Refined high-content imaging-based phenotypic drug screening in zebrafish xenografts.

Zebrafish xenotransplantation models are increasingly applied for phenotypic drug screening to identify small compounds for precision oncology. Larval zebrafish xenografts offer the opportunity to perform drug screens at high-throughput in a complex in vivo environment. However, the full potential of the larval zebrafish xenograft model has not yet been realized and several steps of the drug screening workflow still await automation to increase throughput. Here, we present a robust workflow for drug screening in zebrafish xenografts using high-content imaging. We established embedding methods for high-content imaging of xenografts in 96-well format over consecutive days. In addition, we provide strategies for automated imaging and analysis of zebrafish xenografts including automated tumor cell detection and tumor size analysis over time. We also compared commonly used injection sites and cell labeling dyes and show specific site requirements for tumor cells from different entities. We demonstrate that our setup allows us to investigate proliferation and response to small compounds in several zebrafish xenografts ranging from pediatric sarcomas and neuroblastoma to glioblastoma and leukemia. This fast and cost-efficient assay enables the quantification of anti-tumor efficacy of small compounds in large cohorts of a vertebrate model system in vivo. Our assay may aid in prioritizing compounds or compound combinations for further preclinical and clinical investigations.

Staging of newly diagnosed Ewing sarcoma: Results of bone marrow aspiration and biopsy versus (18)FDG-PET/CT imaging for bone marrow involvement.

BACKGROUND: Ewing sarcoma (ES) is an aggressive bone or extraosseous tumour with an unfavourable prognosis when bone marrow metastases are present at diagnosis. The gold standard diagnosis for bone marrow (BM) involvement is cytological and pathological analysis through bone marrow aspiration and biopsy (BMAB). Several recent studies suggest that these invasive and painful procedures could be replaced by 18F-fluorodeoxyglucose-positron emission tomography/computed tomography ((18)FDG-PET/CT), as this nuclear imaging technique is highly sensitive at detecting bone and extraosseous metastases of ES. METHODS: In order to study the precision of (18)FDG-PET/CT in the evaluation of bone marrow metastases at diagnosis, we compared the imaging results with cytological/histological analyses performed on BM samples. We retrospectively studied 180 patients with ES recorded at the Léon Bérard Centre over the past 10 years, who were evaluated by (18)FDG-PET/CT and BMAB at diagnosis. RESULTS: Of the 180 patients, 13 displayed marrow metastases by cytological/histological examination, and only one of these did not have (18)FDG-PET/CT signs of bone marrow involvement, whereas the 167 remaining patients without marrow metastasis all had a negative (18)FDG-PET/CT, except for one. Hence, the sensitivity and specificity of (18)FDG-PET/CT in these patients was 92.3% and 99.4%, respectively. The overall survival at five years of all patients was 67.4% but decrease to 38.5% in the group with bone marrow metastases. CONCLUSION: Given the results presented herein the bone sarcoma group of the French Sarcoma Group suggests that invasive BMAB no longer be systematically performed for the staging at the diagnosis of ES.

Loss of SMARCB1 expression in colon carcinoma.

SMARCB1 is a tumor suppressor gene, which is part of SWI/SNF complex involved in transcriptional regulation. Recently, loss of SMARCB1 expression has been reported in gastrointestinal carcinomas. Our purpose was to evaluate the incidence and prognostic value of SMARCB1 loss in colon carcinoma (CC). Patients with stage III CC (n= 1695), and a second cohort of 23 patients with poorly differentiated CC were analyzed. Immunohistochemistry for SMARCB1 was performed on tissue microarrays, and cases with loss of expression were controlled on whole sections. Loss of SMARCB1 was compared with the clinico-pathological and molecular characteristics, and the prognostic value was evaluated. Loss of SMARCB1 was identified in 12 of 1695 (0.7%) patients with stage III CC. Whole section controls showed a complete loss in only one of these cases, corresponding to a medullary carcinoma. SMARCB1 loss was not associated with histological grade, tumor size nor survival. In the cohort of poorly differentiated CC, we detected 2/23 (8.7%) cases with loss of SMARCB1; one was rhabdoid while the other had medullary and mucinous histology. These 2 cases were deficient for MisMatched Repair (dMMR) and mutated for BRAF. SMARCB1 loss is rare in stage III CC, but appears more frequent in poorly differentiated CC.

