Identical genetic changes in different histologic components of Wilms' tumors

The contribution of YTHDF2 gene rs3738067 A>G to the Wilms tumor susceptibility

YTHDF2 is responsible for maintaining the dynamic N⁶-methyladenosine (m⁶A) modification balance and influences a variety of cancers. We tested whether YTHDF2 gene rs3738067 A>G polymorphism is related to Wilms tumor by genotyping samples of Chinese children (450 cases and 1317 controls). However, the rs3738067 A>G polymorphism showed no statistical significance with Wilms tumor susceptibility. Stratification analysis also revealed that there was no remarkable association of rs3738067 variant AG/GG genotype with Wilms tumor risk in every subgroup (age, gender, and clinical stages). In all, the results indicated YTHDF2 gene rs3738067 A>G polymorphism could not alter Wilms tumor risk significantly.

Biomarker recommendation for PD-1/PD-L1 immunotherapy development in pediatric cancer based on digital image analysis of PD-L1 and immune cells

Anti-PD-1/PD-L1 immunotherapy could offer an alternative to traditional chemo- and/or radiotherapy to treat pediatric cancer patients. To unveil the potential benefit of this new therapeutic approach, the prevalence of PD-L1 and other relevant immune markers using quantitative digital image analysis (DIA) could help to clarify this point. A bridging study was first conducted using commercially available normal formalin-fixed paraffin-embedded (FFPE) tonsils to compare immunostaining patterns and intensities from PD-L1, tumor infiltrating lymphocyte (TIL) markers CD3, CD8, FoxP3, CD45RO, and macrophage marker CD68 in adult (n = 5) and pediatric (n = 10) samples. Then, commercially available pediatric FFPE tumor samples from five prevalent pediatric solid tumor indications: ganglioneuroblastoma (n = 7); neuroblastoma (n = 23); nephroblastoma (n = 30); osteosarcoma (n = 24); and rhabdomyosarcoma (n = 25) were immunostained and their images (n = 654) digitally analyzed using predefined algorithms. The qualitative analysis of staining patterns and intensities in all 15 tonsils for all 6 biomarkers was similar regardless of age category. Quantitative DIA showed that PD-L1 values varied across cancer-types, nephroblastoma having the lowest counts. PD-L1 counts in ganglioneuroblastoma, our pediatric indication with the highest average value, was approximately 12-times lower than in a similar nonsmall cell lung cancer study, an indication approved for anti-PD-1/PD-L1 immunotherapies. Variable values were measured for the TIL markers CD3, CD8, and CD45RO. FoxP3 was scant across all indications. The macrophage marker CD68 showed highest values in ganglioneuroblastoma, with lowest levels in nephroblastoma. In conclusion, the low PD-L1 levels uncorrelated with TIL values from the present biomarker morphological study suggest that a PD-L1 immunohistochemistry patient selection strategy used for anti-PD-1/PD-L1 monotherapy in adult tumors may not succeed in these pediatric indications.

Genetic variation frequencies in Wilms' tumor: A meta-analysis and systematic review

Over the last few decades, numerous biomarkers in Wilms' tumor have been confirmed and shown variations in prevalence. Most of these studies were based on small sample sizes. We carried out a meta-analysis of the research published from 1992 to 2015 to obtain more precise and comprehensive outcomes for genetic tests. In the present study, 70 out of 5175 published reports were eligible for the meta-analysis, which was carried out using Stata 12.0 software. Pooled prevalence for gene mutations WT1, WTX, CTNNB1, TP53, MYCN, DROSHA, and DGCR8 was 0.141 (0.104, 0.178), 0.147 (0.110, 0.184), 0.140 (0.100, 0.190), 0.410 (0.214, 0.605), 0.071 (0.041, 0.100), 0.082 (0.048, 0.116), and 0.036 (0.026, 0.046), respectively. Pooled prevalence of loss of heterozygosity at 1p, 11p, 11q, 16q, and 22q was 0.109 (0.084, 0.133), 0.334 (0.295, 0.373), 0.199 (0.146, 0.252), 0.151 (0.129, 0.172), and 0.148 (0.108, 0.189), respectively. Pooled prevalence of 1q and chromosome 12 gain was 0.218 (0.161, 0.275) and 0.273 (0.195, 0.350), respectively. The limited prevalence of currently known genetic alterations in Wilms' tumors indicates that significant drivers of initiation and progression remain to be discovered. Subgroup analyses indicated that ethnicity may be one of the sources of heterogeneity. However, in meta-regression analyses, no study-level characteristics of indicators were found to be significant. In addition, the findings of our sensitivity analysis and possible publication bias remind us to interpret results with caution.

