Differential Expression of Cell Cycle Regulators in Phenotypic Variants of Transgenically Induced Bladder Tumors: Implications for Tumor Behavior

Preclinical Models for Bladder Cancer Research

At diagnosis, more than 70% of bladder cancers (BCs) are at the non-muscle-invasive bladder cancer (NMIBC) stages, which are usually treated with transurethral resection followed by intravesical instillation. For the remaining advanced cancers, systemic therapy is the standard of care, with addition of radical cystectomy in cases of locally advanced cancer. Because of the difference in treatment modalities, different models are needed to advance the care of NMIBC and advanced BC. This article gives a comprehensive review of both in vitro and in vivo BC models and compares the advantages and drawbacks of these preclinical systems in BC research.

Clinicopathologic Characterization of Post-Renal Transplantation BK Polyomavirus-Associated Urothelial CarcinomaSingle Institutional Experience

OBJECTIVES

To review rare cases of BK polyomavirus (BKPyV) associated urologic carcinomas in kidney transplant recipients at one institution and in the literature.

METHODS

We describe the clinicopathologic features of BKPyV-associated urologic carcinomas in a single-institution cohort.

RESULTS

Among 4,772 kidney recipients during 1994 to 2014, 26 (0.5%) and 26 (0.5%) developed posttransplantation urothelial carcinomas (UCs) and renal cell carcinomas (RCCs), respectively, as of 2017. Six (27%) UCs but none of the RCCs expressed large T antigen (TAg). TAg-expressing UCs were high grade with p16 and p53 overexpression (P < .05 compared to TAg-negative UCs). Tumor genome sequencing revealed BKPyV integration and a lack of pathogenic mutations in 50 cancer-relevant genes. Compared to TAg-negative UCs, TAg-expressing UCs more frequently presented at advanced stages (50% T3-T4) with lymph node involvement (50%) and higher UC-specific mortality (50%).

CONCLUSIONS

Post-renal transplantation BKPyV-associated UCs are aggressive and genetically distinct from most non-BKPyV-related UCs.

Mechanisms behind Temsirolimus Resistance Causing Reactivated Growth and Invasive Behavior of Bladder Cancer Cells In Vitro

Background: Although mechanistic target of rapamycin (mTOR) inhibitors, such as temsirolimus, show promise in treating bladder cancer, acquired resistance often hampers efficacy. This study evaluates mechanisms leading to resistance. Methods: Cell growth, proliferation, cell cycle phases, and cell cycle regulating proteins were compared in temsirolimus resistant (res) and sensitive (parental—par) RT112 and UMUC3 bladder cancer cells. To evaluate invasive behavior, adhesion to vascular endothelium or to immobilized extracellular matrix proteins and chemotactic activity were examined. Integrin α and β subtypes were analyzed and blocking was done to evaluate physiologic integrin relevance. Results: Growth of RT112res could no longer be restrained by temsirolimus and was even enhanced in UMUC3res, accompanied by accumulation in the S- and G2/M-phase. Proteins of the cdk-cyclin and Akt-mTOR axis increased, whereas p19, p27, p53, and p73 decreased in resistant cells treated with low-dosed temsirolimus. Chemotactic activity of RT112res/UMUC3res was elevated following temsirolimus re-exposure, along with significant integrin α2, α3, and β1 alterations. Blocking revealed a functional switch of the integrins, driving the resistant cells from being adhesive to being highly motile. Conclusion: Temsirolimus resistance is associated with reactivation of bladder cancer growth and invasive behavior. The α2, α3, and β1 integrins could be attractive treatment targets to hinder temsirolimus resistance.

BK virus-associated collecting duct carcinoma of the renal allograft in a kidney-pancreas allograft recipient

BK polyomavirus (BKV) nephropathy is a major concern in renal transplantation. Its main consequence is graft loss, which occurs in more than 50% of the cases. De novo renal cell carcinoma in renal allograft is a very rare event. Most of these tumors are papillary or clear cell carcinomas. We report herein the first case of collecting duct carcinoma of the renal allograft in a kidney-pancreas allograft adult recipient. Collecting duct carcinoma occurs long after the cure of a BKV nephropathy. At this time, BKV viremia and viruria were negative as well as the immunostaining for SV40 in the non-tumor kidney. The viral oncoprotein Tag persists only in the tumor cells. To preserve pancreas graft function, we maintained immunosuppression levels. After a 9-months follow-up, the evolution was free from clinical and radiological progression. The oncogenic role of BKV remains controversial in human cancers. However, strong experimental data have shown an association between BKV infection and urologic neoplasms. Further works might precise the exact role of polyomaviruses in renal carcinogenesis. In the meantime, clinical vigilance for early diagnostic of these tumors is mandatory after BKV nephropathy.

Archetype and Rearranged Non-coding Control Regions in Urothelial Bladder Carcinoma of Immunocompetent Individuals

BACKGROUND

Polyomaviruses (PyVs) are potential transforming viruses. Despite their involvement in human tumours still being debated, there is evidence to suggest a role for PyVs in bladder carcinoma (BC). Therefore, a possible association between PyVs and BC was investigated.

MATERIALS AND METHODS

Urine, blood and fresh bladder tissue specimens were collected from 29 patients with BC. PyV prevalence, non-coding control region (NCCR) organization and genotypic analysis were assessed.

RESULTS

Data showed a significant prevalence of John Cunningham (JC) PyV in BC tissues and in urine with respect to BKPyV, while simian virus 40 was not revealed. A BKPyV rearranged NCCR sequence was isolated, whereas a JCPyV archetypal structure was consistently retained. A prevalence of European genotypes was observed.

