Concezio Di Rocco

MicroRNA profiling in human medulloblastoma

Medulloblastoma is an aggressive brain malignancy with high incidence in childhood. Current treatment approaches have limited efficacy and severe side effects. Therefore, new risk‐adapted therapeutic strategies based on molecular classification are required. MicroRNA expression analysis has emerged as a powerful tool to identify candidate molecules playing an important role in a large number of malignancies. However, no data are yet available on human primary medulloblastomas. A high throughput microRNA expression profiles was performed in human primary medulloblastoma specimens to investigate microRNA involvement in medulloblastoma carcinogenesis. We identified specific microRNA expression patterns which distinguish medulloblastoma differing in histotypes (anaplastic, classic and desmoplastic), in molecular features (ErbB2 or c‐Myc overexpressing tumors) and in disease‐risk stratification. MicroRNAs expression profile clearly differentiates medulloblastoma from either adult or fetal normal cerebellar tissues. Only a few microRNAs displayed upregulated expression, while most of them were downregulated in tumor samples, suggesting a tumor growth‐inhibitory function. This property has been addressed for miR‐9 and miR‐125a, whose rescued expression promoted medulloblastoma cell growth arrest and apoptosis while targeting the proproliferative truncated TrkC isoform. In conclusion, misregulated microRNA expression profiles characterize human medulloblastomas, and may provide potential targets for novel therapeutic strategies.

A survey of the first complication of newly implanted CSF shunt devices for the treatment of nontumoral hydrocephalus

The results of an international multicenter study concerning the first complication of newly implanted cerebrospinal fluid shunts in nontumoral hydrocephalus are the subject of the present report. The authors have collected information on 773 cases from four continents. In particular, the following data were evaluated in relation to the general incidence of complications recorded in the first follow-up year: the patients age at the operation, the etiology of hydrocephalus, the type of CSF shunt device used, and the modality of the surgical procedures. The overall complication rate in the series was 29%. Age and etiology of hydrocephalus appear to play a major role in influencing the complication rate; on the other hand, the choice of a specific CSF shunt device seems to be less important in this respect.

Hedgehog controls neural stem cells through p53-independent regulation of Nanog

Hedgehog (Hh) pathway has a pivotal function in development and tumorigenesis, processes sustained by stem cells (SCs). The transcription factor Nanog controls stemness acting as a key determinant of both embryonic SC self‐renewal and differentiated somatic cells reprogramming to pluripotency, in concert with the loss of the oncosuppressor p53. How Nanog is regulated by microenvironmental signals in postnatal SC niches has been poorly investigated. Here, we show that Nanog is highly expressed in SCs from postnatal cerebellum and medulloblastoma, and acts as a critical mediator of Hh‐driven self‐renewal. Indeed, the downstream effectors of Hh activity, Gli1 and Gli2, bind to Nanog‐specific cis‐regulatory sequences both in mouse and human SCs. Loss of p53, a key event promoting cell stemness, activates Hh signalling, thereby contributing to Nanog upregulation. Conversely, Hh downregulates p53 but does not require p53 to control Nanog. Our data reveal a mechanism for the function of Hh in the control of stemness that represents a crucial component of an integrated circuitry determining cell fate decision and involved in the maintenance of cancer SCs.

Prognostic factors and outcome of children with severe head injury: an 8-year experience

Abstract.Objectives: Our aim was to analyze prognostic factors and their association with outcome among children with severe head injury. Methods: We conducted a retrospective study among children with severe head injury admitted to our Pediatric Intensive Care Unit (PICU) from November 1992 to December 2000. The patients were immediately evaluated for the severity of head injury (Glasgow Coma Score, GCS), clinical presentation, cerebral axial tomography, early complications (hypoxia and hypotension), metabolic and hematological alterations and early post-traumatic seizures. Six months after injury we applied the Glasgow Outcome Score (GOS). Correlations with GOS were evaluated using univariate and multivariate logistic models. Results: In all, 122 children with severe head injury were identified. The patients presented the following scores: 18 (14.7.0%) children had a GOS of 1; 2 had a GOS of 2 (1.6%); 27 (22.2%) a GOS of 3 and 75 (61.5%) a GOS of 4 or 5. A low GOS was significantly and independently associated with low GCS, multiple trauma, the presence of hypoxia and hypotension, disseminated intravascular coagulation (DIC), hyperglycemia and early post-traumatic seizures. Hematological alterations (white blood cells) were also associated with a low GOS, though not significantly. Conclusion: In addition to GCS, types of trauma and brain lesion, hypoxia and hypotension, hemocoagulative disorders (DIC), hyperglycemia and early post-traumatic seizures are predictors of GOS. A knowledge of these prognostic factors and the correct management of children with severe head injury helps clinicians to improve outcome and to reduce morbidity and mortality.

