Wnt activation affects proliferation, invasiveness and radiosensitivity in medulloblastoma.

Medulloblastomas (MBs) associated with the Wnt activation represent a subgroup with a favorable prognosis, but it remains unclear whether Wnt activation confers a less aggressive phenotype and/or enhances radiosensitivity. To investigate this issue, we evaluated the biological behavior of an MB cell line, UW228-1, stably transfected with human ß-catenin cDNA encoding a nondegradable form of ß-catenin (UW-B) in standard culture conditions and after radiation treatment. We evaluated the expression, transcriptional activity, and localization of ß-catenin in the stably transfected cells using immunofluorescence and WB. We performed morphological analysis using light and electron microscopy. We then analyzed changes in the invasiveness, growth, and mortality in standard culture conditions and after radiation. We demonstrated that (A) Wnt activation inhibited 97 % of the invasion capability of the cells, (B) the growth of the UW-B cells was statistically significantly lower than that of all the other control cells (p < 0.01), (C) the mortality of irradiated UW-B cells was statistically significantly higher than that of the controls and their nonirradiated counterparts (p < 0.05), and (D) morphological features of neuronal differentiation were observed in the Wnt-activated cells. In tissue samples, the Ki-67 labeling index (LI) was lower in ß-catenin-positive samples compared to non-ß-catenin positive ones. The Ki-67 LI median (LI = 40) of the nuclear ß-catenin-positive tumor samples was lower than that of non-nuclear ß-catenin-positive samples (LI = 50), but the difference was not statistically significant. Overall, our data suggest that activation of the Wnt pathway reduces the proliferation and invasion of MBs and increases the tumor's radiosensitivity.

Skeletal muscle satellite cells in amyotrophic lateral sclerosis.

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.

The complex puzzle underlying the pathophysiology of acute coronary syndromes: from molecular basis to clinical manifestations.

Acute coronary syndromes (ACS) still represent a major cause of death in Western countries; in the vast majority of cases, coronary atherosclerosis represents the common pathological lesion to all forms of ACS. It is currently believed that plaque complication (rupture, fissuration, and so on), with the consequent superimposed thrombosis, is a key factor ultimately leading to the clinical occurrence of ACS. Over the last two decades, our understanding of the basic mechanisms involved in the pathophysiology of ACS has progressed significantly and the crucial role of inflammation in this phenomenon is now widely recognized. The sequence of events is represented by plaque complication (i.e., rupture, fissuration or erosion), exposure of tissue factor and other prothrombotic substances, such as von Willebrand factor and collagen, to the blood flow, activation of platelets and of the coagulation cascade and thrombus formation within the coronary artery. However, not all complicated plaques cause the clinical occurrence of ACS and similar complicated plaques may cause different clinical manifestations. A complex interaction between different factors, such as arterial vessel wall substrates, degree of inflammation of the culprit lesion, local rheological characteristics of blood flow, as well as factors present in the circulating blood, will determine the severity (complete vs incomplete occlusion) and the persistence of coronary blood flow cessation, which, in turn, will be largely responsible for the clinical picture. Targeting tissue factor, the key player in the activation of the coagulation cascade, may represent an important therapeutic strategy to prevent the clinical manifestation of ACS.