Transitional cell carcinoma expresses high levels of Fas ligand in vivo

Clinical utility of urinary soluble Fas in screening for bladder cancer

AIM

Early diagnosis of carcinoma of urinary bladder remains a challenge. Urine cytology, as an adjunct to cystoscopy, is less sensitive for low-grade tumors. Soluble Fas (sFas), a cell-surface receptor and member of the tumor necrosis factor superfamily, is frequently expressed in urinary bladder carcinoma. The objective of this study was to investigate the urinary sFas for diagnosis of transitional cell carcinoma (TCC) of urinary bladder.

METHODS

We examined urinary sFas concentration in 74 controls and 117 cases of TCC, both primary and recurrent disease, by using enzyme-linked immunosorbent assay and compared it with urinary cytology.

RESULT

Urinary sFas concentration was found to be significantly higher in the patient as compared to control group (P < 0.05). An optimal cutoff value of 174.0 pg/mL was proposed. The urinary sFas level was found to have an approximate sensitivity and specificity of 88.03% and 89.19% (P < 0.001), whereas urine cytology had sensitivity of 66.67% and specificity of 95.95%. sFas had better sensitivity in higher grade and both primary and recurrent cases of urinary bladder cancer in comparison with cytology. Out of 15 node positive bladder cancer cases, 13 had high urinary sFas levels, whereas 12 were urinary cytology positive for malignancy.

CONCLUSION

Urinary sFas can be used as a non-invasive diagnostic biomarker for TCC of urinary bladder, both for primary and recurrent disease.

Prognostic impact of apoptosis marker Fas (CD95) and its ligand (FasL) on bladder cancer in Egypt: study of the effect of schistosomiasis

Objective:

The Fas–Fas ligand (FasL) system has been recognized as a major pathway for the induction of apoptosis in cells and tissues. Fas-mediated apoptosis is deeply involved in cancer cell death brought about by the immune system. This study was performed to determine the Fas and FasL expression in human bladder cancer and the impact of schistosomiasis infection.

Material and methods:

Of the 75 patients, 25 with chronic bilharzial cystitis and 50 with bladder cancer were included in this study. Ten control patients were included in the study, following their consent. Fas and FasL expressions in bladder tissue were determined by indirect immunohistochemistry using avidin-biotin-peroxidase complex (ABC) method.

Results:

The association of bilharziasis with malignancy raised the incidence of Fas positive immunoreactivity to 100%. The number of malignant cases positive for Fas decreased with progress of tumour grade and stage. All control cases were negative for FasL expression. The percentage of positive FasL malignant cases increased with increasing tumour grade or stage.

Conclusion:

Malignant bladder lesions express high levels of Fas and decreased expression of Fas is associated with disease progression. Urinary bladder carcinoma acquires the functional FasL during tumour progression that may induce apoptosis of anti tumour T lymphocytes. Fas and FasL are recommended to be considered important tumour markers to define aggressive bladder cancer and may be included in defining the surveillance protocol for superficial bladder cancer.

Isolinderanolide B, a butanolide extracted from the stems of Cinnamomum subavenium, inhibits proliferation of T24 human bladder cancer cells by blocking cell cycle progression and inducing apoptosis

Isolinderanolide B (IOB), a butanolide extracted from the stems of Cinnamomum subavenium, was investigated for its antiproliferative activity in T24 human bladder cancer cells. To identity the anticancer mechanism of IOB, its effect on apoptosis, cell cycle distribution, and levels of p53, p21 Waf1/Cip1, Fas/APO-1 receptor, and Fas ligand was assayed. Enzyme-linked immunosorbent assay showed that the G0/G1 phase arrest is because of increase in the expression of p21 Waf1/Cip1. An enhancement in Fas/APO-1 and membrane-bound Fas ligand (mFasL) might be responsible for the apoptotic effect induced by IOB. This study reports the novel finding that the induction of p21 Waf1/Cip1 and activity of the Fas/mFas ligand apoptotic system may participate in the antiproliferative activity of IOB in T24 cells.

