MMP-2 siRNA Inhibits Radiation-Enhanced Invasiveness in Glioma Cells

Our previous work and that of others strongly suggests a relationship between the infiltrative phenotype of gliomas and the expression of MMP-2. Radiation therapy, which represents one of the mainstays of glioma treatment, is known to increase cell invasion by inducing MMP-2. Thus, inhibition of MMP-2 provides a potential means for improving the efficacy of radiotherapy for malignant glioma.We have tested the ability of a plasmid vector-mediated MMP-2 siRNA (p-MMP-2) to modulate ionizing radiation-induced invasive phenotype in the human glioma cell lines U251 and U87. Cells that were transfected with p-MMP-2 with and without radiation showed a marked reduction of MMP-2 compared to controls and pSV-transfected cells. A significant reduction of proliferation, migration, invasion and angiogenesis of cells transfected with p-MMP-2 and in combination with radiation was observed compared to controls. Western blot analysis revealed that radiation-enhanced levels of VEGF, VEGFR-2, pVEGFR-2, p-FAK, and p-p38 were inhibited with p-MMP-2-transfected cells. TUNEL staining showed that radiation did not induce apoptosis in U87 and U251 cells while a significant increase in TUNEL-positive cells was observed when irradiated cells were simultaneously transfected with p-MMP-2 as compared to controls. Intracranial tumor growth was predominantly inhibited in the animals treated with p-MMP-2 alone or in combination with radiation compared to controls.MMP-2 inhibition, mediated by p-MMP-2 and in combination with radiation, significantly reduced tumor cell migration, invasion, angiogenesis and tumor growth by modulating several important downstream signaling molecules and directing cells towards apoptosis. Taken together, our results demonstrate the efficacy of p-MMP-2 in inhibiting radiation-enhanced tumor invasion and progression and suggest that it may act as a potent adjuvant for radiotherapy in glioma patients

Differential expression and localization of TIMP-1 and TIMP-4 in human gliomas

Studies have suggested that an imbalance of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) may contribute to the malignant phenotype of gliomas. In this study, we have undertaken a detailed analysis of expression of the TIMP family in normal human brain and malignant gliomas at both the mRNA and protein level. Reverse transcription-PCR (RT-PCR) analyses of total RNA from surgical tumour specimens revealed unique expression patterns for the 4 members of the TIMP family, with TIMP-1 and -4 showing positive and negative correlations, respectively, with glioma malignancy. By RT-PCR, TIMP-2 and TIMP-3 expression did not change with tumour grade. In situ hybridization localized TIMP-1 to glial tumour cells and also to the surrounding tumour vasculature. TIMP-4 transcripts were predominantly localized to tumour cells, though minor expression was found in vessels. Recombinant TIMP-4 reduced invasion of U251 glioma cells through Matrigel, and U87 clones overexpressing TIMP-4 showed reduced invasive capacity in vitro. TIMP-4, but not TIMP-1, blocked Membrane Type-1-MMP-mediated progelatinase-A (MMP-2) activation in human umbilical vein endothelial cells. The differential expression and localization of individual TIMPs may contribute to the pathophysiology of human malignant gliomas, particularly with regard to tumour vascularization. © 2001 Cancer Research Campaign http://www.bjcancer.co

Diffuse glioma growth: a guerilla war

In contrast to almost all other brain tumors, diffuse gliomas infiltrate extensively in the neuropil. This growth pattern is a major factor in therapeutic failure. Diffuse infiltrative glioma cells show some similarities with guerilla warriors. Histopathologically, the tumor cells tend to invade individually or in small groups in between the dense network of neuronal and glial cell processes. Meanwhile, in large areas of diffuse gliomas the tumor cells abuse pre-existent “supply lines” for oxygen and nutrients rather than constructing their own. Radiological visualization of the invasive front of diffuse gliomas is difficult. Although the knowledge about migration of (tumor)cells is rapidly increasing, the exact molecular mechanisms underlying infiltration of glioma cells in the neuropil have not yet been elucidated. As the efficacy of conventional methods to fight diffuse infiltrative glioma cells is limited, a more targeted (“search & destroy”) tactic may be needed for these tumors. Hopefully, the study of original human glioma tissue and of genotypically and phenotypically relevant glioma models will soon provide information about the Achilles heel of diffuse infiltrative glioma cells that can be used for more effective therapeutic strategies

