PAX5 Research Articles

Informative comprehension of detection of chimeric genes PAX3/ 7-FKHR in prognostically unfavourable forms of rhabdomiosarcomas in children

Informative comprehension of detection of chimeric genes PAX3/ 7-FKHR in prognostically unfavourable forms of rhabdomiosarcomas in children

Failure of CDKN2A/B (INK4A/B–ARF)-mediated tumor suppression and resistance to targeted therapy in acute lymphoblastic leukemia induced by BCR-ABL

Deletions of the CDKN2A/B tumor suppressor locus and of the IKAROS and PAX5 genes that promote B-lineage development occur frequently in lymphoid, but not myeloid leukemias initiated by the BCR-ABL tyrosine kinase. Why is this the case, and how do these genetic lesions contribute to an aggressive disease that fails to durably respond to targeted kinase inhibitors?

Primary Diffuse Large B-Cell Lymphoma of Bone Displays Preferential Rearrangements of the c-MYCorBCL2Gene

We selected a series of 63 primary diffuse large B-cell lymphomas (DLBCLs) of bone collected in tissue microarrays from centers in France and Brazil. These cases were classified according to the expression of antigens associated with germinal center (GC; n = 42) or non-GC (n = 21) stages of B-cell differentiation. By fluorescence in situ hybridization, we found a substantial number of cases with a rearrangement of BCL2 (9/32) and c -MYC (n = 3), whereas the PAX5, BCL6, BCL1 cyclin D1, and ALK genes were in germline configuration. It is interesting that 1 case, with a GC phenotype, showed dual BCL2 and c -MYC rearrangement. The majority of the cases with rearrangements were of the GC phenotype. These results, associated with the lack of BCL6 rearrangement, suggest that bone DLBCL represents a specific group within extranodal B-cell lymphomas.

Determinative roles of FGF and Wnt signals in iris‐derived lens regeneration in newt eye

Total regeneration of experimentally excised lens from the dorsal part of the iris-pigmented epithelium of newts has been a key model of tissue regeneration via cells originating from a foreign tissue. Due to the strict spatial restriction of the lens origin in the newt iris, it has often been assumed that only the dorsal iris cells are endowed with an intrinsic potential to give rise to lens tissues. However, our reinvestigation of the process revealed completely different mechanisms underlying lens regeneration and its spatial restriction, comprising the following two steps: (i) Fibroblast growth factor (FGF) 2-dependent proliferation of iris-pigmented epithelium and activation of early lens genes (Pax6, Sox2, MafB) over the entire circumference of the iris; and (ii) dorsal iris-restricted activation of the canonical Wnt signals (involving Wnt2b and Frizzeld4) that leads to localized expression of late lens genes (Prox1, Sox1, beta-crystallin). Injection of FGF2 into normal eyes specifically elicited the second lens development from the dorsal iris, and the administration of recombinant Wnt3a to the cultured iris-pigmented epithelium caused even ventral iris-derived lens development. Thus, it is concluded that the regulation of FGF2 and Wnt signals is a determinative of the iris-derived lens regeneration in the newt eye.

Cis-regulatory organization of the Pax6 gene in the ascidian Ciona intestinalis

The Pax6 gene has attracted intense research interest due to its apparently important role in the development of eyes and the central nervous system (CNS) in many animal groups. Pax6 is also of interest for comparative genomics since it has not been duplicated in tetrapods, making for a direct orthology between the Ciona intestinalis gene CiPax6 and Pax6 in mammals. CiPax6 has been shown to be expressed in the anterior brain, caudal nerve cord, and in parts of the brain associated with the photoreceptive ocellus. This information was extended here using in-situ hybridization, and shows that CiPax6 transcripts mark the lateral regions of the nerve cord, remarkably similar to Pax6 expression in the mouse. As a means of dissecting the cis-regulation of CiPax6 we tested 8 kb of sequence using transient reporter transgene assays. Three separate regions were found that work together to drive the overall CiPax6 expression pattern. A 211 bp sequence 2 kb upstream of the first exon was found to be a major enhancer driving expression in the sensory vesicle (the anterior portion of the ascidian brain). Other upstream sequences were shown to work with the sensory vesicle enhancer to drive expression in the remainder of the CNS. An “eye enhancer” was localized to the first intron, which controls specific expression in the central portion of the sensory vesicle, including photoreceptor cells. The fourth intron was found to repress ectopic expression of the reporter gene in middle portions of the embryonic brain. Aspects of this overall regulatory organization are similar to the organization of the Pax6 homologs in mice and Drosophila, particularly the presence of intronic elements driving expression in the eye, brain and nerve cord.