CONCLUSION

Our data would suggest a JCPyV involvement in cancer progression and a BKPyV association with BC pathogenesis in immunocompetent patients. However, further work is necessary to better understand the exact role of PyVs in urothelial carcinogenesis.

BK Polyomavirus Tubulointerstitial Nephritis With Urothelial Hyperplasia in a Kidney Transplant

Polyomavirus nephropathy is characterized histopathologically by evidence of viral replication and acute tubular injury with interstitial inflammation, tubulitis, and intranuclear inclusions. Polyomavirus nephropathy typically develops in the kidney transplant as a combination of the unique nature of the transplanted tissue and the immunomodulated status of the patient. We present a case in which a patient had lingering BK viremia and declining kidney function following receipt of lung and kidney transplants. A kidney biopsy was performed, which demonstrated BK polyomavirus tubulointerstitial nephritis, resultant cytopathic changes and tubular/ductal injury, associated urothelial hyperplasia with foci of squamous metaplasia, suspected membranous glomerulopathy, and moderate arterial/arteriolar sclerosis. There was also evidence of more proximal nephron viral involvement, with glomerular parietal epithelium infection and injury present. This case shows impressive BK polyomavirus-associated urothelial hyperplasia in the kidney, which to our knowledge has not been previously illustrated in the literature. There have been numerous studies attempting to show the association of polyomaviruses with the development of carcinoma, and this case report is significant because it is an example of viral-induced changes that are concerning and hold potential for malignant transformation.

Significant in vivo anti-inflammatory activity of Pytren4Q-Mn a superoxide dismutase 2 (SOD2) mimetic scorpiand-like Mn (II) complex

Background

The clinical use of purified SOD enzymes has strong limitations due to their large molecular size, high production cost and immunogenicity. These limitations could be compensated by using instead synthetic SOD mimetic compounds of low molecular weight.

Background/Methodology

We have recently reported that two SOD mimetic compounds, the Mn^II complexes of the polyamines Pytren2Q and Pytren4Q, displayed high antioxidant activity in bacteria and yeast. Since frequently molecules with antioxidant properties or free-radical scavengers also have anti-inflammatory properties we have assessed the anti-inflammatory potential of Pytren2Q and Pytren4Q Mn^II complexes, in cultured macrophages and in a murine model of inflammation, by measuring the degree of protection they could provide against the cellular injury produced by lipopolisacharide, a bacterial endotoxin.

Principal Findings

In this report we show that the Mn^II complex of Pytren4Q but not that of Pytren2Q effectively protected human cultured THP-1 macrophages and whole mice from the inflammatory effects produced by LPS. These results obtained with two molecules that are isomers highlight the importance of gathering experimental data from animal models of disease in assessing the potential of candidate molecules.

Conclusion/Significance

The effective anti-inflammatory activity of the Mn^II complex of Pytren4Q in addition to its low toxicity, water solubility and ease of production would suggest it is worth taking into consideration for future pharmacological studies.

Modelling bladder cancer in mice: opportunities and challenges

The prognosis and treatment of bladder cancer have improved little in the past 20 years. Bladder cancer remains a debilitating and often fatal disease, and is among the most costly cancers to treat. The generation of informative mouse models has the potential to improve our understanding of bladder cancer progression, as well as to affect its diagnosis and treatment. However, relatively few mouse models of bladder cancer have been described, and in particular, few that develop invasive cancer phenotypes. This Review focuses on opportunities for improving the landscape of mouse models of bladder cancer.

BK virus-associated urothelial carcinoma of a ureter graft in a renal transplant recipient: a case report

BACKGROUND

Urothelial carcinomas of ureter grafts in renal transplant patients are rare. Here we report our experience with a case of BK virus-associated urothelial carcinoma in a ureter graft.

CASE REPORT

A 47-year-old man developed chronic renal failure secondary to diabetes mellitus and started maintenance hemodialysis in September 2007. Two months later, the patient received a renal transplant from his 70-year-old mother. The patient developed BK virus-associated nephropathy 1 year after transplantation and presented with a decline in renal function and hydronephrosis in the transplanted kidney 4 years 6 months after transplantation. Cystoscopy and retrograde pyelography revealed an irregular filling defect in the ureter graft. Cytologic diagnosis of his urine revealed a high-grade urothelial carcinoma. Computerized tomography showed a cT2 ureteral tumor and no involvement of other organs. The patient subsequently underwent a transplant nephroureterectomy with bladder cuff resection. Histopathologic findings revealed a high-grade urothelial carcinoma, pT2, in the ureter graft with SV40-positive staining. The patient was closely observed without adjuvant chemotherapy therapy and remained disease free 1 year after surgery. Renal transplant recipients with BK virus infection are at high risk of developing urologic malignancies. Close attention is necessary to diagnose post-transplantation urologica malignancies as early as possible.

In vivo disruption of an Rb-E2F-Ezh2 signaling loop causes bladder cancer

Bladder cancer is a highly prevalent human disease in which retinoblastoma (Rb) pathway inactivation and epigenetic alterations are common events. However, the connection between these two processes is still poorly understood. Here, we show that the in vivo inactivation of all Rb family genes in the mouse urothelium is sufficient to initiate bladder cancer development. The characterization of the mouse tumors revealed multiple molecular features of human bladder cancer, including the activation of E2F transcription factor and subsequent Ezh2 expression and the activation of several signaling pathways previously identified as highly relevant in urothelial tumors. These mice represent a genetically defined model for human high-grade superficial bladder cancer. Whole transcriptional characterizations of mouse and human bladder tumors revealed a significant overlap and confirmed the predominant role for Ezh2 in the downregulation of gene expression programs. Importantly, the increased tumor recurrence and progression in human patients with superficial bladder cancer is associated with increased E2F and Ezh2 expression and Ezh2-mediated gene expression repression. Collectively, our studies provide a genetically defined model for human high-grade superficial bladder cancer and demonstrate the existence of an Rb-E2F-Ezh2 axis in bladder whose disruption can promote tumor development.

