Suppression of Invasion and MMP-9 Expression in NIH 3T3 and v-H-Ras 3T3 Fibroblasts by Lovastatin through Inhibition of Ras Isoprenylation

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Lovastatin, a hydroxymethylglutaryl coenzyme A reductase inhibitor, was found to block the synthesis of cholesterol and to affect posttranslational modification or isoprenylation, which is essential for membrane localization and biological activity of several proteins including Ras in the signal transduction pathway. Ras activates a multitude of downstream activities with roles in cellular processing, including invasion and metastasis. We investigated the anti-invasive activity of lovastatin in NIH 3T3 and v-H-Ras-transformed NIH 3T3 (v-H-Ras 3T3) cells. Lovastatin suppressed cell invasion in vitro in a dose-dependent manner. By zymographic assay, a decrease in matrix metalloproteinase-9 (MMP-9) activity but not matrix metalloproteinase-2 (MMP-2) activity by lovastatin was detected. RT-PCR demonstrated a reduction in gene expression of MMP-9 after treatment with lovastastin. To confirm the lovastatin-induced down-regulation of MMP-9 expression, we transfected an MMP-9/luciferase reporter vector, under MMP-9 promoter control, into both NIH 3T3 and v-H-Ras 3T3. A reduction in luciferase activity was observed with lovastatin treatment. In addition, lovastatin also reduced AP-1 and NFκB binding activities. These anti-invasive features were attenuated by the presence of mevalonate. These results suggest that down-regulation of MMP-9 contributes to the anti-invasive activity of lovastatin. Furthermore, we added exogenous mevalonate, which enhances the potency of cell invasion, and Ras farnesyltransferase inhibitor (manumycin A), which inhibits the potency of cell invasion. In accordance, Western blot analysis showed that lovastatin decreased membrane localization of Ras proteins. These data indicate that the anti-invasion activity of lovastatin happens through a decrease in Ras isoprenylation and functions.