Fig 2: Tissue renin–angiotensin systems in endometrial cancer. In tumour tissue, upregulation of cathepsin D and (P)RR allows for greater activation of prorenin, potentially leading to increased enzymatic cleavage of Ang I from AGT. Additionally, increased ACE1 abundance may lead to increased production of the biologically active Ang II. Together, upregulation of the pro-angiogenic/pro-proliferative components may lead to increased activation of both (P)RR- and AGTR1-mediated intracellular signalling cascades to stimulate the production of TGFB1 and PI3KR1 and promote tumourigenesis. The role of increased ACE2 and presence of MAS1 and AGTR2 may enhance tumour development by stimulating vascularisation; however, this is unknown.

Fig 3: Tissue renin–angiotensin system cascade. Prorenin is activated by the (pro)renin receptor ((P)RR) and possibly by proteolysis, to cleave angiotensin (Ang) I from angiotensinogen (AGT). Angiotensin-converting enzyme (ACE) then converts Ang I to the biologically active Ang II. Ang II can bind to angiotensin II type 1 receptor (AGTR1) to promote proliferation, angiogenesis, fibrosis, migration and invasion through stimulation of growth factors and intracellular signalling pathways. Furthermore, angiotensin (Ang) II binds to angiotensin II type 2 receptor (AGTR2) and antagonises AGTR1 activation. Ang I can also be further converted by angiotensin-converting enzyme 2 (ACE2) to Ang(1–7). Ang(1–7) acts upon its receptor Mas. This results in antagonism of Ang II/AGTR1 stimulation, thus inhibiting proliferation, angiogenesis, fibrosis, migration and invasion.

Fig 4: Hepatic PRR knockdown attenuated MCD diet–induced liver fibrosis. (A) PRR mRNA expression in quiescent HSCs from normal chow (NC)-fed mice and in vivo–activated HSCs isolated from mice fed MCD diet for 12 weeks (n = 6 in each group). *P < .05 vs the quiescent HSC group. (B) Hepatic dual immunofluorescence of PRR and a-SMA in mice fed with NC or MCD diet. Scale bar: 100 µm. (C–H) MCD diet–fed mice were treated with lentiviral scramble shRNA or PRR shRNA (n = 6–8 in each group). Mice fed the NC diet (vehicle) and that received lentiviral-scramble shRNA served as controls (n = 6). (C) Western blot analysis of hepatic PRR levels and transcript expression of hepatic renin. (D) Sirius red staining of liver sections and quantification of the positively stained areas. Scale bar: 200 µm. (E) Hepatic hydroxyproline levels. (F) Western blot for a-SMA with quantitative analysis. (G) Hepatic transcript expression of profibrotic genes. The expression levels in the mice treated with vehicle and lentiviral scramble shRNA were assigned arbitrarily as 1. (H) Western blot analysis of phosphorylated and total ERK1/2, TGF-ß1, p-Smad3, and Smad3 in mouse livers. *P < .05 vs mice treated with vehicle and scramble virus. #P < .05 vs mice fed with MCD diet and scramble virus. DAPI, diamidino-2-phenylindole; NV, normal mice treated with vehicle; p-ERK, phosphorylated extracellular signal regulated kinase; p-SMAD3, phosphorylated SMAD3; t-ERK, total extracellular signal regulated kinase.

Fig 5: Hepatic PRR knockdown ameliorated TAA-induced liver fibrosis with suppression of ERK/TGF-ß1/Smad3 pathway. Vehicle or TAA-administered mice were treated with lentivirus-delivered scramble shRNA or PRR shRNA (n = 6–8 in each group). (A) Western blot of hepatic PRR levels (left) and expression of hepatic renin mRNA (right) in the 4 groups. (B) Representative images of liver sections after Sirius red staining for the quantification of positively stained area. Scale bar: 100 µm. (C) Hepatic hydroxyproline levels. (D) Western blot of a-SMA with quantitative analysis. (E) Hepatic transcript expression of Col1a1, PAI-1 (Serpine1), Timp1, and Fn1. The expression levels in mice treated with vehicle and scramble virus were assigned arbitrarily as 1. (F) Western blot analysis of phosphorylated and total ERK1/2 (p/t-ERK1/2), TGF-ß1, phosphorylated Smad3 (p-Smad3), and Smad3 in mouse livers. *P < .05 vs mice treated with vehicle and scramble virus. #P < .05 vs mice treated with TAA and scramble virus.