Suggested role for neutrophil extracellular trap formation in Ewing sarcoma immune microenvironment.

Ewing sarcoma (EWS) is a highly aggressive cancer with a survival rate of 70%-80% for patients with localized disease and under 30% for those with metastatic disease. Tumor-infiltrating neutrophils (TIN) can generate extracellular net-like DNA structures known as neutrophil extracellular traps (NETs). However, little is known about the presence and prognostic significance of tumor-infiltrating NETs in EWS. Herein, we investigated 46 patients diagnosed with EWS and treated in the Tel Aviv Medical Center between 2010 and 2021. TINs and NETs were identified in diagnostic biopsies of EWS by immunofluorescence. In addition, NETs were investigated in neutrophils isolated from peripheral blood samples of EWS patients at diagnosis and following neoadjuvant chemotherapy. The relationships between the presence of TINs and NETs, pathological and clinical features, and outcomes were analyzed. Our results demonstrate that TIN and NETs at diagnosis were higher in EWS patients with metastatic disease compared with those with local disease. High NET formation at diagnosis predicted poor response to neoadjuvant chemotherapy, relapse, and death from disease (p < 0.05). NET formation in peripheral blood samples at diagnosis was significantly elevated among patients with EWS compared with pediatric controls and decreased significantly following neoadjuvant chemotherapy. In conclusion, NET formation seems to have a role in the EWS immune microenvironment. Their presence can refine risk stratification, predict chemotherapy resistance and survival, and serve as a therapeutic target in patients with EWS.

Genetic Markers Among the Israeli Druze Minority Population With End-Stage Kidney Disease.

RATIONALE & OBJECTIVE: Genetic etiologies have been identified among approximately 10% of adults with chronic kidney disease (CKD). However, data are lacking regarding the prevalence of monogenic etiologies especially among members of minority groups. This study characterized the genetic markers among members of an Israeli minority group with end-stage kidney disease (ESKD). STUDY DESIGN: A national-multicenter cross-sectional study of Israeli Druze patients (an Arabic-speaking Near-Eastern transnational population isolate) who are receiving maintenance dialysis for ESKD. All study participants underwent exome sequencing. SETTING & PARTICIPANTS: We recruited 94 adults with ESKD, comprising 97% of the total 97 Druze individuals throughout Israel being treated with dialysis during the study period. PREDICTORS: Demographics and clinical characteristics of kidney disease. OUTCOME: Genetic markers. ANALYTICAL APPROACH: Whole-exome sequencing and the relationship of markers to clinical phenotypes. RESULTS: We identified genetic etiologies in 17 of 94 participants (18%). None had a previous molecular diagnosis. A novel, population-specific, WDR19 homozygous pathogenic variant (p.Cys293Tyr) was the most common genetic finding. Other monogenic etiologies included PKD1, PKD2, type IV collagen mutations, and monogenic forms of noncommunicable diseases. The pre-exome clinical diagnosis corresponded to the final molecular diagnosis in fewer than half of the participants. LIMITATIONS: This study was limited to Druze individuals, so its generalizability may be limited. CONCLUSIONS: Exome sequencing identified a genetic diagnosis in approximately 18% of Druze individuals with ESKD. These results support conducting genetic analyses in minority populations with high rates of CKD and for whom phenotypic disease specificity may be low. PLAIN-LANGUAGE SUMMARY: Chronic kidney disease (CKD) affects many people worldwide and has multiple genetic causes. However, there is limited information on the prevalence of genetic etiologies, especially among minority populations. Our national-multicenter study focused on Israeli Druze patients. Using exome-sequencing, we identified previously undetected genetic causes in nearly 20% of patients, including a new and population-specific WDR19 homozygous pathogenic variant. This mutation has not been previously described; it is extremely rare globally but is common among the Druze, which highlights the importance of studying minority populations with high rates of CKD. Our findings provide insights into the genetic basis of end-stage kidney disease in the Israeli Druze, expand the WDR19 phenotypic spectrum, and emphasize the potential value of genetic testing in such populations.

