Treatment of muscle-invasive bladder cancer: progress and new challenges

Pro-chemotherapeutic effects of antibody against extracellular domain of claudin-4 in bladder cancer

Bladder cancer displays an aggressive phenotype in the muscle-invasive phase, and is associated with a high mortality rate. Therefore, novel molecular therapeutic targets are needed to improve patient survival. A monoclonal antibody against the extracellular domain of the claudin-4 (CLDN4) tight junction protein was established by immunizing rats with a plasmid vector encoding human CLDN4. A hybridoma clone, producing a rat monoclonal antibody recognizing CLDN4 (clone 4D3), was obtained. Immunohistochemistry by using the 4D3 antibody showed that CLDN4 expression was associated with local invasion, nodal metastasis, distant metastasis, and advanced stage in 86 cases of bladder cancer. The 4D3 antibody inhibited growth, invasion, and survival, associated with abrogation of the intratumoral microenvironment; lowered concentrations of epidermal growth factor and vascular endothelial growth factor were found in three-dimensional cultures of T24 and RT4 cells. In combination with cisplatin therapy, 4D3 enhanced cisplatin cytotoxicity by increasing cellular permeability, leading to increased intracellular cisplatin concentrations. In mouse models of subcutaneous tumors and lung metastasis, 4D3 enhanced tumor growth inhibition, alone and with concurrent cisplatin treatment. The anti-tumor activity of the newly established 4D3 antibody suggests that it may be a powerful tool in CLDN4-targeting therapy, and in combination with chemotherapy.

Methylation-mediated silencing of Dlg5 facilitates bladder cancer metastasis

Dlg5 (Discs large homolog 5), a member of the membrane-associated guanylate kinase adaptor family of scaffolding proteins, has been shown to participate in cancer progression. However, little is known about whether abnormal expression of Dlg5 facilitates bladder cancer metastasis. In the current study we initiated a study analyzing Dlg5 expression and its roles in human bladder cancer metastasis. The expression of Dlg5 is decreased in most bladder cancer tissues compared with adjacent normal tissues, and Dlg5 expression is further downregulated in patients with muscle-invasive tumors. DNA methylation analysis showed a methylation of Dlg5 gene in bladder cancer cell lines and in bladder cancer tumors, especially in muscle-invasive tumors. Hypermethylation of Dlg5 in bladder tumors is tightly correlated with silencing of Dlg5 expression, which is further functionally validated by demethylation analysis in bladder cancer cell lines. Knockdown of Dlg5 increases cancer cell invasion in vitro and promotes cancer metastasis in vivo. Of clinical significance, Kaplan-Meier analysis showed that downregulation of Dlg5 is significantly associated with reduced overall survival in patients with bladder cancer.

CONCLUSION

These data suggest that inhibition of Dlg5 by DNA hypermethylation contributes to provoke invasive phenotypes in bladder tumor.

Cytoplasmic mislocalization of the orphan nuclear receptor Nurr1 is a prognostic factor in bladder cancer

BACKGROUND

Nurr1 belongs to a novel class of orphan nuclear receptors (the NR4A family). The authors have previously shown that Nurr1 is important in carcinogenesis. In the current study, they examined the clinicopathologic relevance of expression patterns of Nurr1 in bladder tumors.

METHODS

Nurr1 expression was determined using immunohistochemical staining in a bladder cancer tissue array (145 tumors). Tumors were classified according to Nurr1 protein levels in both cytoplasm and nucleus. Disease-specific survival and recurrence-free survival were investigated by Kaplan-Meier analysis and Cox proportional hazards analysis in multivariate models and correlated with variables such as tumor stage, growth pattern, and clinical outcome (recurrence and survival). In vitro, Nurr1 was examined for its role in bladder cancer cell proliferation and migration using small interfering RNA silencing.

RESULTS

Nurr1 expression in tumor cells correlated with increasing tumor stage and invasive growth pattern. Disease-specific survival was significantly shorter in patients whose tumors demonstrated a high level of cytoplasmic Nurr1 compared with those with lower levels of cytoplasmic Nurr1 expression. Furthermore, cytoplasmic Nurr1 expression level was found to be an independent predictor of disease-specific survival (odds ratio, 4.894; P < .001). In vitro, silencing of endogenous Nurr1 attenuated the migration of bladder cancer cells.

CONCLUSIONS

The expression of Nurr1 in the cytoplasm correlates with adverse outcome and is an independent prognostic marker for tumor progression and survival in patients with bladder cancer. This might represent a novel target in bladder cancer therapy.

The type 1 insulin-like growth factor receptor is over-expressed in bladder cancer

OBJECTIVE

To analyse bladder cancer biopsies and investigate the pattern of expression of the type 1 insulin-like growth factor receptor (IGF1R), a receptor tyrosine kinase that mediates tumour cell proliferation, motility and protection from apoptosis.

MATERIALS AND METHODS

Formalin-fixed specimens of bladder cancer (40 whole-mount, 80 cores on a tumour microarray) and normal bladder (15 samples) were stained immunohistochemically for the IGF1R. The IGF1R expression was also measured by quantitative reverse transcription-polymerase chain reaction (Q-RT-PCR) on RNA extracted from fresh frozen bladder cancers (61) and benign bladder (12).

