Tumorigenic pathways in low-stage bladder cancer based on p53, MDM2 and p21 phenotypes

Association of MDM2 Overexpression in Ameloblastomas with MDM2 Amplification and BRAFV600E Expression

Ameloblastoma is a rare tumor but represents the most common odontogenic neoplasm. It is localized in the jaws and, although it is a benign, slow-growing tumor, it has an aggressive local behavior and high recurrence rate. Therefore, alternative treatment options or complementary to surgery have been evaluated, with the most promising one among them being a targeted therapy with the v-Raf murine sarcoma viral oncogene homologue B (BRAF), as in ameloblastoma the activating mutation V600E in BRAF is common. Studies in other tumors have shown that the synchronous inhibition of BRAF and human murine double minute 2 homologue (MDM2 or HDM2) protein is more effective than BRAF monotherapy, particularly in the presence of wild type p53 (WTp53). To investigate the MDM2 protein expression and gene amplification in ameloblastoma, in association with BRAFV600E and p53 expression. Forty-four cases of ameloblastoma fixed in 10% buffered formalin and embedded in paraffin were examined for MDM2 overexpression and BRAFV600E and p53 expression by immunohistochemistry, and for MDM2 ploidy with fluorescence in situ hybridization. Sixteen of forty-four (36.36%) cases of ameloblastoma showed MDM2 overexpression. Seven of sixteen MDM2-positive ameloblastomas (43.75%) were BRAFV600E positive and fifteen of sixteen MDM2-positive ameloblastomas (93.75%) were p53 negative. All MDM2 overexpressing tumors did not show copy number alterations for MDM2. Overexpression of MDM2 in ameloblastomas is not associated with MDM2 amplification, but most probably with MAPK activation and WTp53 expression. Further verification of those findings could form the basis for the use of MDM2 expression as a marker of MAPK activation in ameloblastomas and the trial of dual BRAF/MDM2 inhibition in the management of MDM2-overexpressing/BRAFV600E-positive/WTp53 ameloblastomas.

MiR-205-5p Functions as a Tumor Suppressor in Gastric Cancer Cells through Downregulating FAM84B

MicroRNAs (miRNAs) participate in the formation of multiple diseases, including gastric cancer (GC), through modulating specific targets. Here, we explored the functions and regulatory mechanisms of miR-205-5p in GC. MiR-205-5p levels were detected in GC cells through qRT-PCR. Besides, the role of miR-205-5p in cell proliferation, cell apoptosis, cell cycle, cell invasion, and metastasis was assessed through CCK-8 assay, colony formation, flow cytometry, scratch assay, transwell, and western blot. Moreover, the Starbase website was used to predict the target gene of miR-205-5p, further verified by a dual-luciferase reporter assay. Furthermore, the functional effects of the family with sequence similarity 84 member B (FAM84B) on GC mediated by miR-205-5p upregulation were further investigated. MiR-205-5p expression was decreased in GC cells. Upregulation of miR-205-5p inhibited cell proliferation and metastasis and induced apoptosis and cycle arrest of GC cells. Moreover, FAM84B was predicted and confirmed as a target of miR-205-5p and negatively related to miR-205-5p. Mechanically, FAM84B overexpression partially rescued the functional effects of miR-205-5p upregulation on GC cell progression. This study suggests the potential of miR-205-5p/FAM84B as novel targets for the treatment of GC.

Phosphatidylinositol 3'-kinase, mTOR, and glycogen synthase kinase-3β mediated regulation of p21 in human urothelial carcinoma cells

BACKGROUND

The PTEN/Phosphatidylinositol 3'-kinase (PI3-kinase) growth factor signaling pathway plays a critical role in epithelial tumor development in a multitude of tissue types. Deletion of the Pten tumor suppressor gene in murine urothelial cells in vivo results in upregulation of cyclin-dependent kinase inhibitor p21. We have previously shown in mice that p21 expression blocks an increase in urothelial cell proliferation due to Pten deletion. In this study, we utilized human urothelial carcinoma cells UMUC-3 and UMUC-14 to identify the signaling pathways downstream of PI3-kinase that regulate p21.

METHODS

Cells were treated with a combination of PI3-kinase stimulating growth factors and kinase inhibitors, or transfected with exogenous genes in order to identify the signaling events that are necessary for p21 induction. Mice with conditional deletion of Pten in bladder urothelium were also examined for evidence of PI3-kinase pathway signaling events that affect p21 expression.