Neutrophil Extracellular Traps in Pediatric Inflammatory Bowel Disease: A Potential Role in Ulcerative Colitis.

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD) and ulcerative colitis (UC), is a chronic inflammatory condition of the gut affecting both adults and children. Neutrophil extracellular traps (NETs) are structures released by activated neutrophils, potentially contributing to tissue damage in various diseases. This study aimed to explore the presence and role of NETs in pediatric IBD. We compared intestinal biopsies and peripheral blood from 20 pediatric IBD patients (UC and CD) to controls. Biopsy staining and techniques for neutrophil activation were used to assess neutrophil infiltration and NET formation. We also measured the enzymatic activity of key NET proteins and evaluated NET formation in UC patients in remission. Both UC and CD biopsies showed significantly higher levels of neutrophils and NETs compared to controls (p < 0.01), with UC exhibiting the strongest association. Peripheral blood neutrophils from UC patients at diagnosis displayed increased NET formation compared to controls and CD patients. Interestingly, NET formation normalized in UC patients following remission-inducing treatment. This pilot study suggests a potential role for NETs in pediatric IBD, particularly UC. These findings warrant further investigation into the mechanisms of NET involvement and the potential for targeting NET formation as a therapeutic strategy.

Prevalence and management of methotrexate-induced neurotoxicity in pediatric patients with osteosarcoma: a single-center experience.

AIMS: To determine the incidence, clinical presentation, and outcome of methotrexate (MTX) associated neurotoxicity in pediatric patients treated for osteosarcoma, with the aim of identifying possible risk factors and suggesting recommended treatment for these sequelae. MATERIALS AND METHODS: All medical files of patients treated for osteosarcoma in a single pediatric haemato-oncology center between November 2011 and August 2021 were retrospectively reviewed. All patients were treated according to the EURAMOS AOST0331 protocol, using cisplatin, doxorubicin, and high-dose MTX at a dose of 12 g/m2 over 4 h. RESULTS: Seventy-eight patients with osteosarcoma were identified (age range 5 to 23 years, 42 males). Seven patients (9%) sustained neurotoxicity following treatment with high-dose MTX. Manifestations of neurotoxicity included among others, generalized seizures, confusion, encephalopathy, dysarthria, and choreiform movements. All but one episode occurred following two sequential cycles of high-dose MTX. All 7 had subacute toxicity, 5-10 days following MTX administration, and 1 had both acute and subacute toxicity. Brain MRI was performed for all patients and demonstrated typical MRI changes attributed to MTX neurotoxicity in 4 of them. Two patients received aminophylline; one patient received dextromethorphan. Patients with normal MRI imaging resumed MTX therapy without any sequels. No risk factors were found for high-dose MTX-related toxicity occurrence. CONCLUSIONS: The time of risk of neurotoxicity due to high-dose MTX treatment for osteosarcoma is days 5-10 following two sequential treatment cycles. These findings together with treatment options for these adverse effects should be detailed in the therapeutic protocol of MTX use among pediatric patients with osteosarcoma.

Lin28 sustains early renal progenitors and induces Wilms tumor.

Wilms Tumor, the most common pediatric kidney cancer, evolves from the failure of terminal differentiation of the embryonic kidney. Here we show that overexpression of the heterochronic regulator Lin28 during kidney development in mice markedly expands nephrogenic progenitors by blocking their final wave of differentiation, ultimately resulting in a pathology highly reminiscent of Wilms tumor. Using lineage-specific promoters to target Lin28 to specific cell types, we observed Wilms tumor only when Lin28 is aberrantly expressed in multiple derivatives of the intermediate mesoderm, implicating the cell of origin as a multipotential renal progenitor. We show that withdrawal of Lin28 expression reverts tumorigenesis and markedly expands the numbers of glomerulus-like structures and that tumor formation is suppressed by enforced expression of Let-7 microRNA. Finally, we demonstrate overexpression of the LIN28B paralog in a significant percentage of human Wilms tumor. Our data thus implicate the Lin28/Let-7 pathway in kidney development and tumorigenesis.