USP28 is a potential prognostic marker for bladder cancer

This study was conducted to analyze the expression of the ubiquitin-specific protease Usp28 and assess its clinical significance in human bladder cancer. mRNA and protein expression levels of Usp28 were determined by real-time polymerase chain reaction (PCR) and Western blot in 24 paired bladder cancers and the adjacent non-cancerous tissues. In addition, the expression of Usp28 protein in 186 bladder cancers was also determined by immunohistochemistry. The relationship between expression of Usp28 and clinico-pathologic features and prognosis was finally evaluated. Usp28 was expressed at a higher level in bladder cancers compared to adjacent non-cancerous tissues at both the mRNA and protein levels in 24 paired samples (all P < 0.01). In immunohistochemical examination, 78 (41.9%) of 186 cases displayed low Usp28 expression in cancerous tissues, whereas 108 (58.1%) cases displayed high Usp28 expression. In the universal analysis, Usp28 correlated strongly with histopathological grade, clinical stage, tumor number and recurrence rate (P = 0.0001, 0.0001, 0.0001 and 0.0051, respectively), but did not correlate with gender or age (P = 0.5588 and 0.6574). After multiple analysis of the above factors and consideration of confounding factors, tumor number, histological grade, clinical stage, and recurrence were related to Usp28 expression (P = 0.001, 0.001, 0.001 and 0.001, respectively). Finally, Usp28 expression was indentified as a independent predictors of survival (P = 0.001). Usp28 protein expression is potentially valuable in prognostic evaluation of bladder cancer.

Polyoma BK Virus: An Oncogenic Virus?

We report a case of a 65-year-old gentleman with a history of end stage renal disease who underwent a successful cadaveric donor kidney transplant four years ago. He subsequently developed BK virus nephropathy related to chronic immunosuppressant therapy. Three years later, misfortune struck again, and he developed adenocarcinoma of the bladder.

Overexpression of Cdk6 and Ccnd1 in chondrocytes inhibited chondrocyte maturation and caused p53-dependent apoptosis without enhancing proliferation

Cell proliferation and differentiation are closely coupled. However, we previously showed that overexpression of cyclin-dependent kinase (Cdk6) blocks chondrocyte differentiation without affecting cell-cycle progression in vitro. To investigate whether Cdk6 inhibits chondrocyte differentiation in vivo, we generated chondrocyte-specific Cdk6 transgenic mice using Col2a1 promoter. Unexpectedly, differentiation and cell-cycle progression of chondrocytes in the Cdk6 transgenic mice were similar to those in wild-type mice. Then, we generated chondrocyte-specific Ccnd1 transgenic mice and Cdk6/Ccnd1 double transgenic mice to investigate the possibility that Cdk6 inhibits chondrocyte differentiation through E2f activation. Bromodeoxyuridine (BrdU)-positive chondrocytes and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive chondrocytes were increased in number, and chondrocyte maturation was inhibited only in Cdk6/Ccnd1 transgenic mice (K6(H)/D1(H) mice), which showed dwarfism. Retinoblastoma protein (pRb) was highly phosphorylated but p107 was upregulated, and the expression of E2f target genes was dysregulated as shown by upregulation of Cdc6 but downregulation of cyclin E, dihydrofolate reductase (dhfr), Cdc25a and B-Myb in chondrocytes of K6(H)/D1(H) mice. Similarly, overexpression of Cdk6/Ccnd1 in a chondrogenic cell line ATDC5 highly phosphorylated pRb, upregulated p107, induced apoptosis, upregulated Cdc6 and downregulated cyclin E, dhfr and B-Myb and p107 small interfering RNA reversed the expression of downregulated genes. Further, introduction of kinase-negative Cdk6 and cyclin D1 abolished all effects by Cdk6/cyclin D1 in ATDC5 cells, indicating the requirement of the kinase activity on these effects. p53 deletion partially restored the size of the skeleton and almost completely rescued chondrocyte apoptosis, but failed to enhance chondrocyte proliferation in K6(H)/D1(H) mice. These findings indicated that Cdk6/Ccnd1 overexpression inhibited chondrocyte maturation and enhanced G1/S cell-cycle transition by phosphorylating pRb, but the chondrocytes failed to accomplish the cell cycle, and underwent p53-dependent apoptosis probably due to the dysregulation of E2f target genes. Our findings also indicated that p53 deletion in addition to the inactivation of Rb was not sufficient to accelerate chondrocyte proliferation, suggesting the resistance of chondrocytes to sarcomagenesis.

