Level of retinoblastoma protein expression correlates with p16 (MTS-1/INK4A/CDKN2) status in bladder cancer

Loss of MTAP Expression by Immunohistochemistry Is a Surrogate Marker for Homozygous 9p21.3 Deletion in Urothelial Carcinoma

Homozygous deletion of the chromosomal region 9p21.3 is common in urothelial carcinoma (UC) and leads to loss of several genes, including CDKN2A and MTAP, resulting in loss of MTAP protein expression. Here, we aimed to explore the diagnostic potential of MTAP immunohistochemistry (IHC) as a surrogate marker for homozygous 9p21.3 deletion (9p21 homozygous deletion [HD]) in UC. MTAP status was determined by IHC on 27 UC tissue specimens with known 9p21.3 status as defined by fluorescence in situ hybridization in matched cytological specimens, by IHC and fluorescence in situ hybridization on a tissue microarray (TMA) containing 359 UC at different stages, and by IHC on 729 consecutive UC from routine practice. Moreover, we analyzed a longitudinal series of matched specimens from 38 patients with MTAP-negative recurrent UC. MTAP loss by IHC was found in all 17 patients with 9p21 HD and in 2/8 cases without 9p21 HD. In the TMA, MTAP loss was more common in metastases (53%) than in muscle-invasive (33%) and non-muscle-invasive UC (29%) (P = .03). In the consecutive series, 164/729 (22%) cases showed loss of MTAP expression. In 41 of these 164 cases (25%), loss of MTAP expression was heterogenous. We also discovered loss of MTAP expression in flat urothelium adjacent to MTAP-negative low-grade UC, suggesting true flat low-grade neoplasia that could not be diagnosed by morphology alone. Longitudinal analysis of recurrences showed persistent negative MTAP status over time in 37/38 (97%) patients. MTAP IHC can serve as a surrogate marker for 9p21 HD in UC and as a diagnostic tool to differentiate reactive urothelium from urothelial neoplasia. It also provides a unique opportunity to study clinicopathological associations and the heterogeneity of 9p21 HD across the whole spectrum of UC manifestations.

The CDK4/6 inhibitor revolution - a game-changing era for breast cancer treatment

Cyclin-dependent kinase (CDK) 4/6 inhibition in combination with endocrine therapy is the standard-of-care treatment for patients with advanced-stage hormone receptor-positive, HER2 non-amplified (HR+HER2-) breast cancer. These agents can also be administered as adjuvant therapy to patients with higher-risk early stage disease. Nonetheless, the clinical success of these agents has created several challenges, such as how to address acquired resistance, identifying which patients are most likely to benefit from therapy prior to treatment, and understanding the optimal timing of administration and sequencing of these agents. In this Review, we describe the rationale for targeting CDK4/6 in patients with breast cancer, including a summary of updated clinical evidence and how this should inform clinical practice. We also discuss ongoing research efforts that are attempting to address the various challenges created by the widespread implementation of these agents.

Survival and Enrichment Analysis of Epithelial-Mesenchymal Transition Genes in Bladder Urothelial Carcinoma

The escalating prevalence of bladder cancer, particularly urothelial carcinoma, necessitates innovative approaches for prognosis and therapy. This study delves into the significance of genes related to epithelial-mesenchymal transition (EMT), a process inherently linked to carcinogenesis and comparatively better studied in other cancers. We examined 1184 EMT-related gene expression levels in bladder urothelial cancer cases through the TCGA dataset. Genes shown to be differentially expressed in relation to survival underwent further network and enrichment analysis to uncover how they might shape disease outcomes. Our in silico analysis revealed a subset of 32 genes, including those significantly represented in biological pathways such as VEGF signaling and bacterium response. In addition, these genes interact with genes involved in the JAK-STAT signaling pathway. Additionally, some of those 32 genes have been linked to immunomodulators such as chemokines CCL15 and CCL18, as well as to various immune cell infiltrates. Our findings highlight the prognostic utility of various EMT-related genes and identify possible modulators of their effect on survival, allowing for further targeted wet lab research and possible therapeutic intervention.

Increased expression of HPV-E7 oncoprotein correlates with a reduced level of pRb proteins via high viral load in cervical cancer

Human Papillomavirus (HPV) is the most common cause of sexually transmitted diseases and causes a wide range of pathologies including cervical carcinoma. Integration of the HR-HPV DNA into the host genome plays a crucial role in cervical carcinoma. An alteration of the pRb pathways by the E7 proteins is one of the mechanisms that's account for the transforming capacity of high-risk papillomavirus. For the proper understanding of the underline mechanism of the progression of the disease, the present study investigate the correlation of concentration of host pRb protein, viral E7 oncoprotein and viral load in early and advanced stages of cervical carcinoma. It was found that the viral load in early stages (stage I and II) was less (log10 transformed mean value 2.6 and 3.0) compared to advanced stages (stage III and IV) (Log10 transformed value 5.0 and 5.8) having high expression of HPV E7 onco-protein and reduced level of pRb protein, signifying the role of viral load and expression level of E7 oncoprotein in the progression of cervical cancer.

Selected Flavonoids to Target Melanoma: A Perspective in Nanoengineering Delivery Systems

Melanoma is a complex type of cancer that depends on several metabolic factors, while the currently used therapies are not always effective and have unwanted side effects. In this review, the main factors involved in the etiology of cutaneous carcinoma are highlighted, together with the main genes and proteins that regulate cancer invasion and metastization. The role of five selected flavonoids, namely, apigenin, epigallocatechin-3-gallate, kaempferol, naringenin, and silybin, in the modulating receptor tyrosine kinase (RTK) and Wnt pathways is reported with their relevance in the future design of drugs to mitigate and/or treat melanoma. However, as phenolic compounds have some difficulties in reaching the target site, the encapsulation of these compounds in nanoparticles is a promising strategy to promote improved physicochemical stabilization of the bioactives and achieve greater bioavailability. Scientific evidence is given about the beneficial effects of loading these flavonoids into selected nanoparticles for further exploitation in the treatment of melanoma.