RESULTS

When cells were treated with PI3-kinase activating growth factors EGF or PDGF, we found that p21 levels increased, in a manner similar to that observed in mice. We used the inhibitors LY294002, Akti-1/2, and rapamycin, to show that p21 induction is dependent upon PI3-kinase and AKT activity, and partially dependent on mTOR. We treated the cells with proteasome inhibitor MG-132 and found that p21 may be degraded in the proteasome to regulate protein levels. Importantly, our findings show that GSK-3β plays a role in diminishing p21 levels in cells. Treatment of cells with the GSK-3β inhibitor SB-216763 increased p21 levels, while exogenous expression of GSK-3β caused a decrease in p21, indicating that GSK-3β actively reduces p21 levels. We found that a combined treatment of LY294002 and SB-216763 improved the cytotoxic effect against UMUC-3 and UMUC-14 carcinoma cells over LY294002 alone, suggesting potential therapeutic uses for GSK-3β inhibitors. Immunohistochemical staining in bladders from wild-type and Pten-deleted mice indicated that GSK-3β inhibitory phosphorylation increases when Pten is deleted.

CONCLUSION

PI3-kinase and AKT cause an upregulation of p21 by suppressing GSK-3β activity and activating mTOR in both cultured human urothelial carcinoma cells and mouse urothelial cells in vivo.

A Polymorphism in HDM2 (SNP309) Associates with Early Onset in Superficial Tumors, TP53 Mutations, and Poor Outcome in Invasive Bladder Cancer

PURPOSE

The HDM2 gene represents one of the central nodes in the p53 pathway. A recent study reported the association of a single nucleotide polymorphism (SNP309) in the HDM2 promoter region with accelerated tumor formation in both hereditary and sporadic cancers. In this study, we aim to evaluate the SNP309 in bladder cancer and to link it to TP53 status.

EXPERIMENTAL DESIGN

SNP309 genotyping and TP53 mutation status were done on 141 bladder tumors and 8 bladder cancer cell lines using a RFLP strategy and TP53 genotyping arrays, respectively. Transcript profiling of a subset of cases (n = 41) was done using oligonucleotide arrays to identify genes differentially expressed regarding their SNP309 status.

RESULTS

Of 141 bladder tumors analyzed, 36.9% displayed the SNP309 wild-type (WT; T/T) genotype, whereas 11.3% were homozygous (G/G) and 51.8% were heterozygous (T/G) cases. Patients with superficial disease and the G/G genotype had an earlier age on onset than those with the T/G or T/T genotypes (P = 0.029). Tumors with SNP309 WT genotype significantly displayed TP53 mutations when compared with tumors harboring G/G or T/G genotypes (P < 0.05). SNP309 WT cases had a poorer overall survival than cases with G/G and T/G genotypes (P < 0.05). TP53 mutation status provided enhanced prognostic value (P < 0.001). Transcript profiling identified TP53 targets among those differentially expressed between tumors displaying G/G or T/G SNP309 versus WT cases.

CONCLUSIONS

SNP309 is a frequent event in bladder cancer, related to earlier onset of superficial disease and TP53 mutation status. SNP309 genotypes were found to be associated with clinical outcome.

Assessing interactions between mdm-2, p53, and bcl-2 as prognostic variables in muscle-invasive bladder cancer treated with neo-adjuvant chemotherapy followed by locoregional surgical treatment

BACKGROUND

Tumor proliferation and apoptosis may be influenced by the mdm-2 gene product, which can block the antiproliferative effects of p53. bcl-2, one of a family of related genes that regulates the apoptotic pathway, exhibits a negative influence. Both individual and cooperative effects of these gene products may affect the biological behavior of primary bladder cancers and long-term outcome to standard therapy.

METHODS

This study retrospectively evaluated the association with survival of mdm-2, p53, and bcl-2 expression in 59 patients with muscle-invasive, node-negative transitional cell carcinoma (TCC) treated with neo-adjuvant chemotherapy followed by locoregional surgery. Each marker was defined as an altered phenotype if >or=20% malignant cells in the primary tumor exhibited staining; normal or minimal expression was defined as <20% cells exhibiting staining.