BK virus-associated urinary bladder carcinoma in transplant recipients: report of 2 cases, review of the literature, and proposed pathogenetic model

Despite strong experimental evidence, BK polyomavirus involvement in human cancers has been controversial. We report 2 cases of kidney ± pancreas transplant recipients with evidence of BK polyomavirus reactivation, who developed aggressive urinary bladder urothelial carcinomas with adenocarcinomatous and/or micropapillary differentiation. Diffuse strong nuclear positivity for viral T antigen, p53, Ki-67, and p16 was observed in both malignancies. The BK polyomavirus role in promoting urothelial neoplasia in transplant recipients may be partly indirect, based on the demonstration by polymerase chain reaction in both tumors of BK polyomavirus with intact open reading frames and close phylogenetic clustering with known replication-competent strains, and viral capsid protein VP1 messenger RNA and intranuclear virions by electron microscopy in 1 tumor. No unique cancer-associated mutations were found, but some viral T antigen mutations were potentially associated with increased rate of viral replication and risk for "rare" carcinogenic events. The BK polyomavirus-induced profound effects on cell activation, cell cycle shift to proliferation, and apoptosis inhibition, in the context of marked immunosuppression, constitute a potentially ideal background for malignant transformation. The long time lapse between transplantation and tumor manifestation, 7 and 11 years, respectively, further supports the concept of multistep carcinogenesis cascade and long-term risk for these patients. We propose a model of changes ranging from viral reactivation to dysplasia to invasive carcinoma. Clinical vigilance is warranted for early diagnosis of BK polyomavirus-related urothelial malignancies in transplant recipients.

Prognostic value of cell-cycle regulation biomarkers in bladder cancer

The determination of prognosis in bladder cancer is currently based on staging methods that rely primarily on the pathological stage of a tumor with limited objective correlates. The development and progression of bladder cancer involve alterations in several cellular pathways. Dysregulation in markers associated with cell-cycle regulation has been the most extensively examined molecular aberration in this cancer. Individual alterations of these markers have been associated with disease outcome, with several observations suggesting that their prognostic potential is independent of pathological stage. While many individual molecules in the cell growth receptor signaling, p53, and retinoblastoma (Rb) pathways have been identified, there is a general lack of consensus on which markers can be adopted in the clinical setting. More recent studies have suggested that the combination of markers as concise panels may be more beneficial in determining the degree of aggressiveness of a given tumor and its impending outcome than individual markers alone. This review will discuss alterations in molecules within pathways controlling cell-cycle regulation in the context of bladder cancer, and their impact on patient outcome when examined individually and in combination.

Modulation of DNA binding by reversible metal-controlled molecular reorganizations of scorpiand-like ligands

DNA interaction with scorpiand azamacrocycles has been achieved through modulation of their binding affinities. Studies performed with different experimental techniques provided evidence that pH or metal-driven molecular reorganizations of these ligands regulate their ability to interact with calf thymus DNA (ctDNA) through an intercalative mode. Interestingly enough, metal-driven molecular reorganizations serve to increase or decrease the biological activities of these compounds significantly.

HDAC inhibition delays cell cycle progression of human bladder cancer cells in vitro

Our aim was to analyze the impact of the histone deacetylase (HDAC)-inhibitor valproic acid (VPA) on bladder cancer cell growth in vitro. RT-4, TCCSUP, UMUC-3, and RT-112 bladder cancer cells were treated with VPA (0.125-1 mmol/l) without and with preincubation periods of 3 and 5 days. Controls remained untreated. Tumor cell growth, cell cycle progression, and cell cycle-regulating proteins were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry, and western blotting, respectively. Effects of VPA on histone H3 and H4 acetylation and HDAC3 and HDAC4 were also determined. Without preincubation, no tumor cell growth reduction was observed with 0.125 and 0.25 mmol/l VPA in TCCSUP, UMUC-3, and RT-112 cells, whereas 0.5 and 1 mmol/l VPA diminished the cell number significantly. VPA (0.25 mmol/l) did exert tumor growth-blocking effects after a 3-day preincubation. To achieve antitumor effects with VPA (0.125 mmol/l), a 5-day preincubation was necessary. A 3-day or 5-day preincubation was also necessary to distinctly delay cell cycle progression, with maximum effects at VPA (1 mmol/l). After the 5-day preincubation, the cell cycle-regulating proteins cdk1, cdk2, cdk4, and cyclins B, D1, and E were reduced, whereas p27 was enhanced. Diminished HDAC3 and 4 expression induced by VPA was accompanied by elevated acetylation of H3 and H4. VPA exerted growth-blocking properties on a panel of bladder cancer cell lines, commensurate with dose and exposure time. Long-term application induced much stronger effects than did shorter application and should be considered when designing therapeutic strategies for treating bladder carcinoma.

p15(INK4b) plays a crucial role in murine lymphoid development and tumorigenesis

To investigate if the cooperation between the Rgr oncogene and the inactivation of INK4b (a CDK inhibitor), as described previously in a sarcoma model, would be operational in a lymphoid system in vivo, we generated a transgenic/knockout murine model. Transgenic mice expressing the Rgr oncogene under a CD4 promoter were crossed into a p15(INK4b)-deficient background. Unexpectedly, mice with a complete ablation of both p15(INK4b) alleles had a lower tumor incidence and higher survival rate when compared with CD4-Rgr progeny with homozygous or heterozygous expression of p15(INK4b). Also, a similar survival pattern was observed in a parallel model in which transgenic mice expressing a constitutively activated N-Ras mutant were crossed into a p15(INK4b)-deficient background. To analyze this paradoxical event, we investigated the hypothesis that the absence of both p15(INK4b) alleles in the presence of the Rgr oncogene could be deleterious for proper thymocyte development. When analyzed, thymocyte development was blocked at the double negative (DN) 3 and DN4 stages in mice missing one or both alleles of p15(INK4b), respectively. We found reduction in overall apoptotic levels in the thymocytes of mice expressing Rgr, compared with their wild-type mice, supporting thymocyte escape from programmed cell death and subsequently facilitating the onset of thymic lymphomas but less for those missing both p15 alleles. These findings provide evidence of the complex interplay between oncogenes and tumor suppressor genes in tumor development and indicate that in the lymphoid tissue the inactivation of both p15 alleles is unlikely to be the first event in tumor development.

