Figure 1.

Representative immunohistochemical-stained-sections of metastatic head and neck cutaneous squamous cell carcinoma tissue samples stained for components of the renin-angiotensin system. Angiotensinogen (A, brown) was expressed on cells within the tumor nests (TNs, arrows), and to a lesser degree in the peri-tumoral stroma (PTS, arrowheads). Renin (B, brown) was not present in the tissue samples. PRR (C, brown), demonstrated cytoplasmic expression of cells within the TNs (arrows), and to a lesser extent cells within the PTS (arrowheads) in two cases. ACE (D, brown) was expressed on the endothelium of the tumor microvessels within the PTS (arrowheads). ACE2 (E, brown) was not present in the tissue samples. AT₂R (F, brown) was expressed by cells within the TNs (arrows) and the PTS (arrowheads). Nuclei were counter-stained with hematoxylin (A–F, blue). Original magnification: 400×. n = 20.