Cell-to-cell heterogeneity of EWSR1-FLI1 activity determines proliferation/migration choices in Ewing sarcoma cells.

Ewing sarcoma is characterized by the expression of the chimeric EWSR1-FLI1 transcription factor. Proteomic analyses indicate that the decrease of EWSR1-FLI1 expression leads to major changes in effectors of the dynamics of the actin cytoskeleton and the adhesion processes with a shift from cell-to-cell to cell-matrix adhesion. These changes are associated with a dramatic increase of in vivo cell migration and invasion potential. Importantly, EWSR1-FLI1 expression, evaluated by single-cell RT-ddPCR/immunofluorescence analyses, and activity, assessed by expression of EWSR1-FLI1 downstream targets, are heterogeneous in cell lines and in tumours and can fluctuate along time in a fully reversible process between EWSR1-FLI1high states, characterized by highly active cell proliferation, and EWSR1-FLI1low states where cells have a strong propensity to migrate, invade and metastasize. This new model of phenotypic plasticity proposes that the dynamic fluctuation of the expression level of a dominant oncogene is an intrinsic characteristic of its oncogenic potential.

EWS-FLI1-mediated suppression of the RAS-antagonist Sprouty 1 (SPRY1) confers aggressiveness to Ewing sarcoma.

Ewing sarcoma is characterized by chromosomal translocations fusing the EWS gene with various members of the ETS family of transcription factors, most commonly FLI1. EWS-FLI1 is an aberrant transcription factor driving Ewing sarcoma tumorigenesis by either transcriptionally inducing or repressing specific target genes. Herein, we showed that Sprouty 1 (SPRY1), which is a physiological negative feedback inhibitor downstream of fibroblast growth factor (FGF) receptors (FGFRs) and other RAS-activating receptors, is an EWS-FLI1 repressed gene. EWS-FLI1 knockdown specifically increased the expression of SPRY1, while other Sprouty family members remained unaffected. Analysis of SPRY1 expression in a panel of Ewing sarcoma cells showed that SPRY1 was not expressed in Ewing sarcoma cell lines, suggesting that it could act as a tumor suppressor gene in these cells. In agreement, induction of SPRY1 in three different Ewing sarcoma cell lines functionally impaired proliferation, clonogenic growth and migration. In addition, SPRY1 expression inhibited extracellular signal-related kinase/mitogen-activated protein kinase (MAPK) signaling induced by serum and basic FGF (bFGF). Moreover, treatment of Ewing sarcoma cells with the potent FGFR inhibitor PD-173074 reduced bFGF-induced proliferation, colony formation and in vivo tumor growth in a dose-dependent manner, thus mimicking SPRY1 activity in Ewing sarcoma cells. Although the expression of SPRY1 was low when compared with other tumors, SPRY1 was variably expressed in primary Ewing sarcoma tumors and higher expression levels were significantly associated with improved outcome in a large patient cohort. Taken together, our data indicate that EWS-FLI1-mediated repression of SPRY1 leads to unrestrained bFGF-induced cell proliferation, suggesting that targeting the FGFR/MAPK pathway can constitute a promising therapeutic approach for this devastating disease.

[Over-reduction after distal radius fracture pinning in young active patients: Prevention by multiple mixed pinning]. / Hyperréduction après brochage des fractures de l'extrémité distale du radius chez le sujet jeune actif. Prévention par brochage mixte multiple.

Over-reduction is a classical complication following pinning of distal radius fractures. Indeed, the pinning techniques derived from Kapandji's technique do not allow anterior stabilization. A literature review and our experience show that it is an underestimated complication that can affect up to one-third of cases, but that is well tolerated if the anterior tilt is less than 20°. Excessive angulation of the dorsal intrafocal K-wires becomes a significant risk factor beyond 60°. Volar comminution of the fracture is an obvious predisposing factor. We will outline our ideas on the topic and present a new pinning technique, which has reduced the over-reduction rate to below 3 %: multiple mixed pinning combines two dorsal intrafocal K-wires with two trans-styloid K-wires along the anterior and posterior cortices of the radius to provide true sagittal stabilization of the fracture. This technique is suitable for fractures without major instability or associated anterior comminution-Milliez types 1 and 2 are its best indications. In our practice, there still is a place for pinning of non-complex fractures in young active subjects. More than 20° malunion in flexion can lead to symptoms; in this instance, isolated opening osteotomy of the radius is the most suitable technique.