The grape and wine constituent piceatannol inhibits proliferation of human bladder cancer cells via blocking cell cycle progression and inducing Fas/membrane bound Fas ligand-mediated apoptotic pathway

Piceatannol (3,3',4,5'-Tetrahydroxy-trans-stilbene) is a polyphenol present in grapes and wine. Piceatannol is a protein kinase inhibitor that modifies multiple cellular targets exerting immunosuppressive, antileukemic, and antitumorigenic activities in several cell lines and animal models. In this study, the antiproliferative activity of piceatannol was investigated. The results showed that piceatannol inhibited the proliferation of T24 and HT1376 human bladder cancer cells by blocking cell cycle progression in the G0/G1 phase and inducing apoptosis. ELISA showed that the G0/G1 phase arrest is due to an increased in the expression of p21/WAF1. An enhancement in Fas/APO-1 and membrane-bound Fas ligand (mFasL) might be responsible for the apoptotic effect induced by piceatannol. Our study reports the novel finding, that the induction of p21/WAF1 and activity of the Fas/mFasL apoptotic system may participate in the antiproliferative activity of piceatannol in T24 and HT1376 cells.

Norsolorinic acid inhibits proliferation of T24 human bladder cancer cells by arresting the cell cycle at the G0/G1 phase and inducing a Fas/membrane-bound Fas ligand-mediated apoptotic pathway

1. Norsolorinic acid, isolated from Aspergillus nidulans, has been shown to have antiproliferative activity in T24 human bladder cancer cells by arresting the cell cycle at the G(0)/G(1) phase and inducing apoptosis. The aim of the present study was to investigate the antiproliferative activity of norsolorinic acid in T24 human bladder cancer cells. 2. The effects of norsolorinic acid (1, 5, 10 and 20 micromol/L) on the proliferation of T24 cells and on the distribution of cells within different phases of the cell cycle were investigated indirectly using an XTT assay and a flow cytometer, respectively. Factors affecting the cell cycle and apoptosis, including p53, p21, Fas receptor, Fas ligand (FasL) and caspase 8 activity, were examined using ELISA. 3. The results showed that norsolorinic acid inhibited proliferation of T24 cells in a dose-dependent manner, with an IC(50) of 10.5 micromol/L. The effect involved the induction of cell cycle arrest at the G(0)/G(1) phase and apoptosis. 4. These results demonstrate that G(0)/G(1) phase arrest is due to increased expression of p21 in cells treated with norsolorinic acid (10 and 20 micromol/L) for 24 h. Moreover, enhanced Fas and membrane-bound Fas ligand (mFasL) may be responsible for the apoptotic effect of norsolorinic acid. Thus, the present study reports, for the first time, that induction of p21 and the Fas/mFas ligand apoptotic system may participate in the antiproliferative action of norsolorinic acid in T24 human bladder cancer cells.

Urine cytology and urine-based markers for bladder urothelial carcinoma detection and monitoring: developments and future prospects

Bladder cancer is currently diagnosed using cystoscopy and cytology in patients with suspicious signs and symptoms. These tests are also used to monitor patients with a history of bladder cancer. The recurrence rate for bladder cancer is high, thus necessitating long-term follow-up. Urine cytology has a high sensitivity and specificity for the detection of high-grade urothelial carcinoma, but lacks the sensitivity to detect low-grade tumors. Recently, multiple noninvasive urine-based bladder cancer tests have been developed. Many markers (BTA stat®, BTA TRAK®, ImmunoCyt™, NMP22® and UroVysion™) have already been approved by the US FDA for bladder cancer surveillance, while other markers are still undergoing development, preclinical and clinical investigation. An ideal bladder cancer test would be noninvasive, highly sensitive and specific, inexpensive, easy to perform and yield highly reproducible results. Many of the tests reviewed herein meet some, but not all, of these criteria.

