High Telomerase RNA Expression Level Is an Adverse Prognostic Factor for Favorable-Histology Wilms' Tumor

Wilms Tumor: An Unexpected Diagnosis in Adult Patients

CONTEXT.—

Wilms tumor (WT) in adult patients is rare and has historically been a diagnostic and therapeutic conundrum, with limited data available in the literature.

OBJECTIVE.—

To provide detailed diagnostic features, molecular profiling, and patient outcomes in a multi-institutional cohort of adult WT patients.

DESIGN.—

We identified and retrospectively examined 4 adult WT cases.

RESULTS.—

Two patients presented with metastatic disease, and diagnoses were made on fine-needle aspiration of their renal masses. The aspirates included malignant primitive-appearing epithelioid cells forming tubular rosettes and necrosis, and cell blocks demonstrated triphasic histology. In the remaining 2 cases, patients presented with localized disease and received a diagnosis on resection, with both patients demonstrating an epithelial-predominant morphology. Tumor cells in all cases were patchy variable positive for PAX8 and WT1 immunohistochemistry. Next-generation sequencing identified alterations previously reported in pediatric WT in 3 of 4 cases, including mutations in ASXL1 (2 of 4), WT1 (1 of 4), and the TERT promoter (1 of 4), as well as 1q gains (1 of 4); 1 case showed no alterations. Three patients were treated with pediatric chemotherapy protocols; during follow-up (range, 26-60 months), 1 patient died of disease.

CONCLUSIONS.—

WT is an unexpected and difficult entity to diagnose in adults and should be considered when faced with a primitive-appearing renal or metastatic tumor. Molecular testing may help exclude other possibilities but may not be sensitive or specific because of the relatively large number of driver mutations reported in WT.

Gene expression analysis and the risk of relapse in favorable histology Wilms' tumor

Introduction and Objectives

Wilms' tumor (WT) relapse occurs in 15% of patients. We aim to investigate the association between the expression of several genetic markers and WT relapse risk.

Materials and methods

The study included 51 children treated for WT at a tertiary center between 2001 and 2019: 23 patients had disease relapse (group A) and 28 remained relapse-free after at least 2 years of follow-up (group B). Patients with syndromic, bilateral synchronous or anaplastic WT were excluded. Autologous renal tissue from 20 patients served as control. Total RNA was isolated from tumor tissue and control. Gene expression levels of WT1, HIF1α, b-FGF, c-MYC and SLC22A18 were assessed using quantitative RT-PCR and normalized to GAPDH. Immunohistochemical staining for WT1 and gene expression levels were compared between the study groups.

Results

Median patient age was 3 (IQR = 2-5) years and 36 (70.6%) had stage I disease. Baseline characteristics were similar between study groups. Relapse occurred at a median of 6.8 (2.8-24.7) months, predominantly in the lungs (11/23, 47.8%). Tumors that relapsed expressed significantly higher levels of WT1, HIF1α, b-FGF and c-MYC and lower levels of SLC22A18 (p < 0.001). Strong immunohistochemical staining for WT1 was seen in 73.9% of group A and 14.29% of group B (p < 0.001). These associations retained statistical significance irrespective of patient and tumor characteristics.

Conclusions

Higher expression levels of WT1, HIF1 α, b-FGF and c-MYC and lower level of SLC22A18 are associated with increased risk of WT relapse. These genetic markers can serve as future prognostic predictors and help stratify patients for treatment.

Genetic changes associated with relapse in favorable histology Wilms tumor: A Children's Oncology Group AREN03B2 study

Over the last decade, sequencing of primary tumors has clarified the genetic underpinnings of Wilms tumor but has not affected therapy, outcome, or toxicity. We now sharpen our focus on relapse samples from the umbrella AREN03B2 study. We show that over 40% of relapse samples contain mutations in SIX1 or genes of the MYCN network, drivers of progenitor proliferation. Not previously seen in large studies of primary Wilms tumors, DIS3 and TERT are now identified as recurrently mutated. The analysis of primary-relapse tumor pairs suggests that 11p15 loss of heterozygosity (and other copy number changes) and mutations in WT1 and MLLT1 typically occur early, but mutations in SIX1, MYCN, and WTX are late developments in some individuals. Most strikingly, 75% of relapse samples had gain of 1q, providing strong conceptual support for studying circulating tumor DNA in clinical trials to better detect 1q gain earlier and monitor response.

TERT Expression in Wilms Tumor Is Regulated by Promoter Mutation or Hypermethylation, WT1, and N-MYC

Simple Summary

The telomerase enzyme adds repetitive genetic sequences to the ends of chromosomes called telomeres to prevent cellular senescence. Gain of telomerase function is one of the hallmarks of human cancer. The telomerase protein is coded by the gene TERT and increased TERT RNA levels have been associated with disease relapse in Wilms tumor, the most common kidney cancer of childhood. This study aimed to determine the mechanisms of increased TERT expression in Wilms tumor. This study found mutations in the TERT promoter, increased methylation of the TERT promoter, and genomic copy number amplifications of TERT as potential mechanisms of TERT activation. Conversely, this study found that inactivating WT1 mutation was associated with low TERT RNA levels and telomerase activity. N-MYC overexpression in Wilms tumor cells resulted in increased TERT promoter activity and TERT transcription. TERT transcription is associated with molecular and histologic subgroups in Wilms tumor and telomere-targeted therapies warrant future investigation.

