Constitutive expression of the Wilms tumor suppressor gene (WT1) in renal cell carcinoma

Identification of novel mycocompounds as inhibitors of PI3K/AKT/mTOR pathway against RCC

PI3K/AKT/mTOR pathway is one of the frequently disrupted signaling pathways in renal cell carcinoma (RCC) that plays a significant role in tumor formation, disease progression and therapeutic resistance. Therefore, novel natural molecules targeting the critical proteins of this pathway will provide the best alternative to existing drugs, which are toxic and develops resistance. Recent studies have recognized the anti-cancer therapeutic potential of mycocompounds. The current study is focused on screening various mycocompounds from Astraeus hygrometricus against key cancer signaling proteins phosphoinositide 3-kinase (PI3K), protein kinase B, PKB (AKT1) and mammalian target of rapamycin (mTOR). We also studied in-silico cancer cells cytotoxicity and ADMET (absorption, distribution, metabolism, excretion and toxicity) profiles to elucidate the molecular mechanism against RCC and also to uncover the pharmacokinetic profile of these compounds. Astrakurkurone and Ergosta-4,6, 8-(14) 22-tetraene-3-one were the two most efficacious compounds with highest interaction scores and bonding. These compounds were both active against RCC4 and VMRC-RCZ cell lines of RCC. The ADME profiles of both were satisfactory based on druglikeness and bioavailability score criteria. Thus, this proposed study identified astrakurkurone and ergosta-4,6, 8-(14) 22-tetraene-3-one as potential anticancer drug candidates, and provides comparative structural insight into their binding to the 3 protein kinases.

Evaluating Established Roles, Future Perspectives and Methodological Heterogeneity for Wilms’ Tumor 1 (WT1) Antigen Detection in Adult Renal Cell Carcinoma, Using a Novel N-Terminus Targeted Antibody (Clone WT49)

Renal cell carcinoma (RCC) is arguably the deadliest form of genitourinary malignancy and is nowadays viewed as a heterogeneous series of cancers, with the same origin but fundamentally different metabolisms and clinical behaviors. Immunohistochemistry (IHC) is increasingly necessary for RCC subtyping and definitive diagnosis. WT1 is a complex gene involved in carcinogenesis. To address reporting heterogeneity and WT1 IHC standardization, we used a recent N-terminus targeted monoclonal antibody (clone WT49) to evaluate WT1 protein expression in 56 adult RCC (aRCC) cases. This is the largest WT1 IHC investigation focusing exclusively on aRCCs and the first report on clone WT49 staining in aRCCs. We found seven (12.5%) positive cases, all clear cell RCCs, showing exclusively nuclear staining for WT1. We did not disregard cytoplasmic staining in any of the negative cases. Extratumoral fibroblasts, connecting tubules and intratumoral endothelial cells showed the same exclusively nuclear WT1 staining pattern. We reviewed WT1 expression patterns in aRCCs and the possible explanatory underlying metabolomics. For now, WT1 protein expression in aRCCs is insufficiently investigated, with significant discrepancies in the little data reported. Emerging WT1-targeted RCC immunotherapy will require adequate case selection and sustained efforts to standardize the quantification of tumor-associated antigens for aRCC and its many subtypes.

Strategies for Manipulating T Cells in Cancer Immunotherapy

T cells are attractive targets for the development of immunotherapy to treat cancer due to their biological features, capacity of cytotoxicity, and antigen-specific binding of receptors. Novel strategies that can modulate T cell functions or receptor reactivity provide effective therapies, including checkpoint inhibitor, bispecific antibody, and adoptive transfer of T cells transduced with tumor antigen-specific receptors. T cell-based therapies have presented successful pre-clinical/clinical outcomes despite their common immune-related adverse effects. Ongoing studies will allow us to advance current T cell therapies and develop innovative personalized T cell therapies. This review summarizes immunotherapeutic approaches with a focus on T cells. Anti-cancer T cell therapies are also discussed regarding their biological perspectives, efficacy, toxicity, challenges, and opportunities.

Molecular Characterization of Clear Cell Renal Cell Carcinoma Reveals Prognostic Significance of Epithelial-mesenchymal Transition Gene Expression Signature

BACKGROUND

There is an ongoing need to develop prognostic biomarkers to improve the management of clear cell renal cell carcinoma (ccRCC).

OBJECTIVE

To leverage enriched pathways in ccRCC to improve risk-stratification.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively identified two complementary discovery cohorts of patients with ccRCC who underwent (1) radical nephrectomy (RNx) with inferior vena cava tumor thrombectomy (patients = 5, samples = 24) and (2) RNx for localized disease and developed recurrence versus no recurrence (n = 36). Patients with localized ccRCC (M0) in The Cancer Genome Atlas (TCGA, n = 386) were used for validation.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

A differential expression gene (DEG) analysis was performed on targeted RNA next-generation sequencing data from both discovery cohorts. Using TCGA for validation, Kaplan-Meier survival analysis and multivariable Cox proportional hazard testing were utilized to investigate the prognostic impact of DEGs, cell cycle proliferation (CCP), and a novel epithelial-mesenchymal transition (EMT) score on progression-free (PFS) and disease-specific (DSS) survival.

RESULTS AND LIMITATIONS

In the discovery cohorts, we observed overexpression of WT1 and CCP genes in the tumor thrombus versus the primary tumor, as well as in patients with recurrence versus those without recurrence. A hallmark pathway analysis demonstrated enrichment of the EMT- and CCP-related pathways in patients with high WT1 expression in the TCGA (validation) ccRCC cohort. CCP and EMT scores were derived in the validation cohort, which was stratified into four risk groups using Youden Index cut points: CCP^low/EMT^low, CCP^low/EMT^high, CCP^high/EMT^low, and CCP^high/EMT^high. The CCP^high/EMT^high risk group was associated with the worst PFS and DSS (both p < 0.001). In a multivariable analysis, CCP^high/EMT^high was independently associated with poor PFS and DSS (hazard ratio = 4.6 and 10.3, respectively; p < 0.001).

CONCLUSIONS

We demonstrate the synergistic prognostic impact of EMT in tumors with a high CCP score. Our novel EMT score has the potential to improve risk stratification and provide potential novel therapeutic targets.

PATIENT SUMMARY

Genes involved in epithelial-mesenchymal transition provides important prognostic information for patients with clear cell renal cell carcinoma.

ISPRF: a machine learning model to predict the immune subtype of kidney cancer samples by four genes

Background

Clear cell renal cell carcinoma (ccRCC) is the most common type of renal cell carcinoma (RCC). Immunotherapy, especially anti-PD-1, is becoming a pillar of ccRCC treatment. However, precise biomarkers and robust models are needed to select the proper patients for immunotherapy.

Methods

A total of 831 ccRCC transcriptomic profiles were obtained from 6 datasets. Unsupervised clustering was performed to identify the immune subtypes among ccRCC samples based on immune cell enrichment scores. Weighted correlation network analysis (WGCNA) was used to identify hub genes distinguishing subtypes and related to prognosis. A machine learning model was established by a random forest (RF) algorithm and used on an open and free online website to predict the immune subtype.

Results

In the identified immune subtypes, subtype2 was enriched in immune cell enrichment scores and immunotherapy biomarkers. WGCNA analysis identified four hub genes related to immune subtypes, CTLA4, FOXP3, IFNG, and CD19. The RF model was constructed by mRNA expression of these four hub genes, and the value of area under the receiver operating characteristic curve (AUC) was 0.78. Subtype2 patients in the independent validation cohort had a better drug response and prognosis for immunotherapy treatment. Moreover, an open and free website was developed by the RF model (https://immunotype.shinyapps.io/ISPRF/).

Conclusions

The current study constructs a model and provides a free online website that could identify suitable ccRCC patients for immunotherapy, and it is an important step forward to personalized treatment.

T-cell receptor-based therapy: an innovative therapeutic approach for solid tumors

T-cell receptor (TCR)-based adoptive therapy employs genetically modified lymphocytes that are directed against specific tumor markers. This therapeutic modality requires a structured and integrated process that involves patient screening (e.g., for HLA-A*02:01 and specific tumor targets), leukapheresis, generation of transduced TCR product, lymphodepletion, and infusion of the TCR-based adoptive therapy. In this review, we summarize the current technology and early clinical development of TCR-based therapy in patients with solid tumors. The challenges of TCR-based therapy include those associated with TCR product manufacturing, patient selection, and preparation with lymphodepletion. Overcoming these challenges, and those posed by the immunosuppressive microenvironment, as well as developing next-generation strategies is essential to improving the efficacy and safety of TCR-based therapies. Optimization of technology to generate TCR product, treatment administration, and patient monitoring for adverse events is needed. The implementation of novel TCR strategies will require expansion of the TCR approach to patients with HLA haplotypes beyond HLA-A*02:01 and the discovery of novel tumor markers that are expressed in more patients and tumor types. Ongoing clinical trials will determine the ultimate role of TCR-based therapy in patients with solid tumors.