Inter-individual variability of stone marten behavioral responses to a highway

Efforts to reduce the negative impacts of roads on wildlife may be hindered if individuals within the population vary widely in their responses to roads and mitigation strategies ignore this variability. This knowledge is particularly important for medium-sized carnivores as they are vulnerable to road mortality, while also known to use available road passages (e.g., drainage culverts) for safely crossing highways. Our goal in this study was to assess whether this apparently contradictory pattern of high road-kill numbers associated with a regular use of road passages is attributable to the variation in behavioral responses toward the highway between individuals. We investigated the responses of seven radio-tracked stone martens (Martes foina) to a highway by measuring their utilization distribution, response turning angles and highway crossing patterns. We compared the observed responses to simulated movement parameterized by the observed space use and movement characteristics of each individual, but naı¨ve to the presence of the highway. Our results suggested that martens demonstrate a diversity of responses to the highway, including attraction, indifference, or avoidance. Martens also varied in their highway crossing patterns, with some crossing repeatedly at the same location (often coincident with highway passages). We suspect that the response variability derives from the individual’s familiarity of the landscape, including their awareness of highway passage locations. Because of these variable yet potentially attributable responses, we support the use of exclusionary fencing to guide transient (e.g., dispersers) individuals to existing passages to reduce the road-kill risk

Association analysis of low-phosphorus tolerance in West African pearl millet using DArT markers

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a food security crop in the harshest agricultural regions of the world. While low soil phosphorus (P) availability is a big constraint on its production, especially in West Africa (WA), information on genomic regions responsible for low-P tolerance in pearl millet is generally lacking. We present the first report on genetic polymorphisms underlying several plant P-related parameters, flowering time (FLO) and grain yield (GY) under P-limiting conditions based on 285 diversity array technology markers and 151 West African pearl millet inbred lines phenotyped in six environments in WA under both high-P and low-P conditions. Nine markers were significantly associated with P-related traits, nine markers were associated with FLO, whereas 13 markers were associated with GY each explaining between 5.5 and 15.9 % of the observed variation. Both constitutive and adaptive associations were observed for FLO and GY, with markers PgPb11603 and PgPb12954 being associated with the most stable effects on FLO and GY, respectively, across locations. There were a few shared polymorphisms between traits, especially P-efficiency-related traits and GY, implying possible colocation of genomic regions responsible for these traits. Our findings help bridge the gap between quantitative and molecular methods of studying complex traits like low-P tolerance in WA. However, validation of these markers is necessary to determine their potential applicability in marker-assisted selection programs targeting low-P environments, which are especially important in WA where resource-poor farmers are expected to be the hardest hit by the approaching global P crisis

Half a century of amyloids: past, present and future

Amyloid diseases are global epidemics with profound health, social and economic implications and yet remain without a cure. This dire situation calls for research into the origin and pathological manifestations of amyloidosis to stimulate continued development of new therapeutics. In basic science and engineering, the cross-ß architecture has been a constant thread underlying the structural characteristics of pathological and functional amyloids, and realizing that amyloid structures can be both pathological and functional in nature has fuelled innovations in artificial amyloids, whose use today ranges from water purification to 3D printing. At the conclusion of a half century since Eanes and Glenner's seminal study of amyloids in humans, this review commemorates the occasion by documenting the major milestones in amyloid research to date, from the perspectives of structural biology, biophysics, medicine, microbiology, engineering and nanotechnology. We also discuss new challenges and opportunities to drive this interdisciplinary field moving forward. This journal i

