Cancer Stem Cells in Head and Neck Metastatic Malignant Melanoma Express Components of the Renin-Angiotensin System

Sam Siljee; Tessa Pilkington; Helen D Brasch; Nicholas Bockett; Josie Patel; Erin Paterson; Paul F Davis; Swee T Tan

doi:10.3390/life10110268

Cancer Stem Cells in Head and Neck Metastatic Malignant Melanoma Express Components of the Renin-Angiotensin System

Life (Basel). 2020 Nov 2;10(11):268. doi: 10.3390/life10110268.

Authors

Sam Siljee¹, Tessa Pilkington¹, Helen D Brasch¹, Nicholas Bockett¹, Josie Patel¹, Erin Paterson¹, Paul F Davis¹, Swee T Tan^{1

2

3}

Affiliations

¹ Gillies McIndoe Research Institute, Wellington 6021, New Zealand.
² Wellington Regional Plastic, Maxillofacial and Burns Unit, Hutt Hospital, Wellington 5010, New Zealand.
³ Department of Surgery, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria 3050, Australia.

Abstract

Components of the renin-angiotensin system (RAS) are expressed by cancer stem cells (CSCs) in many cancer types. We here investigated expression of the RAS by the CSC subpopulations in human head and neck metastatic malignant melanoma (HNmMM) tissue samples and HNmMM-derived primary cell lines. Immunohistochemical staining demonstrated expression of pro-renin receptor (PRR), angiotensin-converting enzyme (ACE), and angiotensin II receptor 2 (AT₂R) in all; renin in one; and ACE2 in none of the 20 HNmMM tissue samples. PRR was localized to cells within the tumor nests (TNs), while AT₂R was expressed by cells within the TNs and the peritumoral stroma (PTS). ACE was localized to the endothelium of the tumor microvessels within the PTS. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) detected transcripts for PRR, ACE, ACE2, and AT₁R, in all the five HNmMM tissue samples and four HNmMM-derived primary cell lines; renin in one tissue sample and one cell line, and AT₂R in none of the five HNmMM tissue samples and cell lines. Western blotting showed variable expression of ACE, PRR, and AT₂R, but not ACE2, in six HNmMM tissue samples and two HNmMM-derived primary cell lines. Immunofluorescence staining of two HNmMM tissue samples demonstrated expression of PRR and AT₂R by the SOX2+ CSCs within the TNs and the OCT4+ CSCs within the PTS, with ACE localized to the endothelium of the tumor microvessels within the PTS.

Keywords: angiotensin II receptor 1; angiotensin II receptor 2; angiotensin-converting enzyme; angiotensin-converting enzyme 2; cancer stem cells; head and neck; metastatic malignant melanoma; pro-renin receptor; renin; renin-angiotensin system.