Genetic profile and immunohistochemical study of clear cell renal carcinoma: Pathological-anatomical correlation and prognosis

INTRODUCTION

Renal cell carcinoma (RCC) accounts for 2-3% of all tumors being the most frequent solid lesion in the kidney.

OBJECTIVE

To determine what genetic alterations and immunohistochemical (IHC) of clear cell renal carcinoma (ccRCC) are associated with prognosis and tumor aggressiveness.

PATIENTS AND METHODS

Experimental analytical study with 57 patients who underwent radical and partial nephrectomy between 2005 and 2011, all with diagnosis of ccRCC and minimum post-operative follow-up of 36 months. The pathological study included IHC determination of biomarkers associated (CAIX, CAM 5.2, CD10, c-erbB-2, EGFR, HIF-1a, Ki67, MDM2, PAX-2 y 8, p53, survivin and VEGFR 1 and 2). Genetic analysis was carried out using multiplex ligation-dependent probe amplification (MLPA). Clinical data were collected and summarized using an access-type database, adding genetic analysis and IHC data of each patient's tumor sample. IHC statistical analysis included Chi-square, Kruskal-Wallis and multivariate analysis. The genetic analysis was performed using multivariate logistic regression (normal/deletion-duplication). Significance level p<0.05.

RESULTS

Pathologic stage was: pT1 (61.8%), pT2 (32.7%); pT3-T4 (5.4%); 16.3% were pN+ and 19.3% M1. 23.6% recurred being predominantly to distance in 83.3%. 27.3% of patients died (73.3% ccCCR). CAIX (Carbonic anhydrase IX) and tumor size were associated with worse Fuhrman grade (p = 0.035; p = 0.001 respectively). Deletion-duplication of genes increased the likelihood: of death (APC, Bcl-2 and CDKN2A by 11, 7 and 4 respectively and SMAD4 reduced the probability by 88%); tumor recurrence (CDKN2A by fifteen fold and VHL reduced the probability by 87%); pT greater than 2 (CCND2, MDM2 and WT1 multiplied by 6, 7 and 9); risk of N+ (CDK4 and EBF1 by 13); distant metastases (BRCA2 and DLEU1 by 5); Fuhrman grade ≥3 (BRCA1, BRCA2 and p53 by 40, 75 and 34 respectively, while that FHIT reduced by 96%). Deletion-duplication of CDK4 and DCC increased survival by a factor of 13 and 16, while that DLEU1 and RUNX1 decreased survival time by 80%.

CONCLUSION

CAIX and tumor size are associated with increased aggressiveness. The mutations to level 5q, 9p, 11p, 12, 13q, 17, 18q and 21q are associated with more aggressive tumors and with worse survival rate.

The Anticancer Efficiency of Citrullus colocynthis Toward the Colorectal Cancer Therapy

BACKGROUND

Colorectal cancer (CRC) remains a major cause of death worldwide. Chemotherapy is associated with some side effects during CRC treatment. Hence, proper employment of lower toxic and approaches exerting lowest side effects are essential. The Citrullus colocynthis (C. colocynthis) seems a potential anticancerous herbal medicine (HM) against CRC mostly via various efficient compounds.

METHODS

We performed a literature review regarding the anticancer traits of C. colocynthis against CRC. The possible active compounds, mechanisms, and combination therapies in vitro and in vivo or clinical trials have been also stated where found.

RESULTS AND CONCLUSION

The anticancerous effects of C. colocynthis has been via a variety of pathways including apoptotic pathways (increase in caspase-3 and inhibiting STAT3 function), antioxidant and anti-inflammatory (TNF-α, nitric oxide, and pro-inflammatory cytokines such as IL-6, IL-8, and IL-1α) traits, inhibition of Wnt/β-catenin signaling pathway, and antiangiogenesis and antimetastatic effects. Future studies will be promising regarding proper application of C. colocynthis compounds following their extraction.

Knockdown of sodium-calcium exchanger 1 induces epithelial-to-mesenchymal transition in kidney epithelial cells

Mesenchymal-to-epithelial transition (MET) and epithelial-to-mesenchymal transition (EMT) are important processes in kidney development. Failure to undergo MET during development leads to the initiation of Wilms tumor, whereas EMT contributes to the development of renal cell carcinomas (RCC). The role of calcium regulators in governing these processes is becoming evident. We demonstrated earlier that Na⁺/Ca²⁺ exchanger 1 (NCX1), a major calcium exporter in renal epithelial cells, regulates epithelial cell motility. Here, we show for the first time that NCX1 mRNA and protein expression was down-regulated in Wilms tumor and RCC. Knockdown of NCX1 in Madin-Darby canine kidney cells induced fibroblastic morphology, increased intercellular junctional distance, and induced paracellular permeability, loss of apico-basal polarity in 3D cultures, and anchorage-independent growth, accompanied by expression of mesenchymal markers. We also provide evidence that NCX1 interacts with and anchors E-cadherin to the cell surface independent of NCX1 ion transport activity. Consistent with destabilization of E-cadherin, NCX1 knockdown cells showed an increase in β-catenin nuclear localization, enhanced transcriptional activity, and up-regulation of downstream targets of the β-catenin signaling pathway. Taken together, knockdown of NCX1 in Madin-Darby canine kidney cells alters epithelial morphology and characteristics by destabilization of E-cadherin and induction of β-catenin signaling.

An integrative study on the impact of highly differentially methylated genes on expression and cancer etiology

DNA methylation is an important epigenetic phenomenon that plays a key role in the regulation of expression. Most of the studies on the topic of methylation's role in cancer mechanisms include analyses based on differential methylation, with the integration of expression information as supporting evidence. In the present study, we sought to identify methylation-driven patterns by also integrating protein-protein interaction information. We performed integrative analyses of DNA methylation, expression, SNP and copy number data on paired samples from six different cancer types. As a result, we found that genes that show a methylation change larger than 32.2% may influence cancer-related genes via fewer interaction steps and with much higher percentages compared with genes showing a methylation change less than 32.2%. Additionally, we investigated whether there were shared cancer mechanisms among different cancer types. Specifically, five cancer types shared a change in AGTR1 and IGF1 genes, which implies that there may be similar underlying disease mechanisms among these cancers. Additionally, when the focus was placed on distinctly altered genes within each cancer type, we identified various cancer-specific genes that are also supported in the literature and may play crucial roles as therapeutic targets. Overall, our novel graph-based approach for identifying methylation-driven patterns will improve our understanding of the effects of methylation on cancer progression and lead to improved knowledge of cancer etiology.

Diagnostic utility of Wilms' tumour-1 protein (WT-1) immunostaining in paediatric renal tumours

Background & objectives:

Renal tumours constitute about 7 per cent of all neoplasms in children. It is important to differentiate Wilms’ tumour (commonest tumour) from non-Wilms’ tumours. The aim of this study was to evaluate the immunoexpression and diagnostic role of Wilms’ tumour-1 protein (WT1) in paediatric renal tumours.

Methods:

A total of 53 cases of renal tumours in children (below 18 yr) who underwent total nephrectomy were included in this retrospective study. WT1 immunostaining was done using mouse monoclonal WT1 antibody (clone: 6F-H2).

Results:

Of the 53 cases, 38 (72%) were of Wilms’ tumour. Non-Wilms’ group (15) included six cases of mesoblastic nephroma (MN), two each of clear cell sarcoma (CCSK), renal cell carcinoma (RCC) and peripheral neuroectodermal tumour (PNET) and one each of angiomyolipoma (AML), rhabdomyosarcoma (RMS) and malignant rhabdoid tumour (MRT). Proportion of WT1 positivity in Wilms’ tumour was 100 per cent in contrast to 26.7 per cent in non-Wilms’ tumours (P<0.001). Epithelial and blastemal components of Wilms’ tumour showed moderate (2+) nuclear and cytoplasmic staining in 80 (24/30) and 75 per cent (24/32) cases, respectively. MN, PNET, CCSK and AML were negative for WT1. RMS, RCC and MRT showed cytoplasmic staining, strongest in RMS. No significant association was seen between WT1 expression and NWTSG (National Wilms’ Tumor Study Group) stage.

