Figure 1. Widespread glucocorticoid generation via 11β-HSD1 activity in healthy tissues and tumor cells.

(A) Simplified glucocorticoid synthetic pathway. Green arrows indicate enzyme-mediated steroid conversions required for de novo corticosterone biosynthesis from cholesterol, including corticosterone generation from its immediate precursor DOC by CYP11B1 (or P450c11β, encoded by Cyp11b1), orange indicates corticosterone generation from inactive metabolite DHC by 11β-HSD1 (Hsd11b1), and black indicates corticosterone inactivation to DHC by 11β-HSD2 (Hsd11b2). Pharmacological inhibitors are listed in order of decreasing specificity (PF-915275 [PF915]; carbenoxolone [CBX]; metyrapone [MET]) and are indicated along with their target enzymes. (B and C) Relative gene expression of Cyp11b1 and Hsd11b1 in adult mouse tissues. Data were acquired from BioGPS, and bars show the means of 2 or more samples per tissue. (D) Corticosterone production by mouse tumor cell lines. 5 × 10⁴ B16 melanoma, EL4 lymphoma, Panc02 pancreatic adenocarcinoma, MC38 colon carcinoma, and Lewis lung carcinoma cells were cultured for 45 minutes with 100 μM metyrapone or carbenoxolone and then cultured overnight with 100 nM DOC or DHC to test CYP11B1 or 11β-HSD1 activity, respectively. Supernatants were diluted in assay buffer and quantified via ELISA. (E) Hsd11b1 gene expression by mouse tumor cell lines. Total RNA was extracted from tumor cell lines and relative Hsd11b1 gene expression quantified via RT-qPCR, normalized to 18S RNA expression. D and E show the means of duplicate wells from 1 of 2 independent experiments. Supporting data are available in Supplemental Figure 1.