Prognostic value of quantifying apoptosis factor expression in favorable histology wilms tumors

Pharmacologic Inhibition of β-Catenin With Pyrvinium Inhibits Murine and Human Models of Wilms Tumor

Wilms tumor (WT) is the most common renal malignancy in children and the fourth most common pediatric solid malignancy in the US. Although the mechanisms underlying the WT biology are complex, these tumors most often demonstrate activation of the canonical Wnt/β-catenin pathway. We and others have shown that constitutive activation of β-catenin restricted to the renal epithelium is sufficient to induce primitive renal epithelial tumors, which resemble human WT. Here we demonstrate that pharmacologic inhibition of β-catenin gene transcription with pyrvinium inhibits tumor growth and metastatic progression in a murine model of WT. Cellular invasion is significantly inhibited in both murine WT-like and human WT cells and is accompanied by downregulation of the oncogenes Myc and Birc5 (survivin). Our studies provide proof of the concept that the canonical Wnt/β-catenin pathway may be a novel therapeutic target in the management of WT.

TP53 mutational status is a potential marker for risk stratification in Wilms tumour with diffuse anaplasia

PURPOSE

The presence of diffuse anaplasia in Wilms tumours (DAWT) is associated with TP53 mutations and poor outcome. As patients receive intensified treatment, we sought to identify whether TP53 mutational status confers additional prognostic information.

PATIENTS AND METHODS

We studied 40 patients with DAWT with anaplasia in the tissue from which DNA was extracted and analysed for TP53 mutations and 17p loss. The majority of cases were profiled by copy number (n = 32) and gene expression (n = 36) arrays. TP53 mutational status was correlated with patient event-free and overall survival, genomic copy number instability and gene expression profiling.

RESULTS

From the 40 cases, 22 (55%) had TP53 mutations (2 detected only after deep-sequencing), 20 of which also had 17p loss (91%); 18 (45%) cases had no detectable mutation but three had 17p loss. Tumours with TP53 mutations and/or 17p loss (n = 25) had an increased risk of recurrence as a first event (p = 0.03, hazard ratio (HR), 3.89; 95% confidence interval (CI), 1.26-16.0) and death (p = 0.04, HR, 4.95; 95% CI, 1.36-31.7) compared to tumours lacking TP53 abnormalities. DAWT carrying TP53 mutations showed increased copy number alterations compared to those with wild-type, suggesting a more unstable genome (p = 0.03). These tumours showed deregulation of genes associated with cell cycle and DNA repair biological processes.

CONCLUSION

This study provides evidence that TP53 mutational analysis improves risk stratification in DAWT. This requires validation in an independent cohort before clinical use as a biomarker.

Survivin gene promoter -31 G/C polymorphism is associated with Wilms tumor susceptibility in Serbian children

Survivin, an apoptotic inhibitor, is overexpressed in various types of cancer. Mechanisms of survivin upregulation are still poorly understood, but single nucleotide polymorphisms in the survivin gene promoter have been shown to modulate survivin expression and consequently the risk for some types of cancer. The aim of the present study was to investigate whether survivin promoter -31 G/C and -241 C/T polymorphisms could represent susceptibility factors for Wilms tumor (WT) development in Serbian population. Genotype and allele frequencies for the 2 polymorphisms in survivin promoter have been analyzed by polymerase chain reaction/restriction fragment length polymorphism in 59 WT patients and 82 controls. The frequencies of alleles and genotypes were significantly different between patients and controls for the -31 G/C polymorphism. Individuals with CC and CG genotypes had significantly decreased risk of WT compared with GG individuals (odds ratio 0.26, 95% confidence interval, 0.07-0.96; odds ratio 0.30, 95% confidence interval, 0.15-0.60). There was also a statistically significant difference in genotype frequencies between intermediate and high-risk prognostic groups (P=0.015). The -241 C/T polymorphism did not show association with WT susceptibility. Our findings suggest that the G allele at -31 survivin gene promoter position is associated with a significantly higher cancer risk in Serbian children, with a gene dosage effect.

Apoptotic protein expression in favorable-histology Wilms tumor correlates with tumor recurrence

PURPOSE

Outcome for patients with Wilms tumor (WT) with favorable histology is good. Deletions of chromosomes 1p and 16q impart a poorer outcome. Value of apoptotic protein expression is not clear.

METHODS

Expression of four immunohistochemically detectable apoptosis-regulating proteins (bcl-2, bcl-x, bax and p53) were analyzed in 30 specimens of WT and compared to recurrence and recurrence-free survival (RFS).

