Local glucocorticoid signalling promotes pancreatic cancer
Pancreatic cancer (PC) represents one of the biggest challenges in terms of cancer treatment, mainly due to its continuously rising incidence, advanced stage at time of diagnosis, and dismal 5-year overall survival, which has not improved in recent decades despite the major advances made in oncological therapies. The limited progress in developing more effective therapies is, in part, attributable to the vast desmoplastic stroma present in PC. Additionally, immunosuppressive steroid-signalling has recently been shown to aid the development and metastasis of various tumour types. Therefore, we sought to explore whether local steroidogenesis and steroid signalling within the tumour microenvironment (TME) play a role in pancreatic cancer development. Reanalysis of publicly available datasets, including single cell RNA sequencing, as well as in vivo metastatic pancreatic ductal adenocarcinoma (PDAC) mouse models, allowed us to identify Hsd11b1 as the key enzyme responsible for locally elevated levels of the immunosuppressive glucocorticoid hormone, corticosterone. We identified fibroblasts as the major Hsd11b1-expressing populations in the pancreatic TME. Specifically, in mice, Hsd11b1 expression is primarily observed in iCAFs. Additionally, we found that patients with higher HSD11B1 expression present an increased mortality rate as well as an enriched fibrotic signature and inhibited immune activity. Collectively, these findings suggest that Hsd11b1 upregulation in iCAFs could be aiding PDAC development by promoting the activation of glucocorticoids directly in the TME. The presence of glucocorticoids inhibits inflammation and could also be enhancing local fibrosis by autocrine signalling in the fibroblast population. Given the urgent need for effective treatments in this fatal disease, targeting HSD11B1 represents a promising therapeutic strategy to overcome the immunosuppressive desmoplastic barrier and improve patient outcomes in pancreatic cancer.