Molecular pathology of the luminal class of urothelial tumors

Molecular subtypes of urothelial carcinoma may be divided into luminal and nonluminal tumors. Nonluminal tumors are composed of cases with basal/squamous-like or small cell/neuroendocrine features, with a consensus on the molecular characteristics of the respective subtype. In contrast, luminal tumors are more disparate with three to five suggested subtypes and with definitions that do not always cohere. To resolve some of these disparities we assembled a cohort of 344 luminal tumors classified as urothelial-like (Uro), with the subtypes UroA, UroAp, UroB, and UroC, or genomically unstable (GU) according to the LundTax system. Cases were systematically analyzed by immunohistochemistry using antibodies for proteins representing important biological processes or cellular states: KRT5, EGFR, and CDH3 for the integrity of a basal cell layer; CCNB1, Ki67, and FOXM1 for proliferation; FGFR3 and ERBB2 for receptor tyrosine kinase status; CCND1, CDKN2A(p16), RB1, and E2F3 for cell cycle regulation; PPARG, GATA3, and TP63 for the differentiation regulatory system; and KRT20 and UPK3 for the differentiation readout. We show that Uro tumors form one, albeit heterogenous, group characterized by FGFR3, CCND1, and RB1 expression, but low or absence of CDKN2A(p16) and ERBB2 expression. The opposite expression pattern is observed in GU cases. Furthermore, Uro tumors are distinguished from GU tumors by showing a high RB1/p16 expression ratio. Class defining characteristics were independent of pathological stage and growth pattern, and thus intrinsic. In Uro tumors, proliferation was limited to a well-defined single layer of basal-like cells in UroA tumors but occurred throughout the tumor parenchyma, independent of the basal layer, in the more progressed UroAp and UroC tumors. A similar change in proliferation topology was not observed in GU. We conclude that luminal urothelial carcinomas consist, at the molecular pathology level, of two major subtypes, the larger heterogenous Uro and the biologically distinct GU subtype. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

CDKN2A as transcriptomic marker for muscle-invasive bladder cancer risk stratification and therapy decision-making

Deletions of the cell cycle control gene CDKN2A are described as progression markers of non-muscle invasive bladder cancer and to be associated with fibroblast growth factor 3 (FGFR3) mutations. The prognostic role of CDKN2A RNA expression in muscle invasive bladder cancer (MIBC) is under discussion. In 80 MIBC patients (m/f 60/20) who underwent radical cystectomy the expression of CDKN2A and FGFR3 was examined with qRT-PCR (test cohort). The MDA cohort (n = 57) and the TCGA cohort (n = 365) served for validation. The expression of drug target genes and TCGA molecular subtypes was correlated with CDKN2A expression. In the test cohort CDKN2Ahigh patients (n = 8; 10.0%) had a significantly shorter recurrence-free (p = 0.018) and disease-specific (p = 0.006) survival compared to the rest of the cohort. A similar stratification was seen in the validation cohorts (CDKN2Ahigh: n = 7, 12.3%, p = 0.001; n = 46, 12.6%, p = 0.011). In the TCGA cohort these patients had a comparably low expression of drug target genes. The expression of CDKN2A significantly differed among TGCA molecular subtypes. 71.7% of CDKN2Ahigh were TCGA basal squamous tumours but also show divergent molecular features compared to this group. In summary CDKN2A RNA expression-based risk stratification of MIBC allows the identification of a CDKN2Ahigh poor prognosis group with low expression of drug target genes.

Companied P16 genetic and protein status together providing useful information on the clinical outcome of urinary bladder cancer

SPEC P16/CEN3/7/17 Probe fluorescence-in-situ-hybridization (FISH) has become the most sensitive method in indentifying the urothelial tumors and loss of P16 has often been identified in low-grade urothelial lesions; however, little is known about the significations of other P16 genetic status (normal and amplification) in bladder cancer.We detected P16 gene status by FISH in 259 urine samples and divided these samples into 3 groups: 1, normal P16; 2, loss of P16; and 3, amplified P16. Meanwhile, p16 protein expression was measured by immunocytochemistry and we characterized the clinicopathologic features of cases with P16 gene status.Loss of P16 occurred in 26.2%, P16 amplification occurred in 41.3% and P16 gene normal occurred in 32.4% of all cases. P16 genetic status was significantly associated with tumor grade and primary tumor status (P = .008 and .017), but not with pathological tumor stage, overall survival, and p16 protein expression. However, P16 gene amplification accompanied protein high-expression has shorter overall survival compared with the overall patients (P = .023), and P16 gene loss accompanied loss of protein also had the tendency to predict bad prognosis (P = .067).Studies show that the genetic status of P16 has a close relation with the stages of bladder cancer. Loss of P16 is associated with low-grade urothelial malignancy while amplified P16 donotes high-grade. Neither P16 gene status nor p16 protein expression alone is an independent predictor of urothelial bladder carcinoma, but combine gene and protein status together providing useful information on the clinical outcome of these patients.

Prognostic significance of Cytokeratin 20-positive lymph node vascular endothelial growth factor A mRNA and chromodomain helicase DNA binding protein 4 in pN0 colorectal cancer patients

BACKGROUND

Cytokeratin 20-positive cells in lymph nodes from pN0 colorectal cancer (CRC) patients were detected previously by us. The aims of this study were to investigate which tumor metastasis-related genes were involved and their potential clinical significance.

RESULTS

Fourteen of 84 (17%) genes were differentially expressed by at least 2-fold. Among them, 10 genes were up-regulated whereas 4 genes were down-regulated. Those differential expressed genes were validated in the second cohort of specimens. Follow-up analysis for 60 months showed that patients with lymph node vascular endothelial growth factor A (VEGF-A) mRNA and chromodomain helicase DNA binding protein 4 (CHD4) mRNA expression higher than the median copies had significantly shorter time to recurrence than those with lower than the median copies. Multivariate analysis showed that VEGF-A mRNA, CHD4 mRNA and lymphatic vessel involvement were independent prognostic factors for disease recurrence.

CONCLUSIONS

VEGF-A mRNA and CHD4 mRNA were up-regulated in CK20-positive pN0 lymph nodes and they may have prognostic significance in pN0 CRC patients.

METHODS

Two cohorts of lymph node specimens from pN0 CRC patients of each with and without CK20-positive cells were recruited. In the first cohort, tumor metastasis genes were profiled using gene expression arrays. Differential expressed genes were validated in the second cohort. Moreover, their prognostic significance was examined by following-up the second cohort of patients with CK20-positive cells for 60 months and all histopathological findings were correlated to recurrence.