RESULTS

The 30 patients included ranged from 4 to 72 months in age (mean 31). The mean available follow-up was 35.3 months (range 1-54). Six patients developed recurrence. The 5-year RFS for blastema-predominant tumors was 40% as compared to 91% for triphasic histology which was significant (p = 0.048). The 5-year RFS in patients with bcl-2 negative tumors was 63% as compared to 100% for bcl-2 positive tumors, the difference being significant (p = 0.019). The 5-year RFS in patients with p-53 positive tumors was 27% as compared to 91% for p-53 negative tumors; however, this difference in the RFS was not statistically significant (p = 0.143). bax and bcl-x expression were not related to the RFS.

CONCLUSIONS

Tumors that are bcl-2 negative have a relatively higher recurrence rate and a poorer RFS. They may benefit from a more intensive follow-up regime for early detection of recurrence.

Microscopic neoplastic thrombosis in localised nephroblastoma: does it influence outcome?

INTRODUCTION

Microscopic neoplastic thrombosis (MNT) is reported to occur frequently in Wilms tumour (WT). The aim of this study is to determine whether MNT influences prognosis in localised WT.

PATIENTS AND METHODS

Records and slides of 80 consecutive, unselected, localised WT patients were retrospectively reviewed. All patients received chemotherapy before surgery according to SIOP Protocol. The median follow-up was 9 years (range 0.5-25.8). The Kaplan-Meier method and the Cox proportional hazard model were applied.

RESULTS

MNT was present in 14 (18%) cases. Out of 14 patients with MNT, 6 presented macroscopic thrombosis and 5 had either blastemal predominance or anaplastic histology. The 5-year overall survival (OS) and progression-free survival (PFS) for the whole population were 95% (95% confidence interval, CI, 87-98%) and 91% (95% CI 82-96%), respectively. The 5-year OS and PFS for MNT positive patients were 92% (95% CI 57-99%) and 77% (95% CI 44-92%), while the 5-year OS and PFS for MNT negative patients were 96% (95% CI 87-99%) and 94% (95% CI 85-98%), respectively; the difference was statistically significant (p<0.05) for PFS. In multivariate analysis, only the presence of anaplasia retained significance with a hazard ratio (HR) of 14.8 and 12.9 (p<0.05) for recurrence and death, respectively.

CONCLUSION

These data suggest that the presence of MNT increases the risk of recurrence. MNT is associated with well-known prognostic factors, such as macroscopic thrombosis (possibly representing regression of macroscopic involvement) and anaplasia. Further prospective studies are needed to clarify the role of MNT as independent prognostic factor.

Regularly methylated novel pro-apoptotic genes associated with recurrence in transitional cell carcinoma of the bladder

Epigenetic silencing of tumor suppressor genes by promoter hypermethylation has been shown for a variety of genes in bladder cancer. Various p53 target genes have been investigated, but only few demonstrated promoter hypermethylation when semiquantitative detection methods were applied. To address to the question whether promoter methylation of novel p53 effector genes is a common event in transitional cell carcinoma of the bladder, we selected the p53 target genes apoptotic protein-activating factor (APAF-1), Caspase 8 (CASP-8), death-associated protein kinase, (DAPK-1) and insulin-like growth-factor-binding protein-3 (IGFBP-3), performing quantitative methylation-specific real-time PCR. The individual level of methylation (normalized index of methylation) was correlated with clinicopathological features as well as the biological behavior of the superficial and muscleinvasive tumors. Tissue was obtained from 110 tumor patients and 20 patients without urological malignancy. The median follow-up of the tumor patients was 52 months. Hypermethylation of the promoter region in tumor specimens was common for APAF-1 (100%), DAPK-1 (74%) and IGFBP-3 (66%), but not for CASP-8 (3.6%). It was seen less frequently and with undetectable or low methylation levels in the normal urothelium group. The APAF-1 methylation levels significantly correlated with tumor stage and tumor grade. The APAF-1 and IGFBP-3 methylation levels were able to separate tumors with higher recurrence risk from low-risk tumors in nonmuscleinvasive and muscleinvasive tumors. In multivariate analysis, APAF-1 and IGFBP-3 methylation levels were independent prognostic markers for recurrence in superficial bladder tumors. This study provides new insights into the role of promoter methylation of selected p53 target genes. The extent of promoter methylation of specific genes offers additional prognostical information and is associated with the outcome in patients with nonmuscleinvasive and muscleinvasive bladder cancer.

Survivin: an inhibitor of apoptosis in pediatric cancer

Survivin is an inhibitor of apoptosis protein (IAP) expressed in a large number of adult malignancies. Its expression levels correlate with more aggressive disease and poor clinical outcome in many of these tumors. As its expression is restricted in normal adult differentiated tissues, it has become of great interest as both a tumor prognostic marker and as a potential biologic target for future anti-cancer therapies. Survivin expression and Survivin-based therapies have been examined in many of the more common pediatric malignancies. We present an overview of Survivin function and current research exploring its biologic and therapeutic roles in pediatric tumors.