Transcriptional regulation of the murine 1‐cys peroxiredoxin gene by the B cell‐specific activator protein, Pax5

Pax5, a member of the paired box gene family of transcription factors, is a B cell-specific activator protein (BSAP) that plays important roles in controlling the expression of lineage- and differentiation-stage specific genes during B lymphopoiesis. We identified two putative Pax5 binding sites in a 668 bp of the murine 1-cys peroxiredoxin (1-cysPrx) promoter region. These sites were located at positions -278 to -262 and -50 to -34 from the translation start site. Gel mobility shift assays showed that recombinant Pax5 protein bound specifically to the nucleotide regions -56 to -24 (MP1 probe) and -284 to -253 (MP2 probe). Furthermore, endogenous Pax5 protein from B lymphoblast cells (IM-9) formed a DNA-protein complex with MP1 and MP2 probes, indicating that Pax5 binding occurs specifically at these sequences in vivo. Transient transfection studies showed that expression of exogenous Pax5 resulted in dose-dependent increases in 1-cysPrx promoter activity, implying that Pax5 functions as a positive transcription factor for 1-cysPrx expression. Further transient cotransfection studies showed that coexpression of Pax5 and histone acetyltransferases (HATs), such as p300, cAMP-response-element-binding protein (CBP) and p300/CBP associated factor (PCAF) enhanced the Pax5-mediated 1-cysPrx promoter activity. Immunoprecipitation studies indicated that Pax5 directly binds to HATs. Chromatin immunoprecipitation assays showed that the recruitment of Pax5 to the promoter induced histone H3 and H4 hyperacetylation of chromatin. Lipopolysaccharides (LPS) stimulation of murine splenocytes resulted in coordinated expression of Pax5 and 1-cysPrx proteins. These findings suggest that Pax5 may function as a transactivator of 1-cysPrx gene expression.

Quantitative differences in chromatin accessibility across regulatory regions can be directly compared in distinct cell-types

Transcriptional activation in eukaryotes is often accompanied by alterations to chromatin structure at specific regulatory sites while other genomic regions may remain unchanged. In this study, we have examined the correlation between expression and chromatin accessibility of the human CR2 gene in a panel of cell lines (U937, REH, Ramos, and Raji) using the CHART-PCR assay with the accessibility agent micrococcal nuclease (MNase). To validate the use of this assay for comparing multiple cell-types, we first tested a series of genomic regions to determine if we could observe consistent, site-specific levels of MNase chromatin accessibility. Promoter regions of the ubiquitously expressed genes GAPDH and β-actin were similar and showed high accessibility to MNase digestion in each of the cell lines, while on the other hand, promoter regions of developmentally restricted genes PAX-7 and SP-A2 showed consistently reduced chromatin accessibility. Since CHART-PCR detected site-specific differences in chromatin accessibility in a manner that could be compared between cell-types, we next examined chromatin accessibility over the CR2 core promoter in the panel of cell lines representing either CR2 expressing or CR2 non-expressing cell-types. Our data revealed significantly enhanced accessibility over the −289 to −101 and the −115 to −12 regions of the CR2 promoter in expressing B-cells (Ramos, Raji) compared to non-expressing cells (U937, REH). Thus, CHART-PCR assays detected a correlation between chromatin accessibility and expression of the human CR2 gene, while the accessibility of other genomic regions was site-specific, but not altered between cell-types.

Methylation of the TPEF‐ and PAX6‐promoters is increased in early bladder cancer and in normal mucosa adjacent to pTa tumours

To evaluate CpG island methylation patterns of cancer-associated genes for their applicability as molecular biomarkers for the detection of superficial bladder cancer and for the discrimination of invasive from noninvasive tumours. We analysed the methylation status of CpG islands in the promoter region of the cancer-associated genes GSTP1, DAPK, MDR1, TPEF, PAX6, and TSLC1 in primary papillary bladder cancer specimens from 39 patients (pT1 10, pTis one, pTa 20, pT2 five). Tumour-adjacent normal mucosa served as the control. The DNAs were bisulphite-treated and submitted to methylation-specific real-time polymerase chain reactions. Only TPEF and PAX6 had substantial CpG island methylation percentages. The TPEF- and PAX6-promoters also had significantly higher methylation rates in tumour tissue compared with the normal tumour-adjacent tissue. Interestingly, the methylation rates of the TPEF- and the PAX6-promoter were higher in adjacent normal tissues from bladders with pTa then in those with pT1 tumours. Our results shed a critical light on the hypothesis that CpG island hypermethylation of the GSTP1-, DAPK-, MDR1- and TSLC1-promoter could represent molecular biomarkers for bladder cancer diagnosis and detection. However, methylated PAX6- or TPEF-promoters could represent biomarkers for this disease. Additional studies are needed to evaluate whether methylation rates of these genes in normal bladder tissues are applicable as accessory markers for the tumour state or its invasive behaviour.