Expression of regulatory proteins and proliferative activity in relation to phenotypic characteristics of upper urothelial carcinoma

BACKGROUND/AIM

Deregulation of the normal cell cycle is common in upper urothelial carcinoma (UUC). The aim of this study was to investigate the expression of regulatory proteins of the cell cycle (p53, p16, cyclin D1, HER-2) and proliferative Ki-67 activity in UUC, and to determine their interaction and influence on the phenotypic characteristics of UUC.

METHODS

In 44 patients with UUC, histopathological and immunohistochemical analyses (p53, p16, cyclin D1, HER-2, and Ki-67) of tumors were done.

RESULTS

Overexpression/altered expression of p53, p16, cyclin D1 or HER-2 was detected in 20%, 57%, 64%, and 57% of tumors, respectively. Eleven (25%) UUC had a high proliferative Ki-67 index. Forty patients (91%) had at least one marker altered, while four (9%) tumors had a wild-type status. Analysis of relationship between expressions of molecular markers showed that only high expression of p53 was significantly associated with altered p16 activity (p < 0.05). High Ki-67 index was associated with the high stage (p < 0.005), solid growth (p < 0.01), high grade (p < 0.05), and multifocality p < 0.05) of UUC, while high expression of p53 was associated with the solid growth (p < 0.05). In regression models that included all molecular markers and phenotypic characteristics, only Ki-67 correlated with the growth (p < 0.0001), stage (p < 0.01), grade (p < 0.05) and multifocality (p < 0.05) of UCC; (Ki-67 and HER-2 expression correlated with the lymphovascular invasion (p < 0.05).

CONCLUSIONS

This investigation showed that only negative regulatory proteins of the cell cycle, p53 and p16, were significantly associated in UUC, while proliferative marker Ki-67 was in relation to the key phenotypic characteristics of UUC in the best way.

The human Rgr oncogene is overexpressed in T-cell malignancies and induces transformation by acting as a GEF for Ras and Ral

The Ras superfamily of GTPases is involved in the modification of many cellular processes including cellular motility, proliferation and differentiation. Our laboratory has previously identified the RalGDS-related (Rgr) oncogene in a DMBA (7,12-dimethylbenz[α]anthracene)-induced rabbit squamous cell carcinoma and its human orthologue, hRgr. In this study, we analyzed the expression levels of the human hRgr transcript in a panel of human hematopoietic malignancies and found that a truncated form (diseased-truncated (Dtr-hrgr)) was significantly overexpressed in many T-cell-derived neoplasms. Although the Rgr proto-oncogene belongs to the RalGDS family of guanine nucleotide exchange factors (GEFs), we show that upon the introduction of hRgr into fibroblast cell lines, it is able to elicit the activation of both Ral and Ras GTPases. Moreover, in vitro guanine nucleotide exchange assays confirm that hRgr promotes Ral and Ras activation through GDP dissociation, which is a critical characteristic of GEF proteins. hRgr has guanine nucleotide exchange activity for both small GTPases and this activity was reduced when a point mutation within the catalytic domain (CDC25) of the protein, (cd) Dtr-hRgr, was utilized. These observations prompted the analysis of the biological effects of hRgr and (cd) hRgr expression in cultured cells. Here, we show that hRgr increases proliferation in low serum, increases invasion, reduces anchorage dependence and promotes the progression into the S phase of the cell cycle; properties that are abolished or severely reduced in the presence of the catalytic dead mutant. We conclude that the ability of hRgr to activate both Ral and Ras is responsible for its transformation-inducing phenotype and it could be an important contributor in the development of some T-cell malignancies.

Deficiency of pRb family proteins and p53 in invasive urothelial tumorigenesis

Defects in pRb tumor suppressor pathway occur in approximately 50% of the deadly muscle-invasive urothelial carcinomas in humans and urothelial carcinoma is the most prevalent epithelial cancer in long-term survivors of hereditary retinoblastomas caused by loss-of-function RB1 mutations. Here, we show that conditional inactivation of both RB1 alleles in mouse urothelium failed to accelerate urothelial proliferation. Instead, it profoundly activated the p53 pathway, leading to extensive apoptosis, and selectively induced pRb family member p107. Thus, pRb loss triggered multiple fail-safe mechanisms whereby urothelial cells evade tumorigenesis. Additional loss of p53 in pRb-deficient urothelial cells removed these p53-dependent tumor barriers, resulting in late-onset hyperplasia, umbrella cell nuclear atypia, and rare-occurring low-grade, superficial papillary bladder tumors, without eliciting invasive carcinomas. Importantly, mice deficient in both pRb and p53, but not those deficient in either protein alone, were highly susceptible to subthreshold carcinogen exposure and developed invasive urothelial carcinomas that strongly resembled the human counterparts. The invasive lesions had a marked reduction of p107 but not p130 of the pRb family. Our data provide compelling evidence, indicating that urothelium, one of the slowest cycling epithelia, is remarkably resistant to transformation by pRb or p53 deficiency; that concurrent loss of these two tumor suppressors is necessary but insufficient to initiate urothelial tumorigenesis along the invasive pathway; that p107 may play a critical role in suppressing invasive urothelial tumor formation; and that replacing/restoring the function of pRb, p107, or p53 could be explored as a potential therapeutic strategy to block urothelial tumor progression.