Apoptotic DNA fragments in serum of patients with muscle invasive bladder cancer: a prognostic entity

Patients with malignancies often possess increased concentrations of cell-free serum DNA. In this study, we investigated serum DNA levels in each 45 patients with bladder cancer (BCA) undergoing radical cystectomy and with benign prostate hyperplasia. A quantitative real-time PCR was used to amplify a 124 bp (PTGS2; mostly apoptotic origin) and a 271 bp (Reprimo; mostly necrotic origin) DNA fragment. Changes in the origin of DNA fragments were specified as the Apoptosis Index (AI, ratio of 124 bp/271 bp fragments). Small and large fragments were increased (p<0.001 and p=0.041) in BCA patients. The AI increase suggests that DNA fragmentation was mostly (p<0.001) caused by apoptosis. High levels of small DNA fragments distinguished between BCA and BPH with high sensitivity (96%) and moderate specificity (62%). DNA levels and the AI were not correlated with clinicopathological parameters. However, an increased AI was correlated with BCA-specific mortality in a multivariate analysis (p=0.011) indicating that the AI is an independent prognostic factor. Thus, cell-free DNA seems to be a useful prognostic marker in patients with BCA.

Functional polymorphisms in the promoter regions of the FAS and FAS ligand genes and risk of bladder cancer in south China: a case–control analysis

BACKGROUND

FAS and FASLG together initiate apoptosis, which prevents tumor development. FAS and FASLG polymorphisms in the promoter regions can alter the transcriptional activities and thus alter risk of cancer. We hypothesized that the FAS -1377G>A, -670A>G, and FASLG -844T>C polymorphisms are associated with risk of bladder cancer.

METHODS

In a hospital-based case-control study of 216 case patients with newly diagnosed bladder transitional cell carcinoma and 252 cancer-free controls frequency-matched by age and sex, we genotyped polymorphisms using PCR-restriction fragment length polymorphism.

RESULTS

We found a statistically significantly increased risk of bladder cancer associated with the FASLG -844CC genotype [adjusted OR=1.51; 95% CI 1.03-2.23] compared with -844 (CT+TT). Consistently, the FAS haplotype genotypes with 2-4 variant (risk) alleles (-1377A and -670A) were associated with an increased risk of bladder cancer compared to 0-1 variants (OR=2.14; 95% CI 1.10-4.16). Furthermore, when we evaluated these three polymorphisms together, we found that the combined genotypes with 4-6 variant (risk) alleles (-1377A, -670A, and -844C) were associated with an increased risk of bladder cancer (OR=1.58; 95% CI 1.07-2.34) compared to 1-3 variants, and this increased risk was more pronounced among subgroups of aged >50 years (OR=1.70; 95% CI 1.11-2.61) and smokers (OR=1.88; 95% CI 1.06-3.32).

CONCLUSIONS

FAS and FASLG polymorphisms appear to jointly contribute to risk of bladder cancer in this southern Chinese population. Larger studies are needed to verify these findings.

Targeting death receptors in bladder, prostate and renal cancer

PURPOSE

We describe key components of normal and aberrant death receptor pathways, the association of these abnormalities with tumorigenesis in bladder, prostate and renal cancer, and their potential application in novel therapeutic strategies targeted toward patients with cancer.

MATERIALS AND METHODS

A MEDLINE literature search of the key words death receptors, TRAIL (tumor necrosis factor related apoptosis inducing ligand), FAS, bladder, prostate, renal and cancer was done to obtain information for review. A brief overview of the TRAIL and FAS death receptor pathways, and their relationship to apoptosis is described. Mechanisms that lead to nonfunction of these pathways and how they may contribute to tumorigenesis are linked. Current efforts to target death receptor pathways as a therapeutic strategy are highlighted.

RESULTS

Activation of tumor cell expressing death receptors by cytotoxic immune cells is the main mechanism by which the immune system eliminates malignant cells. Death receptor triggering induces a caspase cascade, leading to tumor cell apoptosis. Receptor gene mutation or hypermethylation, decoy receptor or splice variant over expression, and downstream inhibitor interference are examples of the ways that normal pathway functioning is lost in cancers of the bladder and prostate. Targeting death receptors directly through synthetic ligand administration and blocking downstream inhibitor molecules with siRNA or antisense oligonucleotides represent novel therapeutic strategies under development.

