Roberta Salaroli

Medullospheres from DAOY, UW228 and ONS-76 cells: increased stem cell population and proteomic modifications.

Background Medulloblastoma (MB) is an aggressive pediatric tumor of the Central Nervous System (CNS) usually treated according to a refined risk stratification. The study of cancer stem cells (CSC) in MB is a promising approach aimed at finding new treatment strategies. Methodology/Principal Findings The CSC compartment was studied in three characterized MB cell lines (DAOY, UW228 and ONS-76) grown in standard adhesion as well as being grown as spheres, which enables expansion of the CSC population. MB cell lines, grown in adherence and as spheres, were subjected to morphologic analysis at the light and electron microscopic level, as well as cytofluorimetric determinations. Medullospheres (MBS) were shown to express increasingly immature features, along with the stem cells markers: CD133, Nestin and β-catenin. Proteomic analysis highlighted the differences between MB cell lines, demonstrating a unique protein profile for each cell line, and minor differences when grown as spheres. In MBS, MALDI-TOF also identified some proteins, that have been linked to tumor progression and resistance, such as Nucleophosmin (NPM). In addition, immunocytochemistry detected Sox-2 as a stemness marker of MBS, as well as confirming high NPM expression. Conclusions/Significance Culture conditioning based on low attachment flasks and specialized medium may provide new data on the staminal compartment of CNS tumors, although a proteomic profile of CSC is still elusive for MB.

Validity of internal expression of the major histocompatibility complex class I in the diagnosis of inflammatory myopathies

Objective The inflammatory myopathies (IMs) are a group of disorders characterised by weakness and inflammation of the skeletal muscles. Muscle biopsy is the most crucial test to confirm the clinical diagnosis, but also the most common cause of misdiagnosis. There are currently no markers specific or sensitive enough to distinguish IMs from other diseases with similar clinical and morphological features, and an international multidisciplinary effort is under way to develop new classification criteria for IMs. Methods Standards for Reporting of Diagnostic Accuracy recommendations to validate a diagnostic test based on the quantification of internal major histocompatibility complex class I (MHC-I) positive fibres were adopted. MHC-I immunostained specimens from 64 patients were scored by two independent blinded investigators, and the percentage of positive fibres was determined. Agreement between investigators was evaluated with the k-weighted statistic. The receiver operating characteristic curve, area under the curve, sensitivity, specificity, and positive and negative predictive values of each percentage range of positive fibres versus the diagnosis of IM were calculated. Results The main difference between IM and non-inflammatory samples was the number of internal MHC-I positive fibres. The k-weighted value was 0.89 for a percentage of MHC-I positive fibres above 50%; the positive predictive value was 100%, and the negative predictive value was 94%. Conclusions This is the first study on the validity of a quantitative analysis of internal MHC-I positive fibres for an IM diagnosis performed according to Standards for Reporting of Diagnostic Accuracy recommendations. The interobserver agreement was almost perfect, thus making the method reproducible. Applying an MHC-I cut-off above 50% is an optimal marker for polymyositis (PM) and dermatomyositis (DM) diagnosis.

Radiobiologic response of medulloblastoma cell lines: involvement of β-catenin?

Medulloblastoma (MB) is the most common brain malignancy in children. Whole neural axis irradiation is the treatment of choice, but it often results in long-term neurocognitive and developmental impairment. Only insights into MB biology will lead to improved therapeutic outcome. Wingless (WNT) signalling deregulation occurs in up to 25% of sporadic tumors, but the specific role of nuclear β-catenin and its involvement in the radioresponse remains unsettled. Therefore we studied the γ-radiation response of two MB cell lines from cellular and molecular points of view. Our data show that the p53 wild-type cell line is more sensitive to ionizing radiations (IR) than the p53 mutated line, but apoptosis is also induced in p53-mutated cells, suggesting an alternative p53-independent mechanism. In addition, this study is the first to demonstrate that γ-rays trigger the WNT system in our in vitro models. Further studies are required to test if this could explain the radiosensitivity of MB and the favorable prognostic value of nuclear β-catenin in this tumor.

Skeletal Muscle Satellite Cells in Amyotrophic Lateral Sclerosis

Abstract Objectives: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease involving progressive muscular paralysis reflecting degeneration of motor neurons. Skeletal muscle tissue seems to play a significant role in ALS pathogenesis. Here, the role of satellite cells (SCs) in ALS muscle atrophy is investigated. Methods: We isolated SCs from ALS human muscle biopsies and we analyzed their ability to grow and expand in vitro. Ultrastructural and immunophenotypical features were analyzed. Quantitative real-time RT-QPCR and western blot (WB) analyses were performed to evaluate MRFs and MyH1 expression. Results: ALS SCs showed a high proliferative potential, but their capacity to proceed through the myogenic program and form myotubes seems altered compared to controls (Ctrls). We observed that differentiating ALS SCs showed some specific features, but they displayed an altered morphology, with a large number of vacuoles. RT-QPCR and WB showed lower Myf-4 and MyH1 compared to Ctrls. Conclusions: Our data suggest that the capacity of ALS SCs to proceed through the myogenic program seems to be altered: SCs seem to lose their ability to regenerate and restore mature myofibers.