Prognostic value of p16 expression in Epstein-Barr virus-positive nasopharyngeal carcinomas

BACKGROUND

Overexpression of p16 is associated with improved outcomes among patients with oropharyngeal carcinoma. However, its role in the outcomes of patients with nasopharyngeal cancer (NPC) remains unclear.

METHODS

Eighty-six patients with NPC treated at MD Anderson Cancer Center from 2000 to 2014 were identified. Epstein-Barr virus (EBV) and human papillomavirus (HPV) status were determined by in situ hybridization (ISH) and p16 by immunohistochemical staining.

RESULTS

EBV positivity was associated with extended overall survival (OS; median, 95.0 vs 44.9 months; p < .004), progression-free survival (PFS; median, 80.4 vs 28.1 months; p < .013), and locoregional control (median, 104.4 vs 65.5 months; p < .043). In patients with EBV-positive tumors, p16 overexpression correlated with improved PFS (median, 106.3 vs 27.1 months; p < .02) and locoregional control (median, 93.6 vs 64.5 months; p < .02).

CONCLUSION

P16 overexpression is associated with improved PFS and locoregional control in patients with EBV-positive NPC. P16 expression may complement EBV status in predicting treatment outcomes for patients with NPC. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1459-E1466, 2016.

Treating cancer with selective CDK4/6 inhibitors

Uncontrolled cellular proliferation, mediated by dysregulation of the cell-cycle machinery and activation of cyclin-dependent kinases (CDKs) to promote cell-cycle progression, lies at the heart of cancer as a pathological process. Clinical implementation of first-generation, nonselective CDK inhibitors, designed to inhibit this proliferation, was originally hampered by the high risk of toxicity and lack of efficacy noted with these agents. The emergence of a new generation of selective CDK4/6 inhibitors, including ribociclib, abemaciclib and palbociclib, has enabled tumour types in which CDK4/6 has a pivotal role in the G1-to-S-phase cell-cycle transition to be targeted with improved effectiveness, and fewer adverse effects. Results of pivotal phase III trials investigating palbociclib in patients with advanced-stage oestrogen receptor (ER)-positive breast cancer have demonstrated a substantial improvement in progression-free survival, with a well-tolerated toxicity profile. Mechanisms of acquired resistance to CDK4/6 inhibitors are beginning to emerge that, although unwelcome, might enable rational post-CDK4/6 inhibitor therapeutic strategies to be identified. Extending the use of CDK4/6 inhibitors beyond ER-positive breast cancer is challenging, and will likely require biomarkers that are predictive of a response, and the use of combination therapies in order to optimize CDK4/6 targeting.

RGD-modifided oncolytic adenovirus exhibited potent cytotoxic effect on CAR-negative bladder cancer-initiating cells

Cancer-initiating cell (CIC) is critical in cancer development, maintenance and recurrence. The reverse expression pattern of coxsackie and adenovirus receptor (CAR) and α_ν integrin in bladder cancer decreases the infection efficiency of adenovirus. We constructed Arg-Gly-Asp (RGD)-modified oncolytic adenovirus, carrying EGFP or TNF-related apoptosis-inducing ligand (TRAIL) gene (Onco^Ad.RGD-hTERT-EGFP/TRAIL), and applied them to CAR-negative bladder cancer T24 cells and cancer-initiating T24 sphere cells. Onco^Ad.RGD-hTERT-EGFP had enhanced infection ability and cytotoxic effect on T24 cells and T24 sphere cells, but little cytoxicity on normal urothelial SV-HUC-1 cells compared with the unmodified virus Onco^Ad.hTERT-EGFP. Notably, Onco^Ad.RGD-hTERT-TRAIL induced apoptosis in T24 cells and T24 sphere cells. Furthermore, it completely inhibited xenograft initiation established by the oncolytic adenovirus-pretreated T24 sphere cells, and significantly suppressed tumor growth by intratumoral injection. These results provided a promising therapeutic strategy for CAR-negative bladder cancer through targeting CICs.

Molecular biology of bladder cancer: new insights into pathogenesis and clinical diversity

Urothelial carcinoma of the bladder comprises two long-recognized disease entities with distinct molecular features and clinical outcome. Low-grade non-muscle-invasive tumours recur frequently but rarely progress to muscle invasion, whereas muscle-invasive tumours are usually diagnosed de novo and frequently metastasize. Recent genome-wide expression and sequencing studies identify genes and pathways that are key drivers of urothelial cancer and reveal a more complex picture with multiple molecular subclasses that traverse conventional grade and stage groupings. This improved understanding of molecular features, disease pathogenesis and heterogeneity provides new opportunities for prognostic application, disease monitoring and personalized therapy.

MDM2 SNP309 promoter polymorphism and p53 mutations in urinary bladder carcinoma stage T1

Background

Urinary bladder carcinoma stage T1 is an unpredictable disease that in some cases has a good prognosis with only local or no recurrence, but in others can appear as a more aggressive tumor with progression to more advanced stages. The aim here was to investigate stage T1 tumors regarding MDM2 promoter SNP309 polymorphism, mutations in the p53 gene, and expression of p53 and p16 measured by immunohistochemistry, and subsequently relate these changes to tumor recurrence and progression. We examined a cohort of patients with primary stage T1 urothelial carcinoma of the bladder and their tumors.

Methods

After re-evaluation of the original slides and exclusions, the study population comprised 141 patients, all with primary stage T1 urothelial carcinoma of the bladder. The hospital records were screened for clinical parameters and information concerning presence of histologically proven recurrence and progression. The paraffin-embedded tumor material was evaluated by immunohistochemistry. Any mutations found in the p53 gene were studied by single-strand conformation analysis and Sanger sequencing. The MDM2 SNP309 polymorphism was investigated by pyrosequencing. Multivariate analyses concerning association with prognosis were performed, and Kaplan-Meier analysis was conducted for a combination of changes and time to progression.

Results

Of the 141 patients, 82 had at least one MDM2 SNP309 G allele, and 53 had a mutation in the p53 gene, but neither of those anomalies was associated with a worse prognosis. A mutation in the p53 gene was associated with immunohistochemically visualized p53 protein expression at a cut-off value of 50%. In the group with p53 mutation Kaplan-Meier analysis showed higher rate of progression and shorter time to progression in patients with immunohistochemically abnormal p16 expression compared to them with normal p16 expression (p = 0.038).