Abstract

Increased TERT mRNA is associated with disease relapse in favorable histology Wilms tumor (WT). This study sought to understand the mechanism of increased TERT expression by determining the association between TERT and WT1 and N-MYC, two proteins important in Wilms tumor pathogenesis that have been shown to regulate TERT expression. Three out of 45 (6.7%) WTs and the corresponding patient-derived xenografts harbored canonical gain-of-function mutations in the TERT promoter. This study identified near ubiquitous hypermethylation of the TERT promoter region in WT compared to normal kidney. WTs with biallelic inactivating mutations in WT1 (7/45, 15.6%) were found to have lower TERT expression by RNA-seq and qRT-PCR and lower telomerase activity determined by the telomerase repeat amplification protocol. Anaplastic histology and increased percentage of blastema were positively correlated with higher TERT expression and telomerase activity. In vitro shRNA knockdown of WT1 resulted in decreased expression of TERT, reduced colony formation, and decreased proliferation of WiT49, an anaplastic WT cell line with wild-type WT1. CRISPR-Cas9-mediated knockout of WT1 resulted in decreased expression of telomere-related gene pathways. However, an inducible Wt1-knockout mouse model showed no relationship between Wt1 knockout and Tert expression in normal murine nephrogenesis, suggesting that WT1 and TERT are coupled in transformed cells but not in normal kidney tissues. N-MYC overexpression resulted in increased TERT promoter activity and TERT transcription. Thus, multiple mechanisms of TERT activation are involved in WT and are associated with anaplastic histology and increased blastema. This study is novel because it identifies potential mechanisms of TERT activation in Wilms tumor that could be of therapeutic interests.

High prevalence of TERT aberrations in myxoid liposarcoma: TERT reactivation may play a crucial role in tumorigenesis

Myxoid liposarcoma (MLPS) is genetically characterized by FUS‐DDIT3 or EWSR1‐DDIT3 gene fusion and the high frequency of hotspot mutations (C228T or C250T) in the promoter region of telomerase reverse transcriptase (TERT) that encodes the TERT protein. The latter leads to telomerase reactivation, a mechanism of telomere maintenance. Although the TERT promoter hotspot mutation is a poor prognostic factor in various tumors, its effect on MLPS has not been reported in detail. In the present study, we examined the clinicopathological characteristics, prognosis, and telomere maintenance mechanisms in 83 primary tumor samples of MLPS, which were resected surgically at the Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan, from 2008 to 2020. TERT promoter hotspot mutations were observed in 77% (63/82) cases, and alternative lengthening of telomeres (ALT) was absent in all cases. Among the cases without TERT promoter hotspot mutations, TERT rearrangements, and minor point mutations in the TERT promoter region were found in 3 and 2 cases, respectively. TERT mRNA expression was observed consistently even in patients for whom no genomic TERT aberrations were detected, and the presence of TERT promoter hotspot mutation did not correlate significantly with either overall and metastasis‐free survival (P = .56, P = .83, respectively) or clinicopathological features. Therefore, patients with MLPS characteristically shows TERT expression and a high prevalence of TERT aberrations. Our findings suggest that TERT aberration is not prognostic factor, but might occur at an early stage and play a key role in tumorigenesis.

Yes-associated protein 1 as a prognostic biomarker and its correlation with telomerase in various cancers

Objectives

The aims of this study were to investigate the expression of Yes-associated protein 1 (YAP1), its prognostic significance, and the correlation between YAP1 and telomerase in various cancers.

Methods

The Gene Expression Profiling Interactive Analysis database was used to analyze RNA sequencing data and the survival rate of patients with various cancers in The Cancer Genome Atlas (TCGA) database. PrognoScan was used to analyze the prognostic value of YAP1 expression in various cancers. Tumor Immune Estimation Resource was used to determine the correlation between YAP1 expression and telomerase in various cancer types based on TCGA data.

Results

The analysis suggested that YAP1 was differentially expressed between tissues of various cancers and non-tumor tissues. High YAP1 expression was also related to a poor prognosis in adrenocortical carcinoma, bladder urothelial carcinoma, and pancreatic adenocarcinoma. Moreover, YAP1 expression was correlated with the expression of telomerase reverse transcriptase and telomerase RNA component in various cancer types.

Conclusion

These results suggest that YAP1 is a potential biomarker with prognostic significance and relevance for oncogene research in various cancer types. The correlation between the expression of YAP1 and telomere-associated genes will help to understand their cancer-promoting mechanisms and interactions.

An organoid biobank for childhood kidney cancers that captures disease and tissue heterogeneity

Kidney tumours are among the most common solid tumours in children, comprising distinct subtypes differing in many aspects, including cell-of-origin, genetics, and pathology. Pre-clinical cell models capturing the disease heterogeneity are currently lacking. Here, we describe the first paediatric cancer organoid biobank. It contains tumour and matching normal kidney organoids from over 50 children with different subtypes of kidney cancer, including Wilms tumours, malignant rhabdoid tumours, renal cell carcinomas, and congenital mesoblastic nephromas. Paediatric kidney tumour organoids retain key properties of native tumours, useful for revealing patient-specific drug sensitivities. Using single cell RNA-sequencing and high resolution 3D imaging, we further demonstrate that organoid cultures derived from Wilms tumours consist of multiple different cell types, including epithelial, stromal and blastemal-like cells. Our organoid biobank captures the heterogeneity of paediatric kidney tumours, providing a representative collection of well-characterised models for basic cancer research, drug-screening and personalised medicine.

Pre-clinical cell culture models capturing the heterogeneity of childhood kidney tumours are limited. Here, the authors establish and characterise an organoid biobank of tumour and matched normal organoid cultures from over 50 children with different subtypes of kidney cancer.

Life History Trade-Offs in Tumors

Purpose

In this paper, we provide an overview of a life history theory and how it applies to cancer evolution.

Recent Findings

We review the literature on trade-offs in tumors, focusing on the trade-offs among cellular proliferation, survival, and motility. Trade-offs are critical natural constraints for almost all evolutionary processes. Many ecological studies show that trade-offs among these cellular functions maintain a genetic diversity. In addition, these trade-offs are not fixed, but rather can shift depending on the ecological circumstances in the microenvironment. This can lead to selection for the cellular capacity to respond to these differing microenvironments in ways that promote the fitness of the cancer cell. We relate these life history trade-offs to the recently developed Evo-Eco indexes and discuss how life history theory can help refine our measures of tumor evolution and ecology.

Summary

Life history theory provides a framework for understanding how the spatial and temporal variability in the tumor microenvironment—in particular resources and threats—affect trade-offs among cell survival, cell proliferation, and cell migration. We discuss how these trade-offs can potentially be leveraged in cancer therapy to increase the effectiveness of treatment.