Identification of genetic variants in pharmacokinetic genes associated with Ewing Sarcoma treatment outcome.

BACKGROUND: Despite the effectiveness of current treatment protocols for Ewing sarcoma (ES), many patients still experience relapse, and survival following recurrence is <15%. We aimed to identify genetic variants that predict treatment outcome in children diagnosed with ES. PATIENTS AND METHODS: We carried out a pharmacogenetic study of 384 single-nucleotide polymorphisms (SNPs) in 24 key transport or metabolism genes relevant to drugs used to treat in pediatric patients (<30 years) with histologically confirmed ES. We studied the association of genotypes with tumor response and overall survival (OS) in a discovery cohort of 106 Spanish children, with replication in a second cohort of 389 pediatric patients from across Europe. RESULTS: We identified associations with OS (P < 0.05) for three SNPs in the Spanish cohort that were replicated in the European cohort. The strongest association observed was with rs7190447, located in the ATP-binding cassette subfamily C member 6 (ABCC6) gene [discovery: hazard ratio (HR) = 14.30, 95% confidence interval (CI) = 1.53-134, P = 0.020; replication: HR = 9.28, 95% CI = 2.20-39.2, P = 0.0024] and its correlated SNP rs7192303, which was predicted to have a plausible regulatory function. We also replicated associations with rs4148737 in the ATP-binding cassette subfamily B member 1 (ABCB1) gene (discovery: HR = 2.96, 95% CI = 1.08-8.10, P = 0.034; replication: HR = 1.60, 95% CI = 1.05-2.44, P = 0.029), which we have previously found to be associated with poorer OS in pediatric osteosarcoma patients, and rs11188147 in cytochrome P450 family 2 subfamily C member 8 gene (CYP2C8) (discovery : HR = 2.49, 95% CI = 1.06-5.87, P = 0.037; replication: HR = 1.77, 95% CI = 1.06-2.96, P = 0.030), an enzyme involved in the oxidative metabolism of the ES chemotherapeutic agents cyclophosphamide and ifosfamide. None of the associations with tumor response were replicated. CONCLUSION: Using an integrated pathway-based approach, we identified polymorphisms in ABCC6, ABCB1 and CYP2C8 associated with OS. These associations were replicated in a large independent cohort, highlighting the importance of pharmacokinetic genes as prognostic markers in ES.

Development of curative therapies for Ewing sarcomas by interdisciplinary cooperative groups in Europe.

Curative therapies for Ewing sarcoma have been developed within cooperative groups. Consecutive clinical trials have systematically assessed the impact and timing of local therapy and the activity of cytotoxic drugs and their combinations. They have led to an increase of long-term disease-free survival to around 70% in patients with localized disease. Translational research in ES remains an area in which interdisciplinary and international cooperation is essential for future progress. This article reviews current state-of-the art therapy, with a focus on trials performed in Europe, and summarizes novel strategies to further advance both the cure rates and quality of survival.

["Floating interphalangeal joint". A case report]. / « Articulation interphalangienne flottante ¼. À propos d'un cas.

We report the case of a combination of closed extra-articular phalangeal fractures of the thumb, creating a floating interphalangeal joint. The lesions described were the result of a direct trauma to the thumb during the earthquake in Haiti in January 2010. It was fixed seven days after the trauma using a percutaneous external fixation with a dorsal frame or Martinique's "Ti'fix" - a modification of the Beaubourg fixator. We describe this simple, economical and improved quality method of fixation. Consolidation permitted the removal of the external fixator a month after surgery, followed by early mobilization. We report the functional and aesthetic results at 1-year follow-up.

MiR-30a-5p connects EWS-FLI1 and CD99, two major therapeutic targets in Ewing tumor.