Interpretation & conclusions:

WT1 helps to differentiate Wilms’ tumour from other paediatric renal tumours. It may help in differentiating the two subgroups of Wilms’ tumour which have distinct molecular pathogenesis and biological behaviour, however, further prospective studies are required for validation of this hypothesis.

Orai1 Expression Is Closely Related with Favorable Prognostic Factors in Clear Cell Renal Cell Carcinoma

Store-operated calcium (Ca(2+)) entry (SOCE) is the principal Ca(2+) entry route in non-excitable cells, including cancer cells. We previously demonstrated that Orai1 and STIM1, the molecular components of SOCE, are involved in tumorigenesis of clear cell renal cell carcinoma (CCRCC). However, a clinical relevance of Orai1 and STIM1 expression in CCRCC has been ill-defined. Here, we investigated the expression of Orai1 and STIM1 in CCRCC, and compared their expression with clinico-pathological parameters of CCRCC and the patients' outcome. Immunohistochemical staining for Orai1 and STIM1 was performed on 126 formalin fixed paraffin embedded tissue of CCRCC and western blot analysis for Orai1 was performed on the available fresh tissue. The results were compared with generally well-established clinicopathologic prognostic factors in CCRCC and patient survival. Membrane protein Orai1 is expressed in the nuclei in CCRCC, whereas STIM1 shows the cytosolic expression pattern in immunohistochemical staining. Orai1 expression level is inversely correlated with CCRCC tumor grade, whereas STIM1 expression level is not associated with tumor grade. The higher Orai1 expression is significantly associated with lower Fuhrman nuclear grade, pathologic T stage, and TNM stage and with favorable prognosis. The expression level of STIM1 is not correlated with CCRCC grade and clinical outcomes. Orai1 expression in CCRCC is associated with tumor progression and with favorable prognostic factors. These results suggest that Orai1 is an attractive prognostic marker and therapeutic target for CCRCC.

Adoptive T-cell therapy for Leukemia

Allogeneic stem cell transplantation (alloSCT) is the most robust form of adoptive cellular therapy (ACT) and has been tremendously effective in the treatment of leukemia. It is one of the original forms of cancer immunotherapy and illustrates that lymphocytes can specifically recognize and eliminate aberrant, malignant cells. However, because of the high morbidity and mortality that is associated with alloSCT including graft-versus-host disease (GvHD), refining the anti-leukemia immunity of alloSCT to target distinct antigens that mediate the graft-versus-leukemia (GvL) effect could transform our approach to treating leukemia, and possibly other hematologic malignancies. Over the past few decades, many leukemia antigens have been discovered that can separate malignant cells from normal host cells and render them vulnerable targets. In concert, the field of T-cell engineering has matured to enable transfer of ectopic high-affinity antigen receptors into host or donor cells with greater efficiency and potency. Many preclinical studies have demonstrated that engineered and conventional T-cells can mediate lysis and eradication of leukemia via one or more leukemia antigen targets. This evidence now serves as a foundation for clinical trials that aim to cure leukemia using T-cells. The recent clinical success of anti-CD19 chimeric antigen receptor (CAR) cells for treating patients with acute lymphoblastic leukemia and chronic lymphocytic leukemia displays the potential of this new therapeutic modality. In this review, we discuss some of the most promising leukemia antigens and the novel strategies that have been implemented for adoptive cellular immunotherapy of lymphoid and myeloid leukemias. It is important to summarize the data for ACT of leukemia for physicians in-training and in practice and for investigators who work in this and related fields as there are recent discoveries already being translated to the patient setting and numerous accruing clinical trials. We primarily focus on ACT that has been used in the clinical setting or that is currently undergoing preclinical testing with a foreseeable clinical endpoint.

Prognostic significance of WT1 expression in soft tissue sarcoma

Background

Soft tissue sarcomas (STS) are rare. We evaluated the WT1 protein expression level in various types of STS and elucidated the value of WT1 as a prognostic factor and a possible therapeutic target.

Methods

Immunohistochemical staining for WT1 was performed in 87 cases of STS using formalin-fixed, paraffin-embedded blocks. The correlation between WT1 expression and clinicopathological factors was analyzed. Survival analysis was conducted in 67 patients. We assessed the validity of WT1 immunohistochemistry as an index of WT1 protein expression using Western blot analysis.

Results

WT1 expression was noted in 47 cases (54.0%). Most rhabdomyosarcomas and malignant peripheral nerve sheath tumors showed WT1 expression (91.7% and 71.4%, respectively; P = 0.005). WT1 expression was related to higher FNCLCC histologic grade and AJCC tumor stage. In the group with high grade STS, strong WT1 expression was correlated with better survival (P = 0.025). The immunohistochemical results were correlated quantitatively with the staining score and the concentration of the Western blot band.

Conclusions

This study demonstrates that various types of STS show positive immunostaining for WT1 and that WT1 expression has a prognostic significance. So STS should be considered candidates for WT1 peptide--based immunotherapy.

Wilms' tumor protein induces an epithelial-mesenchymal hybrid differentiation state in clear cell renal cell carcinoma

The Wilms' tumor transcription factor (WT1) was originally classified as a tumor suppressor, but it is now known to also be associated with cancer progression and poor prognosis in several malignancies. WT1 plays an essential role in orchestrating a developmental process known as mesenchymal-to-epithelial transition (MET) during kidney development, but also induces the reverse process, epithelial-to-mesenchymal transition (EMT) during heart development. WT1 is not expressed in the adult kidney, but shows elevated expression in clear cell renal cell carcinoma (ccRCC). However, the role of WT1 in this disease has not been characterized. In this study, we demonstrate that WT1 is upregulated in ccRCC cells that are deficient in the expression of the von Hippel-Lindau tumor suppressor protein (VHL). We found that WT1 transcriptionally activated Snail, a master transcriptional repressor that is known to induce EMT. Although Snail represses E-cadherin and induces mesenchymal characteristics, we found partial maintenance of E-cadherin and associated epithelial characteristics in kidney cells and ccRCC cells that express WT1, since WT1 upregulates E-cadherin expression and competes with Snail repression. These findings support a novel paradigm in which WT1 induces an epithelial-mesenchymal hybrid transition (EMHT), characterized by Snail up-regulation with E-cadherin maintenance, a tumor cell differentiation state in which cancer cells keep both EMT and MET characteristics which may promote tumor cell plasticity and tumor progression.

Active specific immunotherapy targeting the Wilms' tumor protein 1 (WT1) for patients with hematological malignancies and solid tumors: lessons from early clinical trials

There is a growing body of evidence that Wilms' tumor protein 1 (WT1) is a promising tumor antigen for the development of a novel class of universal cancer vaccines. Recently, in a National Cancer Institute prioritization project, WT1 was ranked first in a list of 75 cancer antigens. In this light, we exhaustively reviewed all published cancer vaccine trials reporting on WT1-targeted active specific immunotherapy in patients with hematological malignancies and solid tumors. In all clinical trials, vaccine-induced immunological responses could be detected. Importantly, objective clinical responses (including stable disease) were observed in 46% and 64% of evaluable vaccinated patients with solid tumors and hematological malignancies, respectively. Immunogenicity of WT1-based cancer vaccines was demonstrated by the detection of a specific immunological response in 35% and 68% of evaluable patients with solid tumors and hematological malignancies, respectively. In order to become part of the armamentarium of the modern oncologist, it will be important to design WT1-based immunotherapies applicable to a large patient population, to standardize vaccination protocols enabling systematic review, and to further optimize the immunostimulatory capacity of the vaccine components. Moreover, improved immunomonitoring tools that reveal clinically relevant T-cell responses will further shape the ideal WT1 immunotherapy strategy. In conclusion, the clinical results obtained so far in WT1-targeted cancer vaccine trials reveal an untapped potential for inducing cancer immunity with minimal side effects and hold promise for a new adjuvant treatment against residual disease and against cancer relapse.

Changes in the expression and subcellular distribution of galectin-3 in clear cell renal cell carcinoma

Background

Clear cell renal cell carcinoma, a solid growing tumor, is the most common tumor in human kidney. Evaluating the usefulness of β-galactoside binding galectin-3 as a diagnostic marker for this type of cancer could open avenues for preventive and therapeutic strategies by employing specific inhibitors of the lectin. To study a putative correlation between the extent of galectin-3 and the development of clear cell renal cell carcinoma, we monitored the quantity and distribution of this lectin in tissue samples from 39 patients.