Novel homozygous ENPP1 mutation causes generalized arterial calcifications of infancy, thrombocytopenia, and cardiovascular and central nervous system syndrome.

Generalized arterial calcifications of infancy (GACI) is caused by mutations in ENPP1. Other ENPP1-related phenotypes include pseudoxanthoma elasticum, hypophosphatemic rickets, and Cole disease. We studied four children from two Bedouin consanguineous families who presented with severe clinical phenotype including thrombocytopenia, hypoglycemia, hepatic, and neurologic manifestations. Initial working diagnosis included congenital infection; however, patients remained without a definitive diagnosis despite extensive workup. Consequently, we investigated a potential genetic etiology. Whole exome sequencing (WES) was performed for affected children and their parents. Following the identification of a novel mutation in the ENPP1 gene, we characterized this novel multisystemic presentation and revised relevant imaging studies. Using WES, we identified a novel homozygous mutation (c.556G > C; p.Gly186Arg) in ENPP1 which affects a highly conserved protein domain (somatomedin B2). ENPP1-associated genetic diseases exhibit phenotypic heterogeneity depending on mutation type and location. Follow-up clinical characterization of these families allowed us to revise and detect new features of systemic calcifications, which established the diagnosis of GACI, expanding the phenotypic spectrum associated with ENPP1 mutations. Our findings demonstrate that this novel ENPP1 founder mutation can cause a fatal multisystemic phenotype, mimicking severe congenital infection. This also represents the first reported mutation affecting the SMB2 domain, associated with GACI.

Mutations in TBX18 Cause Dominant Urinary Tract Malformations via Transcriptional Dysregulation of Ureter Development.

Congenital anomalies of the kidneys and urinary tract (CAKUT) are the most common cause of chronic kidney disease in the first three decades of life. Identification of single-gene mutations that cause CAKUT permits the first insights into related disease mechanisms. However, for most cases the underlying defect remains elusive. We identified a kindred with an autosomal-dominant form of CAKUT with predominant ureteropelvic junction obstruction. By whole exome sequencing, we identified a heterozygous truncating mutation (c.1010delG) of T-Box transcription factor 18 (TBX18) in seven affected members of the large kindred. A screen of additional families with CAKUT identified three families harboring two heterozygous TBX18 mutations (c.1570C>T and c.487A>G). TBX18 is essential for developmental specification of the ureteric mesenchyme and ureteric smooth muscle cells. We found that all three TBX18 altered proteins still dimerized with the wild-type protein but had prolonged protein half life and exhibited reduced transcriptional repression activity compared to wild-type TBX18. The p.Lys163Glu substitution altered an amino acid residue critical for TBX18-DNA interaction, resulting in impaired TBX18-DNA binding. These data indicate that dominant-negative TBX18 mutations cause human CAKUT by interference with TBX18 transcriptional repression, thus implicating ureter smooth muscle cell development in the pathogenesis of human CAKUT.

A Dominant Mutation in Nuclear Receptor Interacting Protein 1 Causes Urinary Tract Malformations via Dysregulation of Retinoic Acid Signaling.

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of CKD in the first three decades of life. However, for most patients with CAKUT, the causative mutation remains unknown. We identified a kindred with an autosomal dominant form of CAKUT. By whole-exome sequencing, we identified a heterozygous truncating mutation (c.279delG, p.Trp93fs*) of the nuclear receptor interacting protein 1 gene (NRIP1) in all seven affected members. NRIP1 encodes a nuclear receptor transcriptional cofactor that directly interacts with the retinoic acid receptors (RARs) to modulate retinoic acid transcriptional activity. Unlike wild-type NRIP1, the altered NRIP1 protein did not translocate to the nucleus, did not interact with RARα, and failed to inhibit retinoic acid-dependent transcriptional activity upon expression in HEK293 cells. Notably, we also showed that treatment with retinoic acid enhanced NRIP1 binding to RARα RNA in situ hybridization confirmed Nrip1 expression in the developing urogenital system of the mouse. In explant cultures of embryonic kidney rudiments, retinoic acid stimulated Nrip1 expression, whereas a pan-RAR antagonist strongly reduced it. Furthermore, mice heterozygous for a null allele of Nrip1 showed a CAKUT-spectrum phenotype. Finally, expression and knockdown experiments in Xenopus laevis confirmed an evolutionarily conserved role for NRIP1 in renal development. These data indicate that dominant NRIP1 mutations can cause CAKUT by interference with retinoic acid transcriptional signaling, shedding light on the well documented association between abnormal vitamin A levels and renal malformations in humans, and suggest a possible gene-environment pathomechanism in this disease.

