Molecular mechanisms of nitric oxide-dependent inhibition of TPA-induced matrix metalloproteinase-9 (MMP-9) in MCF-7 cells

✍ Scribed by Christine Jespersen; Anke Doller; El-Sayed Akool; Malte Bachmann; Roswitha Müller; Paul Gutwein; Heiko Mühl; Josef Pfeilschifter; Wolfgang Eberhardt

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 379 KB
• Volume: 219
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.21658

✦ Synopsis

Abstract

Matrix metalloproteinase‐9 (MMP‐9) is implicated in the invasion and metastasis of breast cancer cells. We investigated the modulatory effects of nitric oxide (NO) on the 12‐O‐tetradecanoylphorbol 13‐acetate (TPA)‐induced MMP‐9 expression in MCF‐7 cells. Different chemical NO donors inhibited the extracellular content of TPA‐induced MMP‐9 protein and MMP‐9 activity as assessed by gelatin‐zymography and ELISA, respectively. Concomitant with the reduction in the extracellular MMP‐9 content NO strongly decreased the steady‐state levels of MMP‐9 mRNA which in turn leads to a lower recruitment of MMP‐9 transcripts to polysomes and to a diminished MMP‐9 translation. Reporter gene assays revealed that the inhibition in MMP‐9 expression by NO is mainly attributed to a 0.67 kb fragment of the 5′‐promoter region of the MMP‐9 gene but independent of the 3′untranslated region thus indicating that MMP‐9 suppression by NO mainly results from transcriptional events. Electrophoretic mobility shift assays (EMSA), showed that NO specifically interferes with the TPA‐induced DNA binding affinity of c‐Jun and c‐Fos without affecting the TPA‐induced increase in the levels of the transcription factors. Using pharmacological inhibitors and small interfering (si)RNA we found that PKCδ is indispensably involved in the TPA‐triggered MMP‐9 expression. Concomitantly, the TPA‐evoked increase in total PKC activity was strongly attenuated in the lysates from NO‐treated MCF‐7 cells, thus suggesting that NO attenuates TPA‐triggered MMP‐9 mainly through a direct inhibition of PKCδ. Modulation of MMP‐9 by NO highlights the complex roles of NO in the regulation of MMP‐9 in breast cancer cells. J. Cell. Physiol. 219: 276–287, 2009. © 2009 Wiley‐Liss, Inc.