Association between Long Interspersed Nuclear Element-1 Methylation and Relative Telomere Length in Wilms Tumor

Background:

DNA hypomethylation of long interspersed nuclear elements-1 (LINEs-1) occurs during carcinogenesis, whereas information addressing LINE-1 methylation in Wilms tumor (WT) is limited. The main purpose of our study was to quantify LINE-1 methylation levels and evaluate their relationship with relative telomere length (TL) in WT.

Methods:

We investigated LINE-1 methylation and relative TL using bisulfite-polymerase chain reaction (PCR) pyrosequencing and quantitative PCR, respectively, in 20 WT tissues, 10 normal kidney tissues and a WT cell line. Significant changes were analyzed by t-tests.

Results:

LINE-1 methylation levels were significantly lower (P < 0.05) and relative TLs were significantly shorter (P < 0.05) in WT compared with normal kidney. There was a significant positive relationship between LINE-1 methylation and relative TL in WT (r = 0.671, P = 0.001). LINE-1 Methylation levels were significantly associated with global DNA methylation (r = 0.332, P < 0.01). In addition, relative TL was shortened and LINE-1 methylation was decreased in a WT cell line treated with the hypomethylating agent 5-aza-2′-deoxycytidine compared with untreated WT cell line.

Conclusion:

These results suggest that LINE-1 hypomethylation is common and may be linked to telomere shortening in WT.

Biomarkers for Wilms Tumor: A Systematic Review

PURPOSE

Wilms tumor is the most common childhood renal malignancy and the fourth most common childhood cancer. Many biomarkers have been studied but there has been no comprehensive summary. We systematically reviewed the literature on biomarkers in Wilms tumor to quantify the prognostic implications of the presence of individual tumor markers.

MATERIALS AND METHODS

We searched for English language studies from 1980 to 2015 performed in patients younger than 18 years with Wilms tumor and prognostic data. The protocol was conducted per PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Two reviewers abstracted data in duplicate using a standard evaluation form. We performed descriptive statistics, then calculated relative risks and 95% confidence intervals for markers appearing in multiple level II or III studies.

RESULTS

A total of 40 studies were included examining 32 biomarkers in 7,381 patients with Wilms tumor. Studies had a median of 61 patients, 24 biomarker positive patients per series and a median followup of 68.4 months. Median percentages of patients with stages 1, 2, 3, 4 and 5 tumors were 28.5%, 26.4%, 24.5%, 14.1% and 1.7%, respectively, and 10.2% had anaplasia. The strongest negative prognostic association was loss of heterozygosity at 11p15, with a risk of recurrence of 5.00, although loss of heterozygosity at 1p and gain of function at 1q were also strongly linked to increased recurrence (2.93 and 2.86, respectively).

CONCLUSIONS

Several tumor markers are associated with an increased risk of recurrence or a decreased risk of overall survival in patients with Wilms tumor. These data suggest targets for development of diagnostic tests and potential therapies.

Evaluation of radiation dose to cardiac and pulmonary tissue among patients with stage IV Wilms tumor and pulmonary metastases

BACKGROUND

Most patients with stage IV Wilms tumor (WT) and pulmonary metastases are treated with surgery, local radiotherapy (RT), and whole-lung irradiation (WLI). The Children's Oncology Group is studying whether WLI should only be given if metastatic lung lesions persist following induction chemotherapy. We hypothesized that radiation dose to cardiac and pulmonary organs are increased when WLI and abdominal RT fields are administered sequentially.

PROCEDURE

We retrospectively identified 16 patients with stage IV WT and pulmonary metastases to model dosimetry plans for concurrent and sequential flank or whole abdomen and whole-lung fields.

RESULTS

Treatment plans were evaluated for dosimetric endpoints to the heart and the lungs. The mean dose (Gy) was significantly higher to the heart (15.8 vs. 12.1, P < 0.0001) and lungs (14.1 vs. 12.2, P < 0.0002) when patients with stage IV WT and pulmonary metastases were treated with sequential RT. The percent tissue organ volumes (V) receiving high RT doses of 15 and 20 Gy (V(15) and V(20)) were negligible in concurrent treatment plans. Comparatively, mean V(15) and V(20) values for sequential treatment plans were 35% and 27%, respectively, for the heart, and 15% and 12%, for the lungs.

CONCLUSIONS

The dose to the heart and lung tissue is significantly increased when WLI and abdominal RT fields are administered sequentially. While omission of WLI may be beneficial for patients achieving good response to induction chemotherapy, the less favorable response group may be subjected to increased risk of cardiac and pulmonary toxicities from sequential WLI.

Prognostic significance of telomere maintenance mechanisms in pediatric high-grade gliomas

Children with high-grade glioma, including diffuse intrinsic pontine glioma (DIPG), have a poor prognosis despite multimodal therapy. Identifying novel therapeutic targets is critical to improve their outcome. We evaluated prognostic roles of telomere maintenance mechanisms in children with HGG, including DIPG. A multi-institutional retrospective study was conducted involving 50 flash-frozen HGG (35 non-brainstem; 15 DIPG) tumors from 45 children (30 non-brainstem; 15 DIPG). Telomerase activity, expression of hTERT mRNA (encoding telomerase catalytic component) and TERC (telomerase RNA template) and alternative lengthening of telomeres (ALT) mechanism were assayed. Cox Proportional Hazard regression analyses assessed association of clinical and pathological variables, TERC and hTERT levels, telomerase activity, and ALT use with progression-free or overall survival (OS). High TERC and hTERT expression was detected in 13/28 non-brainstem HGG samples as compared to non-neoplastic controls. High TERC and hTERT expression was identified in 13/15 and 11/15 DIPG samples, respectively, compared to controls. Evidence of ALT was noted in 3/11 DIPG and 10/19 non-brainstem HGG specimens. ALT and telomerase use were identified in 4/19 non-brainstem HGG and 2/11 DIPG specimens. In multivariable analyses, increased TERC and hTERT levels were associated with worse OS in patients with non-brainstem HGG, after controlling for tumor grade or resection extent. Children with HGG and DIPG, have increased hTERT and TERC expression. In children with non-brainstem HGG, increased TERC and hTERT expression levels are associated with a worse OS, making telomerase a promising potential therapeutic target in pediatric HGG.