Targeted therapy aimed at cancer stem cells: Wilms' tumor as an example.

Wilms' tumor (WT), a common renal pediatric solid tumor, serves as a model for a malignancy formed by renal precursor cells that have failed to differentiate properly. Here we review recent evidence showing that the tumors' heterogeneous cell population contains a small fraction of cancer stem cells (CSC) identified by two markers: Neural Cell Adhesion Molecule 1 (NCAM1) expression and Aldehyde dehydrogenase 1 (ALDH1) enzymatic activity. In vivo studies show these CSCs to both self-renew and differentiate to give rise to all tumor components. Similar to other malignancies, the identification of a specific CSC fraction has allowed the examination of a novel targeted therapy, aimed at eradicating the CSC population. The loss of CSCs abolishes the tumor's ability to sustain and propagate, hence, causing tumor degradation with minimal damage to normal tissue.

Weight loss and response to chemotherapy in pediatric patients with osteosarcoma.

BACKGROUND: Weight loss and malnutrition are common findings in pediatric oncology patients, but their prognostic significance is controversial. We sought to evaluate the correlation between weight loss and response to neo-adjuvant chemotherapy in pediatric patients with osteosarcoma. PROCEDURE: All medical files of patients treated for osteosarcoma in a single pediatric haemato-oncology center between January 2011 and October 2022 were retrospectively reviewed. RESULTS: Sixty-three patients were suitable for study inclusion. Data on changes in their body weight between the initiation of neo-adjuvant chemotherapy and local therapy (tumor resection) were extracted. Response to chemotherapy was assessed by the percentage of tumor necrosis at the time of surgery. There was a significant direct correlation between a weight loss of 3% and above and good response to chemotherapy as demonstrated by tumor necrosis above 90%. CONCLUSIONS: Low caloric intake may imitate a caloric restriction diet that was proven to improve response to therapy in some oncological diseases. Further prospective trials are needed for the establishment of recommended caloric intake during chemotherapy in pediatric patients with osteosarcoma.

Altered neutrophil extracellular traps formation among medical residents with sleep deprivation.

Resident physicians on long-term night shifts often face sleep deprivation, affecting the immune response, notably neutrophils, vital to innate defense mechanisms. Sleep-deprived residents exhibit altered neutrophil counts and reduced phagocytosis and NADPH oxidase activity, critical to combating infections. Our study focused on neutrophil extracellular traps (NETs), a defense process against pathogens not previously linked to sleep loss. Results revealed that sleep-deprived residents exhibited a 19.8 % reduction in NET formation compared to hospital workers with regular sleep patterns (P < 0.01). Additionally, key NETs proteins, Neutrophil Elastase and Myeloperoxidase, were less active in sleep-deprived individuals (1.53mU; P < 0.01 and 0.95U; P < 0.001 decrease, accordingly). Interestingly, the ability to form NETs resumed to normal levels three months post-residency among pediatric residents. The causal relationship between reduced NETs due to sleep deprivation and the increased susceptibility to infections, as well as its implications for infection severity, is a critical area for further investigation.

Neutrophils extracellular traps formation may serve as a biomarker for disease activity in oligoarticular juvenile idiopathic arthritis: a pilot study.