Overexpression of the human ZNF300 gene enhances growth and metastasis of cancer cells through activating NF-kB pathway

Zinc finger proteins (ZNF) play important roles in various physiological processes. Here we report that ZNF300, a novel zinc finger protein, identified specifically in humans, promotes tumour development by modulating the NF-κB pathway. Inflammatory factors were found to induce ZNF300 expression in HeLa cell line, and ZNF300 expression further enhanced NF-κB signalling by activating TRAF2 and physically interacting with IKKβ. Furthermore, ZNF300 overexpression increased ERK1/2 phosphorylation and the expression of c-myc, IL-6, and IL-8 but decreased the expression of p21^waf-1 and p27^Kip1; whose down-regulation led to the opposite effect. Most importantly, ZNF300 overexpression stimulated cancer cell proliferation in vitro and significantly enhanced tumour development and metastasis in mouse xenograft model, while knocking down ZNF300 led to the opposite effects. We have identified a novel function for ZNF300 in tumour development that may uniquely link inflammation and NF-κB to tumourigenesis in humans but not in mice.

Defining and redefining the nephron progenitor population

It has long been appreciated that the mammalian kidney arises via reciprocal interactions between an epithelial ureteric epithelium and the surrounding metanephric mesenchyme. More recently, lineage tracing has confirmed that the portion of the metanephric mesenchyme closest to the advancing ureteric tips, the cap mesenchyme, represents the progenitor population for the nephron epithelia. This Six2(+)Cited1(+) population undergoes self-renewal throughout nephrogenesis while retaining the potential to epithelialize. In contrast, the Foxd1(+) portion of the metanephric mesenchyme shows no epithelial potential, developing instead into the interstitial, perivascular, and possibly endothelial elements of the kidney. The cap mesenchyme rests within a nephrogenic niche, surrounded by the stroma and the ureteric tip. While the role of Wnt signaling in nephron induction is known, there remains a lack of clarity over the intrinsic and extrinsic regulation of cap mesenchyme specification, self-renewal, and nephron potential. It is also not known what regulates cessation of nephrogenesis, but there is no nephron generation in response to injury during the postnatal period. In this review, we will examine what is and is not known about this nephron progenitor population and discuss how an increased understanding of the regulation of this population may better explain the observed variation in final nephron number and potentially facilitate the reinitiation or prolongation of nephron formation.

Wilms tumor arising in a child with X-linked nephrogenic diabetes insipidus

We report on a child with X-linked nephrogenic diabetes insipidus (NDI) who developed Wilms tumor (WT). Nephrogenic diabetes insipidus is caused by mutations of the arginine vasopressin receptor (AVPR2) or aquaporin-II (AQP2) genes. Wilms tumor is also genetically heterogeneous and is associated with mutations of WT1 (15-20%), WTX (20-30%) and other loci. The boy presented at 5 months with failure to thrive, polyuria, hypernatremia and abdominal mass. Analysis of leukocyte DNA showed a novel missense mutation (Q174H) of the AVPR2 gene, which was not present in his mother. In cells (WitS) isolated from the tumor, WTX mRNA expression and coding sequence were intact. However, we identified a 44-kb homozygous deletion of the WT1 gene spanning exons 4 to 10. The WT1 deletion was not present in leukocyte DNA from the patient or his mother. We also noted strong beta-catenin (CTNNB1) expression in the tumor cells and identified a heterozygote missense Ser45Cys mutation of exon 3 of CTNNB1. However, the mutation was absent both in the constitutional DNA of the patient and his mother. The concurrence of WT and NDI has not been previously reported and may be unrelated. Nevertheless, this case nicely illustrates the sequence of events leading to sporadic Wilms tumor.

