Chondrodysplasia with multiple dislocations: comprehensive study of a series of 30 cases.

The group of chondrodysplasia with multiple dislocations includes several entities, characterized by short stature, dislocation of large joints, hand and/or vertebral anomalies. Other features, such as epiphyseal or metaphyseal changes, cleft palate, intellectual disability are also often part of the phenotype. In addition, several conditions with overlapping features are related to this group and broaden the spectrum. The majority of these disorders have been linked to pathogenic variants in genes encoding proteins implicated in the synthesis or sulfation of proteoglycans (PG). In a series of 30 patients with multiple dislocations, we have performed exome sequencing and subsequent targeted analysis of 15 genes, implicated in chondrodysplasia with multiple dislocations, and related conditions. We have identified causative pathogenic variants in 60% of patients (18/30); when a clinical diagnosis was suspected, this was molecularly confirmed in 53% of cases. Forty percent of patients remain without molecular etiology. Pathogenic variants in genes implicated in PG synthesis are of major importance in chondrodysplasia with multiple dislocations and related conditions. The combination of hand features, growth failure severity, radiological aspects of long bones and of vertebrae allowed discrimination among the different conditions. We propose key diagnostic clues to the clinician.

Radiation-induced perturbation of cell-to-cell signalling and communication.

The investigation of the bystander phenomena (i.e. the induction of damage in cells not directly traversed by radiation) is strictly related to the study of the mechanisms of intercellular communication and of the perturbative effects of radiation. A new possible way to try to solve the bystander puzzle is through a 'systems radiation biology' approach with the total integration of experimental and theoretical activities. In particular, this contribution will focus on: (1) 'ad hoc' experiments designed to quantify key parameters involved in intercellular signalling (focusing, as a pilot study, on release, decay and internalization of interleukine-6 molecules, their modulation by radiation, and possible differences between in vivo/in vitro behaviour); (2) the implementation and the development of two different modelling approaches: a stochastic model (based on a Monte Carlo code) that takes account of the local mechanisms of release and internalization of signalling molecules (e.g. cytokines) and an analytical model where signal molecules are treated as a population and their temporal behaviour is described by differential equations. This approach provided instruments to investigate the complex phenomena of signal transmission and the role of cell communication to guarantee (maintain) the robustness of the in vitro experimental systems against the effects of perturbations.

In-vitro effects of the tyrosine kinase inhibitor imatinib on glioblastoma cell proliferation.

Glioblastoma (GBL) is the most malignant brain tumour in adults, causing the death of most patients within 9-12 months of diagnosis. Treatment is based on a combination of surgery, radiation therapy, and chemotherapy. With these treatment modalities, however, responses are extremely poor, so identification of novel treatment strategies is highly warranted. Platelet-derived growth factors (PDGF) and their receptors are commonly coexpressed in GBL, suggesting that stimulation of autocrine PDGF receptors may contribute to their growth. Interest in these receptors as drug target for glioblastoma treatment has increased with the clinical availability of the PDGFR kinase inhibitor antagonist imatinib mesylate (STI571). In this study, T98G and A172 human GBL cell lines were analysed for their sensitivity to treatment with imatinib. In particular, we focussed our attention on analysis of DNA distribution by flow cytometry at different times of incubation with different imatinib concentrations (1-30 microM: ). Our results show that imatinib induces growth arrest in T98G and A172 cells in the G(0)/G(1) phase of the cell cycle, at all the concentrations tested, as early as 24 h after treatment. However we have also seen, by means of annexin V staining, that at 20 and 30 microM: concentrations, in concomitance with a significant growth arrest in the G(0)/G(1) phase, there is an increase of apoptotic cells 48 h after treatment, suggesting that imatinib at low concentrations (1-10 microM: ) could act as a cytostatic agent whereas at high concentrations (20, 30 microM: ) it mainly behaves as a cytotoxic agent.

Influence of imatinib mesylate on radiosensitivity of astrocytoma cells.