Ewing sarcoma is a pediatric bone tumor characterized in 85% of cases by the fusion between EWS and FLI1 genes that results in the expression of the EWS-FLI1 aberrant transcription factor. Histologically, the Ewing tumor expresses high levels of the CD99 membrane glycoprotein. It has been recently described that CD99 expression contributes to the Ewing tumor oncogenesis by modulating growth and differentiation of tumor cells. Different studies have also shown that overexpression of EWS-FLI1 induces CD99 expression in non-Ewing cells. At the opposite, the knockdown of EWS-FLI1 expression by siRNA approaches has no significant effect on CD99 mRNA level in Ewing cells. Here, by in vivo and in vitro studies, we show that while EWS-FLI1 inhibition has only slight effects on the amount of CD99 transcript, it induces a dramatic decrease of the CD99 protein expression level, hence suggesting post-transcriptional regulations, possibly mediated by microRNAs. To further investigate this issue, we identified a set of 91 miRNAs that demonstrate EWS-FLI1 modulation, three of them being predicted to bind CD99 3' untranslated region (30'UTR). Among these, we show that miR-30a-5p has the ability to interact with the 30'UTR region of CD99 and to regulate its expression. Moreover, the re-expression of miRNA-30a-5p in Ewing cell line induces decreased cell proliferation and invasion. In this study, we therefore show that miR-30a-5p constitutes a major functional link between EWS-FLI1 and CD99, two critical biomarkers and therapeutic targets in Ewing sarcoma.

P-cadherin is a direct PAX3-FOXO1A target involved in alveolar rhabdomyosarcoma aggressiveness.

Alveolar rhabdomyosarcoma (ARMS) is an aggressive childhood cancer of striated muscle characterized by the presence of the PAX3-FOXO1A or PAX7-FOXO1A chimeric oncogenic transcription factor. Identification of their targets is essential for understanding ARMS pathogenesis. To this aim, we analyzed transcriptomic data from rhabdomyosarcoma samples and found that P-cadherin expression is correlated with PAX3/7-FOXO1A presence. We then show that expression of a PAX3 dominant negative variant inhibits P-cadherin expression in ARMS cells. Using mouse models carrying modified Pax3 alleles, we demonstrate that P-cadherin is expressed in the dermomyotome and lies genetically downstream from the myogenic factor Pax3. Moreover, in vitro gel shift analysis and chromatin immunoprecipitation indicate that the P-cadherin gene is a direct transcriptional target for PAX3/7-FOXO1A. Finally, P-cadherin expression in normal myoblasts inhibits myogenesis and induces myoblast transformation, migration and invasion. Conversely, P-cadherin downregulation by small hairpin RNA decreases the transformation, migration and invasive potential of ARMS cells. P-cadherin also favors cadherin switching, which is a hallmark of metastatic progression, by controlling N- and M-cadherin expression and/or localization. Our findings demonstrate that P-cadherin is a direct PAX3-FOXO1A transcriptional target involved in ARMS aggressiveness. Therefore, P-cadherin emerges as a new and attractive target for therapeutic intervention in ARMS.

Segmental chromosomal alterations lead to a higher risk of relapse in infants with MYCN-non-amplified localised unresectable/disseminated neuroblastoma (a SIOPEN collaborative study).

BACKGROUND: In neuroblastoma (NB), the presence of segmental chromosome alterations (SCAs) is associated with a higher risk of relapse. METHODS: In order to analyse the role of SCAs in infants with localised unresectable/disseminated NB without MYCN amplification, we have performed an array CGH analysis of tumours from infants enrolled in the prospective European INES trials. RESULTS: Tumour samples from 218 out of 300 enroled patients could be analysed. Segmental chromosome alterations were observed in 11%, 20% and 59% of infants enroled in trials INES99.1 (localised unresectable NB), INES99.2 (stage 4s) and INES99.3 (stage 4) (P<0.0001). Progression-free survival was poorer in patients whose tumours harboured SCA, in the whole population and in trials INES99.1 and INES99.2, in the absence of clinical symptoms (log-rank test, P=0.0001, P=0.04 and P=0.0003, respectively). In multivariate analysis, a SCA genomic profile was the strongest predictor of poorer progression-free survival. CONCLUSION: In infants with stage 4s MYCN-non-amplified NB, a SCA genomic profile identifies patients who will require upfront treatment even in the absence of other clinical indication for therapy, whereas in infants with localised unresectable NB, a genomic profile characterised by the absence of SCA identifies patients in whom treatment reduction might be possible. These findings will be implemented in a future international trial.

The constitutive activity of the ALK mutated at positions F1174 or R1275 impairs receptor trafficking.