Biology of urothelial tumorigenesis: insights from genetically engineered mice

Urothelium, one of the slowest cycling epithelia in the body, embodies a unique biological context for cellular transformation. Introduction of oncogenes into or removing tumor suppressor genes from the urothelial cells or a combination of both using the transgenic and/or knockout mouse approaches has provided useful insights into the molecular mechanisms of urothelial transformation and tumorigenesis. It is becoming increasingly clear that over-activation of the receptor tyrosine kinase (RTK) pathway, as exemplified by the constitutively activated Ha-ras oncogene, is both necessary and sufficient to initiate the low-grade, non-invasive urothelial carcinomas. Dosage of the mutated Ha-ras, but not concurrent inactivation of pro-senescence molecules p16Ink4a and p19Arf, dictates whether and when the low-grade urothelial carcinomas arise. Inactivation of both p53 and pRb, a prevailing paradigm previously proposed for muscle-invasive urothelial tumorigenesis, is found to be necessary but insufficient to initiate this urothelial carcinoma variant. Instead, downregulation in p53/pRb co-deficient urothelial cells of p107, a pRb family member, is associated with the genesis of the muscle-invasive bladder cancers. p53 deficiency also seems to be capable of cooperating with that of PTEN in eliciting invasive urothelial carcinomas. The genetically engineered mice have improved the molecular definition of the divergent pathways of urothelial tumorigenesis and progression, helped delineate the intricate crosstalk among different genetic alterations within a urothelium-specific context, identified new prognostic markers and novel therapeutic targets potentially applicable for clinical intervention, and provided in vivo platforms for testing preventive strategies of bladder cancer.

Mutant fibroblast growth factor receptor 3 induces intracellular signaling and cellular transformation in a cell type- and mutation-specific manner

Although activating mutations of FGFR3 are frequent in bladder tumors, little information is available on their specific effects in urothelial cells or the basis for the observed mutation spectrum. We investigated the phenotypic and signaling consequences of three FGFR3 mutations (S249C, Y375C, and K652E) in immortalized normal human urothelial cells (TERT-NHUC) and mouse fibroblasts (NIH-3T3). In TERT-NHUC, all mutant forms of FGFR3 induced phosphorylation of FRS2α and ERK1/2, but not AKT or SRC. PLCγ1 phosphorylation was only observed in TERT-NHUC expressing the common S249C and Y375C mutations, and not the rare K652E mutation. Cells expressing S249C and Y375C FGFR3 displayed an increased saturation density, related to increased proliferation and viability. This effect was significantly dependent on PLCγ1 signaling and undetectable in cells expressing K652E FGFR3, which failed to phosphorylate PLCγ1. In contrast to TERT-NHUC, expression of mutant FGFR3 in NIH-3T3 resulted in phosphorylation of Src and Akt. Additionally, all forms of mutant FGFR3 were able to phosphorylate Plcγ1 and induce morphological transformation, cell proliferation, and anchorage independent growth. Our results indicate that the effects of mutant FGFR3 are both cell type- and mutation-specific. Mutant FGFR3 may confer a selective advantage in the urothelium by overcoming normal contact inhibition of proliferation.

Lymphatic vessel density and function in experimental bladder cancer

BACKGROUND

The lymphatics form a second circulatory system that drains the extracellular fluid and proteins from the tumor microenvironment, and provides an exclusive environment in which immune cells interact and respond to foreign antigen. Both cancer and inflammation are known to induce lymphangiogenesis. However, little is known about bladder lymphatic vessels and their involvement in cancer formation and progression.

METHODS

A double transgenic mouse model was generated by crossing a bladder cancer-induced transgenic, in which SV40 large T antigen was under the control of uroplakin II promoter, with another transgenic mouse harboring a lacZ reporter gene under the control of an NF-kappaB-responsive promoter (kappaB-lacZ) exhibiting constitutive activity of beta-galactosidase in lymphatic endothelial cells. In this new mouse model (SV40-lacZ), we examined the lymphatic vessel density (LVD) and function (LVF) during bladder cancer progression. LVD was performed in bladder whole mounts and cross-sections by fluorescent immunohistochemistry (IHC) using LYVE-1 antibody. LVF was assessed by real-time in vivo imaging techniques using a contrast agent (biotin-BSA-Gd-DTPA-Cy5.5; Gd-Cy5.5) suitable for both magnetic resonance imaging (MRI) and near infrared fluorescence (NIRF). In addition, IHC of Cy5.5 was used for time-course analysis of co-localization of Gd-Cy5.5 with LYVE-1-positive lymphatics and CD31-positive blood vessels.

RESULTS

SV40-lacZ mice develop bladder cancer and permitted visualization of lymphatics. A significant increase in LVD was found concomitantly with bladder cancer progression. Double labeling of the bladder cross-sections with LYVE-1 and Ki-67 antibodies indicated cancer-induced lymphangiogenesis. MRI detected mouse bladder cancer, as early as 4 months, and permitted to follow tumor sizes during cancer progression. Using Gd-Cy5.5 as a contrast agent for MRI-guided lymphangiography, we determined a possible reduction of lymphatic flow within the tumoral area. In addition, NIRF studies of Gd-Cy5.5 confirmed its temporal distribution between CD31-positive blood vessels and LYVE-1 positive lymphatic vessels.

