New molecular targets for PET and SPECT imaging in neurodegenerative diseases

The pathophysiology of neurodegenerative diseases (ND) such as Alzheimer's disease (AD) and Parkinson's disease (PD) has not yet been completely elucidated. However, in the past few years, there have been great knowledge advances about intra-and extracellular proteins that may display impaired function or expression in AD, PD and other ND, such as amyloid beta (AB), alpha-synuclein, tau protein and neuroinfiammatory markers. Recent developments in the imaging techniques of positron emission tomography (PET) and single photon emission computed tomography (SPECT) now allow the non-invasive tracking of such molecular targets of known relevance to ND in vivo. This article summarizes recent findings of PET and SPECT studies using these novel methods, and discusses their potential role in the field of drug development for ND as well as future clinical applications in regard to differential diagnosis of ND and monitoring of disease progression.Brazilian Agency: CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES) Brazilian agenc

Analysis of the expression of proteins involved in cell cycle control, apoptosis, angiogenesis, migration and invasion of C6 rat glioma cells in vitro and in vivo, after treatment with <font face=\"symbol\">g-linolenic acid (GLA) and a novel diruthenium containing ibuprofen complex (Ru-Ibp).

Os gliomas são tumores cerebrais intracraniais caracterizados pelo seu rápido crescimento e pela sua resistência à quimioterapia e radioterapia atuais. Assim, a procura por novos agentes terapêuticos com múltiplos mecanismos de ação têm identificado o ácido g-linolênico (GLA), antiinflamatórios não esteroidais (AINEs) e compostos contendo rutênio como possíveis candidatos. Dessa forma, a principal proposta deste projeto foi entender melhor o mecanismo de ação dessas drogas sobre as células C6 de glioma de rato. Foram analisadas proteínas envolvidas no controle do ciclo celular, apoptose, angiogênese, invasão e migração através de RT-PCR e Western Blotting após tratamento in vitro e in vivo. Alterações da expressão de ciclina D1, E2F-1, pRb, p27, p21, p16, p65, c-myc, ERK1/2, nm23 e b, MMP-2, Brevican GPI e Secretado, Tenascina-R, Tenascina-C, VEGF-A, Flt1, Flk1, Bax, PPARg, p53, COX-2, EP1, 2, 3 e 4, Ku70 e 80 foram encontradas. Em conclusão, o GLA e o complexo Rutênio-Ibuprofeno possuem múltiplos alvos que levam à inibição da proliferação celular.Gliomas are intracranial tumors of cerebral origin characterized for its rapid growth and resistance to both conventional chemotherapy and radiotherapy. The search for new therapeutics agents with multiple mechanisms of action has identified g-linolenic acid (GLA), nonsteroidal anti-inflammatory drugs (NSAIDs) and ruthenium containing compounds as possible candidates. The aim of this study was to better know the mechanism of action of these drugs on C6 rat glioma cells. Expression of proteins involved in control of the cell cycle, apoptosis, angiogenesis, invasion and migration was analyzed using RT-PCR and Western Blotting methods after treatment in vitro and in vivo. Alterations in cyclin D1, E2F-1, pRb, p27, p21, p16, p65, c-myc, ERK1/2, nm23 e b, MMP-2, GPI and Secreted Brevican, Tenascin-R, Tenascin-C, VEGF-A, Flt1, Flk1, Bax, PPARg, p53, COX-2, EP1, 2, 3 and 4, Ku70 and 80 expression were observed. In conclusion, GLA and Ruthenium-Ibuprofen complex has multiple target wich translate into the inhibition of proliferation

Bioaccessibility of Shore Magic® collagen, a low-molecular-weight collagen supplement, in different in vitro barrier models