Children's Oncology Group's 2013 blueprint for research: renal tumors

Renal malignancies are among the most prevalent pediatric cancers. The most common is favorable histology Wilms tumor (FHWT), which has 5-year overall survival exceeding 90%. Other pediatric renal malignancies, including anaplastic Wilms tumor, clear cell sarcoma, malignant rhabdoid tumor, and renal cell carcinoma, have less favorable outcomes. Recent clinical trials have identified gain of chromosome 1q as a prognostic marker for FHWT. Upcoming studies will evaluate therapy adjustments based on this and other novel biomarkers. For high-risk renal tumors, new treatment regimens will incorporate biological therapies. A research blueprint, viewed from the perspective of the Children's Oncology Group, is presented.

Adult Wilms' tumor - diagnosis and current therapy

INTRODUCTION

Wilms' tumour is one of the commonest malignant tumours of childhood. It appears mainly in the first 5 years of life. Incidental examples of nephroblastoma in adults have been described in literature (about 3% of all described cases). There are diagnostic and therapeutic difficulties in that older age group. The preoperative diagnosis of nephroblastoma in adults is difficult because there are no specific radiographic findings that allow to distinguished it from the more common adult renal tumors. Histopathologically, there is no difference between adult and childhood Wilms' tumor.

MATERIALS AND METHODS

The PubMed database and current literature search was conducted for reports on clinical and histopathological features of nephroblastoma in adults. We also reviewed the literature in terms of treatment strategy, toxicity and prognostic factors.

RESULTS

Up till now, several biological factors have been identified that may be in future new prognostic factors. Modern treatment regiments improved OS in this group of patients (OS rates of 90%). The prognosis remain still worse for about 25% of patients with anaplastic, bilateral and recurrent disease.

CONCLUSIONS

Due to the fact that nephroblastoma is a very rare type of cancer, adult patients should be treated in an individual way based on the available schemes used in children. Toxicity in adults is higher than in children.

Methylation of the RASSF1A promoter is predictive of poor outcome among patients with Wilms tumor

BACKGROUND

Wilms tumor (WT) has a survival rate of 90% following multimodality therapy. Nevertheless, there are some groups of patients with event-free survival rates less than 75%. In addition to clinical prognostic factors, loss of heterozygosity at 1p and/or 16q has been used to determine treatment intensity. However, the incidence of this abnormality is low, and new biomarkers are still needed.

PROCEDURE

We analyzed methylation status of three tumor suppressor genes; Ras-association domain family 1 protein, isoform A (RASSF1A), DCR2, and CASP8, in 84 WTs using conventional methylation-specific PCR (cMSP), and the results were correlated with outcome. Furthermore, we analyzed the methylation status of RASSF1A by quantitative MSP (qMSP) in 171 WTs, and evaluated clinical and genetic differences between the methylated and unmethylated tumors.

RESULTS

RASSF1A was the most frequently methylated gene identified by cMSP, and associated with a poor outcome. Patients with a RASSF1A-methylated tumor had shorter overall and event-free survival periods (P = 0.043 and 0.018, respectively), when a cut-off value of 7% by qMSP was used. The methylation was more frequent in tumors of older children than younger children (P < 0.001), and in advanced-stage tumors than early stage tumors (P = 0.001). However, multivariate analysis could not confirm the prognostic significance of RASSF1A methylation, possibly because of a small number of advanced stage tumors examined. RASSF1A methylation was correlated with LOH at 1p and/or 16q (P = 0.017), but not with WT1 abnormality, suggesting the methylation and LOH to involve the same tumorigenic pathway.

CONCLUSIONS

The methylation status of RASSF1A might be a novel biomarker to predict outcome of WT patients.

Telomerase-independent paths to immortality in predictable cancer subtypes

The vast majority of cancers commandeer the activity of telomerase - the remarkable enzyme responsible for prolonging cellular lifespan by maintaining the length of telomeres at the ends of chromosomes. Telomerase is only normally active in embryonic and highly proliferative somatic cells. Thus, targeting telomerase is an attractive anti-cancer therapeutic rationale currently under investigation in various phases of clinical development. However, previous reports suggest that an average of 10-15% of all cancers lose the functional activity of telomerase and most of these turn to an Alternative Lengthening of Telomeres pathway (ALT). ALT-positive tumours will therefore not respond to anti-telomerase therapies and there is a real possibility that such drugs would be toxic to normal telomerase-utilising cells and ultimately select for resistant cells that activate an ALT mechanism. ALT exploits certain DNA damage response (DDR) components to counteract telomere shortening and rapid trimming. ALT has been reported in many cancer subtypes including sarcoma, gastric carcinoma, central nervous system malignancies, subtypes of kidney (Wilm's Tumour) and bladder carcinoma, mesothelioma, malignant melanoma and germ cell testicular cancers to name but a few. A recent heroic study that analysed ALT in over six thousand tumour samples supports this historical spread, although only reporting an approximate 4% prevalence. This review highlights the various methods of ALT detection, unravels several molecular ALT models thought to promote telomere maintenance and elongation, spotlights the DDR components known to facilitate these and explores why certain tissues are more likely to subvert DDR away from its usually protective functions, resulting in a predictive pattern of prevalence in specific cancer subsets.

Race disparities in Wilms tumor incidence and biology

BACKGROUND

Wilms tumor (WT) is thought to arise in children of Black African ancestry with greater frequency than in Whites. To clarify the biological basis for race disparities in WT, we first verified that Black children residing in Tennessee have an increased incidence of WT, and second, established molecular profiles in WT that are specific to race.

