Cancer stem cells in liver metastasis from colon adenocarcinoma express components of the renin-angiotensin system

Abstract

Aim: We have recently identified a cancer stem cell (CSC) subpopulations within the tumor nests (TNs) and another within the peritumoral stroma (PTS) in liver metastasis from colon adenocarcinoma (LMCA). This study investigated the expression of components of the renin-angiotensin (RAS): pro-renin receptor (PRR), angiotensin converting enzyme (ACE), and angiotensin II receptor 1 (ATIIR1) and angiotensin II receptor 2 (ATIIR2) in LMCA.Methods: 3,3-Diaminobenzidine (DAB) immunohistochemical (IHC) staining was performed on 16 LMCA samples for PRR, ACE, ATIIR1 and ATIIR2. Immunofluorescence (IF) IHC staining was performed to investigate co-expression of these components of the RAS with SOX2 or OCT4. NanoString analysis (n = 6) and Western blotting (WB, n = 3) were performed on snap-frozen LMCA samples to confirm mRNA and protein expression, respectively.Results: DAB IHC staining showed the expression of PRR, ACE, ATIIR1 and ATIIR2 within all LMCA samples. NanoString analysis and WB confirmed gene and protein expression of these components of the RAS. IF IHC staining demonstrated expression of PRR, ATIIR1 and ATIIR2 by the SOX2+ CSCs within the TNs and the OCT4+ CSCs within the PTS. ACE was expressed on the endothelium of the microvessels within the PTS.Conclusion: These finding suggests the CSCs within LMCA maybe a novel therapeutic target by manipulation of the RAS