CONCLUSIONS

Research into the death receptor pathways has demonstrated the key role that pathway aberrations have in the initiation and progression of malignancies of the bladder, prostate and kidney. This new understanding has resulted in exciting approaches to restore the functionality of these pathways as a novel therapeutic strategy.

Soluble Fas—A promising novel urinary marker for the detection of recurrent superficial bladder cancer

BACKGROUND

The objective of this study was to test the hypothesis that elevated urinary levels of soluble Fas (sFas) would aid in the surveillance of patients with a past history of nonmuscle-invasive transitional cell carcinoma (TCC) of the urinary bladder.

METHODS

sFas levels were determined in cell lysates and supernatants from 2 human bladder cancer cell lines (T24 and TCC-SUP) and in voided urine from 188 consecutive patients who were at risk for TCC recurrence, 31 patients who had noncancerous urologic conditions, and 10 healthy individuals. The authors also obtained barbotage cytology and voided nuclear matrix protein 22 (NMP22) levels. sFas was analyzed continuously and categorically on the basis of its quintile distribution.

RESULTS

sFas was present in cell lysates and conditioned media from both cell lines. sFas levels were found to be higher in the TCC group (n = 122 patients) compared with the control group (P < .001). Higher levels of sFas were associated with positive cytology assay results (P < .001), higher NMP22 levels (P < .001), NMP22 levels > 10 U/mL (P < .001), and tumor stage > or = T1 (P < .001). The areas under the receiver operating characteristics (ROC) curves of sFas and NMP22 for bladder cancer detection were 0.757 (95% confidence interval, 0.694-0.819) and 0.704 (95% confidence interval, 0.637-0.772), respectively. In the > 75% sensitivity region of the ROC curves, sFas was consistently more specific than NMP22. In multivariate analyses, sFas, NMP22, and cytology all were found to be associated with the presence of bladder cancer (P values < or = .009), but only sFas and cytology were associated with tumor stage > or = T1 (P values < or = .026).

CONCLUSIONS

sFas was produced and released by bladder TCC cells. Urine sFas was an independent predictor of bladder cancer recurrence and invasiveness in patients who had a past history of nonmuscle invasive bladder TCC, and it outperformed NMP22.

Prognostic impact of FAS/CD95/APO-1 in urothelial cancers: decreased expression of Fas is associated with disease progression

The death receptor Fas (Apo1/CD95) and Fas ligand (FasL) system is recognised as a major pathway for the induction of apoptosis in vivo, and antiapoptosis via its blockade plays a critical role in carcinogenesis and progression in several malignancies. However, the function of Fas–FasL system in urothelial cancer (UC) has not been elucidated. We therefore investigated the expression of Fas, FasL and Decoy receptor 3 for FasL (DcR3) in UC specimens and cell lines, and examined the cytotoxic effect of an anti-Fas-activating monoclonal antibody (mAb) in vitro. Immunohistochemical examinations of Fas-related molecules were performed on 123 UC and 30 normal urothelium surgical specimens. Normal urothelium showed Fas staining in the cell membrane and cytoplasm. In UC, less frequent Fas expression was significantly associated with a higher pathological grade (P<0.0001), a more advanced stage (P=0.023) and poorer prognosis (P=0.010). Fas and the absence thereof were suggested to be crucial factors with which to select patients requiring more aggressive treatment. Moreover, low-dose anti-Fas-activating mAb sensitised resistant cells to adriamycin, and this synergistic effect could be applied in the development of new treatment strategy for UC patients with multidrug-resistant tumours.

c-FLIP expression in bladder urothelial carcinomas: its role in resistance to Fas-mediated apoptosis and clinicopathologic correlations

OBJECTIVES

To investigate the incidence of Fas (exon 9) mutations and the expression of Fas, Fas-Fas ligand (FasL) system, and cellular FLICE-like inhibitory protein (c-FLIP) in relation to standard clinicopathologic parameters and patient outcome in bladder carcinoma. Disruption of apoptotic cell death has been implicated in tumor aggressiveness in bladder urothelial carcinomas. The FasL system is involved in the execution of apoptosis induced by the immune system. c-FLIP protein constitutes an important endogenous inhibitor of Fas and other death receptor-mediated apoptosis.