BACKGROUND: Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in children, causing significant morbidity. Despite the dramatic improvement in treatment, many patients do not achieve complete remission, and biomarkers for subclinical disease, flares, and response to treatment are lacking. Neutrophils and neutrophil extracellular traps (NETs) play key roles in the pathogenesis of autoimmune and inflammatory conditions. In this study, we characterized neutrophil enzyme activity and NETs formation in oligoarticular and polyarticular JIA and explored their association with disease activity. METHODS: Neutrophils from 6 healthy controls and 7 patients with oligoarticular and polyarticular JIA were freshly isolated at time of diagnosis and after glucocorticoid intra-articular injection. Enzymatic activity of neutrophil granular enzymes was monitored by colorimetry and PMA-activated NETs formation was assessed using fluorescent microscopy. RESULTS: In this pilot and feasibility study, we revealed that NETs were significantly increased in oligoarticular JIA patients at time of diagnosis compared to healthy controls. Anti-inflammatory treatment using intra-articular steroid injection normalized NETs formation in these patients. Correlation between NETs formation and clinical Juvenile Activity Disease Activity Score-10 (cJADAS-10) was linear and significant (P = 0.007) in oligo but not in poly JIA patients. CONCLUSIONS: This is the first study exploring the link of NETs formation with oligo and poly JIA activity. We demonstrated a statistically significant linear correlation between cJADAS-10 and NETs formation in oligo but not in poly JIA patients. Hence, we suggest that NETs may reflect clinical disease activity in JIA, and may serve as a putative biomarker. Further work is needed to validate these initial results and determine the dynamics of NETs formation in JIA.

Selinexor, a selective inhibitor of nuclear export, inhibits human neutrophil extracellular trap formation in vitro.

Neutrophils are central players in the innate immune system. To protect against invading pathogens, neutrophils can externalize chromatin to create neutrophil extracellular traps (NETs). While NETs are critical to host defense, they also have deleterious effects, and dysregulation of NETs formation has been implicated in autoimmune diseases, atherosclerosis and thrombotic conditions, cancer progression and dissemination, and acute respiratory distress syndrome. Here, we report that selinexor, a first-in-class selective inhibitor of nuclear export approved for the treatment of multiple myeloma and diffuse large B-cell lymphoma, markedly suppressed the release of NETs in vitro. Furthermore, we demonstrate a significant inhibitory effect of selinexor on NETs formation, but not on oxidative burst or enzymatic activities central to NETs release such as neutrophil elastase, myeloperoxidase or peptidyl arginine deiminase type IV. The inhibitory effect of selinexor was demonstrated in neutrophils activated by a variety of NETs-inducers, including PMA, TGF-ß, TNF-α and IL-8. Maximal inhibition of NETs formation was observed using TGF-ß, for which selinexor inhibited NETs release by 61.6%. These findings pave the way to the potential use of selinexor in an effort to reduce disease burden by inhibition of NETs.

Characterization of alternative mRNA splicing in cultured cell populations representing progressive stages of human fetal kidney development.

Nephrons are the functional units of the kidney. During kidney development, cells from the cap mesenchyme-a transient kidney-specific progenitor state-undergo a mesenchymal to epithelial transition (MET) and subsequently differentiate into the various epithelial cell types that create the tubular structures of the nephron. Faults in this transition can lead to a pediatric malignancy of the kidney called Wilms' tumor that mimics normal kidney development. While human kidney development has been characterized at the gene expression level, a comprehensive characterization of alternative splicing is lacking. Therefore, in this study, we performed RNA sequencing on cell populations representing early, intermediate, and late developmental stages of the human fetal kidney, as well as three blastemal-predominant Wilms' tumor patient-derived xenografts. Using this newly generated RNAseq data, we identified a set of transcripts that are alternatively spliced between the different developmental stages. Moreover, we found that cells from the earliest developmental stage have a mesenchymal splice-isoform profile that is similar to that of blastemal-predominant Wilms' tumor xenografts. RNA binding motif enrichment analysis suggests that the mRNA binding proteins ESRP1, ESRP2, RBFOX2, and QKI regulate alternative mRNA splicing during human kidney development. These findings illuminate new molecular mechanisms involved in human kidney development and pediatric kidney cancer.

NCAM1/FGF module serves as a putative pleuropulmonary blastoma therapeutic target.