Hydrolyzed collagen consists of peptides, which exert important biological functions in different body systems. This study aimed at testing the biological effects of a low molecular weight collagen (LMWC), namely Shore Magic® Collagen (SMC), in a series of in vitro assays and three different in vitro barrier models with translational significance. We also compared SMC's biological activities with its trypsinized form (TSMC). SMC enhanced migration in both epithelial and endothelial cells; and increased the adhesion of epithelial cells, but surprisingly not of endothelial cells. It also diminished the tightness in the gut and blood-brain barriers in vitro while TSMC did not. SMC induced both neurogenesis and BJ epithelial cell proliferation of cells growing below the in vitro barriers. In conclusion, the intact form of SMC shows enhanced bioavailability and efficiency compared with TSMC

Gamma-linolenic acid inhibits both tumour cell cycle progression and angiogenesis in the orthotopic C6 glioma model through changes in VEGF, Flt1, ERK1/2, MMP2, cyclin D1, pRb, p53 and p27 protein expression

<p>Abstract</p> <p>Background</p> <p>Gamma-linolenic acid is a known inhibitor of tumour cell proliferation and migration in both <it>in vitro </it>and <it>in vivo </it>conditions. The aim of the present study was to determine the mechanisms by which gamma-linolenic acid (GLA) osmotic pump infusion alters glioma cell proliferation, and whether it affects cell cycle control and angiogenesis in the C6 glioma <it>in vivo</it>.</p> <p>Methods</p> <p>Established C6 rat gliomas were treated for 14 days with 5 mM GLA in CSF or CSF alone. Tumour size was estimated, microvessel density (MVD) counted and protein and mRNA expression measured by immunohistochemistry, western blotting and RT-PCR.</p> <p>Results</p> <p>GLA caused a significant decrease in tumour size (75 ± 8.8%) and reduced MVD by 44 ± 5.4%. These changes were associated with reduced expression of vascular endothelial growth factor (VEGF) (71 ± 16%) and the VEGF receptor Flt1 (57 ± 5.8%) but not Flk1. Expression of ERK1/2 was also reduced by 27 ± 7.7% and 31 ± 8.7% respectively. mRNA expression of matrix metalloproteinase-2 (MMP2) was reduced by 35 ± 6.8% and zymography showed MMP2 proteolytic activity was reduced by 32 ± 8.5%. GLA altered the expression of several proteins involved in cell cycle control. pRb protein expression was decreased (62 ± 18%) while E2F1 remained unchanged. Cyclin D1 protein expression was increased by 42 ± 12% in the presence of GLA. The cyclin dependent kinase inhibitors p21 and p27 responded differently to GLA, p27 expression was increased (27 ± 7.3%) while p21 remained unchanged. The expression of p53 was increased (44 ± 16%) by GLA. Finally, the BrdU incorporation studies found a significant inhibition (32 ± 11%) of BrdU incorporation into the tumour <it>in vivo</it>.</p> <p>Conclusion</p> <p>Overall the findings reported in the present study lend further support to the potential of GLA as an inhibitor of glioma cell proliferation <it>in vivo </it>and show it has direct effects upon cell cycle control and angiogenesis. These effects involve changes in protein expression of VEGF, Flt1, ERK1, ERK2, MMP2, Cyclin D1, pRb, p53 and p27. Combination therapy using drugs with other, complementary targets and GLA could lead to gains in treatment efficacy in this notoriously difficult to treat tumour.</p

Gamma-linolenic Acid Alters Ku80, E2F1, and Bax Expression and Induces Micronucleus Formation in C6 Glioma Cells In Vitro

