Uroplakin Gene Expression by Normal and Neoplastic Human Urothelium

Abstract

cDNA sequences for human uroplakins UPIa, UPIb, UPII, and UPIII were cloned and used to investigate uroplakin transcription by normal and neoplastic urothelial cells. Normal urothelium expressed mRNA for all four uroplakins, although UPIII could be detected only by ribonuclease protection assay. By in situ hybridization, UPIa and UPII were confined to superficial cells and UPIb was also expressed by intermediate cells. Cultured normal human urothelial cells showed a proliferative basal/intermediate cell phenotype and constitutive expression of UPIb only. Uroplakin expression by transitional cell carcinoma cell lines was related to their differentiated phenotype in vitro. RT4 cells expressed all uroplakins, VM-CUB-3 expressed three uroplakins, RT112 and HT1376 cells expressed only UPIb in high abundance, and COLO232, KK47, and EJ cells had no detectable expression. These results correlated with patterns of uroplakin expression in tumors. UPIa and UPII were detected superficially only in well differentiated transitional cell carcinoma papillae. UPIb was positive in seven of nine and overexpressed in five of nine noninvasive transitional cell carcinomas and was also present in four of eight invasive transitional cell carcinomas. Lymph node metastases retained the same pattern of UPIb expression as the primary tumor. Unlike the three differentiation-regulated uroplakins, UPIb may have an alternative role in urothelial cell/tissue processes.

FOXA1 and IRF-1 intermediary transcriptional regulators of PPARγ-induced urothelial cytodifferentiation

“…6 UPK1b is the least differentiation-restricted of the uroplakins, being expressed by proliferating NHU cells and overexpressed in 50% superficial urothelial cell carcinomas, suggesting it may have an alternative function in non-differentiated urothelium. 10 The specific immunolocalisation of both FOXA1 and IRF-1 to the nuclei of suprabasally-positioned urothelial cells in situ is consistent with a role in cytodifferentiation. This is the first report of FOXA1 and IRF-1 localisation in human urothelium, although FOXA1 expression has been demonstrated previously in bladder, prostate and other epithelial tissues in the adult rat, and is expressed throughout the urothelium of the renal pelvis in adult mice 21 and in the developing mouse lung and bladder.…”

“…The urothelium is comprised of basal, intermediate and superficial cell zones, which may be distinguished on the basis of differential cytokeratin (CK) 8 and claudin 9 isotype expression profiles and by the expression of urothelium-specific uroplakins (UPK) by the superficial cells. 10,11 Whereas claudins are components of the intercellular tight junctions that determine paracellular barrier function, the uroplakins interact to form characteristic asymmetric unit membrane (AUM) plaques in the superficial apical membrane, which contribute to transcellular barrier function. 12 Although there has been considerable progress towards understanding the molecular basis of AUM plaque development, 13 by contrast, very little is known of the signalling mechanisms that drive the process of urothelial cytodifferentiation.…”

“…9,10,15 Previously, we have shown that in EGFR-inhibited NHU cell cultures, the specific activation of PPARg results in the induction of a programme of differentiation, leading eventually to de novo expression of late/terminal differentiation markers, including UPK1a, UPK2, UPK3a, CK20 and claudin 3. 6,7,9 We proposed that the PPARg-mediated induction of differentiation in NHU cells was indirect for two reasons: (a) the induction of late/terminal differentiation markers was first detected several days after PPARg activation and only reached a maximum after 4 days and (b) bioinformatics analysis did not identify high-affinity PPRE-binding sites within the upstream promoter regions of the uroplakin, CK13 and CK20 genes.…”

Persistent uroplakin expression in advanced urothelial carcinomas: implications in urothelial tumor progression and clinical outcome

“…This was proven to be the case in cultured normal urothelial cells, where incomplete differentiation and/or hyper-proliferation led to a profound reduction of all UPs, particularly on a protein level (22). Similarly, in a number of human bladder cancer cell lines, UPs are either down-regulated (RT4, RT112) or undetectable (J82, T24) (23) [unpublished observation]. These results suggest that, like many epithelial differentiation markers, UP expression is profoundly perturbed and/or down-regulated during urothelial transformation.…”

Mesenchymal Stem Cells for Cell Therapy and Tissue Regeneration in Urology

“…It is now possible to expand a urothelial strain from a single surgical specimen that initially covers a surface area of 1 cm 2 to one covering a surface area of 4202 m 2 (the equivalent area of one football field) within 8 weeks 17 . Now, normal human bladder epithelial and muscle cells can be efficiently harvested from surgical material, extensively expanded in culture, and their differentiation characteristics, growth requirements, and other biologic properties can be studied 17,19,20,[31][32][33][34][35][36][37][38][39][40] . In addition, human urothelial and muscle cells can attach and form sheets of cells when seeded onto polymer scaffolds.…”