RESULTS

Altered mdm-2, p53, and bcl-2 expression was observed in 37%, 54%, and 46% of patients, respectively. In single marker analysis, altered p53 expression correlated with long-term survival (P = 0.05) but mdm-2 (P = 0.42) or bcl-2 (P = 0.17) did not. In the multiple-marker analysis, a prognostic index simultaneously assessing mdm-2, p53, and bcl-2 correlated with survival (P = 0.01). The 5-year survival for patients in which all markers were normally expressed was 54% compared with 25% in those with all three markers aberrantly expressed. Patients with aberrant expression of either one or two markers had an intermediate 5-year survival (49%). There was no association of molecular markers either alone or in combination with pathologic downstaging after neo-adjuvant chemotherapy.

CONCLUSION

The cooperative effects of phenotypes determined by mdm-2, p53, and bcl-2 expression may predict survival in patients with muscle-invasive TCC of the bladder.

Prognostic factors in survival of patients with stage Ta and T1 bladder urothelial tumors: the role of G1-S modulators (p53, p21Waf1, p27Kip1, cyclin D1, and cyclin D3), proliferation index, and clinicopathologic parameters

We studied 159 cases of superficial (stage Ta or T1) bladder tumors to determine the significance on survival of a subset of regulators of transition from G1 to S phase of the cell cycle (p53, p21Waf1, p27Kip1, cyclin D1, cyclin D3) and tumor proliferation (Ki-67 [MIB-1]). Clinical findings (patient age, sex, tumor size, grade, stage [Ta or T1]) were included in the analysis. Univariate analysis revealed association of tumor size (P = .0353), grade in stage Ta tumors (P = .0074), cyclin D1 expression (P = .0182), and Ki-67 index (P = .0033) with disease-free survival and of tumor size (P = .0005), stage (P = .0494), cyclin D3 expression (P = .0105), and Ki-67 index (P = .0272) with overall survival. Cox multivariate analysis revealed cyclin D1 expression and high proliferation index (disease-free) and tumor size, cyclin D3 expression, and high proliferation index (overall survival) as independent predictors. Results suggest that alterations of the progression from the G1 to S phase of the cell cycle are common in papillary urothelial bladder tumors. High tumor proliferation, expression of cyclins D1 and D3, and tumor size at diagnosis might be relevant predictors of survival in patients with stage Ta and T1 bladder urothelial tumors.

Prognostic Factors in Stage T1 Grade 3 Bladder Cancer Survival: The Role of G1–S Modulators (p53, p21Waf1, p27kip1, Cyclin D1, and Cyclin D3) and Proliferation Index (ki67-MIB1)

OBJECTIVE

To determine the prognostic value of a subset of regulators of the transition from G1-to-S phase of cell cycle in stage T1 grade 3 bladder cancers.

METHODS

Fifty-one such cases were investigated to determine the significance on patient's survival of p53, p21Waf1, p27Kip1, Cyclin D1, Cyclin D3, and ki67-MIB1 (proliferation index). The statistical analysis included Kaplan-Meier methodology with Log-rank test and Cox' proportional hazard analysis.

RESULTS

Tumor size (p=0.0034), and the labeling index of ki67-MIB1 (p=0.0034), p53 (p=0.0332), p27kip1 (p=0.0059) and Cyclin D1 (p=0.0103) were associated to disease-free survival. Progression-free survival was related to tumor size (p<0.0001), ki67 (p=0.0163), p53 (p=0.0041), p27kip1 (p=0.0161), Cyclin D1 (p<0.0001) and Cyclin D3 (p<0.0001). Patient's overall survival was associated to Cyclin D3 (p<0.0001), p53 (p=0.0017), p21Waf1 (p=0.0142), Cyclin D1 (p<0.0001), ki67-MIB1 (p=0.0450), and tumor size (p=0.0296). Down-regulation of p27kip1 and Cyclin D3 over-expression (disease-free), over-expression of p53, Cyclin D1 and Cyclin D3 (progression-free), and over-expression of Cyclin D3 (overall survival) were independent predictors by Cox's multivariate analysis. Down-regulation of p27kip1 (p<0.001, R.R. 0.997, 95%C.I. 0.995-0.999), and over-expression of Cyclin D1 (p<0.001, R.R. 1.009, 95%C.I. 1.004-1.014) and Cyclin D3 (p=0.005, R.R. 1.013, 95%C.I. 1.004-1.022) were the main independent predictors.

CONCLUSION

Down-regulation of p27kip1 and over-expression of Cyclin D1 and Cyclin D3 might be relevant predictors of survival in stage T1 grade 3 bladder cancers, thus selecting a group of patients at higher risk of malignant behavior.

Can p53 staining be used to identify patients with aggressive superficial bladder cancer?

