Increased circulating levels of interleukin-6 induce perturbation in redox-regulated signaling cascades in muscle of dystrophic mice

Duchenne muscular dystrophy (DMD) is an X-linked genetic disease in which dystrophin gene is mutated, resulting in dysfunctional or absent dystrophin protein. The pathology of dystrophic muscle includes degeneration, necrosis with inflammatory cell invasion, regeneration, and fibrous and fatty changes. Nevertheless, the mechanisms by which the absence of dystrophin leads to muscle degeneration remain to be fully elucidated. An imbalance between oxidant and antioxidant systems has been proposed as a secondary effect of DMD. However, the significance and precise extent of the perturbation in redox signaling cascades is poorly understood. We report that mdx dystrophic mice are able to activate a compensatory antioxidant response at the presymptomatic stage of the disease. In contrast, increased circulating levels of IL-6 perturb the redox signaling cascade, even prior to the necrotic stage, leading to severe features and progressive nature of muscular dystrophy

Counteracting muscle wasting in aging and neuromuscular diseases: the critical role of IGF-1

Most muscle pathologies are characterized by the progressive loss of muscle tissue due to chronic degeneration combined with the inability of regeneration machinery to replace the damaged muscle. These pathological changes, known as muscle wasting, can be attributed to the activation of several proteolytic systems, such as calpain, ubiquitin-proteasome and caspases, and to the alteration in muscle growth factors. Among them, insulin-like growth factor-1 (IGF-1) has been implicated in the control of skeletal muscle growth, differentiation, survival, and regeneration and has been considered a promising therapeutic agent in staving off the advance of muscle weakness. Here we review the molecular basis of muscle wasting associated with diseases, such as sarcopenia, muscular dystrophy and Amyotrophic Lateral Sclerosis, and discuss the potential therapeutic role of local IGF-1 isoforms in muscle aging and diseases

Molecular mechanisms regulating skeletal muscle homeostasis: effects of V1a AVP receptor over-expression

The maintenance of a working skeletal musculature is conferred by its capacity to regenerate after mechanical or pathological injury. Most muscle pathologies are characterized by the progressive loss of muscle tissue due to chronic degeneration combined with the inability of the regeneration machinery to replace damaged myofibers. Cachexia or muscle wasting is characterized by a loss of adipose and muscle mass associated with a compromised muscle regenerative ability. Arg-vasopressin (AVP) is a potent myogenesis promoting factor and activates both the calcineurin and CaMK pathways, whose combined activation leads to the formation of transcription factor complexes in vitro. The local over-expression of V1a AVP receptor (V1aR) in injured muscle results in enhanced regeneration. V1aR over-expressing muscle exhibits early activation of satellite cells and regeneration markers and accelerated differentiation. Here we investigated the role of V1aR over-expression in animals undergoing cachexia as a result of muscle over-expression of a specific cytokine (TNF). In these conditions, the local V1aR over-expression counteracts the negative effects of cachexia on muscle, as demonstrated by morphological and biochemical analysis. In particular, the presence of V1aR results in increased Pax-7, myogenin and myosin expression levels both in wild type and in cachectic muscles. The positive effects of V1aR on muscle homeostasis are due to the promotion of the calcineurin-IL-4 pathway and to the inhibition of atrophic genes expression mediated by FOXO phosphorylation. This study highlights a novel in vivo role for the AVP-dependent pathways which may suggest a potential gene therapy approach for many diseases affecting muscle homeostasis

Expression of Reelin in cancer stem cells isolated from human glioblastoma

Reelin is a large secreted extracellular matrix glycoprotein which contributes to positioning, migration and laminar organization of several central nervous system structures during neurodevelopment. Recent studies reported the expression of Reelin and its intracellular adapter protein DAB1 in neuroblastoma, where it appears to be involved in cell motility and invasiveness. Interestingly, our data obtained by immunolocalization analysis show the expression of Reelin in both tumor and peritumoral area of glioblastoma (GBM). It is known that many solid tumors may originate from cancer stem cells (CSC) which are usually resistant to common therapies and might be involved in tumor progression. Therefore, we evaluated the expression of Reelin in CSC neurospheres isolated from both tumor (GCSC) and peritumoral area (PCSC) of GBM. Immunocytochemistry analysis showed the expression of Reelin in both cell types, suggesting that this protein may contribute to neurosphere tridimensional organization and possibly to cell migration during tumor progression. This is the first evidence of Reelin expression in human GBM which might indicate a pivotal role of this protein in the regulation of tumor development. Our data may open potential avenues for GBM treatment by targeting Reelin signaling activity

Molecular mechanisms regulating skeletal muscle homeostasis: effects of V1a AVP receptor over-expression.