Methods

Galectin-3 concentrations in normal, intermediate and tumor tissues were examined by immunofluorescence microscopy and on immunoblots with antibodies directed against galectin-3 and renal control proteins. The cell nuclei were isolated to determine quantities of galectin-3 that were transferred into this compartment in normal or tumor samples.

Results

Immunofluorescence data revealed a mosaic pattern of galectin-3 expression in collecting ducts and distal tubules of normal kidney. Galectin-3 expression was significantly increased in 79% of tumor samples as compared to normal tissues. Furthermore, we observed an increase in nuclear translocation of the lectin in tumor tissues.

Conclusions

Our data indicate that changes in the cellular level of galectin-3 correlate with the development of clear cell renal cell carcinoma, which is in line with previously published data on this specific type of tumor. In most of these studies the lectin tends to be highly expressed in tumor tissues. Furthermore, this study suggests that the increase in the proportion of galectin-3 affects the balance from a cytosolic distribution towards translocation into the nucleus.

Wilms' tumour 1 can suppress hTERT gene expression and telomerase activity in clear cell renal cell carcinoma via multiple pathways

Background:

Wilms' tumour 1 (WT1) gene was discovered as a tumour suppressor gene. Later findings have suggested that WT1 also can be oncogenic. This complexity is partly explained by the fact that WT1 has a number of target genes.

Method:

WT1 and its target gene human telomerase reverse transcriptase (hTERT) were analysed in clear cell renal cell carcinoma (ccRCC). In vitro experiments were performed to examine the functional link between WT1 and hTERT by overexpression of WT1 isoforms in the ccRCC cell line, TK-10.

Results:

WT1 demonstrated lower RNA expression in ccRCC compared with renal cortical tissue, whereas hTERT was increased, showing a negative correlation between WT1 and hTERT (P=0.005). These findings were experimentally confirmed in vitro. The WT1 generated effect on hTERT promoter activity seemed complex, as several negative regulators of hTERT transcription, such as SMAD3, JUN (AP-1) and ETS1, were activated by WT1 overexpression. Downregulation of potential positive hTERT regulators, such as cMyc, AP-2α, AP-2γ, IRF1, NFX1 and GM-CSF, were also observed. Chromatin immunoprecipitation analysis verified WT1 binding to the hTERT, cMyc and SMAD3 promoters.

Conclusion:

The collected data strongly indicate multiple pathways for hTERT regulation by WT1 in ccRCC.

Update on vaccine development for renal cell cancer

Renal cell carcinoma (RCC) remains a significant health concern that frequently presents as metastatic disease at the time of initial diagnosis. Current first-line therapeutics for the advanced-stage RCC include antiangiogenic drugs that have yielded high rates of objective clinical response; however, these tend to be transient in nature, with many patients becoming refractory to chronic treatment with these agents. Adjuvant immunotherapies remain viable candidates to sustain disease-free and overall patient survival. In particular, vaccines designed to optimize the activation, maintenance, and recruitment of specific immunity within or into the tumor site continue to evolve. Based on the integration of increasingly refined immunomonitoring systems in both translational models and clinical trials, allowing for the improved understanding of treatment mechanism(s) of action, further refined (combinational) vaccine protocols are currently being developed and evaluated. This review provides a brief history of RCC vaccine development, discusses the successes and limitations in such approaches, and provides a rationale for developing combinational vaccine approaches that may provide improved clinical benefits to patients with RCC.

Adoptive transfer of unselected or leukemia-reactive T-cells in the treatment of relapse following allogeneic hematopoietic cell transplantation

Adoptive transfer of in vivo generated antigen-specific donor-derived T-cells is increasingly recognized as an effective approach for the treatment or prevention of EBV lymphomas and cytomegalovirus infections complicating allogeneic hematopoietic cell transplants. This review examines evidence from preclinical experiments and initial clinical trials to critically assess both the potential and current limitations of adoptive transfer of donor T-cells sensitized to selected minor alloantigens of the host or to peptide epitopes of proteins, differentially expressed by clonogenic leukemia cells, such as the Wilms tumor protein, WT-1, as a strategy to treat or prevent recurrence of leukemia in the post-transplant period.

Prognostic value of WT1 protein expression level and MIB-1 staining index as predictor of response to WT1 immunotherapy in glioblastoma patients

The use of Wilms' tumor 1 (WT1) immunotherapy is considered to be an innovative approach for the treatment of malignant gliomas. Because of its novelty, tools that can accurately predict response to this therapy are still lacking. In this article, we investigated the role of WT1 protein expression level (score 1-4) and MIB-1 staining index in predicting survival outcome after therapy in patients with recurrent or progressive glioblastoma multiforme. Tumor samples from 37 patients enrolled in a phase II clinical trial on WT1 immunotherapy were immunohistochemically analyzed for WT1 levels and MIB-1 index. Results showed that median progression-free survival (PFS) was longer in the WT1 high expression group (score 3 and 4) compared with that of the low expression group (score 1 and 2) (20.0 weeks vs. 8.0 weeks; P = 0.022), and that the median overall survival (OS) was likewise longer in the former compared to the latter group (54.4 weeks vs. 28.4 weeks; P = 0.035). Furthermore, within the WT1 high expression group, tumors with intermediate staining intensity (WT1 score 3) have both the longest median PFS and OS, 24.4 weeks and 69.4 weeks, respectively. On the other hand, no significant correlation was noted between MIB-1 staining index and survival. In conclusion, our study has shown that WT1 protein expression level, not MIB-1 staining index, can be used as a prognostic marker to foretell outcome after immunotherapy, and that patients whose tumors have intermediate WT1 expression have the best survival outcome.

WT1 mRNA level in peripheral blood is a sensitive biomarker for monitoring minimal residual disease in acute myeloid leukemia

The Wilms' tumor gene 1 (WT1) encodes a transcription factor that is involved in normal cellular development and cell survival. WT1 mRNA is overexpressed in the minimal residual disease (MRD) of patients with hematopoietic malignancy patients, particularly acute myeloid leukemia (AML). MRD represents the condition with the low levels of leukemia cells in the bone marrow and is known as a sign of recurrence. In hematopoietic malignancies, definition of remission is based on the lack of MRD at submicroscopic level. Between December 2005 and June 2008, we started to measure WT1 mRNA levels in the peripheral blood (PB) from patients by quantitative real-time PCR in Aomori Prefectural Central Hospital. Three hundreds and eight samples from 95 patients were evaluated. The patients included AML (55 patients), acute lymphoblastic leukemia (11), myelodysplastic syndrome (20), malignant lymphoma (5), chronic myeloid leukemia (1), prostatic carcinoma (1), and leukopenia (2). Among the 55 AML patients, 21 patients were pretreated with remission induction therapy. In the clinical course of 21 patients, timely therapeutic approaches could be started for relapse by the early detection of WT1 mRNA overexpression before the morphological findings were apparent. Monitoring WT1 mRNA is helpful to identify patients at high-risk relapse. High overall survival rate (71.2%, 15/21, median: 24.6 months, range 1.1-35.6 months) was achieved in 3 years. The overall survival rate of 34 post-treatment patients was 61.7% (median: 23.5 months, range 0.13-126.5 months after treatment start). In conclusion, the WT1 mRNA level is a sensitive biomarker for monitoring MRD.

Promyelocytic leukemia zinc finger protein regulates interferon-mediated innate immunity

Interferons (IFNs) direct innate and acquired immune responses and, accordingly, are used therapeutically to treat a number of diseases, yet the diverse effects they elicit are not fully understood. Here, we identified the promyelocytic leukemia zinc finger (PLZF) protein as a previously unrecognized component of the IFN response. IFN stimulated an association of PLZF with promyelocytic leukemia protein (PML) and histone deacetylase 1 (HDAC1) to induce a decisive subset of IFN-stimulated genes (ISGs). Consequently, PLZF-deficient mice had a specific ISG expression defect and as a result were more susceptible to viral infection. This susceptibility correlated with a marked decrease in the expression of the key antiviral mediators and an impaired IFN-mediated induction of natural killer cell function. These results provide new insights into the regulatory mechanisms of IFN signaling and the induction of innate antiviral immunity.