Intracellular Distribution of β-Catenin in Human Medulloblastoma Cell Lines with Different Degree of Neuronal Differentiation

Gene mutations impairing the functions of the WNT signaling transduction pathway have been found in approximately 15% of human sporadic medulloblastomas. To understand the functional role of the WNT pathway in medulloblastoma, we have investigated the intracellular distribution of β-catenin in a series of 17 human medulloblastomas to correlate such expression with neuronal differentiation and in cultured cell models following functional silencing of the APC gene by small-interference RNA (siRNA). Transient siRNA transfection resulted in a 50% reduction of the APC gene product levels in both DAOY and D283MED cell lines. In the former, less-differentiated cell line, β-catenin levels remained unchanged or were slightly reduced, but β-catenin translocated in the nucleus following APC gene siRNA silencing. In contrast, in the more differentiated D283MED cells, β-catenin levels increased about twofold while mainly maintaining the cytoplasmic and cell membrane localization. Cytoplasmic/nuclear localization of β-catenin was present in 12 of 17 cases of medulloblastoma with a prevalent distribution in the classic, 6/7 cases, and large cell/anaplastic variant, 4/4 cases. The nodular/desmoplastic lesions showed strongly positivity in the cell membrane mainly of intranodular cells with advanced neuronal differentiation. These observations support an important functional role of WNT/β-catenin pathway in neuronal differentiation in medulloblastoma.

Ultrastructural changes in LGMD1F.

A large Italo‐Spanish kindred with autosomal‐dominant inheritance has been reported with proximal limb and axial muscle weakness. Clinical, histological and genetic features have been described. A limb girdle muscular dystrophy 1F (LGMD1F) disease locus at chromosome 7q32.1–32.2 has been previously identified. We report a muscle pathological study of two patients (mother and daughter) from this family. Muscle morphologic findings showed increased fiber size variability, fiber atrophy, and acid‐phosphatase‐positive vacuoles. Immunofluorescence against desmin, myotilin, p62 and LC3 showed accumulation of myofibrils, ubiquitin binding protein aggregates and autophagosomes. The ultrastructural study confirmed autophagosomal vacuoles. Many alterations of myofibrillar component were detected, such as prominent disarray, rod‐like structures with granular aspect, and occasionally, cytoplasmic bodies. Our ultrastructural data and muscle pathological features are peculiar to LGMD1F and support the hypothesis that the genetic defect leads to a myopathy phenotype associated with disarrangement of the cytoskeletal network.

XAV939-Mediated ARTD Activity Inhibition in Human MB Cell Lines

Diphtheria toxin-like ADP-ribosyltransferases 1 and 5 (ARTD-1, ARTD-5) are poly ADP-ribose enzymes (PARP) involved in non-homologous end-joining (NHEJ), which is the major pathway of double-strand break (DSB) repair. In addition, ARTD-5, or Tankyrase (TNKS), is a positive regulator of the WNT signaling implicated in the development and biological behavior of many neoplasms, such as Medulloblastoma (MB), in which radiotherapy is an essential part of the treatment. The use of radiosensitizing agents may improve the therapeutic index in MB patients by increasing the efficacy of radiotherapy, while reducing toxicity to the neuroaxis. ARTD-5 seems to be a good molecular target for improving the current treatment of MB. In this study, we used the small molecule XAV939, a potent ARTD-5 inhibitor with a slight affinity for ARTD-1, in different human MB cell lines. XAV939 inhibited the WNT pathway and DNA-PKcs in our MB cells, with many biological consequences. The co-administration of XAV939 and ionizing radiations (IR) inhibited MB cells proliferation and clonogenic capacity, decreased their efficacy in repairing DNA damage, and increased IR-induced cell mortality. In conclusion, our in vitro data show that XAV939 could be a very promising small molecule in MB treatment, and these results lay the basis for further in vivo studies with the aim of improving the current therapy available for MB patients.

Deleterious effects of tributyltin on porcine vascular stem cells physiology

The vascular functional and structural integrity is essential for the maintenance of the whole organism and it has been demonstrated that different types of vascular progenitor cells resident in the vessel wall play an important role in this process. The purpose of the present research was to observe the effect of tributyltin (TBT), a risk factor for vascular disorders, on porcine Aortic Vascular Precursor Cells (pAVPCs) in term of cytotoxicity, gene expression profile, functionality and differentiation potential. We have demonstrated that pAVPCs morphology deeply changed following TBT treatment. After 48h a cytotoxic effect has been detected and Annexin binding assay demonstrated that TBT induced apoptosis. The transcriptional profile of characteristic pericyte markers has been altered: TBT 10nM substantially induced alpha-SMA, while, TBT 500nM determined a significant reduction of all pericyte markers. IL-6 protein detected in the medium of pAVPCs treated with TBT at both doses studied and with a dose response. TBT has interfered with normal pAVPC functionality preventing their ability to support a capillary-like network. In addition TBT has determined an increase of pAVPC adipogenic differentiation. In conclusion in the present paper we have demonstrated that TBT alters the vascular stem cells in terms of structure, functionality and differentiating capability, therefore effects of TBT in blood should be deeply explored to understand the potential vascular risk associated with the alteration of vascular stem cell physiology.