LAUSR

0123456789();: Nature reviews | Urology ACE2 over­ expression in subcutaneous 786­ O xeno­ grafts in mice delayed tumour formation Targeting the angiotensinconverting enzyme 2 (ACE2)–angiotensin (Ang)-(1–7) pathway could be a promising therapeutic strategy in clear cell renal cell carcinoma (ccRCC) and could help extend the usefulness of VEGFRtyrosine kinase inhibitor (TKI) therapy, according to new data published in Science Translational Medicine. Increased expression of ACE2 (an enzyme that belongs to the renin–angiotensin system) has been shown to prevent tumour growth and epithelialtomesenchymal transition in preclinical models of cancer. ACE2 generates Ang-(1-7), a heptapeptide that has been shown to act through the MAS receptor. Khanna and colleagues observed that increased ACE2 expression in 533 tumour samples from The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma database correlated with significantly improved survival outcomes, including overall survival, diseasespecific survival and progressionfree interval, which were independent of gender, cancer stage and cancer grade on multivariable analysis. Samples from the top and bottom quartiles of ACE2 expression were then subjected to transcriptomic analysis, which revealed 298 significantly upregulated genes and 103 significantly downregulated genes associated with high ACE2 expression. Gene ontology and pathway enrichment analysis showed effects on biological categories associated with multiple transporters and biosynthesis and metabolism of multiple metabolites. Further pathway enrichment analysis revealed a significant effect of increased ACE2 expression on multiple metabolic, inflammatory and cardiovascular signalling pathways. Stable or transient overexpression of ACE2 in A498 and 786O ccRCC cell lines reduced the number of colonies formed and the total area colonized in vitro. Delineation of the downstream modulators of ACE2 enzymatic activity showed that sunitinib treatment did not affect expression of MAS. Treatment of ACE2overexpressing cells with a MAS blocker (A779) reversed the reduction in cell proliferation caused by ACE2 overexpression. In A498 and 786O cells, treatment with Ang-(1–7) increased intracellular cAMP in a concentrationdependent manner and reduced the number of colonies formed by A498 cells. In vivo, ACE2 overexpression in subcutaneous 786O xenografts in mice delayed tumour formation. Further in vivo experiments showed that sunitinib treatment of A498 cellderived ccRCC xenografts caused reduced ACE2 protein expression and enzymatic activity, which was shown by quantification of Ang-(1–7) generation in membranes isolated from tumour tissue. Combination treatment of A498 and 786O xenografts with sunitinib and Ang-(1–7) reduced tumour growth compared with sunitinib alone and blocking MAS with A779 reversed this effect. In a syngeneic mouse RCC model (RENCA), treatment with an antiPDL1 antibody (BioXCell, #BE0101) plus a VEGFRTKI (axitinib) plus Ang-(1–7) significantly reduced tumour growth compared with combination treatment with only axitinib plus antiPDL1. These results suggest that targeting the ACE2–Ang-(1–7) axis could be a promising treatment option for patients with ccRCC, especially in combination with VEGFRTKIs and antiPDL1 therapies.