Conclusions

MDM2 SNP309 promoter polymorphism and mutations in p53 were not associated with worse prognosis in this cohort of patients with primary stage T1 urinary bladder carcinoma. However, patients with abnormal p16 expression and a mutated p53 gene had a higher rate of and a shorter time to progression, and p53 gene mutation was associated with an abnormal immunohistochemistry for p53 at a cut-off of 50%.

Small cell carcinoma of the urinary bladder: a rare, aggressive neuroendocrine malignancy

Small cell carcinoma of the urinary bladder is a rare, often fatal, disease. Its presenting symptoms and gross morphology are similar to those of conventional urothelial carcinoma, whereas its prognosis is much poorer with frequent metastasis. Small cell carcinoma of the urinary bladder shares similar histology with its counterparts in other organs; however, its immunoreactivity to conventional neuroendocrine markers is low. Its diagnosis is thus considered permissible on morphologic grounds alone. Multimodal treatments are often employed, although no definite treatment algorithm has been established. For this extremely aggressive malignancy with an as-yet inconclusive etiology, further studies are needed to clarify its molecular pathogenesis to serve as a basis for diagnostic markers and therapeutic targets. The clinical, morphologic, immunoreactive, molecular, and therapeutic features of bladder small cell carcinoma are reviewed, including a detailed discussion on the utility of immunohistochemical markers.

Immunohistochemical evaluation of cell cycle regulators: impact on predicting prognosis in stage t1 urinary bladder cancer

Background and Objective. The cell cycle is regulated by proteins at different checkpoints, and dysregulation of this cycle plays a role in carcinogenesis. Matrix metalloproteinases (MMPs) are enzymes that degrade collagen and promote tumour infiltration. The aim of this study was to evaluate the expression of various cell cycle regulators and MMPs and to correlate such expression with progression and recurrence in patients with stage T1 urothelial carcinoma of the bladder (UCB). Patients and Methods. This population-based cohort study comprised 201 well-characterized patients with primary stage T1 urothelial carcinoma of the bladder. Immunohistochemistry was performed on formalin-fixed material to quantify expression of cell cycle regulators and two MMPs. Results. Normal expression of p53 and abnormal expression of MMP9 were associated with greater risk of tumour recurrence. Also, normal p16 expression was related to a lower risk of tumour progression. MMP2, p21, cyclin D1, and pRb showed no significant results that could estimate progression or recurrence. Conclusions. Normal p16 expression is associated with a lower risk of tumour progression, but immunohistochemistry on cell cycle regulators and MMPs has little value in predicting the prognosis in stage T1 UCB.

A first in human phase 1 study of CG0070, a GM-CSF expressing oncolytic adenovirus, for the treatment of nonmuscle invasive bladder cancer

PURPOSE

We assessed the safety, pharmacokinetics and anticancer activity of intravesical CG0070, a cancer selective, replication competent adenovirus, for the treatment of nonmuscle invasive bladder cancer.

MATERIALS AND METHODS

A total of 35 patients received single or multiple (every 28 days × 3 or weekly × 6) intravesical infusions of CG0070 at 1 of 4 dose levels (1 × 10(12), 3 × 10(12), 1 × 10(13) or 3 × 10(13) viral particles). Response to treatment was based on cystoscopic assessment and biopsy or urine cytology. Urine and plasma CG0070, and granulocyte-monocyte colony-stimulating factor were measured in all patients. A subset of 18 patients was assessed for retinoblastoma phosphorylation status.

RESULTS

Grade 1-2 bladder toxicities were the most common adverse events observed. A maximum tolerated dose was not reached. High levels of granulocyte-monocyte colony-stimulating factor were detected in urine after administration in all patients. Virus replication was suggested based on an increase in urine CG0070 genomes between days 2 and 5 in 58.3% of tested patients (7 of 12). The complete response rate and median duration of the complete response across cohorts was 48.6% and 10.4 months, respectively. In the multidose cohorts the complete response rate for the combined groups (every 28 days and weekly × 6) was 63.6% (14 of 22 patients). In an exploratory, retrospective assessment patients with borderline or high retinoblastoma phosphorylation who received the multidose schedules had an 81.8% complete response rate (9 of 11).

CONCLUSIONS

Intravesical CG0070 was associated with a tolerable safety profile and antibladder cancer activity. Granulocyte-monocyte colony-stimulating factor transgene expression and CG0070 replication were also suggested.

Urothelial tumor initiation requires deregulation of multiple signaling pathways: implications in target-based therapies

Although formation of urothelial carcinoma of the bladder (UCB) requires multiple steps and proceeds along divergent pathways, the underlying genetic and molecular determinants for each step and pathway remain undefined. By developing transgenic mice expressing single or combinatorial genetic alterations in urothelium, we demonstrated here that overcoming oncogene-induced compensatory tumor barriers was critical for urothelial tumor initiation. Constitutively active Ha-ras (Ras*) elicited urothelial hyperplasia that was persistent and did not progress to tumors over a 10 months period. This resistance to tumorigenesis coincided with increased expression of p53 and all pRb family proteins. Expression of a Simian virus 40 T antigen (SV40T), which disables p53 and pRb family proteins, in urothelial cells expressing Ras* triggered early-onset, rapidly-growing and high-grade papillary UCB that strongly resembled the human counterpart (pTaG3). Urothelial cells expressing both Ras* and SV40T had defective G(1)/S checkpoint, elevated Ras-GTPase and hyperactivated AKT-mTOR signaling. Inhibition of the AKT-mTOR pathway with rapamycin significantly reduced the size of high-grade papillary UCB but hyperactivated mitogen-activated protein kinase (MAPK). Inhibition of AKT-mTOR, MAPK and STAT3 altogether resulted in much greater tumor reduction and longer survival than did inhibition of AKT-mTOR pathway alone. Our studies provide the first experimental evidence delineating the combinatorial genetic events required for initiating high-grade papillary UCB, a poorly defined and highly challenging clinical entity. Furthermore, they suggest that targeted therapy using a single agent such as rapamycin may not be highly effective in controlling high-grade UCB and that combination therapy employing inhibitors against multiple targets are more likely to achieve desirable therapeutic outcomes.

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.

Diffusion-weighted magnetic resonance imaging in patients selected for radical cystectomy: detection rate of pelvic lymph node metastases

OBJECTIVE

To evaluate whether DW-MRI improves the detection of pelvic lymph nodes metastates in patients with bladder cancer undergoing radical cystectomy.