METHODS

The expression of Fas, FasL, and c-FLIP was quantified immunohistochemically in paraffin-embedded tissues from 53 patients for whom clinical information was available. DNA extracted from the same samples was screened for mutations in Fas exon 9 by single-strand conformation polymorphism and sequencing. The effect of Fas, FasL, and c-FLIP on clinical outcome was assessed by univariate and multivariate analyses.

RESULTS

Positive immunostaining was detected for Fas, FasL, and c-FLIP in 72%, 66%, and 81% of cases, respectively. Concurrent expression of Fas and FasL was seen in 27 samples (51%), of which 22 (81.5%) also displayed c-FLIP positivity. FasL and c-FLIP expression increased with advancing stage but was absent from normal urothelium. None of the 53 urothelial carcinoma samples analyzed showed evidence of mutations by polymerase chain reaction single-strand conformation polymorphism and direct sequencing. Survival analysis demonstrated that although both FasL and c-FLIP expression adversely affected survival, only c-FLIP remained statistically significant on multivariate analysis.

CONCLUSIONS

The frequent expression and coexpression of Fas, FasL, and c-FLIP in urothelial carcinomas implicates c-FLIP as an inhibitor of the Fas-FasL-induced death pathway in these tumors. Moreover, c-FLIP conveys independent prognostic information in the presence of classical prognosticators.

Decreased Fas expression in advanced-stage bladder cancer is not related to p53 status

OBJECTIVES

The Fas-Fas ligand system is an important regulator of apoptosis and is involved in tumor development. Invasive cancers downregulate Fas expression to evade antitumor immune responses. Fas is a transcriptional target of p53, which is often mutated in bladder cancers. Therefore, Fas expression and its relation to p53 mutation was investigated.

METHODS

Expression of Fas protein and p53 status was studied by immunohistochemistry in 83 bladder cancer specimens. In addition, mRNA levels for soluble (decoy) and membrane-bound forms of Fas were compared between 10 bladder cancer cell lines and primary uroepithelial cells by quantitative TaqMan polymerase chain reaction. Mutational analysis of the death domain of the Fas gene was performed in all cell lines.

RESULTS

Organ-confined tumors maintained specific Fas staining at the cell membrane and often also in the cytoplasm. In higher stage carcinomas, Fas expression became restricted to a smaller fraction of cells or was lacking entirely. The correlation of Fas staining with tumor stage was highly significant but no correlation to tumor grade or survival was found. Furthermore, no statistically significant relationship was observed with either the presence or lack of mutated p53 accumulation. Membrane-bound Fas mRNA was decreased in most, and soluble Fas was increased in all transitional cell carcinoma lines compared with primary uroepithelial cells. No mutations in the death domain were detected.

CONCLUSIONS

Fas downregulation occurring in advanced bladder cancer is unrelated to p53 mutations. The results of immunohistochemistry and mRNA studies of soluble and membrane-bound Fas in transitional cell carcinoma lines support the hypothesis of immune evasion in advanced bladder cancer.

Molecular biology of transitional cell carcinoma

Transitional cell carcinoma (TCC) is the fifth most common solid malignancy in the USA. Radical cystectomy will cure a substantial fraction of patients with minimally invasive TCC, but approximately 50% of patients with muscle-invasive or extravesical disease treated by radical cystectomy alone die of metastatic TCC. Transitional cell carcinoma have a diverse collection of biologic and functional characteristics. This is reflected in a differing clinical course. The limited value of established prognosticators, make the analysis of new molecular parameters of interest in predicting the prognosis of bladder cancer patients; in particular, high-risk patient groups that are at risk of progression and recurrence. Over the past decade, there had been major progress in the elucidation of the molecular genetic changes leading to the development of TCC. This review will highlight these important advances and emphasize the ways in which molecular biology is likely to affect the development of future therapies.