CONCLUSION

SV40-lacZ mice permit the visualization of lymphatics during bladder cancer progression. Gd-Cy5.5, as a double contrast agent for NIRF and MRI, permits to quantify delivery, transport rates, and volumes of macromolecular fluid flow through the interstitial-lymphatic continuum. Our results open the path for the study of lymphatic activity in vivo and in real time, and support the role of lymphangiogenesis during bladder cancer progression.

p53 and retinoblastoma pathways in bladder cancer

A majority of the aggressive, invasive bladder carcinomas have alterations in the p53 and retinoblastoma genes and pathways. Examination of the alterations in the molecules in these pathways that regulate the cell cycle and their effects on the prognosis of bladder cancer are areas of active research. While defects in the p53-Mdm2-p14 axis have been implicated in urothelial cancer, perturbations in the cyclin-dependent kinases and their inhibitors have also been extensively studied in this context. Genetic alterations of the retinoblastoma gene and aberrant post-translational modifications of its protein have also been incriminated in invasive bladder cancer. This article reviews the individual prognostic roles of alterations in these molecules in the context of bladder cancer. Additionally, we review findings from recent studies that are attempting to analyze these markers in combination in an effort to construct molecular panels that can serve as more robust outcome predictors. More importantly, alterations in these molecules are now becoming enticing targets for novel therapeutics. We also review some of these agents that can restore the tumor cells' altered homeostatic mechanisms, thereby having potential in transitional cell carcinoma therapy. Future management of bladder cancer will employ validated marker panels for outcome prediction, and novel genetic and pharmacologic agents that will be able to target molecular alterations in individual tumors based on their respective profiles.

Heterogeneous Abnormalities of CCND1 and RB1 in Primary Cutaneous T-Cell Lymphomas Suggesting Impaired Cell Cycle Control in Disease Pathogenesis

Upregulation of cyclin D1/B-cell leukemia/lymphoma 1 (CCND1/BCL1) is present in most mantle cell lymphomas with the t(11;14)(q13;q32) translocation. However, little is known about the abnormalities of CCND1 and its regulator RB1 in primary cutaneous T-cell lymphomas (CTCL). We analyzed CCND and RB status in CTCL using fluorescent in situ hybridization (FISH), immunohistochemistry (IHC), and Affymetrix expression microarray. FISH revealed loss of CCND1/BCL1 in five of nine Sézary syndrome (SS) cases but gain in two cases, and RB1 loss in four of seven SS cases. IHC showed absent CCND1/BCL1 expression in 18 of 30 SS, 10 of 23 mycosis fungoides (MF), and three of 10 primary cutaneous CD30+ anaplastic large-cell lymphoma (C-ALCL). Increased CCND1/BCL1 expression was seen in nine MF, seven C-ALCL, and six SS cases. Absent RB1 expression was detected in 8 of 12 MF and 7 of 9 SS cases, and raised RB1 expression in 7 of 8 C-ALCL. Affymetrix revealed increased gene expression of CCND2 in four of eight CTCL cases, CCND3 in three cases, and CDKN2C in two cases with a normal expression of CCND1 and RB1. These findings suggest heterogeneous abnormalities of CCND and RB in CTCL, in which dysregulated CCND and RB1 may lead to impaired cell cycle control.

Genetic alterations in urothelial bladder carcinoma: an updated review

New oncogenes and tumor suppressor genes that play an important role in the pathogenesis of urothelial bladder carcinoma have been discovered. The objectives of this review were to summarize the most important oncogenes and tumor suppressor genes involved in urothelial carcinoma and to address their role in pathogenesis, their prognostic value, and their potential use as therapeutic targets. The collected data led the authors to propose a common pathway in which the fibroblastic growth factor receptor 3 (FGFR3) mutation seems to be the earliest genetic abnormality responsible for the transformation from normal tissue to atypia and dysplasia. Three different progression pathways were proposed: The first operative pathway is from dysplasia to superficial papillary pathologic Ta (pTa) tumors to pT1 tumors and, ultimately, to pT2 tumors with FGFR3 and tuberous sclerosis complex 1 (TSC1) the responsible genes. The second major operative pathway is from dysplasia, to carcinoma in situ, and to solid pT1 and pT2 tumors. The third pathway of progression is from dysplasia to papillary T1 and pT2 tumors. The genes involved in the last 2 pathways are the p53, serine threonine protein kinase 15 (STK15), triple-function domain (TRIO), fragile histidine triad (FHIT), p63 genes; and alterations of 20q and 5p, alterations of adhesions, angiogenesis, and matrix-remodeling gene products also are involved. Finally, murine leukemia viral oncogene homologue 1 (RAF1) and CD9 are involved in the progression from papillary pT1 tumors to pT2 tumors.

Altered phenotype of cultured urothelial and other stratified epithelial cells: implications for wound healing

The differentiation of cultured stratified epithelial cells can deviate significantly from that of normal epithelium, leading to suggestions that cultured cells undergo abnormal differentiation, or a truncated differentiation. Thus cultured epidermal and corneal epithelial cells stop synthesizing their tissue-specific keratin pair K1/K10 and K3/K12, respectively. The replacement of these keratins in the suprabasal compartment by K6/K16 keratins that are made by all stratified squamous epithelia during hyperplasia rules out a truncated differentiation. Importantly, the keratin pattern of in vivo corneal epithelium undergoing wound repair mimics that of cultured rabbit corneal epithelial cells. Although cultured urothelial cells continue to synthesize uroplakins, which normally form two-dimensional crystalline urothelial plaques covering almost the entire apical urothelial surface, these proteins do not assemble into crystals in cultured cells. Cultured epithelial cells can, however, rapidly regain normal differentiation on the removal of mitogenic stimuli, the use of a suitable extracellular matrix, or the transplantation of the cells to an in vivo, nonmitogenic environment. These data suggest that cultured epithelial cells adopt altered differentiation patterns mimicking in vivo regenerating or hyperplastic epithelia. Blocking the synthesis of tissue-specific differentiation products, such as the K1 and K10 keratins designed to form extensive disulfide cross-links in cornified cells, or the assembly of uroplakin plaques allows epithelial cells to better migrate and proliferate, activities that are of overriding importance during wound repair. Cultured urothelial and other stratified epithelial cells provide excellent models for studying the regulation of the synthesis and assembly of differentiation products, a key cellular process during epithelial wound repair.

