Cytokeratin expression patterns in normal and malignant urothelium, a review of the biological and diagnostic implications

The cytokeratins are the intermediate filament proteins characteristic of epithelial cells. In human cells, some 20 different cytokeratin isotypes have been identified. Epithelia1 cells express between two and ten cytokeratin isotypes and the consequent profile which reflects both epithelial type and differentiation status may be useful in tumour diagnosis. The transitional epithelium or urothelium of the urinary tract shows alterations in the expression and configuration of cytokeratin isotypes related to stratification and differentiation. In transitional cell carcinoma, changes in cytokeratin profile may provide information of potential diagnostic and prognostic significance. The intensification of immunolabelling with some CK8 and CK18 antibodies may underly an active role in tumour invasion and foci of CK17-positive cells may represent proliferating populations. Loss of CK13 is a marker of grade and stage and de novo expression of CK14 is indicative of squamous differentiation and an unfavourable prognosis. However, perhaps the most important recent finding is the demonstration that a normal CK20 expression pattern is predictive of tumour non-recurrence and can be used to make an objective differential diagnosis between transitional cell papilloma and carcinoma. This review will consider cytokeratin expression in urothelium and discuss the application of cytokeratin typing to the diagnosis and prognosis of patients with TCC

Differentiation potential of urothelium from patients with benign bladder dysfunction

OBJECTIVE : To develop a novel in vitro approach to test the hypothesis that failure of urothelial differentiation underlies the aetiopathology of interstitial cystitis (IC), where there is evidence of compromised urinary barrier function, as benign dysfunctional bladder disease encompass several poorly understood clinically defined conditions, including IC, idiopathic detrusor overactivity (IDO) and stress urinary incontinence (SUI). MATERIALS AND METHODS : Biopsy-derived urothelial cells from dysfunctional bladder biopsies were propagated as finite cell lines and examined for their capacity to differentiate in vitro, as assessed by the acquisition of a transitional cell morphology, a switch from a cytokeratin (CK)13lo/CK14hi to a CK13hi/CK14lo phenotype, expression of claudin 3, 4 and 5 proteins, and induction of uroplakin gene transcription. RESULTS : Two of 12 SUI cell lines showed early senescent changes in culture and were not characterized further; one of seven IC, one of five IDO and a further three SUI cell lines had some evidence of senescence at passage 3. Of the seven IC-derived cell lines, four showed a near normal range of differentiation-associated responses, but the remainder showed little or no response. Most IDO cell lines (four of five) showed a normal differentiation response, but at least three of the 10 SUI cell lines showed some compromise of differentiation potential. CONCLUSION : This study supports the existence of a subset of patients with IC in whom a failure of urothelial cytodifferentiation might contribute to the disease, and provides a novel platform for investigating the cell biology of urothelium from SUI and other benign dysfunctional conditions

Role of PPAR? and EGFR signalling in the urothelial terminal differentiation programme

Recently, considerable interest has focused on the ability of activated peroxisome proliferator-activated receptor (PPAR) to promote cytodifferentiation in adipocytes and some carcinoma cells; however, the role of PPAR in normal epithelial cytodifferentiation is unknown. Using uroplakin (UP) gene expression as a specific correlate of terminal urothelial cytodifferentiation, we investigated the differentiation-inducing effects of PPAR activation in normal human urothelial (NHU) cells grown as finite cell lines in monoculture. Two high-affinity activators of PPAR, troglitazone (TZ) and rosiglitazone (RZ) induced the expression of mRNA for UPII and UPIb and, to a lesser extent, UPIa. The specificity of the effect was shown by pretreating cells with a PPAR antagonist, GW9662, which attenuated the TZ-induced response in a dose-specific manner. The PPAR-mediated effect on UP gene expression was maximal when there was concurrent inhibition of autocrine-activated epidermal growth factor receptor (EGFR) signalling through either the phosphatidylinositol 3-kinase or extracellular signal-regulated kinase (ERK) pathways. The use of a specific EGFR tyrosine kinase inhibitor, PD153035, correlated with PPAR dephosphorylation and translocation to the nucleus, indicating a mechanism for regulating the balance between proliferation and differentiation. This is the first identification of specific factors involved in regulating differentiation-associated gene changes in urothelium and the first unambiguous evidence of a role for PPAR signalling in the terminal differentiation programme of a normal epithelium

Expression of CD44 on bile ducts in primary sclerosing cholangitis and primary biliary cirrhosis.

AIM: To examine expression of CD44, a transmembrane glycoprotein involved in lymphocyte homing and activation, in inflammatory liver diseases. METHODS: Formalin fixed, paraffin embedded tissues were obtained from normal, uninvolved liver from patients undergoing partial hepatectomy for metastatic carcinoma (9) and transplant hepatectomy specimens from patients with primary biliary cirrhosis (12), primary sclerosing cholangitis (8), autoimmune hepatitis (3), hepatitis C (3), and secondary sclerosing cholangitis (1). Expression of CD44 (using antibodies to three core epitopes), HLA-DR, and lymphocyte phenotypic markers was studied by immunohistochemistry. RESULTS: CD44 expression was not detected in either hepatocytes or biliary epithelial cells in normal livers. In sections from all 27 transplant hepatectomy specimens, CD44 was positive in bile duct epithelial cells but not in hepatocytes. The proportion of CD44+ ducts was much higher in biliary disease than in chronic hepatitis. By contrast, expression of HLA-DR was detected in a relatively small percentage of bile ducts. Activated, memory phenotype CD4+ T lymphocytes were increased in the parenchyma of all diseased livers and an infiltrate of activated CD8+ cells within the biliary epithelium was evident in inflammatory biliary disease. CONCLUSIONS: CD44 appears to play an important role in the development of autoimmune biliary disease by promoting lymphoepithelial interactions, whereas HLA-DR may be involved in the subsequent progression of these conditions