Molecular evidence supporting field effect in urothelial carcinogenesis

Evidence for transformation of fibroadenoma of the breast to malignant phyllodes tumor

Fibroadenoma (FA) and phyllodes tumor (PT) of the breast are biphasic tumors composed of variable proportions of epithelial and stromal cells. We identified a case of synchronous FA and PT in the same breast mass. Using laser capture microdissection, loss of heterozygosity analysis was performed on these components to gain potential insight into the histogenetic relationship between FA and PT. Genomic DNA was analyzed at 10 microsatellite loci by polymerase chain reaction. Both tumors showed allelic loss at D7S522. In addition, phylloid tumor showed allelic loss at TP53 and D22S264, not observed in FA. Our data suggest that FA and PT are clonally related and allelic loss at TP53 and D22S264 may be implicated in the progression of FA to phyllode tumor.

Sigma-2 receptor expression in bovine papillomavirus-associated urinary bladder tumours

The expression of sigma-2 receptors was investigated in nine urothelial tumours of the urinary bladder of cattle. Each tumour was associated with the presence of DNA of bovine papillomavirus type-2 (BPV-2) and expression of the E5 viral oncoprotein. Five tumours were classified as low-grade carcinoma on the basis of morphological criteria and calculation of mean nuclear area (MNA) and mean nuclear perimeter (MNP). Four tumours were classified as high-grade carcinoma. Sigma-2 receptors were overexpressed in both types of carcinoma. In control normal bovine bladder tissue the density of receptors (expressed as the B(max)) was 0.37 pmol/mg of protein. Low-grade carcinomas had a mean B(max) of 1.37+/-0.32 pmol/mg of protein (range 1.03-1.86) and in high-grade carcinomas the mean B(max) was 10.9+/-2.8 pmol/mg of protein (range 8.2-14). The difference in B(max) between low- and high-grade carcinomas was statistically significant (P=0.0001).

Staging and reporting of urothelial carcinoma of the urinary bladder

Significant progress has been made in the standardization of bladder neoplasm classification and reporting. Accurate staging using the American Joint Committee on Cancer/International Union Against Cancer (AJCC/UICC) TNM system is essential for patient management, and has been reinforced by clinical evidence in recent years. It is now recognized that 'superficial' bladder carcinomas are a heterogenous group of tumors with diverse biological and clinical manifestations. The term 'superficial,' therefore, is no longer used for bladder tumor nomenclature. Recognition of diagnostic pitfalls associated with lamina propria invasion is critical for the evaluation of bladder tumor specimens. Neither the 1973 nor the 2004 WHO grading system appears to be useful for predicting the clinical outcome of invasive urothelial carcinoma. This review will discuss recent progress and controversial issues on the staging and substaging of bladder carcinomas. Essential elements for handling and reporting of bladder tumor specimens will also be discussed.

The role of chemotherapy in upper tract urothelial carcinoma

Locally advanced upper tract urothelial carcinoma has a poor prognosis. While surgery represents the only potentially curable therapeutic intervention, recurrences are common and typically systemic in nature. It is thus reasonable to consider perioperative chemotherapy in an effort to decrease the risk of recurrence. There are very little direct data providing clinical guidance in this scenario. For urothelial cancer of the bladder, there are randomized phase III data demonstrating a survival advantage with neoadjuvant cisplatin-based combination chemotherapy. Although arguments favoring adjuvant chemotherapy could be made for upper tract urothelial cancer, the loss of renal function that occurs with nephrectomy can complicate administration of appropriate perioperative treatment. Therefore, by analogy to urothelial carcinoma of the lower tract, it is argued that cisplatin-based neoadjuvant chemotherapy should be the standard of care for patients with locally advanced upper tract urothelial cancer.

Molecular Pathology of the Genitourinary Tract: Prostate and Bladder

The knowledge of cellular mechanisms in tumors of the prostate and bladder has grown exponentially. Molecular technologies have led to the discovery of TMPRSS2 in prostate cancer and the molecular pathways distinguishing low- and high-grade urothelial neoplasms. UroVysion with fluorescence in situ hybridization is already commonplace as an adjunct to cytologic diagnosis of urothelial neoplasms. This trend portends the future in which classification and diagnosis of tumors of the prostate and bladder through morphologic analysis will be supplemented by molecular information correlating with prognosis and targeted therapy. This article outlines tumor molecular pathology of the prostate and bladder encompassing current genomic, epigenomic, and proteonomic findings.

