Cancer stem cell subpopulations in metastatic melanoma to the brain express components of the renin-angiotensin system

Abstract

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-Asubpopulation 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.

Therapeutic Targeting of Cancer Stem Cells in Human Glioblastoma by Manipulating the Renin-Angiotensin System

“…The RAS was implicated in the hallmarks of cancer [67,68]. We demonstrated the expression of components of the RAS: PRR, ACE, ATIIR1 and ATIIR2 by CSCs in different cancer types including head and neck cutaneous squamous cell carcinoma (SCC) [69], oral cavity SCC (OCSCC) affecting the lip [70], buccal mucosa [71] and oral tongue [72], liver metastases from colon adenocarcinoma [73] and metastatic melanoma to the brain [74]. More importantly, components of the RAS: PRR, ATIIR1 and ATIIR2 were shown to be expressed by the CSCs in GB; with ACE, PRR, ATIIR1 and ATIIR2 localizing to the endothelium of the microvessels [75] (Figure 2).…”

Cancer Stem Cells in Head and Neck Cutaneous Squamous Cell Carcinoma Express Cathepsins

“…Recent reports demonstrate the expression of RAS on CSC components in many cancer types, including glioblastoma, 20 oral tongue 21 and buccal mucosal 22 SCC, metastatic colon adenocarcinoma, 15 and metastatic malignant melanoma. 24 Recent literature suggests a key role for the RAS in tumorigenesis, 29 – 31 with many studies demonstrating a reduced recurrence and overall increased survival of cancer patients who are administered RAS inhibitors. 48 , 49 We have recently shown the expression of the RAS components: PRR, ACE, AT 1 R, and AT 2 R by these CSC subpopulations in MDHNcSCC.…”

“…Expression of components of the renin–angiotensin system (RAS) by CSCs has been demonstrated in different cancer types, including glioblastoma, 20 OCSCC, 21 – 23 metastatic colon adenocarcinoma, 15 and metastatic malignant melanoma, 24 suggesting the potential of targeting CSCs by modulating the RAS. 25 , 26 …”

Therapeutic Targeting of Cancer Stem Cells in Human Glioblastoma by Manipulating the Renin-angiotensin System

“…The RAS has been implicated in the hallmarks of cancer (George, Thomas et al 2010, Wegman-Ostrosky, Soto-Reyes et al 2015. We have demonstrated the expression of components of the RAS: PRR, ACE, ATIIR1 and ATIIR2 by CSCs in different cancer types including head and neck cutaneous squamous cell carcinoma (SCC) (Nallaiah, Lee et al 2019), oral cavity SCC (OCSCC) affecting the lip (Ram, Brasch et al 2017), buccal mucosa (Featherston, Yu et al 2016) and oral tongue , liver metastases from colon adenocarcinoma (Narayanan, Wickremesekera et al 2019) and metastatic melanoma to the brain (Wickremesekera, Brasch et al 2019). More importantly, components of the RAS: PRR, ATIIR1 and ATIIR2 have been shown to be expressed by the CSCs in GB with ACE and also PRR, ATIIR1 and ATIIR2 localizing to the endothelium of the microvessels (Figure 2).…”

“…The concept of circulating CSCs and 'liquid biopsy" has been proposed as an alternative to obtaining histological specimens for diagnosis and molecular typing of the tumors (van Schaijik, Wickremesekera et al 2019). It presents an alternative mechanism local recurrence of GB, implicating epithelial-to-mesenchymal (EMT) and mesenchymal-to-epithelial (MET) transformational pathways (Fedele, Cerchia et al 2019), a paradigm counterintuitive to the concept of activation of regional noncirculating quiescent GB CSCs causing local recurrence of GB.…”