Human urinary bladder transitional cell carcinomas acquire the functional Fas ligand during tumor progression

The interaction between FasL on tumor cells and Fas on lymphocytes may represent a tumor immune escape mechanism. We explored FasL expression and function in human urinary bladder transitional cell carcinomas (TCCs). FasL expression was observed in situ in 45% of TCCs (n = 45) and was absent in normal urothelium (n = 20). A correlation existed between FasL expression and high tumor grade (0% in G1, 14% in G2, and 75% in G3; P < 0.0001) and stage (13% in superficial Ta-T1 versus 81% in invasive T2-T4; P < 0.0001). FasL function was shown by the ability of two FasL-positive primary culture TCC cell lines (established from two FasL-positive invasive TCCs) to induce Fas-mediated killing not only of conventional Fas-sensitive targets (such as Jurkat cells or phytohemagglutinin-lymphoblasts), but also of autologous T lymphocytes generated in a mixed lymphocyte tumor-cell culture. In addition, an association between FasL expression by TCC cells and activated caspase-8, -9, and -3 expression by interferon-gamma-producing CD8-positive tumor-infiltrating lymphocytes was observed in situ. Our results show a functional expression of TCC-expressed FasL that correlates with tumor progression. These results suggest that TCC-expressed FasL may induce apoptosis of anti-tumor T lymphocytes in vivo, providing new insights on the mechanisms involved in bladder TCC progression.

Molecular aspects of bladder cancer III. Prognostic markers of bladder cancer

The current pathological and clinical parameters provide important prognostic information, yet still have limited ability to predict the true malignant potential of most bladder tumors. In the last years, investigation of the basic mechanisms involved in carcinogenesis and tumor progression by molecular biology has provided a host of markers which are of potential diagnostic or prognostic value for bladder carcinoma. These markers may serve as tools for early and accurate prediction of tumor recurrence, progression and development of metastases and for prediction of response to therapy. The precise prediction of tumor biological behavior would facilitate treatment selection for patients who may benefit from radical surgical treatment or adjuvant therapy. We provide a current, comprehensive review of the literature on bladder tumor markers with a special emphasis on their prognostic potential. The literature suggests that currently no single marker is able to accurately predict the clinical course of bladder tumors and thus would serve as a reliable prognosticator. A combination of prognostic markers could predict which superficial tumors need an aggressive form of therapy and which invasive tumors require adjuvant therapy. Altogether, the most promising markers are, at this point, Ki-67 and p53 expression as well as matrixmetalloproteinase complex and angiogenesis.

Evaluation of cellular tumour rejection mechanisms in the peritumoral bladder wall after bacillus Calmette-Guérin treatment

OBJECTIVE

To compare the immunological status of normal and peritumoral bladder walls, and to characterize immunocompetent cells before and during intravesical instillations of bacillus Calmette-Guérin (BCG).

PATIENTS AND METHODS

Twenty-three patients with superficial urothelial bladder carcinoma (stages pTa to pT1, grades 1-3) were treated with six weekly instillations of 150 mg of BCG (Pasteur strain). Biopsies of cystoscopically normal bladder wall were taken before, 3 weeks and 3 months after BCG instillation. The controls comprised bladder biopsy specimens from 13 brain-dead ventilated kidney donors. Local infiltrating cell types, i.e. lymphocyte infiltrates (CD4, CD8, CD20, CD3, interleukin-2-receptor-positive, natural killer, gammadelta), macrophages and dendritic cells, adhesion and costimulatory molecules (ICAM-1 and B7-BB1) and major histocompatibility complex (MHC) class I and class II antigens were assessed using semi-quantitative immunohistochemical analysis.