[Bladder carcinoma cell lines as models of the pathobiology of bladder cancer. Review of the literature and establishment of a new progression series]

BACKGROUND

Tumour cell lines represent valuable preclinical models to decipher underlying biology and identify potential therapy targets and pharmacologically useful compounds. Approximately 50 human bladder cancer cell lines have been established to date, mainly from invasive and metastatic tumours. Two of these, namely T24 and 253J, were experimentally further developed into progression series. These models have provided important insights into later tumour progression events and metastatic dissemination. Only a few cell lines are available as models of non-invasive papillary bladder cancer and no progression series have yet been established.

MATERIAL AND METHODS

During the course of establishing a doxorubicin-resistant variant cell line of the human papillary bladder carcinoma cell line BFTC-905, a unique cell colony was identified, apparently involving cells with divergent growth patterns. Subsequent subculturing yielded three daughter cell lines, BFTC-905-compact, BFTC-905-diffuse und BFTC-905-diffuse M. Their fundamental characterization included basic cell morphology, cell membrane expression of E-Cadherin, karyotype analysis, invasion and colony forming capacity in soft agar. The clonal origin of the newly established daughter cell lines was assessed by means of molecular genetic methods.

RESULTS

We could identify important differences in multiple transformation related traits among the cell lines of the BFTC-905 progression series. Both diffuse cell lines (BFTC-905-diffuse und BFTC-905-diffuse M) differed from the BFTC-905-compact cell line by growing in a less organized,"diffuse" manner, which involved colonies of cells exhibiting apparently normal cell-to-cell adhesion as well as individual cells outside of them. This diminution of the cell-to-cell adhesion was accompanied by a corresponding decrease of membranous E-Cadherin. The BFTC-905-diffuse M cell line displayed a dramatic increase in the overall chromosome number, resulting in a hypertetraploid karyotype. At the same time, this cell line, as the only one in the progression series, acquired the ability to grow independent of anchorage in soft agar. All three cell lines remained noninvasive. Allelic distribution of highly polymorphic DNA-markers in the cell lines of the BFTC-905 progression series provided unequivocal evidence of their common origin.

CONCLUSION

The newly established BFTC-905 progression series manifests two aspects of the early progression of non-invasive bladder carcinoma, not exhibited by any other progression series published so far, namely dynamic changes in the expression of E-Cadherin and a complex karyotypic evolution. It may thus contribute important insights into further understanding of the pathobiology of bladder cancer.

Cell lineage analysis of a mouse tumor

Revealing the lineage relations among cancer cells can shed light on tumor growth patterns and metastasis formation, yet cell lineages have been difficult to come by in the absence of a suitable method. We previously developed a method for reconstructing cell lineage trees from genomic variability caused by somatic mutations. Here, we apply the method to cancer and reconstruct, for the first time, a lineage tree of neoplastic and adjacent normal cells obtained by laser microdissection from tissue sections of a mouse lymphoma. Analysis of the reconstructed tree reveals that the tumor initiated from a single founder cell, approximately 5 months before diagnosis, that the tumor grew in a physically coherent manner, and that the average number of cell divisions accumulated in cancerous cells was almost twice than in adjacent normal lung epithelial cells but slightly less than the expected figure for normal B lymphocytes. The cells were also genotyped at the TP53 locus, and neoplastic cells were found to share a common mutation, which was most likely present in a heterozygous state. Our work shows that the ability to obtain data regarding the physical appearance, precise anatomic position, genotypic profile, and lineage position of single cells may be useful for investigating cancer development, progression, and interaction with the microenvironment.

Hypermethylation of tumor-suppressor gene CpG islands in small-cell carcinoma of the urinary bladder

Small-cell carcinoma of the urinary bladder (SCBC) is a rare tumor, which shows a common clonal origin with urothelial carcinoma. It bears a high metastatic potential, even when discovered in a localized state. Identifying the molecular underpinnings of this disease may elucidate useful clinical information regarding prevention, diagnosis, prognosis, treatment, and surveillance. As DNA methylation is widely recognized as having a pivotal role in the process of carcinogenesis, we analyzed the DNA methylation status of four frequently hypermethylated tumor suppressors in small-cell and transitional-cell carcinoma (TCC) arising concomitantly in 13 patients. Fourteen cases of pure TCC were also included in the analysis. We identified frequent methylation of RASSF1 and MGMT and infrequent methylation of MLH1 and DAPK1 in cases of concomitant TCC and SCBC. Similar rates of methylation were found in pure and concomitant histopathologies, with the exception of MGMT, which was much less frequently methylated in pure TCC. These findings suggest that SCBC and TCC have common origins, establish DNA methylation of some tumor suppressors as frequent occurrences in both histopathologies, and suggest that MGMT methylation may be an SCBC-specific epimutation.

