Epidermal growth factor upregulates matrix metalloproteinase-7 expression through activation of PEA3 transcription factors

Abstract

MMP-7 is a member of the matrix metalloproteinase family and has been shown to be involved in early intestinal tumorigenesis. However, the factors which regulate MMP-7 gene transcription in the context of early colon cancer remain to be elucidated. Epidermal growth factor (EGF) and the EGF receptor have also been demonstrated to be important in the establishment of colon adenomas. We were therefore interested in addressing the question of whether MMP-7 could be regulated by EGF and in identifying the molecular mechanisms through which this process occurs. Herein, we have demonstrated that EGF enhanced the endogenous expression of MMP-7 in a number of human colon cancer cell lines. Analysis of the MMP-7 promoter sequence reveals the presence of a number of transcription factor binding sites including ETS and AP-1 sites. Results using PEA3, ETS and AP-1 artificial promoters showed that EGF enhanced PEA3 transcription factor activity by up to 70% in comparison to non-treated cell lines. Western blot analysis of nuclear extracts from EGF stimulated cells demonstrated that there was an increase in PEA3 protein when compared to non-treated cells. In addition, using a MAPK inhibitor we have shown that EGF can mediate this increase in PEA3 transcription factors via the MAPK pathway. Using EMSA analysis we also observed that the EGF stimulated increase in PEA3 transcription factors led to increased binding to specific ETS sites within the MMP-7 promoter. These data demonstrate for the first time that EGF directly enhances MMP-7 expression via the activation of PEA3 transcription factors.