A tumor suppressor and oncogene: the WT1 story

The Wilms' tumor 1 (WT1) gene encodes a transcription factor important for normal cellular development and cell survival. The initial discovery of WT1 as the causative gene in an autosomal-recessive condition identified it as a tumor suppressor gene whose mutations are associated with urogenital disease and the development of kidney tumors. However, this view is not in keeping with the frequent finding of wild-type, full-length WT1 in human leukemia, breast cancer and several other cancers including the majority of Wilms' tumors. Rather, these observations suggest that in those conditions, WT1 has an oncogenic role in tumor formation. In this review, we explore the literature supporting both views of WT1 in human cancer and in particular human leukemias. To understand the mechanism by which WT1 can do this, we will also examine its functional activity as a transcription factor and the influence of protein partners on its dual behavior.

Functional annotation of IFN-alpha-stimulated gene expression profiles from sensitive and resistant renal cell carcinoma cell lines

The antiproliferative, antiviral, and immunomodulatory properties of interferons (IFNs) have led to its therapeutic implementation. IFNs effects are mediated by a complex network of signal transducers, culminating in IFN-stimulated gene (ISG) induction. This complexity leads to diverse clinical responses to IFN, from no response to complete regression of disease. Elucidation of ISG induction patterns is, therefore, essential to understand and maximize its therapeutic potential. To correlate ISG expression profiles with IFN responsiveness, two renal cell carcinoma (RCC) cell lines differing in antiviral and apoptotic response to IFN were treated with IFN-alpha for different times, and expression profiles were analyzed using a customized microarray containing 850 unique putative ISGs. Genes with similar kinetics of induction in both cell lines were clustered and analyzed for gene function. Seven sets of coordinately regulated genes were identified by k-means cluster analysis, and significant functional similarities were identified for five of the seven sets. Strikingly, expression of genes associated with transcription temporally preceded expression of those involved in signal transduction. Enhanced antiviral sensitivity to IFN was coincident with sustained expression of ISGs involved in transcriptional regulation. However, no difference in Stat1 activation was observed between the cell lines. Analysis of ISG expression patterns suggests that subtle differences in transcription profiles contribute to differences in IFN responsiveness.

My approach to the diagnosis of mesothelial lesions

Mesothelial lesions pose considerable diagnostic challenges not only because benign tumours, reactive proliferations and malignant mesothelioma can mimic one another, but also because the morphological patterns displayed by malignant mesothelioma can simulate a variety of epithelial and non-epithelial malignancies. Immunohistochemical markers can aid in distinguishing epithelioid malignant mesothelioma from metastatic adenocarcinoma, but because no single marker reliably separates all cases, a panel of stains is recommended. Immunohistochemical studies are of more limited value in sarcomatoid malignant mesothelioma, and other features often play an essential role. The separation of reactive mesothelial proliferations from malignant mesothelioma on small biopsy can be quite difficult, as distinguishing features, such as stromal invasion, often cannot be adequately assessed. In adequately sampled lesions, however, the distinction between malignant mesothelioma, benign mesothelial proliferations and other tumours can be achieved in most cases by using a carefully integrated approach that incorporates clinical and radiographic data, immunohistochemical studies and, in selected cases, histochemical and ultrastructural techniques.

Monitoring of WT1-specific cytotoxic T lymphocytes after allogeneic hematopoietic stem cell transplantation

Donor-derived cytotoxic T lymphocytes (CTL) that respond to tumor antigens emerge after hematopoietic stem cell transplantation (HSCT), particularly in association with the status of immune recovery. To analyze the frequency of CTL against PR1, PRAME and WT1 after HSCT, a tetramer-based analysis was performed in 97 samples taken from 35 patients (9 AML, 11 MDS, 2 CML, 4 ALL, 7 lymphoma and 2 renal cell carcinoma [RCC]) with the HLA-A02 phenotype. Regarding PR1, only 1 sample showed the presence of tetramer-positive cells (0.04%/lymphocyte). Similarly, in PRAME, only 10 of 97 samples were sporadically positive with low titers. For WT1, positive results were detected in 39 of 97 samples and 7 (2 CML, 1 ALL, 2 lymphoma and 2 RCC) patients clearly showed positive results more than once. On the basis of these results, we performed serial analyses of WT1-specific CTL during the clinical course in 2 patients with RCC, who underwent HSCT with a reduced-intensity regimen, to examine the precise correlation between the kinetics of CTL, the occurrence of GVHD and the observed clinical response. A higher positive rate for WT1-specific CTL and a correlation with the clinical response suggest that WT1 may be a useful antigen for a wider monitoring application.

Prognostic significance of Wilms tumor gene (WT1) mRNA expression in soft tissue sarcoma

BACKGROUND

There have been several recent reports that Wilms tumor gene (WT1) mRNA is overexpressed in many types of neoplasms, and those results suggested that WT1 has oncogenic properties. The objective of the current study was to evaluate the prognostic significance of WT1 mRNA expression in patients with soft tissue sarcoma.

METHODS

Levels of WT1 mRNA expression were examined by quantitative, real-time reverse transcriptase-polymerase chain reaction analysis in frozen tissue samples from 52 patients with soft tissue sarcoma. Various clinicopathologic factors were analyzed along with the disease-specific survival rate for correlations with WT1 mRNA expression levels.

RESULTS

The levels of WT1 mRNA expression in a variety of soft tissue sarcomas were significantly greater compared with the levels in normal soft tissue samples (P = .0212). No significant correlation was observed between the level of WT1 mRNA expression and clinicopathologic factors, including gender, age, primary tumor site, tumor depth, tumor size, histologic grade, and distant metastasis at initial presentation. The disease-specific survival rate for patients with high WT1 mRNA expression levels was found significantly poorer compared with the rate for patients with low WT1 mRNA expression levels (P = .0182). Moreover, multivariate analysis indicated that a high WT1 mRNA expression level was an independent, adverse prognostic factor for disease-specific survival (hazards ratio, 2.6; P = .0488).

CONCLUSIONS

WT1 mRNA expression level can serve as a potent prognostic indicator in soft tissue sarcoma patients.

The expression of NOV and WT1 in renal cell carcinoma: a quantitative reverse transcriptase-polymerase chain reaction analysis

PURPOSE

The NOV gene was first identified as an aberrantly expressed gene in avian nephroblastomas induced by myeloblastosis-associated virus. Its expression has been shown to be altered in avian and human nephroblastomas, and to be a target of WT1 regulation. We analyzed the mRNA level of human NOV together with the mRNA level of WT1 in sporadic renal cell carcinoma (RCC).

MATERIALS AND METHODS

We quantified NOV and WT1 mRNA levels in surgical specimens from 57 patients with RCC using quantitative real-time polymerase chain reaction analysis.

RESULTS

NOV mRNA levels decreased significantly in RCC compared with normal kidney tissue (p <0.001). The NOV mRNA level was higher in papillary than in clear cell RCCs (p = 0.040) and higher in G1 than G2 and 3 tumors (p = 0.01). WT1 was down-regulated in RCCs. No significant relationship was found for NOV and WT1 mRNA levels in our study.

CONCLUSIONS

To our knowledge this is the first study to investigate the expression level of the NOV gene in a panel of human RCC tissues together with paired normal renal tissue. Our data indicate that NOV is associated with carcinogenesis and the progression of RCC, and the NOV expression level is different in papillary-type and clear cell-type RCC. There is a possibility that the regulation of NOV expression is different from the pathway regulated by WT1.

Differential Expression of WT1 Gene Product in Non-Hodgkin Lymphomas

The tumor suppressor gene wt1 (Wilms tumor 1) encodes a zinc finger transcription factor reported to be expressed in many tumors, including mesotheliomas, carcinomas, and acute leukemias. However, WT1 expression in non-Hodgkin lymphomas (NHLs) has not been studied. The authors assessed for WT1 expression in six lymphoma/leukemia cell lines using Western blot methods after subcellular fractionation. We also assessed for WT1 expression in 167 NHLs using immunohistochemical methods. The B-cell NHLs analyzed were 18 diffuse large B-cell lymphomas, 13 marginal zone B-cell lymphomas, 9 small lymphocytic lymphomas, (DLBCLs), 8 follicular lymphomas, 6 mantle cell lymphomas, 5 Burkitt lymphomas, 3 lymphoplasmacytic lymphomas, and 2 B-cell lymphoblastic lymphomas. The T-cell NHLs analyzed were 43 anaplastic large cell lymphomas (ALCLs), 26 peripheral T-cell lymphomas unspecified, 13 angioimmunoblastic T-cell lymphomas, 6 cutaneous ALCLs, 6 cases of mycosis fungoides, 5 extranodal NK/T-cell lymphomas of nasal type, and 4 T-cell lymphoblastic lymphomas. WT1 levels were higher in cytoplasmic extracts than in nuclear extracts of the Karpas 299 and SU-DHL-1 lymphoma cell lines but were higher in nuclear extracts than in the cytoplasmic extracts of the Jurkat, HH, U-937, and K562 leukemia cell lines. In NHLs, WT1 was positive in 4 of 5 (80%) Burkitt lymphomas, 9 of 12 (75%) ALK-positive ALCLs, 3 of 6 (50%) lymphoblastic lymphomas (2 of 4 T-cell, 1 of 2 B-cell), 14 of 31 (45%) ALK-negative ALCLs, 6 of 18 (33%) DLBCLs, and 1 of 6 (17%) cutaneous ALCLs. WT1 was negative in all other NHLs tested. WT1 immunoreactivity was primarily cytoplasmic in all positive NHLs except T-cell lymphoblastic lymphoma. In conclusion, WT1 protein is frequently detected in the cytoplasm of a subset of high-grade NHLs.