Pleuropulmonary blastoma (PPB) is a rare pediatric lung neoplasm that recapitulates developmental pathways of early embryonic lungs. As lung development proceeds with highly regulated mesenchymal-epithelial interactions, a DICER1 mutation in PPB generates a faulty lung differentiation program with resultant biphasic tumors composed of a primitive epithelial and mesenchymal stroma with early progenitor blastomatous cells. Deciphering of PPB progression has been hampered by the difficulty of culturing PPB cells, and specifically progenitor blastomatous cells. Here, we show that in contrast with in-vitro culture, establishment of PPB patient-derived xenograft (PDX) in NOD-SCID mice selects for highly proliferating progenitor blastoma overexpressing critical regulators of lung development and multiple imprinted genes. These stem-like tumors were sequentially interrogated by gene profiling to show a FGF module that is activated alongside Neural cell adhesion molecule 1 (NCAM1). Targeting the progenitor blastoma and these transitions with an anti-NCAM1 immunoconjugate (Lorvotuzumab mertansine) inhibited tumor growth and progression providing new paradigms for PPB therapeutics. Altogether, our novel in-vivo PPB xenograft model allowed us to enrich for highly proliferating stem-like cells and to identify FGFR and NCAM1 as two key players that can serve as therapeutic targets in this poorly understood and aggressive disease.

Whole exome sequencing in childhood-onset lupus frequently detects single gene etiologies.

BACKGROUND: Systemic lupus erythematosus (SLE) comprise a diverse range of clinical manifestations. To date, more than 30 single gene causes of lupus/lupus like syndromes in humans have been identified. In the clinical setting, identifying the underlying molecular diagnosis is challenging due to phenotypic and genetic heterogeneity. METHODS: We employed whole exome sequencing (WES) in patients presenting with childhood-onset lupus with severe and/or atypical presentations to identify cases that are explained by a single-gene (monogenic) cause. RESULTS: From January 2015 to June 2018 15 new cases of childhood-onset SLE were diagnosed in Edmond and Lily Safra Children's Hospital. By WES we identified causative mutations in four subjects in five different genes: C1QC, SLC7A7, MAN2B1, PTEN and STAT1. No molecular diagnoses were established on clinical grounds prior to genetic testing. CONCLUSIONS: We identified a significant fraction of monogenic SLE etiologies using WES and confirm the genetic locus heterogeneity in childhood-onset lupus. These results highlight the importance of establishing a genetic diagnosis for children with severe or atypical lupus by providing accurate and early etiology-based diagnoses and improving subsequent clinical management.

In Vivo Expansion of Cancer Stemness Affords Novel Cancer Stem Cell Targets: Malignant Rhabdoid Tumor as an Example.

Cancer stem cell (CSC) identification relies on transplantation assays of cell subpopulations sorted from fresh tumor samples. Here, we attempt to bypass limitations of abundant tumor source and predetermined immune selection by in vivo propagating patient-derived xenografts (PDX) from human malignant rhabdoid tumor (MRT), a rare and lethal pediatric neoplasm, to an advanced state in which most cells behave as CSCs. Stemness is then probed by comparative transcriptomics of serial PDXs generating a gene signature of epithelial to mesenchymal transition, invasion/motility, metastasis, and self-renewal, pinpointing putative MRT CSC markers. The relevance of these putative CSC molecules is analyzed by sorting tumorigenic fractions from early-passaged PDX according to one such molecule, deciphering expression in archived primary tumors, and testing the effects of CSC molecule inhibition on MRT growth. Using this platform, we identify ALDH1 and lysyl oxidase (LOX) as relevant targets and provide a larger framework for target and drug discovery in rare pediatric cancers.

Wilms Tumor NCAM-Expressing Cancer Stem Cells as Potential Therapeutic Target for Polymeric Nanomedicine.