RESULTS

Before BCG the peritumoral bladder wall had fewer macrophages than control bladder wall. BCG treatment restored normal numbers of macrophages and enhanced T helper lymphocytes, B lymphocytes, natural killer cells, activated lymphocytes, dendritic cells, normal MHC class I, adhesion (ICAM-1) and costimulatory (B7-BB1) expression. The enhancement of these immunological variables was transient, with a return to baseline 3 months after BCG instillation.

CONCLUSIONS

These results support the concept that there is a host-immune escape associated with bladder cancer. BCG therapy may temporarily restore impaired tumour rejection mechanisms in the peritumoral bladder wall, suggesting a need for maintenance therapy after the first course of BCG.

Soluble Fas and Fas-ligand in bladder cancer in vitro and in vivo

Circulating soluble Fas (sFas) and expression of Fas-ligand on cancer cells are mechanisms of immune escape. The aim of the present study was to investigate expression and production of Fas and Fas-ligand on bladder cancer cell lines of different grade as a basic mechanism of their secretion in vivo. sFas and sFas-ligand serum levels of patients with different stage of bladder cancer were examined to determine the possible clinical use of these molecules as tumor markers. Bladder cancer cell lines RT4 (G1), RT112 (G1), T24 (G3) and SUP (G4) were analyzed by flowcytometry for Fas and Fas-ligand expression. To determine if the Fas-ligand gene is transcribed in these bladder cancer cell lines, RT-PCR was performed on mRNA extracted from these cell lines. Production of sFas and sFas-ligand was examined in cell culture supernatants of the cancer cells as well as in the serum of 62 patients with bladder cancer by a specific ELISA test. We demonstrate that Fas is expressed in similar levels on all human bladder carcinoma cell lines. In T24 (G3) and SUP (G4) cell lines we were able to detect the Fas-ligand protein, whereas no Fas-ligand protein could be found in RT4 and RT112 (G1) cells. Fas-ligand mRNA was expressed in all bladder cancer cell lines. Furthermore, all bladder cancer cell lines produce sFas but no sFas-ligand in spite of mRNA expression. The range of sFas levels in the serum of all patients with bladder cancer was large and did not show a correlation to the histopathological stage of bladder cancer. Although there is in vitro evidence that sFas and Fas-ligand play a role in bladder cancer, no correlation between the sFas and s Fas-ligand serum levels and the histopathological stage of bladder cancer could be found. Therefore, serum sFas and sFas-ligand have to date limited clinical relevance.

Bladder cancer cells acquire competent mechanisms to escape Fas-mediated apoptosis and immune surveillance in the course of malignant transformation

Mechanisms of resistance against Fas-mediated cell killing have been reported in different malignancies. However, the biological response of immune escape mechanisms might depend on malignant transformation of cancer cells. In this study we investigated different mechanisms of immune escape in 2 well-differentiated low-grade (RT4 and RT112) and 2 poorly differentiated high-grade (T24 and TCCSUP) bladder cancer cell lines. Fas, the receptor of Fas-ligand, is expressed and shedded by human transitional bladder carcinoma cell lines RT4, RT112, T24 and TCCSUP. Cytotoxicity and apoptosis assays demonstrate that in spite of the Fas expression, poorly differentiated T24 and TCCSUP cells are insensitive towards either recombinant Fas-ligand or agonistic apoptosis-inducing monoclonal antibody against Fas. In poorly differentiated T24 and TCCSUP cell lines we were able to detect marked Fas-ligand protein by flow cytometry and Western blot analysis. In grade 1 RT4 and RT112 cells only minor expression of Fas-ligand possibly because of proteinase action. Fas-ligand mRNA translation or post-translational processing seems to be regulated differentially in the cancer cell lines depending on malignant transformation. In co-culture experiments we show that poorly differentiated cells can induce apoptosis and cell death in Jurkat cells and activated peripheral blood mononuclear cells. This in vitro study suggests that bladder cancer cells can take advantage of different mechanisms of immune evasion and become more competent in avoiding immune surveillance during transformation to higher-grade malignant disease. © 2001 Cancer Research Campaign www.bjcancer.com