Postirradiation osteosarcoma of the mandible with heterologous differentiation

Heterologous differentiation in osteosarcoma is rare, with only 17 cases previously described in the literature. We report a case of a mandibular osteoblastic osteosarcoma with rhabdomyosarcomatous differentiation in a 45-year-old man who had a history of Hodgkin lymphoma that was treated with chemotherapy and radiation. Radiographs showed a destructive osteoblastic tumor of the mandible that was proven by biopsy to be osteosarcoma. After the patient underwent neoadjuvant chemotherapy, the tumor was resected. It contained a high-grade osteosarcoma composed of osteoblastic and chondroblastic elements that had no definitive response to therapy. Within the center of the lesion was a discrete focus of pleomorphic cells with rhabdomyosarcomatous differentiation that was confirmed by immunohistochemical stains for desmin, myogenin, and myogenic differentiation antigen 1. The patient received additional chemotherapy and radiation therapy but developed lung, brain, and spinal metastases and died 7 months after surgery. To our knowledge, this is the first report of osteosarcoma of the mandible with heterologous differentiation.

Rhabdomyoblastic pulmonary lesions in a patient with Wilms tumor: choristomas or metastases?

New lesions that occur while patients are receiving treatment for malignant tumors may represent not only difficulties in arriving at the correct diagnosis, but also impact on subsequent therapeutic options. We encountered a patient developing new pulmonary lesions during and after receiving treatment for Stage II Wilms tumor (WT). The presence of mature rhabdomyoblasts in multiple biopsy specimens allowed rational decisions to be made regarding subsequent therapy. This and other published experiences suggest that patients with WT may develop choristomas or have tumors, which undergo cytodifferentiation. Methodologies are now available allowing differentiation of these two processes.

Wilms' tumour: connecting tumorigenesis and organ development in the kidney

Wilms' tumour, or nephroblastoma, is a common childhood tumour that is intimately linked to early kidney development and is often associated with persistent embryonic renal tissue and other kidney abnormalities. WT1, the first gene found to be inactivated in Wilms' tumour, encodes a transcription factor that functions as both a tumour suppressor and a critical regulator of renal organogenesis. Our understanding of the roles of WT1 in tumour formation and organogenesis have advanced in parallel, providing a striking example of the intersection between tumour biology, cellular differentiation and normal organogenesis.

Cytogenetically unrelated clones in different histologic components of a Wilms tumor

Wilms tumor (WT) is a triphasic malignant neoplasm comprised of variable proportions of epithelial, blastemal, and mesenchymal (stromal) elements. Cytogenetic analysis of these tumors has revealed a number of recurring abnormalities, including hyperdiploidy and structural abnormalities of chromosomes 1, 7, 11, and 16. We describe a WT in which apparently unrelated cytogenetic clones were detected at diagnosis, when the predominant histologic component was blastema, and after therapy, when the tumor was composed primarily of stroma. At diagnosis, a pseudodiploid karyotype was present, characterized by an X;14 insertion with concurrent deletion of 14q. In contrast, the post-therapy specimen had a hyperdiploid karyotype with a constellation of gains typical for WT. The presence of clonal abnormalities in both the blastemal and mesenchymal components of a WT supports the hypothesis that the stromal component is neoplastic, rather than reactive. The clonal abnormalities seen in different histologic components of the same WT are typically related or identical. The finding in this case of apparently unrelated clones is unusual. Possible etiologies for this biclonality, and clinical implications, are discussed.

Pan-cytokeratin immunoexpression in Wilms' tumors: a simple approach for understanding tumor epithelial differentiation

Wilms' tumor is one of the most common solid tumors in children and is an interesting model for understanding the pathogenesis of embryonal tumors. Cytokeratins are intracellular fibrous proteins present in tissue of epithelial origin. The immunoexpression of the pan-cytokeratin AE1AE3 was studied in paraffin-embedded tissue sections from 24 Wilms' tumors (12 with nephrogenic rests) and also tissue samples from 15 corresponding normal kidneys, to evaluate epithelial differentiation in the genesis of Wilms' tumor. We observed that the intensity of the expression of AE1AE3 in the epithelial component of Wilms' tumors directly correlated with the degree of maturity of the epithelial structures correspondent to the collecting ducts.