The mantainance a working skeletal musculature is conferred by its remarkable capacity to regenerate after mechanical or pathological injury. Most muscle pathologies are characterized by the progressive loss of muscle tissue due to chronic degeneration combined with the inability of the regeneration machinery to replace damaged myofibers. In particular, cachexia or muscle wasting is characterized by a dramatic loss of adipose and muscle mass associated with a compromised muscle regenerative ability. Arg-vasopressin (AVP) is a potent myogenesis promoting factor and activates both the calcineurin and CaMK pathways, whose combined activation leads to the formation of transcription factor complexes in vitro. The local over-expression of V1a AVP receptor (V1aR) in injured muscle results in enhanced regeneration. V1aR over-expressing muscle exhibits: early activation of satellite cells and regeneration markers, accelerated differentiation, increased cell population expressing hematopoietic stem cell markers and its conversion to the myogenic lineage. Here we investigated the role of V1aR over-expression in animals undergoing cachexia as a result of muscle over-expression of a specific cytokine (TNF-). In these conditions, the local V1aR overexpression counteracts the negative effects of cachexia on muscle, as demonstrated by morphological and biochemical analysis. In particular, the presence of V1aR results in increased Pax-7, myogenin and myosin expression levels both in wild type and in cachectic muscles. The positive effects of V1aR on muscle homeostasis are due to the promotion of the calcinuerin-IL- 4 pathway and to the inhibition of atrophic genes expression mediated by FOXO phosphorilation. This study highlights a novel in vivo role for the AVP-dependent pathways which may represent a potential gene therapy approach for many diseases affecting muscle homeostasis

Evaluation of the Reelin signaling in cancer stem cells isolated from tumor and peritumor tissue of glioblastoma

Reelin is a large secreted extracellular glycoprotein that plays a critical role in the regulation of neuronal migration during brain development. Reelin is thought to guide migrating neurons by interacting with cell surface receptors, very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor 2 (ApoER2), and a3 b1integrin, inducing tyrosine phosphorylation of the intracellular adapter protein Disabled-1 (Dab-1) that instructs neurons to reach their correct laminar position in the cortex. Recent evidence supports a role of Reelin in the control of cell proliferation through the activation of mitogen protein kinase (ERK) pathway. We have previously shown, by immunohistochemistry and stereological analysis, the expression of Reelin in both Glioblastoma (GBM) and in peritumor tissue. Moreover, we reported the expression of Reelin in cancer stem cells isolated from both tumor (GCSC) and peritumor tissue (PCSC), suggesting that this protein might contribute to neurosphere formation. Here we investigated by both Real-Time Polymerase Chain Reaction (RT-PCR) and Western Blotting (WB) analysis the gene and protein expression of Reelin and its intracellular adapter Dab-1 in GCSC and PCSC derived from four different patients. Analysis of gene and protein expression indicates higher level of Reelin and DAB-1 in PCSC compared to GCSC. These data suggest a possible role for Reelin and Dab-1 in the control of cell migration and GBM invasiveness

Evaluation of the Reelin signaling in cancer stem cells isolated from tumor and peritumor tissue of glioblastoma

Reelin is a large secreted extracellular glycoprotein that plays a critical role in the regulation of neuronal migration during brain development. Reelin is thought to guide migrating neurons by interacting with cell surface receptors, very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor 2 (ApoER2), and a3 b1integrin, inducing tyrosine phosphorylation of the intracellular adapter protein Disabled-1 (Dab-1) that instructs neurons to reach their correct laminar position in the cortex. Recent evidence supports a role of Reelin in the control of cell proliferation through the activation of mitogen protein kinase (ERK) pathway. We have previously shown, by immunohistochemistry and stereological analysis, the expression of Reelin in both Glioblastoma (GBM) and in peritumor tissue. Moreover, we reported the expression of Reelin in cancer stem cells isolated from both tumor (GCSC) and peritumor tissue (PCSC), suggesting that this protein might contribute to neurosphere formation. Here we investigated by both Real-Time Polymerase Chain Reaction (RT-PCR) and Western Blotting (WB) analysis the gene and protein expression of Reelin and its intracellular adapter Dab-1 in GCSC and PCSC derived from four different patients. Analysis of gene and protein expression indicates higher level of Reelin and DAB-1 in PCSC compared to GCSC. These data suggest a possible role for Reelin and Dab-1 in the control of cell migration and GBM invasiveness

Neurohypophyseal hormones: novel actors of striated muscle development and homeostasis

