Transglutaminase 2 promotes epithelial-to-mesenchymal transition by regulating the expression of matrix metalloproteinase 7 in colorectal cancer cells via the MEK/ERK signaling pathway

Abstract

Tissue transglutaminase 2 (TGM2) and matrix metalloproteinase 7 (MMP7) are suggested to be involved in cancer development and progression, however, their specific role in colon cancer remains elusive. The present study investigated whether TGM2 and MMP7 influence epithelial-mesenchymal-transition (EMT) processes of colon cancer cells. TGM2 was either overexpressed or knocked down in SW480 and HCT-116 cells, and MMP7 expression and activity analyzed. Conversely, MMP7 was silenced and its correlation with TGM2 expression and activity examined. Co-immunoprecipitation served to evaluate TGM2-MMP7-interaction. TGM2 and MMP7 expression were correlated with invasion, migration, EMT marker expression (E-cadherin, N-cadherin, Slug, Snail), and ERK/MEK signaling. TGM2 overexpression enhanced MMP7 expression and activity, promoted cell invasion, migration and EMT, characterized by increased N-cadherin and Snail/Slug expression. TGM2 knockdown resulted in the opposite effects. Knocking down MMP7 was associated with reduced TGM2 protein expression, cell invasion and migration. Down-regulation of MMP7 diminished ERK/MEK signaling, whereas its up-regulation activated this pathway. The ERK-inhibitor GDC-0994 blocked phosphorylation of MEK/ERK and suppressed TGM2 and MMP7. TGM2 communicates with MMP7 in colon cancer cells forces cell migration and invasion by the MEK/ERK signaling pathway and triggers EMT. Inhibiting TGM2 could thus offer new therapeutic options to treat patients with colon cancer, particularly to prevent metastatic progression.

Keywords: Epithelial-mesenchymal transition; Matrix metalloproteinase 7; Tissue transglutaminase 2; colon cancer.