Versican isoform V1 regulates proliferation and migration in high-grade gliomas.

Versican is a large chondroitin sulphate proteoglycan produced by several tumor cell types, including high-grade gliomas. Increased expression of distinct versican isoforms in the extracellular matrix plays a role in tumor cell growth, adhesion and migration. We have recently shown that transforming growth factor (TGF-beta)2, an important modulator of glioma invasion, interacts with versican isoforms V0/V1 during malignant progression of glioma in vitro. However, the distinct subtype of versican that modulates these effects could not be specified. Here, we show that transient down-regulation of V1 by siRNA leads to a significant reduction of proliferation and migration in glioblastoma cell lines and glioblastoma progenitor cells, whereas tumor cell attachment stays unaffected. We conclude that V1 plays a predominant role in modulating central pathophysiological mechanisms as proliferation and migration in glioblastoma. Considering that TGF-beta is a master regulator of glioma pathophysiology, and that V0/1 is induced by TGF-beta2, therapeutic regulation of V1 may induce meaningful effects on glioma cell migration not only in vitro, but also in vivo.

Direct evidence of intra- and interhemispheric corticomotor network degeneration in amyotrophic lateral sclerosis: an automated MRI structural connectivity study.

Although the pathogenesis of amyotrophic lateral sclerosis (ALS) is uncertain, there is mounting neuroimaging evidence to suggest a mechanism involving the degeneration of multiple white matter (WM) motor and extramotor neural networks. This insight has been achieved, in part, by using MRI Diffusion Tensor Imaging (DTI) and the voxelwise analysis of anisotropy indices, along with DTI tractography to determine which specific motor pathways are involved with ALS pathology. Automated MRI structural connectivity analyses, which probe WM connections linking various functionally discrete cortical regions, have the potential to provide novel information about degenerative processes within multiple white matter (WM) pathways. Our hypothesis is that measures of altered intra- and interhemispheric structural connectivity of the primary motor and somatosensory cortex will provide an improved assessment of corticomotor involvement in ALS. To test this hypothesis, we acquired High Angular Resolution Diffusion Imaging (HARDI) scans along with high resolution structural images (sMRI) on 15 patients with clinical evidence of upper and lower motor neuron involvement, and 20 matched control participants. Whole brain probabilistic tractography was applied to define specific WM pathways connecting discrete corticomotor targets generated from anatomical parcellation of sMRI of the brain. The integrity of these connections was interrogated by comparing the mean fractional anisotropy (FA) derived for each WM pathway. To assist in the interpretation of results, we measured the reproducibility of the FA summary measures over time (6months) in control participants. We also incorporated into our analysis pipeline the evaluation and replacement of outlier voxels due to head motion and physiological noise. When assessing corticomotor connectivity, we found a significant reduction in mean FA within a number of intra- and interhemispheric motor pathways in ALS patients. The abnormal intrahemispheric pathways include the corticospinal tracts involving the left and right precentral gyri (lh.preCG, rh.preCG) and brainstem (bs); right postcentral gyrus (rh.postCG) and bs; lh.preCG and left posterior cingulate gyrus (lh.PCG); rh.preCG and right posterior cingulate gyrus (rh.PCG); and the rh.preCG and right paracentral gyrus (rh.paraCG). The abnormal interhemispheric pathways included the lh.preCG and rh.preCG; lh.preCG and rh.paraCG; lh.preCG and right superior frontal gyrus (rh.supFG); lh.preCG and rh.postCG; rh.preCG and left paracentral gyrus (lh.paraCG); rh.preCG and left superior frontal gyrus (lh.supFG); and the rh.preCG and left caudal middle frontal gyrus (lh.caudMF). The reproducibility of the measurement of these pathways was high (variation less than 5%). Maps of the outlier rejection voxels, revealed clusters within the corpus callosum and corticospinal projections. This finding highlights the importance of correcting for motion artefacts and physiological noise when studying clinical populations. Our novel findings, many of which are consistent with known pathology, show extensive involvement and degeneration of multiple corticomotor pathways in patients with upper and lower motor neuron signs and provide support for the use of automated structural connectivity techniques for studying neurodegenerative disease processes.

Effects of prolonged repetitive stimulation of median, ulnar and peroneal nerves.