Gamma-linolenic acid (GLA) is an inhibitor of tumor cell proliferation in both in vitro and in vivo conditions. The aim of this study was to investigate the effects of 150 mu M GLA on the expression of E2F1, cyclin D1, bax, bcl2, Ku70, and Ku80 in C6 rat glioma cells. The Ku proteins were chosen as previous studies have shown that loss or reduction in their expression causes increased DNA damage and micronucleus formation in the presence of radiation. The fact that GLA exposure is known to enhance the efficacy of radiation treatment raised the question whether the Ku proteins could be involved in this effect as seen for other molecules such as roscovitine and flavopiridol. GLA altered the mRNA expression of E2F1, cyclin D1, and bax, but no changes were found for bcl2, Ku70, and Ku80. Alterations in protein expression were observed for bax, Ku80, and E2F1. The 45% decrease in E2F1 expression was proportional to decreased cell proliferation (44%). Morphological analysis found a 25% decrease in mitotic activity in the GLA-treated cells, which was accompanied by a 49% decrease in S-phase by FACS analysis. A 39% increase in the number of micronuclei detected by Hoechst fluorescence points to GLA`s effects on cell division even at concentrations that do not produce significant increases in apoptosis. Most important was the finding that Ku80 expression, a critical protein involved in DNA repair as a heterodimer with Ku70, was decreased by 71%. It is probable that reduced Ku80 is responsible for the increase in micronucleus formation in GLA-treated cells in a similar manner to that found in Ku80 null cells exposed to radiation. The decreased expression of Ku80 and E2F1 could make cells more susceptible to radiotherapy and chemotherapy. (C) 2009 IUBM

Diruthenium(II, III) complexes of ibuprofen, aspirin, naproxen and indomethacin non-steroidal anti-inflammatory drugs: Synthesis, characterization and their effects on tumor-cell proliferation

[Ru-2(dNSAID)(4)Cl] and novel [Ru-2(dNSAID)(4)(H2O)(2)]PF6 complexes, where dNSAID = deprotonated carboxylate from the non-steroidal anti-inflammatory drugs (NSIDs), respectively: ibuprofen, Hibp (1) and aspirin, Hasp (2); naproxen, Hnpx (3) and indomethacin, Hind (4), have been prepared and characterized by optical spectroscopic methods. All of the compounds exhibit mixed valent Ru-2(II, III) cores where metal-metal bonds are stabilized by four drug-carboxylate bridging ligands in paddlewheel type structures. The diruthenium complexes and their parent NSAIDs showed no significant effects for Hep2 human larynx or T24/83 human bladder tumor. In contrast, the coordination of Ru-2(II,III) core led to synergistic effects that increased significantly the inhibition of C6 rat glioma proliferation in relation to the organic NSAIDs naproxen and ibuprofen, The possibility that the complexes Ru-2-ibp and Ru-2-npx may exert effects (anti-angiogenic and anti-matrix metalloprotease) that are similar to those exhibited by NAMI-A opens new horizons for in vivo C6 glioma model studies. (C) 2007 Elsevier Ltd. All rights reserved

The novel ruthenium-gamma-linolenic complex [Ru(2)(aGLA)(4)Cl] inhibits C6 rat glioma cell proliferation and induces changes in mitochondrial membrane potential, increased reactive oxygen species generation and apoptosis in vitro

The present study reports the synthesis of a novel compound with the formula [Ru(2)(aGLA)(4)Cl] according to elemental analyses data, referred to as Ru(2)GLA. The electronic spectra of Ru(2)GLA is typical of a mixed valent diruthenium(II,III) carboxylate. Ru(2)GLA was synthesized with the aim of combining and possibly improving the anti-tumour properties of the two active components ruthenium and gamma-linolenic acid (GLA). The properties of Ru(2)GLA were tested in C6 rat glioma cells by analysing cell number, viability, lipid droplet formation, apoptosis, cell cycle distribution, mitochondrial membrane potential and reactive oxygen species. Ru(2)GLA inhibited cell proliferation in a time and concentration dependent manner. Nile Red staining suggested that Ru(2)GLA enters the cells and ICP-AES elemental analysis found all increase in ruthenium from <0.02 to 425 mg/Kg in treated cells. The sub-G1 apoptotic cell population was increased by Ru(2)GLA (22 +/- 5.2%) when analysed by FACS and this was confirmed by Hoechst staining of nuclei. Mitochondrial membrane potential was decreased in the presence of Ru(2)GLA (44 +/- 2.3%). In contrast, the cells which maintained a high mitochondrial membrane potential had an increase (18 +/- 1.5%) in reactive oxygen species generation. Both decreased mitochondrial membrane potential and increased reactive oxygen species generation may be involved in triggering apoptosis in Ru(2)GLA exposed cells. The EC(50) for Ru(2)GLA decreased with increasing time of exposure from 285 mu M at 24h, 211 mu M at 48 h to 81 mu M at 72 h. In conclusion, Ru(2)GLA is a novel drug with anti proliferative properties in C6 glioma cells and is a potential candidate for novel therapies in gliomas. Copyright (C) 2009 John Wiley & Sons, Ltd.Brazilian research foundations FAPESPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNP

