Renata Boldrini

Antagomir-17-5p Abolishes the Growth of Therapy- Resistant Neuroblastoma through p21 and BIM

We identified a key oncogenic pathway underlying neuroblastoma progression: specifically, MYCN, expressed at elevated level, transactivates the miRNA 17-5p-92 cluster, which inhibits p21 and BIM translation by interaction with their mRNA 3′ UTRs. Overexpression of miRNA 17-5p-92 cluster in MYCN-not-amplified neuroblastoma cells strongly augments their in vitro and in vivo tumorigenesis. In vitro or in vivo treatment with antagomir-17-5p abolishes the growth of MYCN-amplified and therapy-resistant neuroblastoma through p21 and BIM upmodulation, leading to cell cycling blockade and activation of apoptosis, respectively. In primary neuroblastoma, the majority of cases show a rise of miR-17-5p level leading to p21 downmodulation, which is particularly severe in patients with MYCN amplification and poor prognosis. Altogether, our studies demonstrate for the first time that antagomir treatment can abolish tumor growth in vivo, specifically in therapy-resistant neuroblastoma.

Hemimegalencephaly and Intractable Epilepsy: Benefits of Hemispherectomy

Summary: We observed 4 children with hemimegalencephaly, (3 boys, 1 girl aged 3–7 years). One child had a linear sebaceous nevus. All patients had a similar clinical, EEG, and neuroradiologic pattern. All patients had mac‐rocrania, hemiparesis, hemianopsia, and psychomotor retardation of variable degree. All cases had an epileptic syndrome with onset during the first days or the first months of life. The seizures were consistently similar: partial motor seizures, generally hemiclonic and asymmetric brief tonic seizures, in series, involving predominantly one side of the body, contralateral to the cerebral damage. The EEG was initially characterized by a hemi‐hypsarrhythmia and afterward, over the malformed hemisphere, by a rather high‐frequency background activity associated with almost continuous transients of spikes, sharp waves, and spike and waves that progressively involved the contralateral hemisphere.

Genotype-Phenotype Relationship in Human ATP6i-Dependent Autosomal Recessive Osteopetrosis

Autosomal-recessive osteopetrosis is a severe genetic disease caused by osteoclast failure. Approximately 50% of the patients harbor mutations of the ATP6i gene, encoding for the osteoclast-specific a3 subunit of V-ATPase. We found inactivating ATP6i mutations in four patients, and three of these were novel. Patients shared macrocephaly, growth retardation and optic nerve alteration, osteosclerotic and endobone patterns, and high alkaline phosphatase and parathyroid hormone levels. Bone biopsies revealed primary spongiosa lined with active osteoblasts and high numbers of tartrate-resistant acid phosphatase (TRAP)-positive, a3 subunit-negative, morphologically unremarkable osteoclasts, some of which located in shallow Howship lacunae. Scarce hematopoietic cells and abundant fibrous tissue containing TRAP-positive putative osteoclast precursors were noted. In vitro osteoclasts were a3-negative, morphologically normal, with prominent clear zones and actin rings, and TRAP activity more elevated than in control patients. Podosomes, alphaVbeta3 receptor, c-Src, and PYK2 were unremarkable. Consistent with the finding in the bone biopsies, these cells excavated pits faintly stained with toluidine blue, indicating inefficient bone resorption. Bone marrow transplantation was successful in all patients, and posttransplant osteoclasts showed rescue of a3 subunit immunoreactivity.

Malignant Pancreatic Endocrine Tumor in a Child With Tuberous Sclerosis

Tuberous sclerosis complex (TSC) is an autosomal dominant condition whose signs and symptoms may vary from a few hypopigmented skin spots to epilepsy, severe mental retardation, and renal failure. The disease is caused by mutations in either TSC1 or TSC2 gene, at chromosome 9q34 and 16p13.3. Inactivation of both alleles at TSC1 or TSC2 loci is associated with the development of hamartomas in different organs, and only rarely with malignant neoplasms. In this study we present a 6-year-old boy with TSC and with a malignant islet cell tumor of the pancreas. Mutation analysis of DNA extracted from peripheral blood cells of the patient identified an R1459X de novo mutation in exon 33 of the TSC2 gene. Immunohistochemical analysis with anti-tuberin antibodies on paraffin-embedded tissue sections showed loss of tuberin immunostaining in tumor cells but normal expression in residual normal pancreas. DNA analysis of tumor and normal cells showed chromosome 16p13 loss of heterozygosity in malignant pancreatic islet cell tumor but not in normal pancreas. These findings suggest a role for tuberin, the TSC2 gene product, in the pathogenesis of malignant pancreatic endocrine tumor.