Transcription factors Xbp-1, Blimp-1, and BSAP are involved in the regulation of plasmacytic differentiation induced by 2-methoxyestradiol in myeloma cell lines

Our previous studies demonstrated that a low concentration of 2-methoxyestradiol (2ME2) could induce the differentiation of myeloma cell lines and CD138+ primary myeloma cells from myeloma patients and up-regulate the expression of messenger RNA (mRNA) and protein for the gene encoding X-box binding protein 1 (Xbp-1) in myeloma cell lines. In the present study, we used phosphorothioated antisense oligodeoxynucleotides (ASODN) to investigate the roles and interactions of transcription factors Xbp-1, B-lymphocyte induced maturation protein 1 (Blimp-1), and PAX-5-encoded B-cell-specific activator protein (BSAP), which are thought to be involved in the regulation of B-lymphocytic or plasmacytic differentiation. Blimp-1 ASODN and Xbp-1 ASODN clearly inhibited myeloma cell differentiation and significantly partially inhibited the differentiation effects induced by 2ME2 at low concentration, whereas PAX-5 ASODN clearly induced myeloma cell differentiation and significantly enhanced 2ME2-induced differentiation effects. Moreover, after incubation with Blimp-1 ASODN, the level of Xbp-1 mRNA clearly declined, whereas the level of PAX-5 mRNA significantly increased in myeloma cells. These results demonstrate that transcription factors Xbp-1, Blimp-1, and PAX-5-encoded BSAP play important roles in the regulation of plasmacytic differentiation and exert their effects on differentiation induced by low 2ME2 concentrations. Our primary study provided the rationale for a promising strategy-the future application of transcription-factor ASODN for clinical patients.

Rearrangement and Deletion of the PAX5 Gene in Pediatric Acute B-Cell Lineage Lymphoblastic Leukemia.

Pediatric acute lymphoblastic leukemia (ALL) is the most common malignant disease in children. The disease results from accumulation of mutations of tumor suppressor genes and oncogenes. Recently, higher resolution SNP-chips (50,000–500,000 probes) have been developed allowing us to identify genes involved at the start sites of deletions/duplications. This permitted us both to identify unbalanced translocations involving t(1;19)(q23;p13) (TCF3/PBX1) and t(12;21)(p13;q11) (ETV6/RUNX1), as well as, to find novel fusion genes involving PAX5 in B-cell lineage ALL. PAX5 gene was rearranged to a variety of partner genes including ETV6, FOXP1, AUTS2 and C20orf112. In each case, tthe C-terminal end of the PAX5 gene was replaced by the partner gene. The PAX5 fusion gene products suppressed transcriptional activity of PAX5 in a dominant negative fashion. We also found a point mutation of PAX5 at codon 26 (Val 26 Gly); and this mutated PAX5 had attenuated transcriptional activity. Expression of PAX5/C20orf112 fusion gene in a B-cell line suppressed endgenous expression of PAX5 target genes including BLK1 and CD19. Furthermore, deletion of PAX5 was common in B-cell lineage ALL (34/339 cases). PAX5 gene is localized on chromosome 9p and concurrent deletion of PAX5 and INK4A genes were frequently detected in B-cell linage ALL. PAX5 gene may behave as a tumor suppressor gene during early development of B-cells and its alteration by either fusion to another gene, point mutation, or deletion may be associated with leukemogenesis of B-cell lineage ALL.

Pax5 Activates Oncogenic Transcription Factors of the Ets Family by Repressing the mir-15a/16-1 microRNA Cluster.

