The Role of β-Catenin Signaling in the Malignant Potential of Cystitis Glandularis

Abstract

Chronic inflammation is a risk factor for malignant transformation in the bladder. The pro-inflammatory cytokine tumor necrosis factor-alpha (TNFalpha) is a mediator of such inflammation that induces nuclear localization of the adherens junction component beta-catenin. This mechanism has a key role in the initiation and progression of the premalignant lesion Barrett's metaplasia of the esophagus. Cystitis glandularis is a metaplastic lesion of the bladder urothelium occurring in the presence of chronic inflammation and in up to 13% of asymptomatic bladders. Two subtypes are described (typical and intestinal/colonic) with uncertain malignant potential. Etiologically and histologically cystitis glandularis mimics Barrett's metaplasia. We investigated the roles of beta-catenin and TNFalpha in cystitis glandularis. Immunohistochemistry and immunofluorescence were used to demonstrate the expression and localization of E-cadherin, beta-catenin and TNFalpha in 9 sections of typical cystitis glandularis and 4 of intestinal/colonic cystitis glandularis. Appropriate controls were used for all experiments. Immunohistochemistry demonstrated normal membranous expression of E-cadherin and beta-catenin in all cystitis glandularis sections with increased TNFalpha expression. Immunofluorescence showed nuclear localization of beta-catenin in the intestinal/colonic subtype only, which was not observed in typical cystitis glandularis. The presence of nuclear beta-catenin suggests that intestinal/colonic cystitis glandularis shares the same signaling pathway with the premalignant lesion Barrett's metaplasia of the esophagus and the intestinal/colonic subtype of cystitis glandularis may have the potential to progress to malignancy. This finding has important implications for the management of this lesion.