PATIENTS AND METHODS

36 patients with CT scan negative for nodal metastates underwent DW-MRI before surgery. Diagnostic accuracy of DW-MRI was compared with histopathological findings.

RESULTS

Mean ADC value was 0.85 × 10(-3) mm(3)/s in the nodal metastatic group and 1 × 10(-3) mm(3)/s in the nodal non-metastatic group (P = 0.02). The ADC cut-off value, obtained by the ROC curve was 0.86 × 10(-3) mm(3)/s. Patient-based sensitivity, specificity and positive and negative predictive values were 76.4%, 89.4%, 26.6%, and 71.4%, respectively.

CONCLUSION

DW-MRI may be used to differentiate metastatic from non-metastatic lymph nodes in patients with high-grade bladder cancer.

Bladder cancer or bladder cancers? Genetically distinct malignant conditions of the urothelium

Despite the fact that the current histopathologic classification for bladder cancer has led to improved concepts for the clinical management of the disease, key questions with regard to assessment of risk for recurrence and/or progression to invasive disease remain. In addition, response to specific therapies cannot be predicted accurately. Bladder tumors comprise a heterogeneous group with respect to both histopathology and clinical behavior. Thus, it is anticipated that a thorough knowledge and interpretation of the molecular alterations involved in tumor development and progression will lead to greater prognostic and predictive power. This may not only lead to better comprehension of the biology of the disease, but may also lead to the development of novel individualized therapies. Novel means of stratification are urgently needed to provide a new subclassification of urothelial lesions. This review discusses and summarizes the genetic alterations that have been reported in bladder cancer and relates these to the current 2-pathway model for tumor development. The molecular pathogenesis of high-grade noninvasive papillary tumors and of T1 tumors is not yet clear, and possibilities are discussed.

Expression of pRb, p53, p16 and cyclin D1 and their clinical implications in urothelial carcinoma

The aim of this study was to assess immunohistochemical expression of p53, pRb, p16, and cyclin D1, alone or in combination, as prognostic indicators and to investigate their correlation with clinocopathologic features of urothelial carcinoma. Immunohistochemical staining for p53, pRb, p16, and cyclin D1 was performed on a tissue microarray from 103 patients with urothelial carcinoma who underwent radical cystectomy. Of the patient samples analyzed, 36 (35%), 61 (59%), 47 (46%) and 30 (29%) had altered expression of p53, pRb, p16, and cyclin D1, respectively. Abnormal expression of p53 and pRb correlated with depth of invasion (P=0.040 and P=0.044, respectively). Cyclin D1 expression was associated with tumor stage and recurrence (P=0.017 and P=0.036, respectively). Altered pRb was significantly correlated with overall survival (P=0.040). According to the expression pattern of pRb and p53, p53/pRb (altered/normal) had worse survival than p53/pRb (normal/altered) (P=0.022). Alteration of all markers had worse survival than all normal (P=0.029). As determined by multivariate analysis, tumor stage, lymph node metastasis and the combined expression of p53 and pRb are independent prognostic factors. In conclusion, immunohistochemical evaluation of cell cycle regulators, especially the p53/pRb combination, might be useful in planning appropriate treatment strategies.

Inverse p16 and p63 expression in small cell carcinoma and high-grade urothelial cell carcinoma of the urinary bladder

Small cell carcinoma (SmCC) of the urinary bladder is a rare, highly aggressive neoplasm. The diagnosis is usually made on morphologic grounds, with the help of immunohistochemistry to document neuroendocrine differentiation. However, neuroendocrine markers generally have low sensitivity, ranging between 30-70%. Recent studies have reported p16 over-expression in SmCC of the lung, suggesting that p16 immunohistochemistry may be useful in the diagnosis of bladder SmCC. This is the first study to analyze the usefulness of p16 in the distinction of small cell and high grade urothelial cell carcinoma (HG-UCC). Fourteen cases of SmCCs and sixteen cases of HG-UCC of the bladder were stained with p16, p63, cytokeratin 20 (CK20), cytokeratin 7 (CK7), chromogranin (Chr), synaptophysin (Syn), and CD56. P16 expression was significantly higher in SmCCs (92.8%) when compared to HG-UCCs (43.7%). P63 and CK20, on the other hand, were positive in the majority of HG-UCCs (81.3% and 50%, respectively), while only 14.3% of SmCCs showed focal immunoreactivity with CK20. The sensitivity of the traditional neuroendocrine markers was low, ranging between 28.6% (Chr) and 71.4% (CD56) in SmCCs. P16 positivity in the absence of p63 and CK20 is highly characteristic of SmCC, while p63 and CK20 positivity with or without p16 expression is typical of HG-UCC.

Regulation of RB transcription in vivo by RB family members

In cancer cells, the retinoblastoma tumor suppressor RB is directly inactivated by mutation in the RB gene or functionally inhibited by abnormal activation of cyclin-dependent kinase activity. While variations in RB levels may also provide an important means of controlling RB function in both normal and cancer cells, little is known about the mechanisms regulating RB transcription. Here we show that members of the RB and E2F families bind directly to the RB promoter. To investigate how the RB/E2F pathway may regulate Rb transcription, we generated reporter mice carrying an eGFP transgene inserted into a bacterial artificial chromosome containing most of the Rb gene. Expression of eGFP largely parallels that of Rb in transgenic embryos and adult mice. Using these reporter mice and mutant alleles for Rb, p107, and p130, we found that RB family members modulate Rb transcription in specific cell populations in vivo and in culture. Interestingly, while Rb is a target of the RB/E2F pathway in mouse and human cells, Rb expression does not strictly correlate with the cell cycle status of these cells. These experiments identify novel regulatory feedback mechanisms within the RB pathway in mammalian cells.

Molecular biomarkers for urothelial carcinoma of the bladder: challenges in clinical use

Conventional clinical and pathological parameters are limited in their capacity to detect patients with urothelial carcinoma of the bladder (UCB) who are at high risk for recurrence or mortality. The assessment of molecular biomarkers in surgical UCB specimens offers additional information on the biology of the disease, and might improve the prediction of oncologic end points. A wide range of candidate biomarkers, including key cell-cycle regulators, apoptotic markers and specific growth factors, have been reported to be of prognostic value. To date, however, no molecular biomarker for UCB has been introduced into clinical practice, mainly owing to insufficient validation and the absence of prospective studies. Knowledge about the value of molecular biomarkers in predicting the response to adjuvant or neoadjuvant therapies is also lacking. Prospective trials need to be initiated in high-risk patients selected on the basis of the expression patterns of molecular biomarkers that have already passed the initial steps towards clinical utility.