A new era for understanding amyloid structures and disease

The aggregation of proteins into amyloid fibrils and their deposition into plaques and intracellular inclusions is the hallmark of amyloid disease. The accumulation and deposition of amyloid fibrils, collectively known as amyloidosis, is associated with many pathological conditions that can be associated with ageing, such as Alzheimer disease, Parkinson disease, type II diabetes and dialysis-related amyloidosis. However, elucidation of the atomic structure of amyloid fibrils formed from their intact protein precursors and how fibril formation relates to disease has remained elusive. Recent advances in structural biology techniques, including cryo-electron microscopy and solid-state NMR spectroscopy, have finally broken this impasse. The first near-atomic-resolution structures of amyloid fibrils formed in vitro, seeded from plaque material and analysed directly ex vivo are now available. The results reveal cross-β structures that are far more intricate than anticipated. Here, we describe these structures, highlighting their similarities and differences, and the basis for their toxicity. We discuss how amyloid structure may affect the ability of fibrils to spread to different sites in the cell and between organisms in a prion-like manner, along with their roles in disease. These molecular insights will aid in understanding the development and spread of amyloid diseases and are inspiring new strategies for therapeutic intervention

Activation of the Oxidative Stress Pathway by HIV-1 Vpr Leads to Induction of Hypoxia-inducible Factor 1α Expression*

The detection of biomarkers of oxidative stress in brain tissue and cerebrospinal fluid of patients with human immunodeficiency virus, type 1 (HIV)-associated dementia indicates the involvement of stress pathways in the neuropathogenesis of AIDS. Although the biological importance of oxidative stress on events involved in AIDS neuropathogenesis and the HIV-1 proteins responsible for oxidative stress remain to be elucidated, our results point to the activation of hypoxia-inducible factor 1 (HIF-1) upon HIV-1 infection and its elevation in brain cells of AIDS patients with dementia. HIF-1 is a transcription factor that is responsive to oxygen. Under hypoxic conditions, HIF-1α becomes stable and translocates to the nucleus where it dimerizes with aryl hydrocarbon receptor nuclear translocator and modulates gene transcription. Activation of HIF-1 can also be mediated by the HIV-1 accessory protein Vpr. In addition, cellular components, including reactive oxygen species, contribute to the induction of HIF-1α. Our results show that Vpr induces reactive oxygen species by increasing H2O2 production, which can contribute to HIF-1α accumulation. Interestingly, increased levels of HIF-1α stimulated HIV-1 gene transcription through HIF-1 association with HIV-1 long terminal repeat. These observations point to the existence of a positive feedback interplay between HIF-1α and Vpr and that, by inducing oxidative stress via activation of HIF-1, Vpr can induce HIV-1 gene expression and dysregulate multiple host cellular pathways

D-peptide-magnetic nanoparticles fragment tau fibrils and rescue behavioral deficits in a mouse model of Alzheimer’s disease

Amyloid fibrils of tau are increasingly accepted as a cause of neuronal death and brain atrophy in Alzheimer's disease (AD). Diminishing tau aggregation is a promising strategy in the search for efficacious AD therapeutics. Previously, our laboratory designed a six-residue, nonnatural amino acid inhibitor D-TLKIVW peptide (6-DP), which can prevent tau aggregation in vitro. However, it cannot block cell-to-cell transmission of tau aggregation. Here, we find D-TLKIVWC (7-DP), a d-cysteine extension of 6-DP, not only prevents tau aggregation but also fragments tau fibrils extracted from AD brains to neutralize their seeding ability and protect neuronal cells from tau-induced toxicity. To facilitate the transport of 7-DP across the blood-brain barrier, we conjugated it to magnetic nanoparticles (MNPs). The MNPs-DP complex retains the inhibition and fragmentation properties of 7-DP alone. Ten weeks of MNPs-DP treatment appear to reverse neurological deficits in the PS19 mouse model of AD. This work offers a direction for development of therapies to target tau fibrils