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase (RTK), which is transiently expressed during development of the central and peripheral nervous system. ALK has been recently identified as a major neuroblastoma predisposition gene and activating mutations have also been identified in a subset of sporadic neuroblastoma tumors. Two hot spots of ALK mutations have been observed at positions F1174 and R1275. Here, we studied stably transfected cell lines expressing wild-type or F1174L- or R1275Q-mutated ALK in parallel with a neuroblastoma cell line (CLB-GE) in which the allele mutated at position F1174 is amplified. We observed that the mutated ALK variants were essentially intracellular and were largely retained in the reticulum/Golgi compartments. This localization was corroborated by a defect of N-linked glycosylation. Although the mutated receptors exhibited a constitutive activation, the minor pool of receptor addressed to the plasma membrane was much more tyrosine phosphorylated than the intracellular pool. The use of antagonist monoclonal antibodies suggested that the constitutive activity of the mutated receptors did not require the dimerization of the receptor, whereas adequate dimerization triggered by agonist monoclonal antibodies increased this activity. Finally, kinase inactivation of the mutated receptors restored maturation and cell-surface localization. Our results show that constitutive activation of ALK results in its impaired maturation and intracellular retention. Furthermore, they provide a rationale for the potential use of kinase inhibitors and antibodies in ALK-dependent tumors.

MicroRNA-206 expression levels correlate with clinical behaviour of rhabdomyosarcomas.

BACKGROUND: Rhabdomyosarcomas (RMSs) are primarily paediatric sarcomas that resemble developing skeletal muscle. Our aim was to determine the effects of microRNAs (miRNA) that have been implicated in muscle development on the clinical behaviour of RMSs. METHODS: Expression levels of miR-1, miR-206, miR-133a and miR-133b were quantified by RT-PCR in 163 primary paediatric RMSs, plus control tissues, and correlated with clinico-pathological features. Correlations with parallel gene expression profiling data for 84 samples were used to identify pathways associated with miR-206. Synthetic miR-206 was transfected into RMS cell lines and phenotypic responses assessed. RESULTS: Muscle-specific miRNAs levels were lower in RMSs compared with skeletal muscle but generally higher than in other normal tissues. Low miR-206 expression correlated with poor overall survival and was an independent predictor of shorter survival in metastatic embryonal and alveolar cases without PAX3/7-FOXO1 fusion genes. Low miR-206 expression also significantly correlated with high SIOP stage and the presence of metastases at diagnosis. High miR-206 expression strongly correlated with genes linked to muscle differentiation and low expression was associated with genes linked to MAPkinase and NFKappaB pathway activation. Increasing miR-206 expression in cell lines inhibited cell growth and migration and induced apoptosis that was associated with myogenic differentiation in some, but not all, cell lines. CONCLUSION: miR-206 contributes to the clinical behaviour of RMSs and the pleiotropic effects of miR-206 supports therapeutic potential.

Molecular pathogenesis of peripheral neuroblastic tumors.

Neuroblastoma (NB) is an embryonal cancer of the sympathetic nervous system observed in early childhood, characterized by a broad spectrum of clinical behaviors, ranging from spontaneous regression to fatal outcome despite aggressive therapies. NB accounts for 8-10% of pediatric cancers and 15% of the deaths attributable to malignant conditions in children. Interestingly, NB may occur in various contexts, being mostly sporadic but also familial or syndromic. This review focuses on recent advances in the identification of the genes and mechanisms implicated in NB pathogenesis. Although the extensive characterization of the genomic aberrations recurrently observed in sporadic NBs provides important insights into the understanding of the clinical heterogeneity of this neoplasm, analysis of familial and syndromic cases also unravels essential clues on the genetic bases of NB. Recently, the ALK gene emerged as an important NB gene, being implicated both in sporadic and familial cases. The identification of gene expression signatures associated with patient's outcome points out the potential of using gene expression profiling to improve clinical management of patients suffering from NB. Finally, based on recent observations integrating genomic analyses, biological data and clinical information, we discuss possible evolution/progression schemes in NB.

[Rhadboid tumours: hSNF/INI1 deficient cancers of early childhood with aggressive behaviour]. / Les tumeurs rhabdoïdes : des tumeurs hSNF5/INI1-déficientes précoces et agressives.