Molecular pathogenesis of bladder cancer

Bladder tumors show widely differing histopathology and clinical behavior. This is reflected in the molecular genetic alterations they contain. Much information has accumulated on somatic genomic alterations in bladder tumors of all grades and stages and when this information is related to the common histopathological appearances, a model for the pathogenesis of two major groups of bladder tumors has emerged. This review summarizes the genetic alterations that have been reported in bladder cancer and relates these to the current two-pathway model for tumor development. The molecular pathogenesis of high-grade noninvasive papillary tumors and of T1 tumors is not yet clear and possibilities are discussed.

Molecular markers in bladder cancer

PURPOSE OF REVIEW

Bladder cancer is a diverse disease whose molecular phenotypes are being elucidated. In this review, we summarize currently known molecular pathways and associated markers in bladder cancer.

RECENT FINDINGS

Genetic and epigenetic aberrations have been closely associated with tumor pathogenesis and prognosis. Cell cycle markers have been most extensively studied. More recently, apoptotic and angiogenic pathways are being investigated. Studying the role of multiple concurrent molecular alterations improves the prognostic ability of these markers. The use of tissue microarrays and high-throughput molecular profiling is accelerating the discovery of new markers.

SUMMARY

Molecular biology is paramount to our understanding of bladder cancer pathogenesis. The search for new markers, and elucidating cross-talk between markers in different pathways, is warranted. Molecular markers have the potential benefit of improving detection, prognosis and treatment of bladder cancer. In addition, understanding the molecular profile of the individual patient could usher us into a new era of improving prediction of the natural history of the disease and providing a more personalized and tailored treatment. Prospective trials are still needed, however, to objectively establish the true benefit of these markers in prognostic and therapeutic arenas.

Multiple biomarkers improve prediction of bladder cancer recurrence and mortality in patients undergoing cystectomy

BACKGROUND

Tested was whether the assessment of 5 established bladder cancer biomarkers (p53, pRB, p21, p27, and cyclin E1) could improve the ability to predict disease recurrence and cancer-specific survival after radical cystectomy in patients with pTa-3N0M0 urothelial carcinoma of the bladder (UCB).

METHODS

The study comprised 191 patients with pTa-3N0M0 UCB treated with radical cystectomy and bilateral lymphadenectomy (median follow-up, 3.1 years). Biomarker expression was assayed on serial tissue microarray slides using quantitative immunohistochemistry using advanced cell imaging and color detection software. Predictive accuracy was quantified using the concordance index and 200-bootstrap resamples were used to reduce overfit bias. Bootstrap-adjusted predictive accuracy estimates were compared using the Mantel-Haenszel test.

RESULTS

UCB recurred in 36 (18.8%) patients and 30 (15.7%) died of bladder cancer; 157 (82.2%) patients had altered expression of at least 1 biomarker. In univariate analyses the number of altered biomarkers had the highest predictive accuracy for both disease recurrence (76.8%, P< .001) and cancer-specific mortality (78.3%, P< .001). Addition of the number of altered biomarkers increased the predictive accuracy of nomograms based on the TNM staging system for disease recurrence and cancer-specific mortality by 10.9% (83.4% vs 72.5%, P< .001) and 8.6% (86.9% vs 78.3, P< .001), respectively.

CONCLUSIONS

Assessment of the number of altered biomarkers in the cystectomy specimen improves the prediction of bladder cancer recurrence and survival in patients with pTa-3N0M0 disease. Prospective evaluation of alteration in these biomarkers can help identify patients who would benefit from adjuvant treatment after radical cystectomy.

Inactivation of the Rb pathway and overexpression of both isoforms of E2F3 are obligate events in bladder tumours with 6p22 amplification

E2F3 and CDKAL1 are candidate genes from the 6p22 region frequently amplified in bladder cancer. Expression of E2F3 isoforms (E2F3a and b) and CDKAL1 were examined and modulated in 6p22-amplified bladder cell lines. Eight lines with amplification showed overexpression of both E2F3 isoforms and CDKAL1. shRNA-mediated knockdown of CDKAL1 had no effect on proliferation. Knockdown of E2F3a or E2F3b alone induced antiproliferative effects, with the most significant effect on proliferation being observed when both isoforms were knocked down together. As E2Fs interact with the Rb tumour suppressor protein, Rb expression was analysed. There was a striking relationship between 6p22.3 amplification, E2F3 overexpression and lack of Rb expression. This was also examined in primary bladder tumours. Array-CGH detected 6p22.3 amplification in 8/91 invasive tumours. Five were studied in more detail. Four showed 13q14.2 loss (including RB1) and expressed no Rb protein. In the fifth, 13q was unaltered but the CDKN2A locus was deleted. This tumour was negative for p16 and positive for Rb protein. As p16 is a negative regulator of the Rb pathway, its loss represents an alternative mechanism for inactivation. Indeed, a phospho-specific Rb antibody showed much Rb protein in a hyperphosphorylated (inactive) form. We conclude that inactivation of the Rb pathway is required in addition to E2F3 overexpression in this subset of bladder tumours.

Forerunner genes contiguous to RB1 contribute to the development of in situ neoplasia

We used human bladder cancer as a model system and the whole-organ histologic and genetic mapping strategy to identify clonal genetic hits associated with growth advantage, tracking the evolution of bladder cancer from intraurothelial precursor lesions. Six putative chromosomal regions critical for clonal expansion of intraurothelial neoplasia and development of bladder cancer were identified by using this approach. Focusing on one of the regions, which includes the model tumor suppressor RB1, we performed allelotyping of single-nucleotide polymorphic sites and identified a 1.34-Mb segment around RB1 characterized by a loss of polymorphism associated with the initial expansion of in situ neoplasia. This segment contains several positional candidate genes referred to by us as forerunner genes that may contribute to such expansion. We subsequently concentrated our efforts on the two neighbor genes flanking RB1, namely ITM2B and CHC1L, as well as P2RY5, which is located inside RB1. Here, we report that ITM2B and P2RY5 modulated cell survival and were silenced by methylation or point mutations, respectively, and thus by functional loss may contribute to the growth advantage of neoplasia. We also show that homozygous inactivation of P2RY5 was antecedent to the loss of RB1 during tumor development, and that nucleotide substitutions in P2RY5 represent a cancer predisposing factor.