MATERIALS AND METHODS

To assess race disparities in WT epidemiology, the Tennessee Cancer Registry (TCR) was queried for all in-state patients less than 20 y of age and registered between 1999 and 2008. To explore race disparities in WT biology, six Black and four White WT specimens acquired in Tennessee were analyzed using imaging mass spectrometry (IMS).

RESULTS

TCR data show that Black children are over-represented among WT patients (29%) relative to all other childhood cancers (18.5%; P = 0.01). WT ranked the fifth most common cancer diagnosis among Blacks, but ninth among Whites. The diagnosis of WT occurred 79% more frequently among Blacks (n = 28) than Whites (n = 69; P = 0.01), and proportionally more Blacks tended to present with distant disease. Although overall survival from WT was not statistically different between Blacks (92.9%) and Whites (94.0%), Black males showed the lowest survival (85%; P = 0.21). IMS analysis identified peptide spectra from both WT blastema and stroma that independently classify specimens according to race with greater than 80% accuracy.

CONCLUSIONS

In Tennessee, Black children appear more susceptible than Whites to develop WT. Race-specific molecular profiles can be determined that may help to clarify pathways of Wilms tumorigenesis and the biological basis for race disparities in WT incidence and biology.

Telomerase reverse transcriptase catalytic subunit expression and proliferation index in Wilms tumor

Telomerase activity provides telomere maintenance in chromosomes. It prevents cells from entering senescence. Telomerase activity is one of the crucial steps in various cancers. Wilms tumor (nephroblastoma) is one of the most common solid tumors of childhood. Hitherto, telomerase reverse transcriptase (TERT) catalytic subunit expression in Wilms tumor has not been investigated widely. The aim of this study was to explore the expression level of human TERT in Wilms tumor and to correlate with some clinical prognosis factors such as tumor weight, stage, histology, and Ki67 expression. This study included 41 nephroblastoma cases of childhood. The telomerase catalytic subunit expression and proliferation index was determined using an immunohistochemical method on archival paraffin-embedded tissue sections. Statistical analysis was done on SPSS 9.05 by Mann-Whitney U test and Spearman's correlation analysis. TERT expression was negative in 11 cases (26.8%), weakly positive in 14 cases (34.1%), and strongly positive in 16 cases (39%). The proliferation index was found to be 20 to 90 (mean 58.9 ± 26.8). Using Spearman correlation analysis, both the TERT expression (p=0.032) and Ki67 index (p=0.048) were found to be correlated with survival rate. Similarly, both the telomerase expression (p=0.011) and the Ki67 index (0.040) were correlated with the weight and dimension of the tumor. But there was no relationship between telomerase expression and Ki67 index (p=0.429). The mean survival time for telomerase negative cases was 56.6 ± 27.3 months, while it was 34.67 ± 28.36 months for positive cases. The Mann-Whitney U test revealed that levels of telomerase (p=0.040) significantly affected the survival rate. In the present study, we showed that the presence of TERT expression correlated with both tumor size and survival time. These findings suggest that senescence may play an important role in WT evolution, and determination of telomere maintenance will be useful to predict survival and follow-up of patients with Wilms tumor.

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.

Current management of wilms' tumor

Wilms' tumor is the most common malignant renal tumor in children. Survival has improved dramatically over time as a result of prospective randomized clinical trials conducted by the pediatric cooperative cancer groups. Current research is directed toward identifying low-risk patients for whom a reduction in treatment intensity would decrease long-term morbidity. This article reviews the most recent advances in the biology and treatment of children with Wilms' tumor.

Telomerase activity and telomerase reverse transcriptase catalytic subunit expression in canine lymphoma: correlation with Ki67 immunoreactivity

Increased telomerase activity (TA) has been found in human and canine solid tumours, stem cells and somatic tissues with enhanced proliferative potential. The relationship between TA in normal and malignant lymphoid tissues remains unclear. The TA and the expression of canine telomerase reverse transcriptase catalytic subunit (dogTERT) messenger RNA (mRNA) were analyzed in malignant lymph nodes from 30 dogs with lymphoma, from two dogs with non-neoplastic illness and from two clinically normal dogs, demonstrating a statistically significant difference between TA in lymphoma lymph nodes (n = 30) and normal nodes (n = 4) but no significant difference in dogTERT mRNA expression. In addition, the expression of telomerase reverse transcriptase catalytic subunit (TERT) protein and Ki67 was analyzed in malignant lymph nodes from 10 dogs with lymphoma and from two clinically normal dogs by immunohistochemistry. TERT expression was associated with Ki67 in all lymphoma nodes (n = 10), and differences were illustrated between TERT and Ki67 expression between lymphoma (n = 10) and non-lymphoma (n = 2) nodes. This data support further investigation of telomerase in canine haematopoietic neoplasia through large-scale prospective studies.

Outcome of pediatric renal tumor treated using the Japan Wilms Tumor Study-1 (JWiTS-1) protocol: a report from the JWiTS group

PURPOSE

In 1996, the Japan Wilms Tumor Study (JWiTS) group was founded to elucidate the efficacy and safety of the regimen established by the National Wilms Tumor Study (NWTS) group in the USA, and a multicenter cooperative study (JWiTS-1) was started in Japan. This report reviews the results of JWiTS-1.

METHODS

A total of 307 patients with malignant renal tumor were enrolled in the JWiTS-1 study between 1996 and 2005. Central pathological diagnosis and follow-up data were available in 210 cases. The protocol regimens were similar to the NWTS-5 regimens. Clinical stage was classified according to the Japanese Staging System.

RESULTS

Five-year overall survival (OS) rate was 91.1% for nephroblastoma, 72.9% for clear cell sarcoma of the kidney (CCSK), and 22.2% for rhabdoid tumor of the kidney (RTK). In the nephroblastoma patients, 5-year OS was 90.5% for stage I disease, 92.2% for stage II, 90.9% for stage III, 86.7% for stage IV, and 78.7% for stage V.

CONCLUSIONS

The OS of patients in the JWiTS-1 study were comparable with the results of other multicenter studies in the USA and Europe. The outcome for patients with nephroblastoma and CCSK was fair. In contrast, the cure rate for those with RTK was not satisfactory. New treatment strategies are needed for patients with RTK.