Rhabdoid tumours are rare aggressive tumours of infancy. The definition classically relies on a characteristic morphology and the inactivation of the hSNF5/INI1 tumour suppressor gene. This entity includes central nervous system tumours (ATRT), renal tumours (RTK) and soft-part tumours. Their rarity and morphological pleomorphism make the diagnosis often challenging. However, the recently introduced immunohistochemistry with anti-INI1 (anti-SMARCB1) antibody is a very useful diagnostic tool. Deletions at the 22q11.2 locus and mutations in hSNF5/INI1 sequence must be investigated in order to confirm the diagnosis and to give insights on a presumable germline mutation. Indeed, a predisposition may be found in up to 30% of cases. The treatment is based on aggressive chemotherapy, surgery and irradiation. The prognosis remains poor and the survival rate is below 30%, whatever the anatomic location. Understanding the role of hSNF5/INI1 within the SWI-SNF complex for the epigenetic regulation of transcription might drive the future targeted therapies.

[Ewing's tumours, genetic and cellular aspects]. / Tumeurs d'Ewing, aspects génétiques et cellulaires.

Ewing's tumour is the second most frequent primary tumour of bone. It is associated in 85% of cases with a specific and recurrent chromosome translocation, a t(11; 22)(q24; q12) which generates a fusion gene between the 5' part of EWS and the 3' part of FLI-1, a member of the ETS family. Less frequently, this gene fusion involves EWS and another member of the ETS family which can be: ERG, ETV1, E1AF or FEV depending on the cases. The EWS-ETS fusion is causative in the development of Ewing's tumour. Its mechanism of action mainly relies on the abnormal transcription regulation of key target genes which are involved in the regulation of cell cycle, signal transduction, migration. The cellular context within which EWS-FLI-1 exerts its oncogenic action is a long standing matter of debate. Recent data converge to suggest that the Ewing cell origin is a mesenchymal stem cell.

In neuroblastic tumours, Schwann cells do not harbour the genetic alterations of neuroblasts but may nevertheless share the same clonal origin.

Neuroblastic tumours are composed of variable proportions of neuroblasts and Schwann cells. Whether both components share a common neoplastic origin is highly debated and discrepant results have been reported about the presence of tumour-related genetic alterations in Schwann cells. We have used X-methylation analysis and array-CGH to investigate contiguous Schwannian and neuroblastic areas in tumours with a nodular pattern. A skewed X inactivation was observed in four out of five stromal components. Interestingly, in these four cases, the X-inactivation profiles of the neuroblastic components were identical to the matched stromal areas. However, whereas all neuroblastic areas displayed chromosomal imbalances, no alteration was found in any Schwann cell components. Similarly, no alteration was observed in a series of 19 tumours with a single stroma-rich component, which occasionally exhibited a skewed X-inactivation pattern (3/17 informative tumours). Altogether, this indicates that most stroma-rich tumours display a polyclonal proliferation and that Schwann cells do not derive from neuroblasts. However, in tumours with both stroma-rich and -poor components, our results suggest that cells from both areas share a common progenitor.

The requirement for SNF5/INI1 in adipocyte differentiation highlights new features of malignant rhabdoid tumors.

ATP-dependent SWI/SNF chromatin remodeling complexes regulate cell-cycle and play critical roles in a variety of differentiation pathways. The core subunit SNF5/INI1 is a tumor suppressor that is inactivated in a highly aggressive childhood cancer of unknown cellular origin, termed malignant rhabdoid tumor (MRT). The highly undifferentiated phenotype of this tumor suggests that the loss-of-function of hSNF5/INI1 impairs specific differentiation programs of the MRT parental cell. Based on the hypothesis that these programs might be reinitialized upon hSNF5/INI1 re-expression in MRTs, we show that some MRT cell lines can differentiate toward the adipogenic lineage. We further show that the knock down of the SNF5/INI1 subunit abrogates adipocyte differentiation of murine 3T3-L1 preadipocytes and of human mesenchymal stem cells. Finally, we provide evidence that hSNF5/INI1 cooperates with C/EBPbeta and PPARgamma2 transcriptional regulators to activate the expression of adipocyte-specific genes. These data indicate that not only the ATPase subunit of the SWI/SNF complex, but also SNF5/INI1 is required for adipocyte differentiation. They further show that MRT cell lines harbor an adipogenic differentiation potential and that the tumor suppressor role of the SNF5/INI1 subunit may rely on its ability to regulate the balance between cell proliferation and differentiation.