We have recently demonstrated that Pax5 promotes B-lymphomagenesis by upregulating key components of B-cell receptor signaling [Cozma et al, J Clin Inv, 117 (8), 2007]. Gene regulation by Pax5 often involves complex formation with other oncogenic transcription factors of the Ets family, namely Myb and Ets1. We determined that expression of these proteins themselves depends on the presence of Pax5, as seen in human diffuse large B-cell lymphomas with Pax5 knockdown and murine lymphomas with epigenetic silencing of Pax5 [Yu et al, Blood , 101:1950–1955, 2003; Johnson et al, Nat Immunol , 5:853–861, 2004]. Upon reconstitution with the Pax5 gene, Myb and Ets1 levels increase sharply. This occurs with little increase in steady-state mRNA levels, suggesting post-transcriptional regulation, possibly by microRNAs. To test this hypothesis, we compared miRNA profiles of Pax5-deficieint and sufficient cells and discovered that several miRNAs are indeed repressed by Pax5. Among them is the miR-15a/16-1 cluster whose predicted targets include both Myb and Ets1. Consistent with this prediction, forced expression of miR-15a/16 brings down Myb and Ets1 protein levels. This is accompanied by impaired Pax5 function and overall suppression of B-lymphomagenesis. Thus, Ets family members (along with previously identified bcl-2) are key targets of the miR-15a/16 locus, a tumor suppressor in chronic lymphocytic leukemia. [Display omitted]

IL-6-Induced C-MYC Down-Regulates the Expression of CD33 in CD33(+) Myeloma Cell Lines.

Since human myeloma cells specifically lose the expression of PAX-5 gene, the master gene of B cell lineage, we frequently detect the ectopic expressions of non-B cell lineage markers such as CD56 and CD33. As for the expression of CD33, we confirmed that CD33 expression was found in primary myeloma cells from about 12% of 120 cases with overt myeloma and also in 2 myeloma cell lines (ILKM8 and Liu01 (a subclone of U266)) in the protein and mRNA levels. In primary myeloma cells as well as CD33(–) myeloma cell lines, DMSO treatment could induce the expression of CD33 in the in vitro culture. In these CD33(+) myeloma cell lines and DMSO-induced myeloma cells, we found that expressions of C/EBPα and PU.1 were markedly increased by gene expression profiling. On the other hand, IL-6 down-regulated the expression of CD33 in CD33(+) myeloma cell lines accompanying with down-regulation of C/EBPα and PU.1 expressions. Also, we found that IL-6 up-regulated the expression of C-MYC and the increased C-MYC bound to the promoter region of C/EBPα gene followed by the down-regulation of C/EBPα expression. It was confirmed that introduction of sh-RNA for C-MYC to two CD33(+) myeloma cell lines blocked the IL-6-induced down-regulation of CD33 and C/EBPα expression. Therefore, these results indicate that IL-6 can reverse the ectopic expression of non-B cell lineage markers by up-regulating C-MYC followed by its down-regulation of C/EBPα expression and also suggest that constitutive activation of STAT3 by IL-6 may keep PAX-5(–) myeloma cells being uncommitted cells to any lineage; myeloma cells could be one of stem cell-like cancer cells.

A procephalic territory in Drosophila exhibiting similarities and dissimilarities compared to the vertebrate midbrain/hindbrain boundary region

BackgroundIn vertebrates, the primordium of the brain is subdivided by the expression of Otx genes (forebrain/anterior midbrain), Hox genes (posterior hindbrain), and the genes Pax2, Pax5 and Pax8 (intervening region). The latter includes the midbrain/hindbrain boundary (MHB), which acts as a key organizer during brain patterning. Recent studies in Drosophila revealed that orthologous sets of genes are expressed in a similar tripartite pattern in the late embryonic brain, which suggested correspondence between the Drosophila deutocerebral/tritocerebral boundary region and the vertebrate MHB. To gain more insight into the evolution of brain regions, and particularly the MHB, I examined the expression of a comprehensive array of MHB-specific gene orthologs in the procephalic neuroectoderm and in individually identified neuroblasts during early embryonic stages 8–11, at which the segmental organization of the brain is most clearly displayed.Results and conclusionI show that the early embryonic brain exhibits an anterior Otx/otd domain and a posterior Hox1/lab domain, but that Pax2/5/8 orthologs are not expressed in the neuroectoderm and neuroblasts of the intervening territory. Furthermore, the expression domains of Otx/otd and Gbx/unpg exhibit a small common interface within the anterior deutocerebrum. In contrast to vertebrates, Fgf8-related genes are not expressed posterior to the otd/unpg interface. However, at the otd/unpg interface the early expression of other MHB-specific genes (including btd, wg, en), and of dorsoventral patterning genes, closely resembles the situation at the vertebrate MHB. Altogether, these results suggest the existence of an ancestral territory within the primordium of the deutocerebrum and adjacent protocerebrum, which might be the evolutionary equivalent of the region of the vertebrate MHB. However, lack of expression of Pax2/5/8 and Fgf8-related genes, and significant differences in the expression onset of other key regulators at the otd/unpg interface, imply that genetic interactions crucial for the vertebrate organizer activity are absent in the early embryonic brain of Drosophila.