The promise of telomere length, telomerase activity and its regulation in the translocation-dependent cancer ESFT; clinical challenges and utility

The Ewing's sarcoma family of tumours (ESFT) are diagnosed by EWS-ETS gene translocations. The resulting fusion proteins play a role in both the initiation and maintenance of these solid aggressive malignant tumours, suppressing cellular senescence and increasing cell proliferation and survival. EWS-ETS fusion proteins have altered transcriptional activity, inducing expression of a number of different target genes including telomerase. Up-regulation of hTERT is most likely responsible for the high levels of telomerase activity in primary ESFT, although telomerase activity and expression of hTERT are not predictive of outcome. However levels of telomerase activity in peripheral blood may be useful to monitor response to some therapeutics. Despite high levels of telomerase activity, telomeres in ESFT are frequently shorter than those of matched normal cells. Uncertainty about the role that telomerase and regulators of its activity play in the maintenance of telomere length in normal and cancer cells, and lack of studies examining the relationship between telomerase activity, regulators of its activity and their clinical significance in patient samples have limited their introduction into clinical practice. Studies in clinical samples using standardised assays are critical to establish how telomerase and regulators of its activity might best be exploited for patient benefit.

Role of prognostic factors in the management of pediatric solid tumors

The importance of prognostic factors in predicting outcome in pediatric oncology is largely recognized, and most current protocols tailor treatment based on risk stratification. Further refinements of classical staging systems are ongoing, and the future of pediatric oncology is in the development of strategies based on individual tumor characteristics. This review details significant advances in our understanding of prognostic factors in the most common pediatric solid tumors and potential applications for clinical management.

Current and emerging chemotherapy treatment strategies for Wilms tumor in North America

Wilms tumor is the most common primary renal malignancy occurring in childhood. Approximately 500 children are diagnosed with Wilms tumor annually in the US alone, most of whom are aged <5 years. Several prognostic factors have been identified, including stage of disease, tumor histology, patient age, tumor weight, and tumor-specific loss of heterozygosity for chromosomes 1p and 16q. During the period from 1969 to 2002, the National Wilms Tumor Study Group coordinated five multicenter Wilms tumor studies. The overall survival rate for Wilms tumor has risen to >90% for patients with tumors of favorable histology. However, the treatment of patients with Wilms tumor with anaplastic histology remains challenging. The optimal treatment strategies for Wilms tumor in relapse will be studied via international collaboration in the near future. Goals of emerging studies include minimizing toxicity while maintaining the outstanding cure rates for patients with a good prognosis and, through advancing biologic understanding and developing novel therapeutic approaches, improving the prognosis for those patients in whom effective cure of their disease continues to elude physicians.

The sensitization of glioma cells to cisplatin and tamoxifen by the use of catechin

Telomerase expression strongly correlates with the grade of malignancy in glioma with inhibition illustrating a definite increase in chemosensitivity. This study was designed to investigate the effects of a green tea derivative, epigallocatechin-3-gallate (EGCG); together with either cisplatin or tamoxifen in glioma, and to investigate whether these effects are mediated through telomerase suppression. EGCG showed a significant cytotoxic effect on 1321N1 cells after 24 h and on U87-MG cells after 72 h (P < 0.001) without significantly affecting the normal astrocytes. Treatment with EGCG inhibited telomerase expression significantly (P < 0.01) and enhanced the effect of cisplatin and tamoxifen in both 1321N1 (P < 0.01) and U87-MG (P < 0.001) cells. EGCG, as a natural product has enormous potential to be an anti-cancer agent capable of enhancing tumour cell sensitivity to therapy.

High cyclin E staining index in blastemal, stromal or epithelial cells is correlated with tumor aggressiveness in patients with nephroblastoma

Purpose

Identifying among nephroblastoma those with a high propensity for distant metastases using cell cycle markers: cyclin E as a regulator of progression through the cell cycle and Ki-67 as a tumor proliferation marker, since both are often deregulated in many human malignancies.

Methodology/Principal Findings

A staining index (SI) was obtained by immunohistochemistry using anti-cyclin E and anti-Ki-67 antibodies in paraffin sections of 54 postchemotherapy nephroblastoma including 42 nephroblastoma without metastasis and 12 with metastases. Median cyclin E and Ki-67 SI were 46% and 33% in blastemal cells, 30% and 10% in stromal cells, 37% and 29.5% in epithelial cells. The highest values were found for anaplastic nephroblastoma. A correlation between cyclin E and Ki-67 SI was found for the blastemal component and for the epithelial component. Univariate analysis showed prognostic significance for metastases with cyclin E SI in stromal cells, epithelial cells and blastemal cells (p = 0.03, p = 0.01 and p = 0.002, respectively) as well as with Ki-67 SI in blastema (p<10⁻⁴). The most striking data were that both cyclin E SI and blastemal Ki-67 SI discriminated between patients with metastases and patients without metastasis among intermediate-risk nephroblastoma.

Conclusions

Our findings show that a high cyclin E SI in all components of nephroblastoma is correlated with tumor aggressiveness and metastases, and that assessment of its expression may have prognostic value in the categorization of nephroblastoma.

Expression of human telomerase reverse transcriptase in bone marrow CD34+ cells from patients with beta-thalassemia major

BACKGROUND

Normal stem cells usually express a low level of telomerase activity that serves to stabilize the chromosomes during cell division and helps prevent cell senescence. Human telomerase reverse transcriptase (hTERT) is a rate-limiting enzyme that dictates the activity of human telomerase and thus decides the life span of cells. The expression of hTERT and its roles in beta-thalassemia major are unclear, however.

STUDY DESIGN AND METHODS

hTERT mRNA expression in bone marrow (BM) CD34+ cells from 25 children with beta-thalassemia major and 15 control subjects was investigated using real-time reverse transcription polymerase chain reaction (RT-PCR) analysis. The serum erythropoietin (sEPO) and hemoglobin (Hb) levels in peripheral blood were also determined. The relationship between hTERT and sEPO as well as Hb was then examined.

