Expression of Glucocorticoid Receptor and FOXO1/phospho-FOXO1 in Bladder Cancer as Independent Prognosticators

Cross-talk between forkhead box O1 (FOXO1), a transcriptional factor known to function as a tumor suppressor via the PI3K/AKT pathway, and glucocorticoid receptor (GR) has been implied in non-urothelial cells. The present study aimed to investigate the association of FOXO1 and GR expression in bladder cancer and its prognostic significance.

Immunohistochemical staining for GR, FOXO1, and p-FOXO1 (a phosphorylated/inactivated form) was performed in a set of bladder cancer tissue microarray comprising 50 low-grade non-invasive tumors, 28 high-grade non-muscle-invasive tumors, and 51 high-grade muscle-invasive tumors. Western blotting for FOXO1 and p-FOXO1 was also conducted in human bladder cancer cells.

GR expression was detected in 109 [84.5%; 39 (30.2%) weakly positive (1+), 39 (30.2%) moderately positive (2+), 31 (24.0%) strongly positive (3+)] tumors, whereas FOXO1 and p-FOXO1 were immunoreactive in 17 [13.2%; 16 (12.4%) 1+, 1 (0.8%) 2+] and 71 [55.0%; 57 (44.2%) 1+, 14 (10.9%) 2+] tumors, respectively. The expression levels of GR were positively and negatively correlated with those of FOXO1 (p=0.003) and p-FOXO1 (p=0.009), respectively. GR(0/1+)/FOXO1(0) and GR(0/1+)/p-FOXO1(1+/2+) were significantly more often observed in high-grade (vs. low-grade) or muscle-invasive (vs. non-muscle-invasive) tumors. Both univariate and multivariate analyses revealed that GR(0/1+)/FOXO1(0) and GR(0/1+)/p-FOXO1(1+/2+) were associated with a significantly higher risk for the recurrence of non-invasive disease or progression of muscle-invasive disease. In 2 GR-positive bladder cancer lines, glucocorticoids (i.e., dexamethasone, prednisone) and a GR antagonist (i.e., RU486) induced the levels of FOXO1 and p-FOXO1 expression, respectively.

The expression levels of GR and FOXO1 or p-FOXO1 were strongly correlated in bladder cancer. Specific GR/FOXO1 and GR/p-FOXO1 expression profiles served as independent predictors of disease recurrence or progression.