Cooperative effect of cell-cycle regulators expression on bladder cancer development and biologic aggressiveness

The aim of this study was to evaluate the association between p53, p21, p27 and Rb expression, alone or in combination, with pathological features and clinical outcomes of urothelial carcinoma of the bladder. Immunohistochemical staining for p53, p21, p27 and pRB was performed on tissue microarrays comprising normal urothelium from nine controls, transurethral resection specimens from 74 patients with Ta, Tis and/or T1 bladder urothelial carcinoma, radical cystectomy specimens from 226 consecutive urothelial carcinoma patients, and lymph nodes with tumor invasion from 50 of the 226 cystectomy patients. All nine controls had normal status of biomarkers. The proportion of biomarkers alterations was highest in lymph node metastases. p53, pRB and p27 were associated with pathologic stage, lymphovascular invasion and lymph node metastases (P-values<or=0.050). Each biomarker alone, each combination of two biomarkers and the number of altered biomarkers were all independently associated with disease recurrence and bladder cancer-specific death (P-values<or=0.046). In patients with organ-confined disease, p53, p21 and p27 were independently associated with disease recurrence and bladder cancer-specific death (P-values<or=0.046). There was a good but not perfect concordance in the expression of biomarkers between matched transurethral resection and cystectomy specimens (n=22; concordance rates: 77-86%) and between matched lymph node and cystectomy specimens (n=50, 70-92%). In conclusion, p53, p21, p27 and pRB have a cooperative/synergistic role in the biologic behavior of bladder urothelial carcinoma. In contrast to the use of single biological markers, evaluation of their combined status may improve prognostic models and help identify patients who might benefit from adjuvant therapies and in decision-making.

Predictive Value of Cell Cycle Biomarkers in Nonmuscle Invasive Bladder Transitional Cell Carcinoma

PURPOSE

We determined whether the combined expression of p53, p21, p27 and pRB is associated with outcomes of patients with nonmuscle invasive bladder transitional cell carcinoma.

MATERIALS AND METHODS

Immunohistochemical staining for p53, p21, p27 and pRB was performed on archival bladder specimens from 9 normal controls and 74 patients who underwent transurethral bladder tumor resection for Ta, Tis and/or T1 transitional cell carcinoma.

RESULTS

Normal urothelium had wild type status of p53, pRB, p21 and p27. p53 expression was altered in 34% of patients with transitional cell carcinoma, pRB in 39%, p21 in 35% and p27 in 47%. When analyzed separately, p53, pRB and p21 were each independently associated with tumor progression. Combination of biomarkers stratified patients into statistically significantly different risk groups for disease recurrence and progression. When tumor stage and grade were modeled with all 4 biomarkers, p53 and p27 were the sole independent predictors of disease recurrence and progression. After controlling for the effects of tumor grade and stage, the incremental number of altered biomarkers was associated with an increased risk of bladder cancer recurrence (p for trend = 0.011) and progression (p for trend = 0.005). The risk ratio for disease recurrence and progression increased incrementally with the number of biomarkers altered.

CONCLUSIONS

Combinations of p53, pRB, p21 and p27 had cooperative/synergistic effects stratifying patients into different risk groups. Higher total numbers of altered biomarkers were independently associated with an increased risk of disease progression and death. Prospective trials are necessary to usher bladder cancer management into the age of molecular biomarkers.

Correlation of cyclin D1 and E1 expression with bladder cancer presence, invasion, progression, and metastasis

The objective of this study was to determine the correlation of the expression of cyclin D1 and E1 with the expression of commonly altered cell cycle regulators and bladder cancer presence, staging, and clinical outcomes. We performed immunohistochemical staining for cyclin D1, cyclin E1, p53, p21, p27, and retinoblastoma protein (pRB) on serial cuts from normal urothelium from 9 controls, radical cystectomy specimens from 226 consecutive patients with advanced transitional cell carcinoma, and lymph nodes with metastasis from 50 of the 226 cystectomy patients. Cyclin D1 and E1 immunoreactivity were considered low when samples demonstrated less than 10% and 30% nuclear reactivity, respectively. Normal bladder urothelium from all 9 control patients showed uniformly intense expression of cyclin D1 and E1. Cyclin D1 expression was low in 99 (43.8%) of 226 cystectomy specimens and 25 (50.0%) of 50 metastatic lymph node specimens. Cyclin D1 immunoreactivity was not associated with any pathologic characteristics or clinical outcomes. Cyclin E1 expression was low in 125 (55.3%) of 226 cystectomy specimens and 22 (44.0%) of 50 metastatic lymph node specimens. Low cyclin E1 expression was significantly associated with advanced pathologic stage, lymphovascular invasion, and lymph node metastases. In multivariate analyses, low cyclin E1 expression was significantly associated with bladder cancer-specific mortality (P = .048), but not disease recurrence (P = .056). Low cyclin E1 expression was significantly associated with altered expression of pRB, p27, and cyclin D1. Low cyclin D1 expression was significantly associated with altered expression of pRB, p21, and cyclin E1. Cyclin E1 expression stratifies patients with bladder transitional cell carcinoma into those with more "indolent" behavior and those with features of biologically and clinically aggressive disease.

Prognostic Significance of the Epstein-Barr Virus, p53, Bcl-2, and Survivin in Nasopharyngeal Cancer

PURPOSE

Nasopharyngeal cancer (NPC) is a malignant epithelial carcinoma which is intimately associated with EBV. The latent presence of EBV affects the function of p53, Bcl-2, and survivin. We thus investigated the relationship between EBV status, p53, Bcl-2, and survivin in biopsy specimens from patients with primary NPC.

EXPERIMENTAL DESIGN

Archival formalin-fixed, paraffin-embedded NPC biopsies were evaluated in 80 patients treated with curative radiation from a single institution. The presence of EBV was determined using EBER in situ hybridization, whereas p53, Bcl-2, and survivin were assessed using immunohistochemistry.