Long term follow up of children with myocarditis treated by immunosuppression and of children with dilated cardiomyopathy

Objective: To describe the treatment and long term outcome after immunosuppressive treatment of children with myocarditis. Methods and results: 114 patients with newly diagnosed dilated cardiomyopathy were divided into three groups, according to the histological pattern: group A, acute myocarditis; group B, borderline myocarditis; and group C, non-inflammatory cardiomyopathy. Groups A and B were treated with cyclosporine and prednisone in addition to conventional treatment. Survivors of the whole cohort were analysed for 13 year transplant-free survival and assessed for left ventricular function. Event-free survival at 13 years was 97 (3)% for group A, 70 (8)% for group B, and 32 (7)% for group C (p < 0.0001). It was 96 (4)% at one year and 83 (5)% at 13 years for the cumulated myocarditis group (A and B). Cardiac function recovered completely in 79% of survivors in group A, 64% in group B, and 36% in group C. The rate of complete recovery in the cumulated group (A and B) was 70%. Conclusions: The high long term survival rate of this cohort of children with myocarditis is probably due to the effect of short term immunosuppression. This result differs from previously published series of conventionally treated children, whose survival probability at one year was about 60%.

ADAR2-editing activity inhibits glioblastoma growth through the modulation of the CDC14B/Skp2/p21/p27 axis.

Grade IV astrocytoma or glioblastoma multiforme (GBM) is one of the most aggressive and lethal tumors affecting humans. ADAR2-mediated A-to-I RNA editing, an essential post-transcriptional modification event in brain, is impaired in GBMs and astrocytoma cell lines. However, the role of ADAR2 editing in astrocytomas remains to be defined. Here, we show that ADAR2 editing rescue in astrocytomas prevents tumor growth in vivo and modulates an important cell cycle pathway involving the Skp2/p21/p27 proteins, often altered in glioblastoma. We demonstrate that ADAR2 deaminase activity is essential to inhibit tumor growth. Indeed, we identify the phosphatase CDC14B, which acts upstream of the Skp2/p21/p27 pathway, as a novel and critical ADAR2 target gene involved in glioblastoma growth. Specifically, ADAR2-mediated editing on CDC14B pre-mRNA increases its expression with a consequent reduction of the Skp2 target protein, as shown both in vitro and in vivo. We found that, compared to normal brain, both CDC14B editing and expression are progressively impaired in astrocytomas from grade I to IV, being very low in GBMs. These findings (1) demonstrate that post-transcriptional A-to-I RNA editing might be crucial for glioblastoma pathogenesis, (2) identify ADAR2-editing enzyme as a novel candidate tumor suppressor gene and (3) provide proof of principle that ADAR2 or its substrates may represent a suitable target(s) for possible novel, more effective and less toxic approaches to the treatment of GBMs.

Clinical and molecular findings in hyperornithinemia-hyperammonemia-homocitrullinuria syndrome

The authors report the clinical and molecular findings in eight patients with hyperornithinemia, hyperammonemia, and homocitrullinuria (HHH) syndrome. The most consistent neurologic finding was spastic paraparesis, seen in five of the eight patients. However, all showed signs of pyramidal tract involvement. A broad spectrum of pathogenetic mutations (including missense, nonsense, splice site, insertion, and deletions) were identified in the ORNT1 gene.

Spindle cell (Kaposiform) hemangioendothelioma with Kasabach‐Merritt syndrome in an infant: Successful treatment with α‐2A interferon

A two-month-old infant developed a vascular tumor of the right flank which upon biopsy proved to be a spindle cell hemangioendothelioma. The increased capillary bed characterizing the neoplasm caused a severe thrombocytopenia together with a consumption coagulopathy (Kasabach-Merritt syndrome). The patient, who was dependent on platelet transfusions, improved quickly after interferon alpha-2a was given at the dosage of 3,000,000 U/m2, with resolution of the Kasabach-Merritt syndrome after three weeks and a 75% decrease of the tumor volume within three months of treatment.