Human BSAP and BLIMP1 conform an autoregulatory feedback loop

AbstractB-lymphocyte–induced maturation protein-1 (BLIMP1), encoded by the PRDM1 gene, is a transcriptional repressor considered a master regulator that is required and sufficient for plasma cell (PC) differentiation. BLIMP1 represses the PAX5 gene, coding for the B-cell lineage–specific activator protein (BSAP), which is required for B-cell identity and survival. Mutations in PAX5 gene as well as in PRDM1 gene have been recently implicated in lymphomas. In the present study, sequence analysis of PRDM1 gene revealed a binding site for BSAP transcription factor. By analyzing different human cell lines, we have found that a specific nuclear factor for B-cell lines binds to a site on the PRDM1 promoter. Electrophoretic mobility shift assays identified this factor as BSAP, and chromatin immunoprecipitation assays confirmed its binding in vivo to the human PRDM1 promoter. Moreover, by ectopically expressing BSAP, and using a PRDM1 promoter with the BSAP-binding site mutated, we demonstrated that this factor represses the expression of BLIMP1. Therefore, repression of PRDM1 by BSAP reveals an autoregulatory negative-feedback loop that could play a relevant role in controlling human PC differentiation.

Secretion and Organization of a Cornea-like Tissue In Vitro by Stem Cells from Human Corneal Stroma

To investigate the potential of human corneal stromal stem cells to assume a keratocyte phenotype and to organize extracellular matrix (ECM) in vitro similar to corneal stromal tissue. Human corneal stromal stem cells (hCSSC) were isolated as side population cells by flow cytometry. Cloned hCSSC were cultured as free-floating pellets in serum-free media for 3 weeks. Gene expression was examined using gene array, quantitative RT-PCR, immunostaining, and immunoblotting. Transmission electron microscopy showed collagen fibril size and alignment. Pellet cultures of hCSSC in serum-free media upregulated the expression of keratocyte-specific genes and secreted substantial ECM containing characteristic stromal components: keratocan, keratan sulfate, collagen I, collagen V, and collagen VI. Abundant connexin 43 and cadherin 11 in pellets demonstrated cell-cell junctions typical of keratocytes in vivo. Electron microscopy of the pellet cultures revealed abundant fibrillar collagen, some of which was aligned in parallel arrays similar to those of stromal lamellae. Gene array identified expression in pellets of several genes highly expressed by keratocytes. Transcripts for these keratocyte genes -- FLJ30046, KERA, ALDH3A1, CXADR, PTGDS, PDK4, MTAC2D1, F13A1 -- were increased by as much as 100-fold in pellets compared with hCSSC. Simultaneously, expression of stem cell genes BMI1, KIT, NOTCH1, SIX2, PAX6, ABCG2, SPAG10, and OSIL was reduced by a similar factor in pellets compared with hCSSC. Scaffolding-free pellet culture of hCSSC induces keratocyte gene expression patterns in these cells and secretion of an organized stroma-like ECM. These cells offer a novel potential for corneal bioengineering.

Expression of the paired box domain Pax7 protein in myogenic cells isolated from the porcine semitendinosus muscle after birth

The paired box domain gene Pax7 plays a pivotal role in satellite cell physiology and may represent one of the candidate genes influencing the dynamic stages of early post-natal growth observed in pig. Quiescent satellite cells express Pax7 and, when activated, they co-express the myogenic bHLH protein MyoD. The aims of this study were to investigate, by immunohistochemistry, the putative differential expression of Pax7 and to ascertain the amount of activated satellite cells (Pax7 +/MyoD +) in myogenic cells isolated at different post-natal time points and in adults. Our results indicate that Pax7 + cells represent between 10 and 15% of the whole myogenic cell population found at birth indicating that these cells provide a modest contribution to the development of new fibres. The number of activated satellite cells (Pax7 +/MyoD +) was scarce after birth but it was higher respect to adults. An interesting result was that at 1 month after birth the number of Pax7 + cells had increased within the pool of myogenic cells with respect to myogenic cells extracted at birth. We speculate that Pax7 might be one of the molecules involved in controlling the proliferation/differentiation ratio in the pool of satellite cells present in post-natal porcine skeletal muscles.

