摘要
Aim: There is increasing appreciation of the role of the renin-angiotensin system (RAS) in carcinogenesis with recent evidence showing expression of the RAS by cancer stem cells (CSCs) in different types of cancer. We have recently demonstrated the presence of three CSC subpopulations within metastatic melanoma (MM) to the brain: a Melan-A+ subpopulation and a Melan-A- subpopulation within the tumor that express OCT4, SALL4, SOX2 and NANOG;and a pSTAT3+ subpopulation localized to the CD34+ endothelium of microvessels within the tumor. In this study we investigated the expression and localization of components of the RAS in relation to these CSCs in MM to the brain. Methods: 3, 3-diaminobenzidine immunohistochemical (IHC) staining of components of the RAS: pro-renin receptor (PRR), angiotensin converting enzyme (ACE), angiotensin Ⅱ receptor 1 (ATIIR1) and angiotensin Ⅱ receptor 2 (ATIIR2) was performed on the same ten samples of MM to the brain included in our previous study. Immunofluorescence IHC staining of these components of the RAS was performed with embryonic stem cell markers OCT4 and NANOG, and endothelial marker CD34, on two of the samples of MM to the brain from the original cohort of ten patients. Western blotting (n = 5) and NanoString mRNA analysis (n = 4) were performed on samples of MM to the brain to confirm protein and mRNA expression of these components of the RAS, respectively. Results: DAB IHC staining showed the presence of PRR, ACE, ATIIR1 and ATIIR2 in all ten samples of MM to the brain. IF IHC staining showed that the CSC subpopulations in MM to the brain expressed PRR, ATIIR1 and ATIIR2;and a CSC subpopulation on the endothelium of the microvessels expressed ACE. Western blotting and NanoString mRNA analysis confirmed protein and mRNA expression of these components of the RAS, respectively. Conclusion: CSCs in MM to the brain expressed components of the RAS. Targeting the CSCs using modulators of the RAS may be a novel therapeutic approach for treating this aggressive cancer.