Down-regulation of RNA Editing in Pediatric Astrocytomas ADAR2 EDITING ACTIVITY INHIBITS CELL MIGRATION AND PROLIFERATION

Since alterations in post-transcriptional events can contribute to the appearance and/or progression of cancer, we investigated whether RNA editing, catalyzed by the ADAR (adenosine deaminases that act on RNA) enzymes, is altered in pediatric astrocytomas. We find a decrease in ADAR2 editing activity that seems to correlate with the grade of malignancy in children. Despite the loss of ADAR2 editing activity in tumor tissues, the high grade astrocytomas do not exhibit alterations in ADAR2 expression when compared with their specific control tissues. However, high expression levels of ADAR1 and ADAR3 were found in tumors when compared with normal tissues dissected in the same area of the brain. We reintroduced either ADAR2 or the inactive version of ADAR2 in three astrocytoma cell lines (U118, A172, U87). The “reverted” editing status is necessary and sufficient for a significant decrease in cell malignant behavior as measured by proliferation, cell cycle, and migration assays. We show that elevated levels of ADAR1, as found in astrocytomas, do indeed interfere with ADAR2 specific editing activity. Furthermore, we show that the endogenous ADAR1 can form heterodimers with ADAR2 in astrocytes.

High Response Rate to Cisplatin/Etoposide Regimen in Childhood Low-Grade Glioma

PURPOSE The aim of this study was to avoid radiotherapy and to induce an objective response in children with low-grade glioma (LGG) using a simple chemotherapy regimen based on cisplatin and etoposide. PATIENTS AND METHODS Thirty-four children (median age, 45 months) with unresectable LGG were treated with 10 monthly cycles of cisplatin (30 mg/m(2)/d on days 1 to 3) and etoposide (150 mg/m(2)/d on days 1 to 3). Tumor originated in the visual pathway in 29 patients, in the temporal lobe in two, in the frontal lobe in two, and in the spine in one. Eight children were affected by neurofibromatosis type 1. Objective tumor response and toxicity were evaluated by magnetic resonance imaging and neurologic and functional tests at 3-month intervals. RESULTS An objective response was obtained in 24 (70%) of 34 patients, whereas the others had stable disease. None of the children were electively irradiated. In 31 previously untreated children, overall survival was 100% and progression-free survival was 78% at 3 years, with a median follow-up of 44 months. Acute toxicity was unremarkable; 28% patients evaluated for acoustic neurotoxicity revealed a loss of perception of high frequencies. CONCLUSION Cisplatin and etoposide combined treatment is one of the most active regimens for LGG in children and allows avoidance of radiotherapy in the vast majority of patients.

Cytogenetic Prognostication Within Medulloblastoma Subgroups

PURPOSE Medulloblastoma comprises four distinct molecular subgroups: WNT, SHH, Group 3, and Group 4. Current medulloblastoma protocols stratify patients based on clinical features: patient age, metastatic stage, extent of resection, and histologic variant. Stark prognostic and genetic differences among the four subgroups suggest that subgroup-specific molecular biomarkers could improve patient prognostication. PATIENTS AND METHODS Molecular biomarkers were identified from a discovery set of 673 medulloblastomas from 43 cities around the world. Combined risk stratification models were designed based on clinical and cytogenetic biomarkers identified by multivariable Cox proportional hazards analyses. Identified biomarkers were tested using fluorescent in situ hybridization (FISH) on a nonoverlapping medulloblastoma tissue microarray (n = 453), with subsequent validation of the risk stratification models. RESULTS Subgroup information improves the predictive accuracy of a multivariable survival model compared with clinical biomarkers alone. Most previously published cytogenetic biomarkers are only prognostic within a single medulloblastoma subgroup. Profiling six FISH biomarkers (GLI2, MYC, chromosome 11 [chr11], chr14, 17p, and 17q) on formalin-fixed paraffin-embedded tissues, we can reliably and reproducibly identify very low-risk and very high-risk patients within SHH, Group 3, and Group 4 medulloblastomas. CONCLUSION Combining subgroup and cytogenetic biomarkers with established clinical biomarkers substantially improves patient prognostication, even in the context of heterogeneous clinical therapies. The prognostic significance of most molecular biomarkers is restricted to a specific subgroup. We have identified a small panel of cytogenetic biomarkers that reliably identifies very high-risk and very low-risk groups of patients, making it an excellent tool for selecting patients for therapy intensification and therapy de-escalation in future clinical trials.