Rab23 GTPase is expressed asymmetrically in Hensen's node and plays a role in the dorsoventral patterning of the chick neural tube

The mouse Rab23 protein, a Ras-like GTPase, inhibits signaling through the Sonic hedgehog pathway and thus exerts a role in the dorsoventral patterning of the spinal cord. Rab23 mouse mutant embryos lack dorsal spinal cord cell types. We cloned the chicken Rab23 gene and studied its expression in the developing nervous system. Chick Rab23 mRNA is initially expressed in the entire neural tube but retracts to the dorsal alar plate. Unlike in mouse, we find Rab23 in chick already expressed asymmetrically during gastrulation. Ectopic expression of Rab23 in ventral midbrain induced dorsal genes (Pax3, Pax7) ectopically and reduced ventral genes (Nkx2.2 and Nkx6) without influencing cell proliferation or neurogenesis. Thus, in the developing brain of chick embryos Rab23 acts in the same manner as described for the caudal spinal cord in mouse. These data indicate that Rab23 plays an important role in patterning the dorso-ventral axis by dorsalizing the neural tube.

Developmental mechanisms for retinal degeneration in the blind cavefish Astyanax mexicanus

The sighted surface-dwelling (surface fish, SF) and the blind cave-living (cavefish, CF) forms of Astyanax mexicanus offer a unique opportunity to study the evolutionary changes in developmental mechanisms that lead to retinal degeneration. Previous data have shown the role of increased midline Sonic Hedgehog (Shh) signalling in cavefish eye degeneration (Yamamoto et al. [2004] Nature 431:844-847). Here, we have compared the major steps of eye development in SF and CF between 14 hours and 5 days of development. We have analyzed cell proliferation through PCNA and phospho-histone H3 staining and apoptosis through TUNEL and live LysoTracker analysis. We have assessed the expression of the major eye development signalling factors Shh and Fgf8, and the eye patterning genes Pax6, Lhx2, Lhx9, and Vax1, together with the differentiation marker GAD65. We show that eye development is retarded in CF and that cell proliferation in CF retina is proportionately similar to SF during early development, yet the retina degenerates after massive apoptosis in the lens and widespread cell death throughout the neuroretina. Moreover, and surprisingly, the signalling, patterning, and differentiation processes leading to the establishment of retinal layers and cell types happen almost normally in CF, although some signs of disorganization, slight heterochronies, and a lack of expression gradients are observable. Our data demonstrate that the evolutionary process of eye degeneration in the blind CF does not occur because of patterning defects of the retina and are consistent with the proposed scenario in which the trigger for eye degeneration in CF is lens apoptosis.

Biphenotypic bigenotypic lymphoma with simultaneous expression of PAX5/BSAP and B‐ and T‐cell markers

Lymphomas are currently categorized according to their origin from a B or T lymphocyte. Immature and less commonly mature (peripheral) lymphomas may harbor rearrangements of both the B- and T-cell antigen receptor genes (dual genotype or bigenotype). Rarely, cells in lymphoma with a single genotype simultaneously express both B- and T-cell markers (biphenotypic lymphomas). We discuss the diagnostic and clinical implications in the case of a 42-yr-old female with a peripheral CD30+ lymphoma that displayed both characteristic B- and T-cell surface antigens and clonal rearrangement of B- and T-cell antigen receptor gene loci. Simultaneous nuclear expression of the transcription factor gene PAX5 suggested that this major driver of B-cell differentiation did not preclude expression of CD3epsilon, generally assumed to be a T-cell associated antigen.

Multicystic renal tumor in a patient with WAGR syndrome

The WAGR syndrome is a combination of Wilms' tumor, aniridia, genitourinary anomalies, and mental retardation. We report on a 2-year-old boy, who had a deletion of the aniridia gene PAX6 and the Wilms' tumor gene 1 (WT1 gene). At the age of 23 months, a 1.7 x 1.9 cm-sized intrarenal tumor was detected by ultrasound examination. According to the protocol of the SIOP study, a cycle of neoadjuvant chemotherapy was prescribed followed by a left-sided nephrectomy. However, postsurgical histomorphology failed to confirm the suspected diagnosis of Wilms' tumor and instead revealed dysgenetic cysts of the kidney. Based on the image morphology in connection with the deletion of the WT1 gene, the tentative diagnosis of a nephroblastoma had to be made. The study protocol of the SIOP does not permit another therapy algorithm.