Benign renal mesenchymoma in the pediatric age group: a novel pathologic and karyotype entity

Benign mesenchymal renal tumors are extremely rare in the pediatric age group. We report a case of a benign renal tumor composed of smooth muscle cells, adipose tissue, and areas of cartilaginous differentiation and expressing a 46,XX, t(8;10)(q21;q24) karyotype in a 13-year-old girl. Although some pediatric renal tumors show a degree of heterologous differentiation, none of them exclusively consist of these three well-differentiated mesenchymal components. The unique features of the present case were further confirmed by the karyotype changes, which to our knowledge, have never been described before in a pediatric renal tumor.

Nephroblastoma Arising in a Germ Cell Tumor of Testicular Origin

We report a nephroblastoma arising in a germ cell tumor of testicular origin occurring in a 22-year-old man. Orchiectomy demonstrated a malignant mixed germ cell tumor composed of mature and immature teratoma with nephroblastoma and rhabdomyosarcoma. Following chemotherapy, the patient developed supraclavicular and retroperitoneal lymphadenopathy. Excision demonstrated metastatic teratoma at both sites. No recurrence was noted with 21 months of additional follow-up. Using tissue microdissection and loss of heterozygosity analysis, we investigated the clonality of the mature teratoma, immature teratoma, nephroblastoma, and rhabdomyosarcoma components of the primary tumor and of the metastatic mature teratoma at the two separate distant sites. Nine microsatellite polymorphic makers were used to examine the pattern of allelic loss in both primary and metastatic tumors. Loss of heterozygosity was found in 4 DNA loci, and the same pattern of allelic loss was demonstrated at all 4 loci in all of the different components of the primary tumor and the metastatic mature teratomas, supporting the germ cell tumor origin of the nephroblastoma component. Loss of heterozygosity on chromosome 17p13 (TP53) was detected in metastatic mature teratoma, but not in the primary tumor. Loss of heterozygosity was observed at 11p13, the locus of WT1 inactivation in patients genetically predisposed to nephroblastoma, and this loss may be an important genetic mechanism in nephroblastomatous differentiation of germ cell tumors. These data support a common clonal origin for nephroblastoma and the other germ cell tumor components.

Analysis of the TP53 gene in laser-microdissected glioblastoma vasculature

Malignant transformation of human gliomas is accompanied by extensive proliferation of stromal blood vessels. Recent data suggest mesenchymal transdifferentiation of neoplastic cells in various human cancers, including colon and breast cancer as well as gliosarcoma. In this study, we have analyzed proliferating stromal blood vessels in glioblastoma multiforme for the presence of mutations in the tumor suppressor gene TP53. Using tissue arrays derived from glioblastoma specimens, cases with significant immunohistochemical p53 accumulation were selected for molecular genetic detection of TP53 mutations in exons 5 to 8. None of the tumors included in this series displayed properties of gliosarcoma. Proliferating glomeruloid stromal vessels were isolated by laser microdissection from paraffin sections. In six cases, single-strand conformation polymorphism analysis for mutations of the TP53 gene in stromal blood vessels compared with adjacent tumor cells and subsequent DNA sequencing of the resulting DNA fragments were carried out. Glioblastoma cells of these cases exhibited TP53 mutations in exons 5, 7 and 8. None of these tumors showed TP53 mutations in microdissected samples from glomeruloid vessels. The absence of TP53 mutations in vascular stromal components of glioblastoma multiforme supports the hypothesis that microvascular proliferations originate from the tumor stroma and are not derived from transdifferentiated glioblastoma cells.