RESULTS

Of the 15 samples of normal bladder, 14 showed negligible (1+) or light (2+) IGF1R immunostaining. By contrast moderate (3+) or heavy (4+) staining for IGF1R was detected in 89 (74%) of the 120 samples of malignant urothelium. Q-RT-PCR showed significantly higher levels of steady-state IGF1R mRNA in tumours (all cases, Ta-T4) than in normal bladder (P < 0.05), indicating up-regulation at the transcriptional level. This difference was particularly evident when comparing normal urothelium with superficial (Ta-T1) or invasive (T2-4) tumours; only the latter showed significant IGF1R over-expression at the RNA level (P < 0.05 vs normal bladder).

CONCLUSION

The IGF1R is up-regulated in bladder cancer compared with non-malignant bladder, and might contribute to a propensity for invasion.

Urothelial Carcinoma with Divergent Histologic Differentiation (Mixed Histologic Features) Predicts the Presence of Locally Advanced Bladder Cancer When Detected at Transurethral Resection

OBJECTIVES

The histologic classification of bladder tumors remains an important predictor of treatment response and patient outcome, with pure nonurothelial tumors associated with poorer outcome compared with pure urothelial carcinoma (UC). Little, however, is known about the significance of UC with divergent (mixed) histologic features at transurethral resection of bladder tumor (TURBT). This study examined the incidence, pathologic spectrum, and clinical significance of this phenomenon.

METHODS

The histologic patterns of 448 consecutive TURBT and 295 subsequent cystectomy specimens from this subgroup were analyzed. The type of divergent tumor differentiation observed in the mixed histologic type cases was categorized and quantified. Pure non-UC cases were excluded. Various clinicopathologic parameters were compared between the mixed histologic type and pure UC cohorts.

RESULTS

UC with mixed histologic features was identified in 25% of all TURBT specimens and was uniformly (100%) high grade and invasive (99%). The most common mixed histologic components were squamous (40%) and glandular (18%). Eleven percent of cases had multiple mixed histologic types. Compared with the pure high-grade UC, UCs with mixed histologic features were associated with muscle invasion at TURBT (chi-square test, P <0.001) and with extravesical disease at cystectomy (chi-square test, P = 0.0001). The presence of mixed histologic features at TURBT was an independent predictor of extravesical disease in a multivariate logistic model (P = 0.007). However, it was not significant for disease-specific survival in the univariate (P = 0.17) or multivariate (P = 0.68) models.

CONCLUSIONS

The results of our study have shown that the presence of mixed histologic features at TURBT indicates locally aggressive disease. Patients with mixed histologic features might benefit from an aggressive multimodality treatment strategy.

Improved detection of bladder carcinoma cells in voided urine by standardized microsatellite analysis

Successful treatment of bladder cancer depends largely on early diagnosis of primary and recurrent disease. Sensitive, specific and noninvasive procedures for detection are especially needed for grade 1 and 2 bladder tumors, because of the relatively low sensitivity of cytology. Here we introduce a novel strategy to improve the sensitivity and reliability of microsatellite analyses by employing marker-specific threshold values for loss-of-heterozygosity (LOH) at 10 loci. These individual cut-offs were experimentally determined with 35 normal control tissues and subsequently validated in a retrospective study with bladder cancer biopsies from 86 patients. In a prospective analysis of voided urines samples and matched blood probes from 91 patients, LOH-analysis, UroVysion FISH and conventional urine cytology were compared with histological findings of consecutive transurethral biopsies. Whereas all samples could be analyzed by our LOH assay, only 56 samples were suitable for all 3 analyses. The highest sensitivity was obtained with our LOH-assay/cytology approach (G1-2: 72%; G3: 96%) being only surpassed by a combination of all 3 techniques (G1-2: 83%; G3: 100%). Since over 93% of the patients with recurrent disease were identified by LOH/cytology-analyses of their voided urine samples, a monitoring scheme alternating cystoscopy with LOH/cytology-examination could now be envisioned to reduce invasive interventions and consequently improve follow-up compliance, especially in patients with low grade tumors.

Antisense oligodeoxynucleotide therapy for bladder cancer: recent advances and future prospects

Despite remarkable progress in therapeutic options for the management of bladder cancer, it remains a challenge for urologists to achieve successful outcomes in the treatment of both superficial and invasive bladder cancers. In this review, recent advances in the field of antisense oligodeoxynucleotide therapy targeting several genes playing functionally important roles in the progression and recurrence of bladder cancer are summarized. Data showing the synergistic antitumor activities of antisense oligodeoxynucleotide therapy, combined with several treatments, including cytotoxic chemotherapy, radiation and other molecular targeting therapies, are also presented. Finally, the future direction of antisense oligodeoxynucleotide therapy in the therapeutic strategy of bladder cancer is discussed. These findings may help clarify the significance of antisense oligodeoxynucleotide therapy as an attractive alternative to conventional strategies.