RESULTS

It was found that hTERT mRNA expression was significantly up regulated in BM CD34+ cells from patients with beta-thalassemia major. Furthermore, a significantly positive correlation was found between hTERT mRNA and sEPO (r = 0.771, p < 0.001). A significantly inverse correlation, however, was found between hTERT mRNA and Hb concentration (r = -0.929, p < 0.001).

CONCLUSION

Our findings suggest that severe anemia with low Hb concentration might up regulate hTERT expression of BM CD34+ cells and sEPO levels in patients with beta-thalassemia major.

Wilms tumour: prognostic factors, staging, therapy and late effects

Wilms tumour is the most common malignant renal tumour in children. Dramatic improvements in survival have occurred as the result of advances in anaesthetic and surgical management, irradiation and chemotherapy. Current therapies are based on trials and studies primarily conducted by large multi-institutional cooperatives including the Société Internationale d'Oncologie Pédiatrique (SIOP) and the Children's Oncology Group (COG). The primary goals are to treat patients according to well-defined risk groups in order to achieve the highest cure rates, to decrease the frequency and intensity of acute and late toxicity and to minimize the cost of therapy. The SIOP trials and studies largely focus on the issue of preoperative therapy, whereas the COG trials and studies start with primary surgery. This paper reviews prognostic factors and staging systems for Wilms tumour and its current treatment with surgery and chemotherapy. Surgery remains a crucial part of treatment for nephroblastoma, providing local primary tumour control and adequate staging and possibly controlling the metastatic spread and central vascular extension of the disease. Partial nephrectomy, when technically feasible, seems reasonable not only in those with bilateral disease but also in those with unilateral disease where the patient has urological disorders or syndromes predisposing to malignancy. Partial nephrectomy, however, is frequently not sufficient for an anaplastic variant of tumour. The late effects for Wilms tumour and its treatment are also reviewed. The treatment of Wilms tumour has been a success story, and currently in excess of 80% of children diagnosed with Wilms tumour can look forward to long-term survival, with less than 20% experiencing serious morbidity at 20 years from diagnosis. The late complications are a consequence of the type and intensity of treatment required, which in turn reflects the nature and extent of the original tumour. Continual international trial development and participation will improve matching of treatment needs with prognosis, reducing long-term complications in the majority. The advent of molecular markers of disease severity and improved functional imaging might help.

Telomerase redefined: Integrated regulation of hTR and hTERT for telomere maintenance and telomerase activity

Telomerase activity is dependent on the expression of 2 main core component genes, hTERT, which encodes the catalytic component and hTR (also called TERC), which encodes the RNA component. The correlation between telomerase activity and carcinogenesis has made this molecule of great interest in cancer research, however in order to fully understand the regulation of telomerase the mechanisms controlling both telomerase genes need to be studied. Some of these mechanisms of regulation have begun to emerge, however many more remain to be deciphered. For many years hTERT has been regarded as the limiting component of telomerase and much of the research in this field has focussed on its regulation, however it was clear from an early stage that hTR expression was also tightly regulated in normal cells and disease. More recently evidence from biochemistry, promoter studies and mouse models has been steadily increasing for a role for hTR as a limiting and essential component for telomerase activity and telomere maintenance. Perhaps the time has come to redefine our view of telomerase regulation. Knowledge of the mechanisms controlling both telomerase genes in normal systems and cancer may aid our understanding of the role of telomerase in carcinogenesis or highlight potential areas for therapeutic intervention. Here we review the essential requirement of hTR for telomere maintenance and telomerase activity in normal tissues and disease and focus on recent advances in our understanding of hTR regulation in relation to hTERT.

CITED1 expression in Wilms' tumor and embryonic kidney

Wilms' tumors, or nephroblastomas, are thought to arise from abnormal postnatal retention and dysregulated differentiation of nephrogenic progenitor cells that originate as a condensed metanephric mesenchyme within embryonic kidneys. We have previously shown that the transcriptional regulator CITED1 (CBP/p300-interacting transactivators with glutamic acid [E]/aspartic acid [D]-rich C-terminal domain) is expressed exclusively in these nephrogenic progenitor cells and is downregulated as they differentiate to form nephronic epithelia. In the current study, we show that CITED1 expression persists in blastemal cell populations of both experimental rat nephroblastomas and human Wilms' tumors, and that primary human Wilms' tumors presenting with disseminated disease show the highest level of CITED1 expression. Unlike the predominantly cytoplasmic subcellular localization of CITED1 in the normal developing kidney, CITED1 is clearly detectable in the nuclear compartment of Wilms' tumor blastema. These findings indicate that CITED1 is a marker of primitive blastema in Wilms' tumors and suggest that persistent expression and/or altered subcellular localization of CITED1 in the condensed metanephric mesenchyme could play a role in Wilms' tumor initiation and pathogenesis.

Pediatric genitourinary tumors

PURPOSE OF REVIEW

We will review the 2005 and 2006 literature on pediatric genitourinary tumors.

RECENT FINDINGS

Survival continues to improve for primary renal, bladder/prostate and testicular tumors in childhood. The addition of more intensive chemotherapy for anaplastic histology disease, recognition of loss of heterozygosity for chromosomes 1p and 16q as an adverse prognostic factor in favorable histology Wilms' tumor, and the utilization of molecular markers to better characterize all renal tumors will better enable individualized therapy. Recognition and treatment of anaplastic histology and bilateral Wilms' tumor remains a challenge. In rhabdomyosarcoma, genitourinary site and embryonal histology confer a relatively favorable prognosis.

SUMMARY

Advances in molecular oncology, diagnostic imaging, surgical approaches and long-term follow-up of childhood cancer survivors drive risk-stratified therapy in pediatric genitourinary tumors.