Molecular genetic evidence supporting the neoplastic nature of the Leydig cell component of ovarian Sertoli-Leydig cell tumors

Sertoli-Leydig cell tumors (SLCT) comprise less than 1% of ovarian tumors. The nature of the Leydig cells has been a subject of controversy and it is unclear whether they are clonally related to the neoplasm or instead proliferate as a non-neoplastic response to the Sertoli-cell component. Twelve ovarian SLCT were identified and hematoxylin and eosin and unstained sections were prepared from formalin-fixed, paraffin-embedded tissue blocks. Tissue samples were microdissected from normal tissue, the Sertoli cell component, and the Leydig cell tumor component using the laser capture microdissection method. If present, tissue was also obtained from any heterologous component. Genomic DNA was extracted from the samples and polymerase chain reaction was used to amplify polymorphic sites at 5 loci: D16S402, TP53, IFNA, D17S855, and D11S1318. X-chromosome inactivation (HUMARA) analysis was also performed. LOH and/or nonrandom X-chromosome inactivation was observed in at least 1 of the 6 amplified loci in the Leydig cell component of 10 of the 12 tumors. LOH and nonrandom X-chromosome inactivation patterns of the Sertoli cell component and Leydig cell component were compared. Concordant allelic loss and/or matching X-chromosome inactivation patterns were observed in 8 (67%) of the 12 tumors. In 7 of these tumors similar LOH or X-chromosome inactivation was observed at 1 site. In 1 tumor similar LOH and/or X-chromosome inactivation was observed at 2 sites. Three tumors had heterologous components. The heterologous components similarly shared LOH/X-chromosome inactivation with the Sertoli cell components at 1 site in 1 case and 2 sites in 2 cases. These data suggest that, at least in some cases, the Leydig cell component of SLCT is neoplastic rather than reactive in nature, and shares a common clonal origin with the coexisting Sertoli cell component. Similarly, the heterologous components, when present, appear to share clonal origin with the Sertoli cell components.

Genetic analysis of multifocal superficial urothelial cancers by array-based comparative genomic hybridisation

The purpose of this study was to investigate the accumulation of genetic alterations during metachronous and/or synchronous development of multifocal low-grade superficial urothelial tumours in the same patient, by using array-based comparative genomic hybridisation (array-CGH) and FGFR mutation analysis. We analysed 24 tumours (pTa-1 G1-2) from five patients. We had previously identified a clonal relationship among the tumours of each patient by microsatellite analysis. This time, unsupervised hierarchical cluster analysis revealed that the tumours from each patient were clustered together independently of the tumours from the other patients. All of the tumours from a single patient showed a set of 2–7 identical regional or whole-arm chromosomal changes. In addition, several individual alterations were also found. Cladistic diagrams revealed that the accumulation of genetic alterations could not be explained by a linear model, and the existence of a hypothetical precursor cell was assumed in four patients. In some cases, FGFR mutation seemed to occur later during multifocal tumour development. Taken together, these findings suggest that low-grade superficial urothelial tumours accumulate minor genetic alterations during multifocal development, although these tumours are genetically stable.

Histogenesis of sarcomatoid urothelial carcinoma of the urinary bladder: evidence for a common clonal origin with divergent differentiation

The histogenesis of sarcomatoid urothelial carcinoma, a rare neoplasm with bidirectional epithelial and mesenchymal differentiation, has been a matter of controversy. To clarify its origin, we analysed the status of X-chromosome inactivation in sarcomatoid urothelial carcinomas from 10 female patients and examined losses of heterozygosity (LOH) in these specimens and in additional 20 tumours from male patients. Six polymorphic microsatellite markers where genetic alterations occur frequently in early or advanced stages of urothelial carcinomas, including D3S3050, D8S261, IFNA, D9S177, D11S569 and TP53, were investigated in the current study. The identical pattern of non-random X-chromosome inactivation in both carcinomatous and sarcomatous components was identified in five of eight informative female patients, and the remaining three informative cases showed a random, but concordant, pattern of X-chromosome inactivation. The concordant X-chromosome inactivation results in all eight informative cases support the concept of a monoclonal origin of both components of this biphasic neoplasm. Among the tumours demonstrating loss of heterozygosity, high incidences of an identical pattern of allelic loss between carcinomatous and sarcomatous components were identified in genetic alterations associated with early carcinogenesis: 86% at D8S261, 78% at D11S569, 75% at D9S177 and 57% at IFNA. In contrast, concordant LOH patterns were less frequently observed for microsatellites related to advanced carcinogenesis: only 40% at D3S3050 and 40% at TP53. The significant overlap of loss of heterozygosity supports a monoclonal cell origin and suggests that clonal divergence may occur during tumour progression and differentiation. Divergent patterns of discordant allelic loss of microsatellite markers imply that heterogeneous pathogenetic pathways may exist in the evolution of this enigmatic neoplasm.