Since the 1980's, novel functional roles of the neurohypophyseal hormones vasopressin and oxytocin have emerged. Several studies have investigated the effects of these two neurohormones on striated muscle tissues, both in vitro and in vivo. The effects of vasopressin on skeletal myogenic cells, developing muscle and muscle homeostasis have been documented. Oxytocin appears to have a greater influence on cardiomyocite differentiation and heart homeostasis. This review summarizes the studies on these novel roles of the two neurohypophyseal hormones, and open the possibility of new therapeutic approaches for diseases affecting striated muscle

Myokines in home-based functional electrical stimulation-induced recovery of skeletal muscle in elderly and permanent denervation

Neuromuscular disorders, disuse, inadequate nutrition, metabolic diseases, cancer and aging produce muscle atrophy and this implies that there are different types of molecular triggers and signaling pathways for muscle wasting. Exercise and muscle contractions may counteract muscle atrophy by releasing a group of peptides, termed myokines, to protect the functionality and to enhance the exercise capacity of skeletal muscle. In this review, we are looking at the role of myokines in the recovery of permanent denervated and elderly skeletal muscle tissue. Since sub-clinical denervation events contribute to both atrophy and the decreased contractile speed of aged muscle, we saw a parallel to spinal cord injury and decided to look at both groups together. The muscle from lifelong active seniors has more muscle bulk and more slow fiber-type groupings than those of sedentary seniors, demonstrating that physical activity maintains slow motoneurons that reinnervate the transiently denervated muscle fibers. Furthermore, we summarized the evidence that muscle degeneration occur with irreversible Conus and Cauda Equina syndrome, a spinal cord injury in which the human leg muscles may be permanently disconnected from the peripheral nervous system. In these patients, suffering with an estreme case of muscle disuse, a complete loss of muscle fibers occurs within five to ten years after injury. Their recovered tetanic contractility, induced by home-based Functional Electrical Stimulation, can restore the muscle size and function in compliant Spinal Cord Injury patients, allowing them to perform electrical stimulation-supported stand-up training. Myokines are produced and released by muscle fibers under contraction and exert both local and systemic effects. Changes in patterns of myokine secretion, particularly of IGF-1 isoforms, occur in long-term Spinal Cord Injury persons and also in very aged people. Their modulation in Spinal Cord Injury and late aging are also key factors of home-based Functional Electrical Stimulation - mediated muscle recovery. Thus, Functional Electrical Stimulation should be prescribed in critical care units and nursing facilities, if persons are unable or reluctant to exercise. This will result in less frequent hospitalizations and a reduced burden on patients' families and public health services

Levetiracetam enhances the Temozolomide effect on glioblastoma stem cell proliferation

Glioblastoma Multiforme (GBM) is a highly aggressive brain tumor in which cancer cells with stem cell-like features, called Cancer Stem Cells (CSCs), were identified. CSCs show a high capacity to resist to standard therapies, finally leading to a poor prognosis. Thus, the development of efficient strategies targeting these cells are urgently needed. We have previously demonstrated the presence of two CSC populations in GBM, one derived from the GBM area called enhanced lesion (GCSC) and the other one from the brain area adjacent to the tumor margin (PCSC), that greatly differ in their growth properties and tumor-initiating ability. Tumor recurrence occurs in tissue neighboring GBM suggesting a growing relevance for this area in translational research. To date the most effective chemotherapies to treat GBM are alkylating agents such as temozolomide (TMZ). Epigenetic mechanisms are increasingly recognized as a major factor contributing to pathogenesis of cancer including glioblastoma. Histone deacetylase (HDAC) inhibitors can interfere with TMZ activity by modulating methylguanine methyltransferase (MGMT) expression, resulting in increased TMZ efficacy. Levetiracetam (LEV), an antiepileptic drug, is known to modulate the transcription of HDAC, ultimately silencing MGMT.Since TMZ is the chemotherapeutic agent most widely used in newly diagnosed adult glioblastoma patients, we evaluated its effects on the proliferation rate of both GCSC and PCSC deriving from five patients, in comparison with the effects of other drugs such as etoposide, irinotecan and car-boplatin. Our results demonstrated that TMZ was the less efficient agent, hence we verified the pos-sibility to increase the effect of TMZ by combining it with LEV. Here we show that LEV signifi-cantly enhances the inhibitory effect of TMZ on the proliferation of the GCSC deriving from four patients and of the PCSC deriving from two patients. This effect seems to be mediated by HDAC6 since its expression is up-regulated in the TMZ resistant cells and correlates with MGMT expression. Taken together our results suggest that GCSC and PCSC differ in their ability to respond to the combined chemotherapeutic treatment we used and that the manipulation of HDAC6 expression might be a potential strategy for treating glioblastoma and overcoming resistance to TMZ