Imatinib mesylate (STI571), an inhibitor of alpha- and beta-platelet-derived growth factor receptors (PDGFR) and other tyrosine kinases, is a well established treatment for chronic myeloid leukaemia and gastrointestinal stromal tumours. Moreover, it is under investigation for the therapy of several other malignant tumours since protein kinases are frequently mutated or otherwise deregulated in human malignancies and they serve as a target for differentiating between tumour cells and normal tissues. The objective of this study was to determine whether gamma radiation could sensitize astrocytoma cell lines to the effects of imatinib in vitro. For this purpose, T98G and MOG-G-UVW astrocytoma cells were treated with imatinib alone or in combination with gamma radiation. The clonogenic survival assays performed with the combination of imatinib with radiation demonstrated that the drug had an additive antiproliferative effect in both cell lines considered. Imatinib confered greater radiosensitivity on the T98G tumour cells effecting a significant decrease in colony formation compared with radiation alone. These data provide a rationale to further investigate the combination of imatinib with radiation, keeping in mind that this may result in unexpected toxicities that are not observed with either treatment alone.

Proliferation and programmed cell death: role of p53 protein in high and low grade astrocytoma.

p53 is a cell cycle regulator that has been well-recognized as the key molecule that triggers the induction and the control of cell proliferation and apoptosis in a wide variety of tumours, including astrocytoma. Apoptosis and proliferation are two processes intimately coupled, that occur simultaneously in tumour tissue. Previous studies of the correlations between proliferation and apoptotic index with p53 expression in astrocytic tumours have remained inconclusive. The aim of this study was to investigate the correlation of p53 expression with the apoptotic index (AI) and the cell proliferation index (PI) in pilocytic astrocytoma (PA) and glioblastoma multiforme (GBM). A correlation of p53 expression with AI and PI was found in pilocytic astrocytoma but not in glioblastoma, probably because of the mutated p53 phenotype in the latter.

Exogenous platelet-derived growth factor (PDGF) induces human astrocytoma cell line proliferation.

Platelet-derived growth factor receptors (PDGFR) regulate several processes in normal cells including cellular proliferation, differentiation and migration, and are widely expressed in a variety of malignancies. In astrocytoma, PDGF ligand and receptor are often overexpressed and PDGFR activity deregulation has been linked to pathogenesis. The issue of the functional capacity of PDGFR has only occasionally been addressed in glioma cells by measuring the proliferative response induced by exogenous PDGF. In the present study, PDGFRalpha expression was evaluated in human grade 2 and 4 astrocytoma cell lines and tissue specimens by immunocytochemistry. The receptor responsiveness to exogenous PDGF was determined in astrocytoma cells with an MTT assay. It was found that astrocytoma cells express PDGFRalpha and respond to PDGF mitogenic action in a grade-dependent manner. The receptor was found to be functional since it induced cell proliferation at different ligand concentrations. We can thus conclude that the proliferative response of human astrocytoma cells is related to their malignancy and receptor status before PDGF stimulation, suggesting a role for PDGFRalpha inhibitors as blockers of malignant cell proliferation.

Immunohistochemical evaluation of minichromosome maintenance protein 7 in astrocytoma grading.

The minichromosome maintenance (MCM) proteins, which play an important role in eukaryotic DNA replication, represent a group of proteins that are currently under investigation as novel diagnostic tumor markers. Several studies have proved a greater reliability of MCM proteins to stain proliferating cells compared to Ki67 protein, a routinely used proliferation marker in histopathology. In the present study, the expressions of MCM7 and Ki67 were estimated in 66 primary human astrocytomas in relation to tumor grade (Grade I-IV, WHO). MCM7 significantly stained more nuclei compared to Ki67 in all the histopathological grades investigated. In addition, a stronger increase of the MCM7 labelling index, in relation to the tumor aggressiveness, was observed.

Minichromosome maintenance protein 7: a reliable tool for glioblastoma proliferation index.

At present there is increasing evidence concerning the value of minichromosome maintenance (MCM) protein expression as a novel indicator of proliferation. In the present study, 15 glioblastoma samples, classified according to WHO, were analysed to evaluate the expression of the principal proliferation markers. The samples examined were subdivided into 2 cytological subsets, small cell (SC) or multiforme cell (MC) glioblastoma, according to the predominant cell type defined in individual specimens. MCM7 detected more cells in the cycle than Ki67 and PCNA and all cases of SC glioblastoma, the most aggressive subset, displayed a significant increase of MCM7-stained nuclei versus those stained with Ki67. These results suggest that the cell cycle-associated proteins MCM are not only useful markers of proliferation, but also valid aids for diagnosis in cerebral glioblastoma.