Chromosome 20q13.2 Gain May Predict Intravesical Recurrence after Nephroureterectomy in Upper Urinary Tract Urothelial Tumors

PURPOSE

Amplification or gain of copy number of chromosome 20q13.2 has been implicated as a causal factor for chromosome instability. We investigated the impact of chromosomal instability and its causative molecular markers, 20q13.2 gain and centrosome amplification, on patient outcome in upper urinary tract transitional cell carcinoma (UUT-TCC).

EXPERIMENTAL DESIGN

The number of centrosomes was assessed by immunohistochemistry. Numerical aberrations of chromosomes 7, 9, and 17 that allowed the estimation of chromosomal instability and 20q13.2 gain were evaluated by fluorescence in situ hybridization in 96 frozen specimens from UUT-TCC and compared with clinicopathologic background and patient outcome.

RESULTS

Chromosomal instability, 20q13.2 gain, and centrosome amplification were detected in 62 of 96 (64.6%), 61 of 96 (63.5%), and 45 of 90 (50.0%) tumors, respectively. 20q13.2 Gain was significantly associated with tumor stage (P = 0.042), chromosomal instability (P < 0.0001), and centrosome amplification (P < 0.0001). Kaplan-Meier analysis showed that 20q13.2 gain was strongly associated with intravesical recurrence-free survival in all patients (P = 0.0050), as well as in patients with grade 2 tumors (P = 0.0011, log-rank test). On multivariate analysis, 20q13.2 gain was found to be the sole independent prognostic factor predicting subsequent intravesical recurrence (hazard ratio, 1.65; 95% confidence interval, 1.03-2.90; P = 0.036).

CONCLUSIONS

20q13.2 gain was strongly associated with a reduced time to intravesical recurrence in all patients. Our data suggest that 20q13.2 gain may be a predictive marker of intravesical recurrence in patients with UUT-TCC.

In situ detection of global DNA hypomethylation in exfoliative urine cytology of patients with suspected bladder cancer

Global DNA hypomethylation is a common phenomenon in bladder cancer. Therefore we investigated whether it is possible to detect and assess global DNA hypomethylation in bladder cancer using a specific monoclonal antibody for 5-methyl-cytosine. Cytospins from exfoliative urine cytology specimens of patients with bladder cancer or a history of bladder cancer, control patients with benign urological diseases and of young healthy volunteers were analyzed. Urothelial carcinoma (UC) cells showed various degrees of nuclear destaining indicating global DNA hypomethylation whereas all specimens from healthy volunteers showed granular nuclear staining indicating regular methylation of repeated DNA sequences. Lowest 5-methylcytosine immunostaining scores were observed in carcinoma cells and a statistically significant difference was observed between urothelial cells of healthy controls or patients with benign disease compared to bladder cancer patients (p<0.01, p<0.05, respectively). In UC cases even morphologically normal urothelial cells often displayed evident hypomethylation. Likewise, in patients with a history of UC, but no cystoscopic evidence of recurrence, morphologically non-malignant urothelial cells presented with some degree of demethylation. Our results strongly support the hypothesis of early global demethylation in bladder cancer. Immunocytochemical staining with the 5-methylcytosine antibody allows simultaneous individual assessment of nuclear morphology and methylation status of a given sample.

High throughput comparative genomic hybridization array analysis of multifocal urothelial cancers

The purpose of this study was to examine genetic alterations occur during synchronous or metachronous multifocal development of urothelial cancers on the whole genome using a comparative genomic hybridization (CGH) array. We used 10 tumor pairs (2 tumors for each patient), in which we had previously defined a clonal relationship by microsatellite analysis. For CGH array analysis, Vysis GenoSensor Array 300 kit was used. An unsupervised hierarchical cluster analysis revealed that the tumors from one patient were clustered together independent of the tumors of all other patients. On the other hand, many genetic divergences among multifocal urothelial cancers were newly found by a CGH array analysis. The concordant genetic alteration patterns of the chromosomal arm in tumor pairs were most frequently observed in 9p, 9q, 8p, 7p, 7q and 11q, while discordant patterns were most frequently found in 15q, 20q, 2q, 10p and 11q. Investigation using a CGH array showed that genetically stable multifocal tumors were less frequent, and that a large percentage of urothelial cancers accumulate genetic alterations during multifocal development by clonal evolution. We might have to consider these genetic accumulations during multifocal development when designing strategies for prevention and detection of recurrent multifocal urothelial cancers. CGH array can be a powerful tool for genetic analysis of multifocal urothelial cancer.