Approximately 10% of patients with superficial bladder cancer (pTa/pT1) recur with life-threatening muscle-invasive disease. Identification of these patients has been a major goal of bladder cancer research. In 1994, it was suggested that p53 immunostaining could identify the cancers that would progress and it was proposed that tumours that stain for p53 should be treated aggressively with radiotherapy or cystectomy. Despite the hundreds of studies published since on the relationship between p53 and progression in superficial bladder cancer, the clinical utility of p53 immunostaining has not been resolved because of limitations concerning the numbers of patients and the length of follow-up. This study set out to overcome these limitations by using tissue from a large multicentre trial that recruited 502 patients with a median follow-up of 10 years. Each of 34 patients that had progressed with >/= pT2 disease or had distant metastases or had died from bladder cancer was compared with one or two matched controls. Sections were stained with a mouse monoclonal antibody to p53, pAb1801. In agreement with many of the earlier studies, p53 immunostaining had prognostic significance. The adjusted hazard ratio for time to progression for the pAb1801-positive versus negative group was 2.5, with 95% confidence intervals of 1.05-5.98 (p = 0.039). The other major risk factor that is associated with progression of superficial bladder cancer is pT1G3 disease. Of the 42 pT1G3 cancers, 14 (33%) progressed. The proportion of cancers with p53 staining that progressed was similar to the proportion of pT1G3 cancers that progressed, but neither the sensitivity nor the specificity of association of p53 staining with progression is sufficient to recommend cystectomy in individual patients.

From microarrays to new therapeutic approaches in bladder cancer

Bladder cancer is a model tumor progressing from superficial to locally invasive and finally metastatic disease. The likelihood of progression is determined to a large extent by the molecular profile of the tumor. From the pre-genomic era only p53 emerged as the molecular prognostic factor able to add value to existing clinical and pathological features of bladder cancer, however it was not introduced to the clinic. Microarray technologies enable us to study expression of thousands of genes in the tumor tissue. This method has already proven to add information to clinical classifiers, to find new tumor suppressor genes and to define p53 related pathways of cell-cycle regulation. In the last decade, progress in the treatment of locally invasive and metastatic bladder cancer was minimal; large Phase III trials with neo/adjuvant chemotherapy were inconclusive. The new paradigm of treatment tailored to an individual patient could be realized in bladder cancer for his chronic clinical course with opportunities to obtain tumor samples for microarray studies. Molecular profiling of two samples taken at the superficial stage and at cystectomy should enable us to study the microevolution of the tumor, to tailor existing treatment options, and to introduce new biologicals to the clinic.Introduction

Expression of p53R2, newly p53 target in oral normal epithelium, epithelial dysplasia and squamous cell carcinoma

Recently, the p53R2 gene has been isolated and shown to play a crucial role in DNA repair after DNA damage. The p53R2 gene encodes the p53 inducible ribonucleotide reductase small subunit 2 homologue, which is part of the p53 pathway. However, the function of p53R2 in human cancer is still unclear. We investigated p53R2 mRNA expression in human oral normal epithelium, epithelial dysplasias and squamous cell carcinomas (SCCs). Surgical or biopsy-proven specimens of 10 normal epithelium, 48 epithelial dysplasias and 63 SCCs were collected in our department. Then, p53R2 was identified by in situ hybridization to visualize and localize the expression of specific mRNAs. The authors examined the p53 gene mutation by polymerase chain reaction-single strand conformation polymorphism analysis. p53, mdm2, p21(WAF1/CIP1) and Ki-67 expression was detected by immunohistochemistry. p53R2 expression was detected in none of ten normal epithelium (0%), ten of 48 dysplasias (20.8%) and 33 of 63 SCCs (52.4%). In oral SCC, the expression of p53R2 was significantly associated with tumor size, lymph node metastasis and histological differentiation (P=0.014, 0.046 and 0.022, respectively). p53R2 expression was significantly associated with p53 abnormality in epithelial dysplasia and SCC (P=0.034 and 0.009, respectively). Of 63 patients, 37 received preoperative radiochemotherapy. p53R2 mRNA expression was significantly associated with the pathologic response to radiochemotherapy (P=0.031). This study suggested that p53R2 expression could be associated with oral carcinogenesis. The presence of p53R2 mRNA expression would be a predictive factor for tumor development, tumor cell differentiation and the sensitivity to radiochemotherapy in oral SCC.