Telomere biology of pediatric cancer

One of the hallmarks of cancer is limitless proliferative capacity, which is tightly associated with the ability to maintain telomeres. Over the last decade, the telomere biology of pediatric cancers has begun to be elucidated. Most pediatric leukemias and embryonal solid tumors activate the enzyme telomerase, a specialized reverse transcriptase that adds nucleotide repeats to telomeres. In general, high levels of tumor telomerase expression are associated with unfavorable outcome, although results vary according to tumor type. Some pediatric tumors, including osteosarcoma and glioblastoma multiforme, lack telomerase activity and maintain telomeres via a recombination-based mechanism called ALT (alternative lengthening of telomeres). Telomerase is a highly attractive therapeutic target for pediatric cancer because the enzyme plays a key role in conferring cellular immortality, is present in most tumors, and is relatively specific for cancer cells. Telomerase inhibitors have been evaluated in preclinical models of adult cancers, but few studies have been conducted on pediatric cancers. Further research is required to define how telomere biology can be used to clinical advantage in malignancies of childhood.

An update on the management of Wilms' tumour

AIMS

To review the management of Wilms' tumour.

METHODS

A search of the literature was performed using the PubMed database (1966 to May 2006) with the search terms 'Wilms' and either 'tumour/tumor' or 'cancer' or 'carcinoma'. This was augmented by manual searches of publications.

FINDINGS

The success of clinical trials in Wilms' tumour patients over the past 30 years has led to an overall survival of 85% and the introduction of less aggressive chemotherapeutic regimes for patients. Large randomised controlled trials have been published on the management of Wilms' tumour by various collaborative groups, including the National Wilms' Tumour Study Group (NWTSG) in North America and the Société Internationale d'Oncologie Pédiatrique (SIOP) plus the United Kingdom Children's Cancer Study Group (UKCCSG) in Europe.

CONCLUSIONS

Controversy exists as to the best approach to the management of these children with regard to neoadjuvant chemotherapy. Challenges remain in the identification of histological and molecular risk factors for the stratification of treatment intensity.

[Wilms' tumor - update 2007]

Due to the close interdisciplinary work of surgeons, radiologists and oncologists, the prognosis for Wilms' tumor (the most common renal tumor in childhood) has been dramatically improved over the last few decades. The treatment of such tumors is currently carried out worldwide by two study groups, in North America the National Wilms' Tumor Study (NWTS) and in Europe the Society of Paediatric Oncology (SIOP). Here we present an overview of the current treatment results and discuss future diagnostic and therapeutic strategies.

Telomerase-independent Regulation of ATR by Human Telomerase RNA

The human telomerase RNA (hTR), together with the telomerase reverse transcriptase, hTERT, constitute the core components of telomerase that is essential for telomere maintenance. While hTR is ubiquitously expressed, hTERT is normally restricted to germ cells and certain stem cells, but both are often deregulated during tumorigenesis. Here, we investigated the effects of changes in hTR cellular levels. Surprisingly, while inhibition of hTR expression triggers a rapid, telomerase-independent, growth arrest associated with p53 and CHK1 activation, its increased expression neutralizes activation of these pathways in response to genotoxic stress. These hTR effects are mediated through ATR and are sufficiently strong to impair ATR-mediated DNA-damage checkpoint responses. Furthermore, in response to low UV radiation, which activates ATR, endogenous hTR levels increase irrespective of telomerase status. Thus, we uncovered a novel, telomerase-independent, function of hTR that restrains ATR activity and participates in the recovery of cells from UV radiation.

A virus-encoded telomerase RNA promotes malignant T cell lymphomagenesis

Telomerase is a ribonucleoprotein complex consisting of two essential core components: a reverse transcriptase and an RNA subunit (telomerase RNA [TR]). Dysregulation of telomerase has been associated with cell immortalization and oncogenesis. Marek's disease herpesvirus (MDV) induces a malignant T cell lymphoma in chickens and harbors in its genome two identical copies of a viral TR (vTR) with 88% sequence identity to chicken TR. MDV mutants lacking both copies of vTR were significantly impaired in their ability to induce T cell lymphomas, although lytic replication in vivo was unaffected. Tumor incidences were reduced by >60% in chickens infected with vTR⁻ viruses compared with animals inoculated with MDV harboring at least one intact copy of vTR. Lymphomas in animals infected with the vTR⁻ viruses were also significantly smaller in size and less disseminated. Constitutive expression of vTR in the chicken fibroblast cell line DF-1 resulted in a phenotype consistent with transformation as indicated by morphological alteration, enhanced anchorage-independent cell growth, cell growth beyond saturation density, and increased expression levels of integrin αv. We concluded that vTR plays a critical role in MDV-induced T cell lymphomagenesis. Furthermore, our results provide the first description of tumor-promoting effects of TR in a natural virus–host infection model.

Analysis by array CGH of genomic changes associated with the progression or relapse of Wilms' tumour

Despite aggressive salvage regimens, approximately half of all children who suffer a Wilms' tumour recurrence will die of their disease. Although there are increasing data on molecular genetic prognostic factors present in the tumour at diagnosis, there is little information regarding the molecular events that occur with Wilms' tumour progression and relapse. In the present study, microarray-based comparative genomic hybridization (aCGH) analysis has been carried out on 58 Wilms' tumour samples, which included 38 untreated primary and 20 recurrent tumours. A higher degree of copy number changes was observed in the recurrent tumours (33.0% genomic clones) than in the primary tumour (21.2%). Paired analysis highlighted the acquisition of 15q gain with high levels of IGF1R expression in the tumour recurrence in two cases. The most statistically significant abnormality acquired between diagnosis and relapse was loss of 17p. One case that experienced 17p loss was classified as favourable histology at diagnosis, but exhibited diffuse anaplasia at recurrence and had a homozygous TP53 deletion. Another instructive case with a constitutional 11p13 deletion presented with bilateral tumours and suffered two subsequent recurrences in the left kidney. A somatic WT1 mutation was found only in the right kidney tumour, while the constitutional 11p13 deletion was the only abnormality detected in the initial left kidney tumour by aCGH. The two subsequent relapses in the left kidney contained an accumulation of additional genetic alterations, including an independent WT1 mutation.