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Induction of membrane-type-1 matrix
metalloproteinase by epidermal growth factor-mediated signaling in gliomas
Timothy E. Van Meter, William C. Broaddus, Harcharan K. Rooprai, Geoffrey
J. Pilkington, Helen L. Fillmore
Department of Neurosurgery, Medical
College of Virginia Campus, Virginia Commonwealth University, Richmond, VA
23298, USA (T.E.V., W.C.B., H.L.F); Institute of Biomedical and Biomolecular
Sciences, University of Portsmouth, School of Pharmacy and Biomedical Sciences,
St. Michael’s Building, White Swan Road, Portsmouth, Hampshire PO1 2DT,
England (H.K.R., G.J.P.); Cellular and Molecular Neuro-Oncology Research Group
(H.K.R., G.J.P.)
Increased expression of membrane-type matrix metalloproteinases (MT-MMPs) has
previously been reported to correlate with increasing grade of malignancy in
gliomas, a relationship shared with alterations in epidermal growth factor
receptor (EGFR) signaling.
To investigate the possibility of a causative role for EGFR signaling in
increasing MT-MMP expression and subsequent peritumoral proteolysis, we
characterized glioma cell lines for expression of MT1-MMP, MT2-MMP, MT3-MMP, and
MT5-MMP by Western blotting and by quantitative real-time polymerase chain
reaction analysis, and for MMP-2 activity following epidermal growth factor
(EGF) stimulation.
EGF stimulation of glioma cell lines resulted in a 2- to 4fold increase in
MT1-MMP mRNA levels.
Although there were slight differences in MT2-, MT3-, and MT5-MMP mRNA
expression following EGF stimulation, none of these demonstrated an increase
similar to that of MT1-MMP expression.
Treatment of high-grade glioma cell lines U251MG and IPSB-18 with EGF for 24 h
resulted in a several-fold increase in MT1-MMP protein (2.5- and 5.1-fold,
respectively) and in cyclin D1 (2.9-fold), as compared to untreated
controls.
No significant increase was detected in other MT-MMPs at the protein
level.
Although there was no detectable increase in proMMP-2 protein, there was an
increase in MMP-2 activity.
Furthermore, the MT1-MMP induction by EGF was prevented by pretreatment with the
EGFR-specific tyrphostin inhibitor AG1478.
Similarly, treatment with the phosphatidylinositol 3-kinase inhibitor LY294002
prevented the induction of MT1-MMP protein by EGF stimulation.
These compounds additionally inhibited EGF-stimulated invasion in Matrigel
Transwell assays.
Our results indicate that one mechanism of EGFR-mediated invasiveness in gliomas
may involve the induction of MT1-MMP.
© 2004 Duke University Press
Source: http://ninetta.ingentaselect.com/vl=12175410/cl=39/nw=1/rpsv/cgi-bin/linker?ini=dup_no&reqidx=/cw/dup/15228517/v6n3/s2/p188
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