Impact of a Single Nucleotide Polymorphism in the MDM2 Gene on Neuroblastoma Development and Aggressiveness: Results of a Pilot Study on 239 Patients

Purpose: MDM2 is a key negative regulator of p53 activity, and a single nucleotide polymorphism (SNP309, T>G change; rs 2279744) in its promoter increases the affinity for the transcription factor SP1, enhancing MDM2 expression. We carried out a pilot study to investigate the effect of this polymorphism on development and behavior of neuroblastoma, an extracranial pediatric tumor with unfrequent genetic inactivation of p53. Experimental Design: We genotyped the MDM2-SNP309 alleles of tumor DNA from 239 neuroblastoma patients and peripheral blood DNA from 237 controls. In 40 of 239 neuroblastomas, the MDM2-SNP309 alleles were also genotyped in peripheral blood DNA. Data were analyzed by two-sided Fishers exact test, log-rank test, and Kaplan-Meier statistics. Where appropriate, data are reported with 95% confidence intervals (CI). Results: The frequency of both the T/G and G/G genotypes or the G/G or T/G genotype only was higher in neuroblastoma DNA samples than in controls: 60.3% (95% CI, 54.1-66.5) versus 47.3% (95% CI, 40.9-53.6), 30.4% (95% CI, 22.4-37.8) versus 15.0% (95% CI, 9.2-20.7), and 52.0% (95% CI, 45.0-59.9) versus 41.9% (95% CI, 35.3-48.5), respectively; Two-Sided Fishers Exact Test P values were 0.006, 0.003, and 0.048, respectively; Odds ratios were 1.69 (95% CI, 1.18-2.43), 2.45 (95% CI, 1.37-4.39) and 1.51 (95% CI, 1.02-2.22), respectively. A significant association (P = 0.016) between heterozygous (T/G)/homozygous (G/G) genotypes at SNP309 and advanced clinical stages was also shown. Homozygous/heterozygous SNP309 variant carriers had a shorter 5-year overall survival than patients with the wild-type allele (P = 0.046; log-rank test). A shorter overall survival in patients with heterozygous/homozygous SNP309 was also observed in the subgroups with age at diagnosis >1 year and adrenal primary tumor (P = 0.024 and P = 0.014, respectively). Conclusions: Data from this pilot study suggest that the MDM2 G/G and T/G-SNP309 alleles are markers of increased predisposition to tumor development and disease aggressiveness in neuroblastoma. However, additional studies with larger patient cohorts are required for a definitive assessment of the clinical relevance of these data.

Mechanisms of Osteoclast Dysfunction in Human Osteopetrosis: Abnormal Osteoclastogenesis and Lack of Osteoclast-Specific Adhesion Structures

Osteoclasts from a patient affected by osteopetrosis were examined in vivo and in vitro. Iliac crest biopsy revealed an osteosclerotic pattern, with prominent numbers of osteoclasts noted for hypernuclearity and incomplete adherence to the bone surface. A population comprising tartrate‐resistant acid phosphatase (TRAP)‐positive, multinucleated and mononuclear cells, and alkaline phosphatase‐positive stromal fibroblasts was obtained in vitro from bone marrow. Mononuclear TRAP‐positive precursors spontaneously fused in culture to form giant osteoclast‐like cells. These cells expressed the osteoclast marker MMP‐9 and calcitonin receptor, and lacked the macrophage marker, Fc receptor. Expression and distribution of c‐src, c‐fms, and CD68, and response to steroid hormones relevant to osteoclast differentiation and function were apparently normal, whereas cell retraction in response to calcitonin was impaired. TRAP‐positive multinucleated cells did not form osteoclast‐specific adhesion structures (clear zone, podosomes, or actin rings). Bone resorption rate was severely reduced in vitro. Focal adhesions and stress fibers were observed en lieu of podosomes and actin rings. Adhesion structures contained low levels of immunoreactive vitronectin receptor, most of this integrin being retained in cytoplasmic vesicles. These data provide the first characterization of abnormal differentiation and function of human osteopetrotic osteoclast‐like cells.