Decreased Proliferation and Altered Differentiation in Osteoblasts from Genetically and Clinically Distinct Craniosynostotic Disorders

Craniosynostoses are a heterogeneous group of disorders characterized by premature fusion of cranial sutures. Mutations in fibroblast growth factor receptors (FGFRs) have been associated with a number of such conditions. Nevertheless, the cellular mechanism(s) involved remain unknown. We analyzed cell proliferation and differentiation in osteoblasts obtained from patients with three genetically and clinically distinct craniosynostoses: Pfeiffer syndrome carrying the FGFR2 C342R substitution, Apert syndrome with FGFR2 P253R change, and a nonsyndromic craniosynostosis without FGFR canonic mutations, as compared with control osteoblasts. Osteoblasts from craniosynostotic patients exhibited a lower proliferation rate than control osteoblasts. P253R and nonsyndromic craniosynostosis osteoblasts showed a marked differentiated phenotype, characterized by high alkaline phosphatase activity, increased mineralization and expression of noncollagenous matrix proteins, associated with high expression and activation of protein kinase Calpha and protein kinase Cepsilon isoenzymes. By contrast, the low proliferation rate of C342R osteoblasts was not associated with a differentiated phenotype. Although they showed higher alkaline phosphatase activity than control, C342R osteoblasts failed to mineralize and expressed low levels of osteopontin and osteonectin and high protein kinase Czeta levels. Stimulation of proliferation and inhibition of differentiation were observed in all cultures on FGF2 treatment. Our results suggest that an anticipated proliferative/differentiative switch, associated with alterations of the FGFR transduction pathways, could be the causative common feature in craniosynostosis and that mutations in distinct FGFR2 domains are associated with an in vitro heterogeneous differentiative phenotype.

Hemimegalencephaly and Intractable Epilepsy: Complications of Hemispherectomy and Their Correlations with the Surgical Technique

Hemispherectomy is required in most cases of hemimegalencephaly in order to control epilepsy refractory to medical treatment. Although there is a general agreement on the effectiveness of the procedure in controlling the seizure disorder, the choice of the surgical technique is still a subject of debate. In particular, anatomical hemispherectomy is blamed to be associated with a higher incidence of surgical complications, namely hydrocephalus and hemosiderosis, than other less ablative operations such as functional hemispherectomies. A series of 15 children with hemimegalencephaly, who had undergone anatomical hemispherectomy (11 cases), functional hemispherectomy (2 cases), and hemidecortication (2 cases) at the Pediatric Neurosurgery Section, Catholic University Medical School, Rome, is reported. Twelve of these patients presented with one or more complications in their postoperative course. Temporary complications, which resolved spontaneously or following medical therapy, included fever, wound breakdown, worsening of preoperative motor deficit, unilateral third cranial nerve deficit, dystonia, and anemia. In 8 patients, postoperative complications led to a second surgical procedure. A CSF shunt was necessary in 5 children, to control a secondary hydrocephalus. Two subjects underwent a toilette of the residual cavity because of persisting chemical abnormalities in CSF parameters. In a child a cranioplasty procedure was necessary as a consequence of an infection of the hemicranial bone flap. There was no apparent correlation between the rate and the type of complications with a specific surgical procedure. On the other hand, the age factor appeared to play an important role in the occurrence of secondary hydrocephalus, as all 5 children with this complication were less than 9 months old at the time of the hemispherectomy. Surgical mortality was nil in this series.

Acquired Chiari type I malformation managed by supratentorial cranial enlargement

IntroductionAcquired Chiari type-I malformation in hydrocephalic patients who have undergone surgical treatment was initially thought to depend on a craniocephalic disproportion induced by the cerebrospinal (CSF) shunt. However, most of the reports in the literature deal with children with lumbo-peritoneal shunts and emphasize the pathogenic role of the cranio–spinal pressure differential across the foramen magnum brought about by this type of shunt.MethodIn the present report, the authors describe two further cases of symptomatic acquired Chiari type-I malformation observed in two adolescents operated on for correction of pseudotumor cerebri in one (lumbo-peritoneal shunt) and of a suprasellar arachnoid cyst (cysto-ventriculo-peritoneal shunt) in the other.ResultsIn both subjects, both the clinical manifestations and the cerebellar tonsillar herniation regressed after supratentorial cranial expansion, without the need for any manipulation of the shunt devices implanted earlier.DiscussionThese results, together with the observation of the concomitant upward and downward herniation of the cerebellum in both patients, indicate that secondary craniocephalic disproportion plays a relevant role in the genesis of acquired Chiari type-I malformation in children bearing extrathecal CSF shunts.