RESULTS

The majority of NPC specimens in this patient cohort were EBER-positive (64 of 78, or 82%), which in turn, was significantly associated with ethnicity (P = 0.0007), and WHO subtype 2A/2B (P = 0.04). EBER-positive tumors were also associated with p53 (P = 0.002), Bcl-2 (P = 0.04), and nuclear survivin (P = 0.03) expression. Patients with EBER-positive NPC fared better, with a 10-year overall survival of 68% versus 48% for EBER-negative patients (P = 0.03). For nuclear survivin, patients with either low or high nuclear survivin fared worse than patients with intermediate survivin expression (P = 0.05), suggesting that there is an optimal proportion of survivin-expressing cells for best function and clinical outcome.

CONCLUSIONS

With an extended median follow-up time of 11.4 years, EBV status remains a strong predictor for overall survival in NPC. EBV-positive NPC has strong molecular associations with p53, Bcl-2, and survivin expression. Furthermore, we provide clinical data revealing the potentially dual nature of survivin in predicting clinical outcome.

Utility of Cell-cycle Modulators to Predict Vascular Invasion and Recurrence After Surgical Treatment of Hepatocellular Carcinoma

BACKGROUND

The outcome of surgical treatment of hepatocellular carcinoma (HCC) could be improved by applying patient selection criteria based on tumoral aggressiveness. Here we analyzed the prognostic role of the expression of several genes involved in cell-cycle regulation in a group of patients with HCC.

METHODS

We retrospectively studied 93 patients (67 transplanted and 26 resections) treated between 1996 and 2000. In micro-thick sections from paraffin-embedded tumoral tissues, the expression of p53, pRb, p16, and cyclin D1 was analyzed. A logistic regression model was used to detect factors related to vascular invasion. A Cox regression model was applied to identify pathologic and molecular factors with the capacity to predict the recurrence of HCC.

RESULTS

Only tumor size>3 cm (odds ratio [OR]: 3.4; 95% CI: 1.2-9.9; P=0.019) and pRb expression (OR: 4.1; 95% CI: 1.02-17; P=0.053) were associated with an increased risk of vascular invasion. The regression model applied to the group of transplanted patients showed three factors that were independently related to recurrence: vascular invasion (OR 7.5; 95% CI: 1.1-51.8; P=0.039); pRb expression (OR: 11; 95% CI: 1.2-96.9; P=0.03); and p16 expression (OR: 69.7; 95% CI: 5.1-9448; P=0.001). In the group of resected patients, pRb expression was associated with higher risk of recurrence only in the univariate analysis (P=0.037). The multivariate analysis showed tumor size>3 cm (OR: 57.5; 95% CI: 1.1-51.8; P=0.039) and vascular invasion (OR: 6.1; 95% CI: 1.05-35.3; P=0.044) to be significantly associated with recurrence.

CONCLUSIONS

Of the molecular factors studied, only pRb expression was useful as a predictive factor of vascular invasion in patients with HCC, and also of recurrence in transplanted patients with this carcinoma. pRb expression may be relevant to consider when selecting patients for resection and when identifying transplanted patients with a high risk of recurrence.

Phase II Trial of Adjuvant Gemcitabine plus Cisplatin-Based Chemotherapy in Patients with Locally Advanced Bladder Cancer

BACKGROUND

Despite the general acceptance of gemcitabine/cisplatin in metastatic bladder cancer, its role and tolerability in the adjuvant setting, in which renal insufficiency is common, is unclear.

PATIENTS AND METHODS

A total of 39 patients with locally advanced transitional cell carcinoma of the bladder (T2-T4, N0-N2) were treated with 4 cycles of gemcitabine/cisplatin/amifostine after radical cystectomy. All toxicities were evaluated by the National Cancer Institute Common Toxicity Criteria. Tumor samples were immunohistochemically stained for pRB, p53, and p16.

RESULTS

Thirty-five patients (90%) completed 4 cycles of chemotherapy. Eleven patients (28%) experienced grade 4 hematologic toxicity, and 14 patients (36%) experienced grade 3 nonhematologic toxicity. The median increase in creatinine was 0.3 mg/dL. With a median follow-up of 22.8 months (range, 7-70 months), 13 patients (33%) had recurrent disease, 1 patient at 6 years after completion of therapy. Twelve patients (31%) died, including 11 (28%) with recurrent disease. Thirty-three tumor blocks were evaluated for pRB, p53, and p16 alterations. In an exploratory analysis, altered expression of p53, p16, and pRB was found in 15 (45%), 22 (67%), and 30 patients (91%), respectively. No association between altered p53 and disease-free or overall survival was detected, but altered p16 and pRB expression was associated with better outcome (P < or = 0.001).

CONCLUSION

Gemcitabine/cisplatin with amifostine is tolerated in the adjuvant setting for patients with locally advanced bladder cancer. The favorable prognostic value of altered p16 and pRB raises the hypothesis of a relative beneficial effect of chemotherapy in this population but needs verification in other studies.

Deregulation of the p16-cyclin D1/cyclin-dependent kinase 4–retinoblastoma pathway involved in the rat bladder carcinogenesis induced by terephthalic acid-calculi

Prolonged cell proliferation in response to irritation by calculi may itself evoke malignant transformation of the urothelium. However, the molecular mechanisms underlying this process are still unknown. The aim of the present study was to investigate cell cycle regulatory mechanisms in bladder carcinogenesis induced by bladder calculi. Six-week-old Wistar rats were consecutively fed a diet containing 5% terephthalic acid (TPA), 5% TPA plus 4% sodium bicarbonate (NaHCO(3)), 4% NaHCO(3), or basal diet for 48 weeks. Animals were killed at weeks 12, 24, and 48. Treatment with 5% TPA caused high incidences of bladder calculi, preneoplastic lesions, and neoplastic lesions. Immunohistochemical examination revealed overexpression of cyclin D1, cyclin-dependent kinase 4 (Cdk4), retinoblastoma (Rb), and proliferating cell nuclear antigen (PCNA) in bladder preneoplastic and neoplastic lesions. In contrast, p16 expression was reduced or absent. These results were confirmed by immunoblotting analysis. Quantitation of mRNA by real-time reverse transcription-polymerase chain reaction (RT-PCR) showed a significant increase in cyclin D1 and PCNA mRNA in tumor cells. None of the 16 transitional cell carcinomas (TCCs) had ras mutations as examined by PCR-single strand conformational polymorphism (PCR-SSCP) analysis. These results suggested that deregulation of p16-cyclin D1/Cdk4-Rb pathway, but not oncogenic activation of ras, plays a crucial role in bladder tumorigenesis induced by bladder calculi.