Cancer stem cells (CSC) form a specific population within the tumor that has been shown to have self-renewal and differentiation properties, increased ability to migrate and form metastases, and increased resistance to chemotherapy. Consequently, even a small number of cells remaining after therapy can repopulate the tumor and cause recurrence of the disease. CSCs in Wilms tumor, a pediatric renal cancer, were previously shown to be characterized by neural cell adhesion molecule (NCAM) expression. Therefore, NCAM provides a specific biomarker through which the CSC population in this tumor can be targeted. We have recently developed an NCAM-targeted nanosized conjugate of paclitaxel bound to a biodegradable polyglutamic acid polymer. In this work, we examined the ability of the conjugate to inhibit Wilms tumor by targeting the NCAM-expressing CSCs. Results show that the conjugate selectively depleted the CSC population of the tumors and effectively inhibited tumor growth without causing toxicity. We propose that the NCAM-targeted conjugate could be an effective therapeutic for Wilms tumor. Mol Cancer Ther; 16(11); 2462-72. ©2017 AACR.

Dissecting Stages of Human Kidney Development and Tumorigenesis with Surface Markers Affords Simple Prospective Purification of Nephron Stem Cells.

When assembling a nephron during development a multipotent stem cell pool becomes restricted as differentiation ensues. A faulty differentiation arrest in this process leads to transformation and initiation of a Wilms' tumor. Mapping these transitions with respective surface markers affords accessibility to specific cell subpopulations. NCAM1 and CD133 have been previously suggested to mark human renal progenitor populations. Herein, using cell sorting, RNA sequencing, in vitro studies with serum-free media and in vivo xenotransplantation we demonstrate a sequential map that links human kidney development and tumorigenesis; In nephrogenesis, NCAM1(+)CD133(-) marks SIX2(+) multipotent renal stem cells transiting to NCAM1(+)CD133(+) differentiating segment-specific SIX2(-) epithelial progenitors and NCAM1(-)CD133(+) differentiated nephron cells. In tumorigenesis, NCAM1(+)CD133(-) marks SIX2(+) blastema that includes the ALDH1(+) WT cancer stem/initiating cells, while NCAM1(+)CD133(+) and NCAM1(-)CD133(+) specifying early and late epithelial differentiation, are severely restricted in tumor initiation capacity and tumor self-renewal. Thus, negative selection for CD133 is required for defining NCAM1(+) nephron stem cells in normal and malignant nephrogenesis.

A human integrin-α3 mutation confers major renal developmental defects.

The development of the mammalian kidney is a highly complex process dependent upon the interplay of various cell types, secreted morphogens, and the extra-cellular matrix (ECM). Although integrins are the most important receptors for ECM proteins and are ubiquitously expressed during kidney development, mice lacking expression of integrin α3 (Itga3) do not demonstrate a reduced number of nephrons, but mostly a disorganized GBM (glomerular basement membrane) leading to proteinuria. Thus, ITGA3 is considered mostly a passive GBM stabilizer and not an active player in nephrogenesis. Recently, mutations in the human ITGA3 were shown to cause congenital nephrotic syndrome, epidermolysis bullosa and interstitial lung disease, otherwise termed NEP syndrome (Nephrotic syndrome, Epidermolysis bullosa and Pulmonary disease). Herein, we performed histological and molecular analysis on the kidneys of a single patient from the initial cohort harboring an ITGA3 mutation, to illuminate the role of ITGA3 in human renal development. We show the patient to harbor a unique phenotype at birth, including severe unilateral renal hypodysplasia. Interrogation of global gene expression in the hypodysplastic kidney versus three controls (fetal, child and adult kidneys) revealed perturbed expression in several renal developmental pathways implicated in hypodysplasia, including the Wnt, BMP (bone morphogenetic protein) and TGF (transforming growth factor) pathways. Moreover, the affected kidney showed upregulation of early embryonic genes (e.g. OCT4 and PAX8) concomitant with downregulated kidney differentiation markers, implying a defect in proper renal differentiation. In conclusion, we show for the first time that ITGA3 is not merely a passive anchor for renal ECM proteins, as predicted by mouse models. Instead, our results may suggest it plays a central role in the interplay of cells, morphogens and ECM, required for proper nephrogenesis, thus adding ITGA3 to the list of CAKUT (congenital anomalies of the kidney and urinary tract)-causing genes.