Abstract 261: Epidermal growth factor receptor (EGFR)-mediated upregulation of matrix metalloproteinase-1(MMP-1) in glioblastoma cell lines involves multiple signaling pathways

Abstract

Abstract Glioblastoma Multiforme (GBM) is a devastating disease with an extremely poor prognosis primarily due to its invasive and infiltrative nature. Matrix metalloproteinases (MMPs) are important enzymes that regulate tumor microenvironment, alter cellular behavior and increase invasion and metastasis in wide variety of cancers. Previous studies from our laboratory have shown that MMP-1 is over expressed in GBM tissue and can influence glioma cell invasion in vitro. Since the epidermal growth factor receptor (EGFR) is amplified in human GBM, we wanted to determine the effect of EGFR activation by epidermal growth factor (EGF) on MMP-1 expression and invasion in human glioma cell lines and if so, determine the signaling mechanisms responsible for this induction. We stimulated glioma cell lines (T98 and U87) with EGF in the presence and absence of the EGFR inhibitor, AG1478. Inhibitors to multiple signaling pathways activated by EGFR induction were also used. All inhibitors tested were added to cells for 2 hrs prior to addition of EGF. In addition, transfections using AKT and STAT3 siRNA were conducted. Western Blotting was performed to examine the levels of MMP-1, EGFR, AKT, STAT3 and ERK. We observed that with EGF treatment, in addition to EGFR activation, AKT was phosphorylated, MMP-1 was induced and that in the presence of AG1478, AKT and EGFR phosphorylation was inhibited in a dose dependent manner. Importantly, MMP-1 up-regulation by EGF was abrogated in cells pretreated with AG1478. EGFR has been shown to up-regulate MAPK, PI3K and STAT3 pathways in glioma and other malignancies. Involvement of the MAPK pathway in the EGFR- mediated induction of MMP-1 was examined using the MAPK inhibitor, U0126. Only a modest decrease in MMP-1 levels was observed following treatment with EGF and U0126, suggesting potential inputs from other signaling pathways. Although there was a modest inhibition of AKT protein levels in cells treated with AKT siRNA, the levels of MMP-1 in these cells were significantly reduced. Current experiments focus on the role of AKT/PI3K and STAT3 signaling pathways in MMP-1 mediated glioma cell invasion. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 261.