Low frequency of genetic lesions in Wilms tumors by representational difference analysis

Genomic representational difference analysis (RDA) was carried out on a total of nine Wilms tumors and one cystic partially differentiated nephroblastoma (CPDN; a sub-type of Wilms) to look for novel genetic deletions involving tumor suppressor genes. Genomic DNA from either short-term cultured Wilms tumor cells or a WT xenograft was used to create driver representations, and genomic DNA from matched normal kidney or normal kidney cells grown in short-term culture was used to create the tester. Genuine difference products were obtained from only one of the tumors. However, none of these fragments were found to be deleted in the original tumor biopsy, microdissected tumor or in the lung metastasis from this patient. It is, therefore, likely that the deletions were due to random losses associated with the genetic instability of the cultured cells from this particular tumor. We did not isolate difference products from any of the other tumors, showing that they did not have chromosomal losses, homozygous deletions or regions of LOH that were detectable by RDA.

Stromal cells and human malignant neuroblasts derived from bone marrow metastasis may share common karyotypic abnormalities: the case of the IGR-N-91 cell line

BACKGROUND

Stage IV neuroblastoma is characterized by tumor invasion and metastatic dissemination. Cell lines derived from such neuroblastomas have a high in vitro proliferation capacity.

PROCEDURE

We established three neuroblastoma cell lines derived from involved bone marrow of three patients with stage IV neuroblastoma and performed a cytogenetic study.

RESULTS

Various culture conditions allowed us to distinguish two cell subpopulations: malignant neuroblasts (Nb-type) and substrate-adherent stromal cells (Str-type). Karyotypic analyses revealed two specific chromosomal abnormalities in diploid malignant IGR-N-331 neuroblasts, der(1)t(1;7)(p22;q11) and der(5)t(5;17)(q35;q21), one unbalanced translocation der(1)t(1;17)(p35;q21)x2 in hyperdiploid malignant IGR-N-337 neuroblasts, and a normal karyotype in both corresponding stromal subpopulations. In contrast, in the IGR-N-91 model, both cell types shared two unbalanced translocations, t(1;4)(q12;p15) and t(2;10)(p14;q11), suggesting that stromal cells and malignant neuroblasts originate from a common stem cell.

CONCLUSIONS

Based on our findings, we postulate that genetically modified stromal cells may influence the metastatic potential of malignant neuroblasts.

Expression of the RNA component of telomerase in Wilms tumor and nephrogenic rest recapitulates renal embryogenesis

Telomerase is a ribonucleoprotein enzyme associated with cellular immortality and has been detected in the vast majority of adult tumors. Wilms tumor is a histologically diverse embryonal malignancy of childhood, and the histological features of Wilms tumor and its precursor lesion, the nephrogenic rest, recapitulate the components of normal renal embryogenesis. Both the epithelial and the stromal components of Wilms tumor arise by differentiation of primitive mesodermal blastema. We compared expression of the RNA component of human telomerase (hTR) in normal developing kidneys, Wilms tumors, and nephrogenic rests and correlated expression of hTR with cell proliferation. Using a radioactive in situ hybridization method, we examined archival material from 17 Wilms tumors (including nine with nephrogenic rests), four therapeutically aborted embryos (37 to 56 days), three fetuses on whom autopsies had been performed, and one neonate for expression of hTR. Proliferative index was measured by immunohistochemical staining for MIB1. In the embryonic kidney, Wilms tumors, and nephrogenic rests, the patterns of hTR expression were similar: expression was usually maximal within the immature epithelial elements followed by the poorly differentiated blastema, but was weak or absent in the immature stroma. Mature tubules, glomeruli, and stroma were negative for hTR expression, as were differentiated heterologous elements present in post-therapy Wilms tumors. There was only a partial relationship between proliferative index and hTR expression. In the embryonic kidney, Wilms tumors, and nephrogenic rests, blastema had the highest proliferative index, whereas the indices were significantly lower in the immature epithelium and stroma. The proliferative index in mature and heterologous elements was low or zero. Thus, the pattern of hTR expression in Wilms tumor and its precursor lesion recapitulates embryogenesis precisely and may represent that aspect of the persistent fetal phenotype which predisposes to the development of malignancy.