It is important to know the effects of prolonged repetitive nerve stimulation (RNS) when it is used in neurophysiological studies. RNS with up to 100 supramaximal stimuli was given to the median, ulnar, and peroneal nerves of normal subjects and the ulnar nerves of subjects with early amyotrophic lateral sclerosis (ALS), recording evoked compound muscle action potentials (CMAPs). In all nerves, there was a decline in the CMAP area and a decrease in CMAP duration. For the peroneal nerve there was a decline in the CMAP amplitude, but a similar decline was not seen in the median or ulnar nerves. Cooling of the muscles resulted in decrement of both the amplitude and area with RNS. In ALS subjects, CMAP amplitude and area both declined after RNS of the ulnar nerve. In this study we describe the changes in CMAP with prolonged RNS among commonly tested normal nerves. Our findings have important implications with regard to RNS.

Biomarkers of disease in a case of familial lower motor neuron ALS.

ALS is a fatal disease with variable clinical course. There is no single reliable marker of disease progression. Sufficient records were available to study the case history of four family members with the uncommon G93V SOD1 mutation. Distal lower motor neuron (LMN) involvement occurred in all family members with onset from 30 to 51 years of age, with progression over more than six years. Between 2002 and 2009, we used electrophysiology as a biomarker to study disease progression in one patient, assessing the number of motor units in three nerves from different limbs. The loss of motor units showed an exponential decline with different half-lives in different nerves. Diffusion tractography was compared with a control to assess upper motor neuron (UMN) involvement and showed asymmetric evidence of abnormalities of the corticospinal tracts, providing evidence of central involvement despite the absence of UMN signs.

Use of respiratory function tests to predict survival in amyotrophic lateral sclerosis.

Respiratory function tests (RFTs) are commonly used as a measure of progression in ALS. This study assessed the ability of various RFTs to predict survival in ALS patients. Subjects with ALS had one or more measurements of seated and supine FVC, maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). Kaplan-Meier (KM) analysis was used to determine whether patients with abnormal RFTs had shorter survival than those with normal RFTs. The sensitivity and specificity of RFTs as predictors of two-year survival were calculated from receiver operating characteristic (ROC) curves. With KM analysis, subjects with abnormal values of seated FVC, supine FVC, MIP and MEP had significantly reduced survival compared to subjects with normal values. With ROC curves, a normal supine FVC was highly predictive for two-year survival and had superior sensitivity over seated FVC. Slower rates of decline in seated or supine FVC were strong predictors of two-year survival. Our study demonstrates that respiratory function measurements are useful to predict survival in ALS patients. We show that measurements of FVC in the supine position are worth including in the assessment of respiratory function in ALS.

Lactate promotes glioma migration by TGF-beta2-dependent regulation of matrix metalloproteinase-2.

Lactate dehydrogenase type A (LDH-A) is a key metabolic enzyme catalyzing pyruvate into lactate and is excessively expressed by tumor cells. Transforming growth factor-beta2 (TGF-beta2) is a key regulator of invasion in high-grade gliomas, partially by inducing a mesenchymal phenotype and by remodeling the extracellular matrix. In this study, we tested the hypothesis that lactate metabolism regulates TGF-beta2-mediated migration of glioma cells. Small interfering RNA directed against LDH-A (siLDH-A) suppresses, and lactate induces, TGF-beta2 expression, suggesting that lactate metabolism is strongly associated with TGF-beta2 in glioma cells. Here we demonstrate that TGF-beta2 enhances expression, secretion, and activation of matrix metalloproteinase-2 (MMP-2) and induces the cell surface expression of integrin alpha(v)beta(3) receptors. In spheroid and Boyden chamber migration assays, inhibition of MMP-2 activity using a specific MMP-2 inhibitor and blocking of integrin alpha(v)beta(3) abrogated glioma cell migration stimulated by TGF-beta2. Furthermore, siLDH-A inhibited MMP2 activity, leading to inhibition of glioma migration. Taken together, we define an LDH-A-induced and TGF-beta2-coordinated regulatory cascade of transcriptional regulation of MMP-2 and integrin alpha(v)beta(3). This novel interaction between lactate metabolism and TGF-beta2 might constitute a crucial mechanism for glioma migration.