinases (MMPs) secreted by lung cancer (LC) and malignant mesothelioma (MM), especially MMP-2 and MMP-9, play crucial roles in tumor invasion and metastasis. We examined the effect of cytokines, mitogens and inhibitors on MMP-2 and MMP-9 expression in LC and MM cell lines. Human LC (A-549) and MM (MSTO-211H) cell lines were cultured in appropriate media. At near confluence, the cells were washed with PBS and incubated in serum-free medium with various concentrations of several cytokines, mitogens and inhibitors. After 24 h the media were removed and analyzed for MMP-2 and MMP-9 by gelatinase zymography and quantitated by densitometry. LC expressed MMP-2 whereas MM expressed MMP-2 and MMP-9. TNF-α, IL-1β, LPS and PMA, stimulated MMP-2 in LC and inhibited MMP-2 in MM, but had no effect on MMP-9. Doxycycline, EGCG and NM inhibited MMP-2 and MMP-9 expression, in both cell lines. Actinomycin-D, cyclohexamide, retinoic acid and dexamethasone inhibited MMP-2 in both cancer cell lines and inhibited MMP-9 in MM. Our results show that cytokines and inhibitors have an up- or down-regulatory effect on MMP-2 and MMP-9 expression in LC and MM, suggesting the clinical value of targeting these proteases for management of LC and MM and their pathogenesis.

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