The Wilms' tumor gene WT1 is a common marker of progenitor cells in fetal liver

It is well known that the Wilms' tumor gene WT1 plays an important role in cell proliferation and differentiation, and in organ development. In this study, to examine the role of the WT1 gene in lineage determination, fetal liver cells from LacZ-transgenic mice, in which WT1 expression was marked by the expression of the LacZ gene driven by WT1 promoter, were FACS-sorted according to LacZ expression of high (LacZ(++)) or undetectable (LacZ(-)) levels, which paralleled endogenous WT1 expression levels. LacZ(++) fetal liver cells were enriched by hepatocyte and endothelial progenitor cells. These results indicated that WT1 expression is a common marker of both hepatocyte and endothelial progenitors. These results also implied a role of the WT1 gene in lineage determination.

Expression of the Wilms' tumor gene product WT1 in glioblastomas and medulloblastomas

The Wilms' tumor gene WT1 was first identified as the gene responsible for a childhood renal tumor, Wilms' tumor. This gene encodes for a zinc finger-containing transcription factor. Although originally identified as a tumor suppressor gene, WT1 is overexpressed in a variety of hematologic malignancies and solid tumors. Recently, WT1 protein has been considered as a new molecular target of cancer immunotherapy for several solid tumors. In the present study, we investigated the expression of WT1 protein and WT1 mRNA in glioblastomas and medulloblastomas. Forty-eight of 51 glioblastoma samples (94%) showed immunohistochemically positive staining of WT1 protein, whereas all 10 medulloblastomas examined were negative. According to the immunohistochemical expression of WT1 protein, WT1 mRNA was also highly expressed in the same glioblastoma tissue. Our results suggest that the WT1 gene may play an important role in the tumorigenesis of glioblastoma, in contrast to medulloblastoma, and be integral in the development of the immunotherapy targeting WT1 protein in patients with glioblastoma.

Morphologic and Molecular Characterization of Renal Cell Carcinoma in Children and Young Adults

A new WHO classification of renal cell carcinoma has been introduced in 2004. This classification includes the recently described renal cell carcinomas with the ASPL-TFE3 gene fusion and carcinomas with a PRCC-TFE3 gene fusion. Collectively, these tumors have been termed Xp11.2 or TFE3 translocation carcinomas, which primarily occur in children and young adults. To further study the characteristics of renal cell carcinoma in young patients and to determine their genetic background, 41 renal cell carcinomas of patients younger than 22 years were morphologically and genetically characterized. Loss of heterozygosity analysis of the von Hippel-Lindau gene region and screening for VHL gene mutations by direct sequencing were performed in 20 tumors. TFE3 protein overexpression, which correlates with the presence of a TFE3 gene fusion, was assessed by immunohistochemistry. Applying the new WHO classification for renal cell carcinoma, there were 6 clear cell (15%), 9 papillary (22%), 2 chromophobe, and 2 collecting duct carcinomas. Eight carcinomas showed translocation carcinoma morphology (20%). One carcinoma occurred 4 years after a neuroblastoma. Thirteen tumors could not be assigned to types specified by the new WHO classification: 10 were grouped as unclassified (24%), including a unique renal cell carcinoma with prominently vacuolated cytoplasm and WT1 expression. Three carcinomas occurred in combination with nephroblastoma. Molecular analysis revealed deletions at 3p25-26 in one translocation carcinoma, one chromophobe renal cell carcinoma, and one papillary renal cell carcinoma. There were no VHL mutations. Nuclear TFE3 overexpression was detected in 6 renal cell carcinomas, all of which showed areas with voluminous cytoplasm and foci of papillary architecture, consistent with a translocation carcinoma phenotype. The large proportion of TFE3 "translocation" carcinomas and "unclassified" carcinomas in the first two decades of life demonstrates that renal cell carcinomas in young patients contain genetically and phenotypically distinct tumors with further potential for novel renal cell carcinoma subtypes. The far lower frequency of clear cell carcinomas and VHL alterations compared with adults suggests that renal cell carcinomas in young patients have a unique genetic background.

7-12 Dimethylbenz[a]anthracene-induced bone marrow hypocellularity is dependent on signaling through both the TNFR and PKR

In addition to being carcinogenic, polycyclic aromatic hydrocarbons (PAHs) are known to cause deleterious effects on the immune system, including a marked reduction in bone marrow granulocytes and B lymphocytes. The molecular mechanisms underlying bone marrow hypocellularity are incompletely understood. Hematopoiesis is governed by the production of cytokines and the resultant signaling pathways that they initiate. Our hypothesis was that PAHs may disrupt cytokine production in the bone marrow resulting in the perturbation in bone marrow cellularity observed after PAH administration. TNF-alpha and IFN-gamma are two cytokines that are involved in the regulation of hematopoiesis. Based on observations made in previous research, we sought to determine if the effects of 7-12 dimethylbenz[a]anthracene (DMBA) on the murine bone marrow were mediated through the actions of these molecules. Transgenic mice that were null for either IFN-gamma or TNF-alpha receptors were injected with DMBA and the resulting bone marrow cellularity compared with wild-type mice. We observed that tumor necrosis factor alpha receptor (TNFR) null mice were protected against DMBA-induced bone marrow hypocellularity, while IFN-gamma null mice were not. In addition, we found that dsRNA-dependent protein kinase (PKR) null mice were also protected from DMBA-induced hypocellularity. PKR is an intracellular signaling molecule that has been demonstrated to be activated by TNFR-mediated signaling. Furthermore, we observed upregulation of PKR in the bone marrow after DMBA administration that was dependent on signaling through TNFR. These results point to a role for TNFR-dependent signaling, operating at least in part via PKR activation, as a mechanism for DMBA-induced bone marrow toxicity.

The lck promoter-driven expression of the Wilms tumor gene WT1 blocks intrathymic differentiation of T-lineage cells

In the thymi of WT1-transgenic (Tg) mice with the 17AA+/KTS- spliced form of the Wilms tumor gene WT1 driven by the lck promoter, the frequencies of CD4-CD8- double-negative (DN) thymocytes were significantly increased relative to those in normal littermates. Of the 4 subsets of CD4-CD8- DN thymocytes, the DN1 (CD44+CD25-) subset increased in both frequency and absolute cell number, whereas the DN2 (CD44+CD25+) and DN3 (CD44-CD25+) subsets decreased, indicating the blocking of thymocyte differentiation from the DN1 to the DN2 subsets. Furthermore, CD4-CD8+ T-cell receptor (TCR) -gammadelta T-cells increased in both frequency and absolute cell number in the spleen and peripheral blood of the WT1-Tg mice relative to those of normal littermates. The CD8 molecules of these CD4-CD8+ TCRgammadelta T-cells were CD8alphabeta, suggesting that they originated from the thymus. These results are the first direct evidence demonstrating that the WT1 gene is involved in the development and differentiation of T-lineage cells.