New diagnostic and prognostic tools in bladder cancer

Many efforts have been made to increase the detection rates and to predict the outcome of bladder cancer. Although to date cystoscopy remains the gold standard method for the detection of new or recurrent bladder cancer, its limitations were emphasized by the results of studies using fluorescence endoscopy that showed an increased detection rate and decreased recurrence after tumor resection. Urine cytology has high specificity and is used routinely as an adjunct to cystoscopy to detect invisible tumors. However, to improve on the low sensitivity of urine cytology, a number of marker tests have been developed. Optimal diagnostic accuracy appears to result from the synergistic combination of cytological markers with urine cytology. The evaluation of new and previously reported markers remains a very active field, but is still limited to inconclusive studies. Tissue and DNA microarrays represent a technological step forward for the analysis of a large number of markers and cohorts of patients that will be required definitively to establish the clinical utility of prognostic tests.

Amplification pattern of 12q13-q15 genes (MDM2, CDK4, GLI) in urinary bladder cancer

The chromosomal region 12q13-q15 is recurrently amplified in bladder cancer. Putative target genes located in this region include MDM2, CDK4, and GLI. To evaluate the involvement of these genes in bladder cancer, we screened a tissue microarray (TMA) containing 2317 samples by fluorescence in situ hybridization (FISH). Amplification was found for MDM2 in 5.1%, for CDK4 in 1.1%, and for GLI in 0.4% of interpretable tumors. Among tumors having amplification of at least one of these 12q13-q15 genes, 76.6% had amplification of MDM2 alone and 6.4% had amplification of CDK4 alone. Coamplifications were seen of MDM2 and CDK4 in 10.6%, and of CDK4 and GLI in 6.4%. Neither coamplifications of all three genes nor isolated GLI amplifications were found. These data suggest a prominent role of MDM2 as a 12q13-q15 amplification target in bladder cancer. However, independent CDK4 amplifications do also occur suggesting either two non-overlapping amplification sites or else a minimal overlapping region between MDM2 and CDK4 perhaps containing another yet unknown oncogene. The frequency of amplification increased significantly from stage pTa to pT1-4 (P<0.04) and from low to high grade (P<0.005). These data are consistent with a high level of genetic instability in invasively growing and high-grade bladder tumors.

Expression of p27Kip1 Protein in Transitional Cell Carcinoma of the Upper Urinary Tract

The expression of p27(Kip1), a negative regulator of the cell cycle, has been reported to correlate with the biological behavior and prognosis of several tumors. However, its prognostic importance in transitional cell carcinoma of the upper urinary tract (TCC-UUT) has not previously been investigated. We investigated p27(Kip1) protein expression using immunohistochemistry in 132 cases of TCC-UUT and also its relation to proliferating cell nuclear antigen (PCNA) immunoreactivity, p53 oncoprotein immunoreactivity, clinicopathologic parameters, and clinical outcome. A positive expression of p27(Kip1) protein was recognized in 94.7% of the samples and was apparent within tumor nuclei. In the normal urothelium, its expression was identified in all cell layers. A positive expression of p53 oncoprotein was recognized in 27.2% of the patients. The PCNA index was 7.4 to 93.1% (mean, 66.4%). Examination of the relationships between the expression of p27(Kip1) protein and clinicopathologic findings, PCNA index, and the expression of p53 oncoprotein revealed that the expression of p27(Kip1) protein decreased significantly with stage and grade. In a univariate analysis of disease-free and overall survival rates, no correlation was found between the expression of p27(Kip1) protein and prognosis. The expression of p27(Kip1) protein appears to be of little or no value in informing the prognosis in TCC-UUT.

Can biological markers predict recurrence and progression of superficial bladder cancer?

Biological markers that are predictive of recurrence and progression of superficial bladder tumors must provide additional information to that provided by multiplicity, size and grade. Field anomalies in normal appearing urothelium of patients with papillary superficial transitional cell carcinoma have been associated with tumor antigens and chromosome 9 deletions. Also, primary tumors with chromosome 9 deletions are associated with a higher risk of recurrence. Abnormal expression of p53, p21 and Ki-67 cell cycle markers have little predictive value for recurrence. However, p53 overexpression or mutation and decreased expression of p27 are associated with cancer progression and survival. New markers, such as mutations in the fibroblast growth factor receptor 3 gene (found in 30% of tumors), anomalies of the PTEN gene and vascular endothelial growth factor expression, may have potential and require further evaluation. Molecular fingerprints of superficial tumors with distinct clinical behavior are being rapidly unravelled. Large-scale clinical studies are urgently needed to provide supportive evidence for their incorporation in clinical management.