Interferon-γ induces regression of epithelial cell carcinoma: critical roles of IRF-1 and ICSBP transcription factors

We have developed an epithelial cell carcinoma model for studying efficacy of IFNgamma gene therapy and have identified components of IFNgamma-signaling pathway responsible for its direct anti-tumor actions. The tumor results from ectopic expression of SV40 Large T-Antigen (SV40 T-Ag) oncogene in lens of transgenic mouse (alphaT3) and complete regression of the tumor is induced by targeting expression of IFNgamma into malignant lens cells. Inflammatory cells are absent in lens of alphaT3 or DT (co-expressing IFNgamma and SV40-T-Antigen) mice and the transformed lens cells are non-immunogenic, suggesting non-involvement of immunologic cells. We show that IFNgamma has direct growth-inhibitory effects on tumor cells, induces death of tumor cells by apoptosis and that these effects are mediated by two transcription factors, IRF-1 (interferon-regulatory factor-1) and ICSBP (interferon-consensus sequence-binding protein) induced by IFNgamma. Furthermore, stable transfection with ICSBP or IRF-1 construct inhibits lens carcinoma cell growth by upregulating Caspase-1, p21(WAF1) and p27 expression. In contrast, tumor progression in alphaT3 lens correlates with inhibition of IRF-1 and ICSBP expression. Our results suggest that IFNgamma gene therapy maybe effective in malignant diseases for which DNA tumor viruses are etiologic agents and that antitumor actions of IRF-1/ICSBP can be exploited therapeutically to circumvent adverse clinical effects associated with IFN therapy.

Cyclin D3 expression in primary Ta/T1 bladder cancer

Cyclin D3 deregulation has recently been reported in bladder cancer but its prognostic significance remains uncertain. A cohort of 159 patients with stage Ta or T1 primary bladder tumours was investigated to determine the significance of cyclin D3 expression in association with other G1-S phase regulators of the cell cycle (p53, p21Waf1, p27kip1, cyclin D1), including tumour proliferation (ki67-MIB1); its association with conventional clinicopathological parameters; and the relationship between cyclin D3 and loss of heterozygosity (LOH) at the 9p21 (p16INK4a locus) chromosome region. The end point of the study was progression-free survival. Cyclin D3, other G1-S phase regulators, and tumour proliferation were investigated by immunohistochemistry and measured by the grid-counting method. To validate the immunohistochemical expression, cyclin D3 was additionally assessed by western blotting in selected cases. LOH at the 9p21 chromosome region (marker D9S171) was assessed in 125 cases using an AB Prism 310 genetic analyser and a set of microsatellite fluorescence-labelled primers. Cyclin D3 overexpression was related to larger tumour size (>5 cm; p < 0.0001) and high tumour proliferation (>10%; p = 0.025). Mean cyclin D3 expression increased with 2004 WHO grading categories in stage Ta (p = 0.035, ANOVA) and stage T1 (p = 0.047, t test) tumours. Cyclin D3 was not related to other clinicopathological parameters, G1-S phase modulators, or 9p21 LOH. Cox's multivariate analysis selected cyclin D3 as an independent predictor of progression-free survival (p = 0.0012, relative risk (RR) = 5.2366) together with tumour size (p = 0.0115, RR = 4.4442) and cyclin D1 (p = 0.0065, RR = 3.3023). Cyclin D3 expression had the highest risk ratio. Our results suggest that expression of cyclin D3 is relevant to the progression-free survival of patients with Ta/T1 bladder carcinomas.

Experimental models of human bladder carcinogenesis

Bladder cancer is the fifth most common cancer in the UK, yet human bladder carcinogenesis remains poorly understood and the response of bladder tumours to radio- and chemo-therapy is unpredictable. The aims of this article are to review human bladder carcinogenesis and appraise the different in vitro and in vivo approaches that have been developed to study the process. The review considers how in vitro models based on normal human urothelial (NHU) cells can be applied to human bladder cancer research. We conclude that recent advances in NHU cell culture offer novel approaches for defining urothelial tissue-specific responses to genotoxic and non-genotoxic carcinogens and elucidating the role of specific genes involved in the mechanisms of bladder carcinogenesis and malignant progression.

Mechanisms of Disease: genetic and epigenetic alterations that drive bladder cancer

There is substantial evidence for the existence of mutually exclusive molecular pathways to tumorigenesis, in the formation of papillary and invasive carcinomas, respectively. The most common genetic alterations in low grade papillary transitional-cell carcinoma (TCC) are loss of heterozygosity of part or all of chromosome 9 and activating mutations of the fibroblast growth factor receptor 3 (FGFR3). The pathway to development of invasive TCC seems to start with dysplasia, progress to carcinoma in situ, followed by invasion of the lamina propria. The most frequent genetic alteration in dysplasia and carcinoma in situ is mutation of TP53, followed by loss of heterozygosity of chromosome 9. A marker for progression in TCC is loss of chromosome 8p, which occurs in approximately 60% of bladder tumors. Global trends of increased genomic instability and aberrant methylation of cytosine residues in DNA correlate with increased tumor invasion and progression. When researching markers of bladder cancer for clinical use, it is important that biomedical pathways and their alterations are measured in the same tumor populations. This review examines the published data and proposes a model for the mechanisms behind bladder cancer development.