Wilms tumor gene (WT1) expression as a panleukemic marker

The Wilms tumor gene (WT1) is expressed in blasts of patients with acute leukemia, irrespective of lineage, and WT1 nuclear protein is detectable in the majority of such blasts. Only very few physiologic hematopoietic progenitors express WT1, but the WT1 expression level of these progenitors and that of leukemic blasts are comparable. Although not specific for acute hematologic malignant diseases, continuous WT1 expression in almost all leukemic blasts strikingly contrasts to its rather transient expression in very few physiologic hematopoietic progenitors. Quantitative and semiquantitative WT1 reverse transcriptase polymerase chain reaction (RT-PCR) protocols have limitations in discriminating physiologic from pathologic overall WT1 expression levels in mononuclear cell preparations. Because of these limitations, reports conflict on the usefulness of long-term monitoring of WT1 expression in patients with acute leukemia. Real-time quantitative WT1 RT-PCR protocols, however, have been developed and tested in small series of patients with acute leukemia. Such protocols hold promise to enable evaluation of the individual treatment response (short-term monitoring) and early diagnosis of imminent relapse through the detection and long-term monitoring of minimal residual disease in patients with acute leukemia. These protocols also should facilitate the notoriously difficult distinction between eosinophilic leukemia and hypereosinophilic syndromes. Data on WT1 expression in leukemic blasts and their physiologic counterparts are discussed in light of clinical relevance.

Cancer immunotherapy targeting WT1 protein

The Wilms tumor gene WT1 is expressed in leukemias and various kinds of solid tumors, including lung and breast cancer, and exerts an oncogenic function in these malignancies, suggesting that WT1 protein is a novel, overexpressed tumor antigen. The WT1 protein, in fact, is an attractive tumor rejection antigen in animal models. Stimulation in vitro of peripheral blood mononuclear cells with HLA-A*2402--and HLA-A*0201--restricted 9-mer WT1 peptides elicits WT1-specific cytotoxic T-lymphocytes (CTLs), and the CTLs kill endogenously WT1-expressing leukemia or solid tumor cells. Furthermore, WT1 immunoglobulin M (IgM) and IgG antibodies are detected in patients with hematopoietic malignancies such as acute myeloid leukemia, chronic myeloid leukemia, and myelodysplastic syndromes, indicating that WT1 protein overexpressed by leukemia cells is indeed immunogenic. Taken together, these results demonstrate that WT1 protein is a promising tumor antigen for cancer immunotherapy against leukemias and various kinds of solid tumors, including lung and breast cancer.

The role of WT1 in oncogenesis: tumor suppressor or oncogene?

Although originally identified as a tumor suppressor gene, WT1 is overexpressed in a variety of hematologic malignancies and solid tumors, including acute leukemia, breast cancer, malignant mesothelioma, renal cell carcinoma, and others. Overexpression of both wild-type and mutant WT1 has been reported. In some cases, this finding represents overexpression of a gene that should be expressed at lower levels, but in other cases, WT1 is expressed at high levels in a tissue type in which there is normally no expression at all. In this review, the mechanisms of altered WT1 expression are explored, including changes in promoter methylation. WT1 target genes that may be important for oncogenesis are discussed, as is the use of WT1 expression as a diagnostic tool. The prognostic implications of altered WT1 expression and the potential for immunotherapy aimed at WT1 are also discussed.

Humoral immune responses against Wilms tumor gene WT1 product in patients with hematopoietic malignancies

Wilms tumor gene WT1 is expressed at high levels in hematopoietic malignancies, such as leukemias and myelodysplastic syndromes (MDS), and in various kinds of solid tumors, including lung cancer, and it exerts an oncogenic function in these malignancies. IgM and IgG WT1 antibodies were measured by means of dot blot assay in 73 patients with hematopoietic malignancies (16 acute myeloid leukemia [AML], 11 acute lymphoid leukemia [ALL], 13 chronic myeloid leukemia [CML], and 33 MDS) and 43 healthy volunteers. Immunoglobulin IgM, IgG, and IgM+IgG WT1 antibodies were detected in 40 (54.8%), 40 (54.8%), and 24 (32.8%), respectively, of the 73 patients with hematopoietic malignancies, whereas 7 (16.2%), 2 (4.7%), and none of the 43 healthy volunteers had IgM, IgG, or IgM+IgG WT1 antibodies, respectively. Furthermore, immunoglobulin isotype class switching of WT1 antibodies from IgM to IgG occurred in conjunction with disease progression from refractory anemia (RA) to RA with excess of blasts (RAEB), and further to RAEB in transformation (RAEB-t) in MDS patients. These results showed that humoral immune responses against the WT1 protein could be elicited in patients with WT1-expressing hematopoietic malignancies, and they suggested that the helper T-cell responses needed to induce humoral immune responses and immunoglobulin isotype class switching from IgM to IgG were also generated in these patients. Our findings may provide new insight into the rationale for elicitation of cytotoxic T-cell responses against the WT1 protein in cancer immunotherapy using the WT1 vaccine.

Utility of WT1 as a reliable tool for the detection of minimal residual disease in children with leukemia

WT1 encodes a transcription factor involved in the pathogenesis of Wilms' tumor. A high level of expression has been reported in blasts from patients with various hematological malignancies. The study was performed to evaluate the utility of monitoring WT1 expression in children with leukemia at diagnosis, during therapy, and following bone marrow transplant. We tested a total of 204 samples prospectively. These included samples from patients with the following diagnoses: acute lymphoblastic leukemia (ALL) at diagnosis (n = 45), at relapse (n = 14), and in remission (n = 45); acute non-lymphoblastic leukemia (ANLL) at diagnosis (n = 14), at relapse (n = 5), and in remission (n = 12); and chronic myelogenous leukemia (CML) in blast crisis (n = 1) and in chronic phase (n = 1). A total of 33 of these patients were transplanted: 19 ALL, 12 ANLL, and 2 CML. In addition, samples from 5 patients with aplastic anemia and 28 controls were obtained from peripheral blood (n = 17), cord blood (n = 3), and bone marrow (n = 8). Primer pairs were designed to locate specific nucleotide sequences for mRNA of WT1. RT-PCR was performed in all samples and compared with K562 cells from ATCC (defined as 1.0) as positive control. A positive test was arbitrarily defined as WT1/K562 > 0.5. Samples at diagnosis and relapse, including 56 out of 59 ALL (95%), 26 ANLL (100%), and 1 CML in blast crisis, demonstrated high levels of WT1 expression. In contrast, only 5 of 90 samples obtained in remission or post-transplant showed high levels of WT1 expression ( P < 0.0001; 95% CI = 0.66-0.94). The five patients with high WT1 expression during follow-up relapsed within 2 to 6 months. In conclusion, we have found that WT1 is consistently elevated in children with leukemia. Significant differences in the level of WT1 expression were noted between these patients during diagnosis and at relapse, and those during remission. More importantly, following bone marrow transplant, a significant high level of WT1 expression preceded clinical relapse by 2 to 6 months. Therefore, WT1 is a reliable marker for monitoring minimal residual disease during therapy as well as in the post-transplant period.

Wilms' tumor gene WT1: its oncogenic function and clinical application

The Wilms' tumor gene WT1 is a gene responsible for the childhood renal tumor. Wilms' tumor, and is defined as a tumor suppressor gene. However, the wild-type WT1 gene is highly expressed in leukemic blast cells of myeloid and lymphoid origin, and thus, WT1 messenger RNA provides a novel tumor marker for detection of minimal residual disease of leukemias and for monitoring disease progression of myelodysplastic syndromes. The WT1 gene exerts an oncogenic function rather than a tumor-suppressor gene function in solid tumors as well as leukemias, and the WT1 gene product is an attractive tumor antigen capable of eliciting cytotoxic T lymphocytes against WT1-expressing tumors.

[Nephroblastoma in adults. Three case reports]

The authors report three nephroblastoma's cases occurred in adult and treated at Ibn Rochd Oncology Center at Casablanca. The average of age was 24 years (19-29 years) and the delay of diagnosis was five months (3-8 months). The most frequent clinical sign was a lumbar fossa mass. At diagnosis, radiological exams revealed that patients presented an advanced stage and metastatic disease in one case. The treatment was a total nephrectomy with ganglioma dissection when the tumor was resectable followed by chemotherapy and radiotherapy. Two patients was in progressive disease despite treatment, and one patient was lost at follow-up. The prognosis of adult's nephroblastoma remains very severe, due to the advanced stage at diagnosis and the mediocre reply to the treatment.