New Perspectives in Nuclear Neurology for the Evaluation of Parkinson's Disease

<p>The pathophysiology of Parkinson's disease (PD) has not yet been completely elucidated. However, during the past few years, significant progress has been made in understanding the intra- and extracellular mechanisms by which proteins such as alpha-synuclein and neuroinflammatory molecules may display impaired function and/or expression in PD. Recent developments in imaging techniques based on positron emission tomography (PET) and single photon emission computed tomography (SPECT) now allow the non-invasive tracking of such molecular targets of known relevance to PD in vivo. This article summarizes recent PET and SPECT studies of new radiopharmaceuticals and discusses their potential role and perspectives for use in the fields of new drug development and early diagnosis for PD, as well to aid in differential diagnosis and monitoring of the progression of PD.</p>

PET imaging of ABC transporters at the blood-brain barrier

The function of ATP-binding cassette (ABC) transporters at the blood-brain barrier (BBB) is to protect the brain from toxic compounds. Additionally, they play a crucial role in the onset and progression of several central nervous system (CNS) diseases as well as in drug resistance. Many compounds were identified as substrates, inhibitors, inducers, or activators for ABC transporters, causing important drug-drug interactions. PET imaging represents an excellent tool for assessing the function and expression of ABC transporters. Over the last years, many PET tracers with different characteristics have been developed, mainly for measuring P-glycoprotein (P-gp) function at the BBB. Although (R)-[11C]verapamil or [11C]N-desmethylloperamide are considered as the "gold standard" P-gp tracers, they have several drawbacks such as its high affinity to P-gp which limits its use for assessing P-gp increased function. Therefore, PET tracers with lower affinity to the transporter have been developed and studied in different species. The assessment of ABC transporters by PET imaging can provide new insight into the physiology and pathophysiology of different CNS diseases and may open new avenues for therapies. Moreover, PET can be used for screening the affinity of new entities toward various ABC transporters and thus enhance the development of CNS drugs

PET Imaging of ABC Transporters at the Blood-Brain Barrier

The function of ATP-binding cassette (ABC) transporters at the blood-brain barrier (BBB) is to protect the brain from toxic compounds. Additionally, they play a crucial role in the onset and progression of several central nervous system (CNS) diseases as well as in drug resistance. Many compounds were identified as substrates, inhibitors, inducers, or activators for ABC transporters, causing important drug-drug interactions. PET imaging represents an excellent tool for assessing the function and expression of ABC transporters. Over the last years, many PET tracers with different characteristics have been developed, mainly for measuring P-glycoprotein (P-gp) function at the BBB. Although (R)-[11C]verapamil or [11C]N-desmethylloperamide are considered as the "gold standard" P-gp tracers, they have several drawbacks such as its high affinity to P-gp which limits its use for assessing P-gp increased function. Therefore, PET tracers with lower affinity to the transporter have been developed and studied in different species. The assessment of ABC transporters by PET imaging can provide new insight into the physiology and pathophysiology of different CNS diseases and may open new avenues for therapies. Moreover, PET can be used for screening the affinity of new entities toward various ABC transporters and thus enhance the development of CNS drugs