Regulation of colorectal cancer cell epithelial to mesenchymal transition by the renin angiotensin system

Abstract

BACKGROUND AND AIM:

Epithelial to mesenchymal transition (EMT) is implicated in tumor progression. We aimed to determine if the renin angiotensin system has a role in colorectal cancer (CRC) cell EMT. METHODS:

Human CRC cell lines DLD-1 and LIM2405 were used in wound scratch migration assays where they were treated with renin angiotensin system peptide ANG II alone or with blockers of ANG II type 1 or 2 receptors (AT1R and AT2R). Levels of epithelial (E-cadherin), mesenchymal (ZEB1, Vimentin) markers, inducible nitric oxide synthase (iNOS), and MMP9 were determined by flow cytometry. Mice bearing CRC liver metastases and treated with blockers for AT1R or AT2R were examined for ZEB1 and iNOS by immunohistochemistry. RESULTS:

ANG II increased in-vitro CRC cell migration in both cell lines, this was inhibited by AT1R (IRB) or AT2R blockade (PD123319). DLD-1 cells treated with AT1R blocker resulted in increased E-cadherin, reduced ZEB1, and Vimentin expression compared with ANG II-treated cells. Treatment with AT2R blocker decreased E-cadherin, no change in ZEB1 or Vimentin expression. AT1R blockade increased iNOS and decreased MMP9 expression in DLD-1 and LIM2405 cells. AT2R blockade decreased iNOS and MMP9 expression in both cell lines. In vivo, ZEB1 staining was higher in ANG II-treated animals compared with control and AT1R blockade treated animals, while activation of the AT2R led to an increase in iNOS compared with control and AT1R blockade. CONCLUSIONS:

ANG II-induced migration of CRC cells via both AT1 and AT2 receptors; the AT1R-mediated effects were associated with changes typical of EMT.