Immunotherapy for leukemia targeting the Wilms' tumor gene

The Wilms' tumor (WT1) gene encodes a zinc finger transcription factor, which is preferentially expressed in acute leukemia cells and chronic myelogenous leukemia cells in blast crisis, but not in most normal cells. These findings strongly suggest that WT1 is a potential target of immunotherapy for human leukemia. We have established a CD8+ cytotoxic T lymphocyte (CTL) clone, designated TAK-1, which is specific for a WT1-derived 9-mer peptide consisting of HLA-A24-binding anchor motifs. TAK-1 lysed both HLA-A24-positive allogeneic cells and autologous cells that were loaded with a WT1-derived peptide. TAK-1 was cytotoxic to HLA-A24-positive leukemia cells, but not to HLA-A24-positive lymphoma cells that did not express WT1, to HLA-A24-negative leukemia cells, or to HLA-A24-positive normal cells. Treating leukemia cells with an antisense oligonucleotide complementary to WT1 reduced TAK-1-mediated cytotoxicity. TAK-1 did not inhibit colony formation of HLA-A24-positive normal bone marrow cells. Recently, other groups have also reported the establishment of HLA-A2-restricted anti-leukemic CTLs specific for WT1-derived peptide. In addition, a murine model of immunotherapy against WT1-expressing tumors has been reported. Recent studies have demonstrated that WT1 is also aberrantly expressed in various kinds of cancer cells. Taken together, these results suggest that immunotherapy targeting WT1 should be effective against both solid tumors and leukemia.

Aberrant expression of Pax-2 mRNA in renal cell carcinoma tissue and parenchyma of the affected kidney

BACKGROUND

Pax proteins are transcription factors that demonstrate oncogenic properties and appear to play a crucial role in ontogenesis. Pax-2 is expressed in early kidney organogenesis, Wilms' tumor and renal cell carcinoma. In order to determine whether the expression of Pax-2 mRNA is a frequent and specific event in renal cell carcinoma, its expression in nephrectomized specimens and cell lines was investigated.

METHODS

The expression of Pax-2 mRNA was examined by reverse transcription polymerase chain reaction in 55 nephrectomized specimens, nine renal parenchyma specimens from patients without renal cell carcinoma and 16 cell lines from various malignant diseases.

RESULTS

All tumor tissue specimens expressed Pax-2 mRNA. In addition, 38 of 55 specimens from the renal parenchyma of the affected kidney expressed Pax-2 mRNA. In contrast, only two of the nine kidney specimens from patients without renal cell carcinoma expressed Pax-2 mRNA, indicating that expression of this protein is significantly higher in renal cell carcinoma (P < 0.01). All three cell lines from renal cell carcinoma expressed Pax-2. In contrast, Pax-2 was only expressed in two of three cell lines from transitional cell carcinoma and in none of the other lines.

CONCLUSION

The results indicate that Pax-2 expression is a frequent and highly specific event in renal cell carcinoma.

Selective elimination of leukemic CD34+ progenitor cells by cytotoxic T lymphocytes specific for WT1

Hematologic malignancies such as acute and chronic myeloid leukemia are characterized by the malignant transformation of immature CD34+ progenitor cells. Transformation is associated with elevated expression of the Wilm's tumor gene encoded transcription factor (WT1). Here we demonstrate that WT1 can serve as a target for cytotoxic T lymphocytes (CTL) with exquisite specificity for leukemic progenitor cells. HLA-A0201– restricted CTL specific for WT1 kill leukemia cell lines and inhibit colony formation by transformed CD34+ progenitor cells isolated from patients with chronic myeloid leukemia (CML), whereas colony formation by normal CD34+ progenitor cells is unaffected. Thus, the tissue-specific transcription factor WT1 is an ideal target for CTL-mediated purging of leukemic progenitor cells in vitro and for antigen-specific therapy of leukemia and other WT1-expressing malignancies in vivo.

Selective elimination of leukemic CD34+ progenitor cells by cytotoxic T lymphocytes specific for WT1

Hematologic malignancies such as acute and chronic myeloid leukemia are characterized by the malignant transformation of immature CD34+ progenitor cells. Transformation is associated with elevated expression of the Wilm's tumor gene encoded transcription factor (WT1). Here we demonstrate that WT1 can serve as a target for cytotoxic T lymphocytes (CTL) with exquisite specificity for leukemic progenitor cells. HLA-A0201– restricted CTL specific for WT1 kill leukemia cell lines and inhibit colony formation by transformed CD34+ progenitor cells isolated from patients with chronic myeloid leukemia (CML), whereas colony formation by normal CD34+ progenitor cells is unaffected. Thus, the tissue-specific transcription factor WT1 is an ideal target for CTL-mediated purging of leukemic progenitor cells in vitro and for antigen-specific therapy of leukemia and other WT1-expressing malignancies in vivo.

Analysis of Wilms tumor gene (WT1) expression in acute leukemia patients with special reference to the differential diagnosis between eosinophilic leukemia and idiopathic hypereosinophilic syndromes

Continuous Wilms' tumor gene (WT1) expression is a typical feature of leukemic blasts in AML, ALL, and blast crisis CML patients. It is easily detectable by a variety of RT-PCR protocols, which differ mainly in their sensitivity. The nuclear WT1 protein can be found in blasts of approximately 50-60% of acute leukemia patients at diagnosis. Conversely, WT1 is only transiently expressed in normal hemopoiesis. Early CD34+ hemopoietic progenitors express WT1, whereas no WT1 mRNA transcripts can be found in mature blood cells and differentiation-induced committed CD34- progenitors. As a powerful complementary diagnostic tool, testing for WT1 expression can be helpful to discriminate between eosinophilic leukemia (EoL) patients and patients with idiopathic hypereosinophilic syndromes. Conflicting data about the usefulness of testing for WT1 expression to monitor minimal residual disease (MRD) in treated leukemia patients will be discussed. Finally, research strategies to circumvent shortcomings in detecting leukemia-associated WT1 expression will be outlined.

HLA class I-restricted lysis of leukemia cells by a CD8+ cytotoxic T-lymphocyte clone specific for WT1 peptide

The Wilms tumor (WT1) gene has been reported to be preferentially expressed in acute leukemia cells, regardless of leukemia subtype and chronic myelogenous leukemia cells in blast crisis, but not in normal cells. This finding suggests strongly that WT1 protein is a potential target of immunotherapy for human leukemia. In this study, we established a CD8+ cytotoxic T-lymphocyte (CTL) clone directed against a WT1-derived peptide and examined its immunologic actions on leukemia cells. A CD8+ CTL clone, designated TAK-1, which lysed autologous cells loaded with a WT1-derived 9-mer peptide consisting of the HLA-A24 (HLA-A*2402)-binding motifs was established by stimulating CD8+ T lymphocytes from a healthy individual repeatedly with WT1 peptide-pulsed autologous dendritic cells. TAK-1 was cytotoxic to HLA-A24–positive leukemia cells expressing WT1, but not to HLA-A24–positive lymphoma cells that did not express WT1, HLA-A24–negative leukemia cells, or HLA-A24–positive normal cells. Treating leukemia cells with an antisense oligonucleotide complementary to the WT1 gene resulted in reduced TAK-1-mediated cytotoxicity, suggesting that target antigen of TAK-1 on leukemia cells is the naturally processed WT1 peptide in the context of HLA-A24. TAK-1 did not inhibit colony formation by normal bone marrow cells of HLA-A24–positive individuals. Because WT1 is overexpressed ubiquitously in various types of leukemia cells, but not in normal cells, immunotherapy using WT1 peptide-specific CTL clones should be an efficacious treatment for human leukemia. (Blood. 2000;95:286-293)

The role of NF-kappaB in the regulation of the expression of wilms tumor suppressor gene WT1

The Wilms tumor suppressor gene, WT1, plays an important role in genitourinary development and the etiology of Wilms tumor. WT1 has a spatially and temporally defined expression in the developing genitourinary system and in specific cells of the hematopoietic system, but the regulatory pathways that control WT1 expression are not well understood. Recently, members of the NF-kappaB family of transcription factors have been proposed as potent activators of the murine WT1 promoter through binding to a NF-kappaB site. Because the human WT1 promoter contains a conserved NF-kappaB site, we investigated whether NF-kappaB also regulates the expression of the human WT1 gene. We activated NF-kappaB through cytokine stimulation or inhibited NF-kappaB through expression of a NF-kappaB "super repressor" in WT1 expressing Wilms tumor, renal carcinoma, and erythroleukemia cultures and examined the level of endogenous WT1 gene expression. Although a transfected NF-kappaB reporter construct was responsive to these manipulations, we found that altering NF-kappaB activity had no effect on endogenous WT1 expression in the cell types used in our study. We conclude that despite the presence of conserved NF-kappaB elements in the murine and human WT1 promoters, NF-kappaB is not required to regulate the expression of the WT1 gene in its natural context.