Biomedical subjects

Maura Poli

Publications and source records attributed to Maura Poli.

7 recordsLinked to original sources

PubMed2006

RNA silencing of the mitochondrial ABCB7 transporter in HeLa cells causes an iron-deficient phenotype with mitochondrial iron overload.

X-linked sideroblastic anemia with ataxia (XLSA/A) is caused by defects of the transporter ABCB7 and is characterized by mitochondrial iron deposition and excess of protoporphyrin in erythroid cells. We describe ABCB7 silencing in HeLa cells by performing sequential transfections with siRNAs. The phenotype of the ABCB7-deficient cells was characterized by a strong reduction in proliferation rate that was not rescued by iron supplementation, by evident signs of iron deficiency, and by a large approximately 6-fold increase of iron accumulation in the mitochondria that was poorly available to mitochondrial ferritin. The cells showed an increase of protoporphyrin IX, a higher sensitivity to H(2)O(2) toxicity, and a reduced activity of mitochondrial superoxide dismutase 2 (SOD2), while the activity of mitochondrial enzymes, such as citrate synthase or succinate dehydrogenase, and ATP content were not decreased. In contrast, aconitase activity, particularly that of the cytosolic, IRP1 form, was reduced. The results support the hypothesis that ABCB7 is involved in the transfer of iron from mitochondria to cytosol, and in the maturation of cytosolic Fe/S enzymes. In addition, the results indicate that anemia in XLSA/A is caused by the accumulation of iron in a form that is not readily usable for heme synthesis.

ATP-Binding Cassette Transporters↗

PubMed2006

Anti-angiogenic, vascular-disrupting and anti-metastatic activities of vinflunine, the latest vinca alkaloid in clinical development.

The aim of this study was to investigate the anti-angiogenic, vascular-disrupting and anti-metastatic properties of vinflunine, the latest vinca alkaloid in phase III clinical development. The effects of vinflunine on in vitro endothelial cell functions relevant to the performance of an already formed vasculature and to the angiogenic process were evaluated. The in vivo anti-angiogenic properties of vinflunine were also investigated, as were its activity against a model of experimental metastasis. In vitro vinflunine induced a rapid change in the morphology of endothelial cells and disrupted the network of capillary-like structures, indicating potential vascular-disrupting activity. Furthermore, vinflunine showed anti-angiogenic properties, since it inhibited endothelial cell migration and the capacity of these cells to organise into a network of capillary-like structures. All these effects were observed under conditions that only marginally affect endothelial cell proliferation. In vivo, vinflunine inhibited bFGF-induced angiogenesis in Matrigel implants at doses 40-20-fold lower than its maximal therapeutic dose (MTD). Treatment of mice with vinflunine reduced the number of liver metastases induced by intrasplenic injection of LS174T cells, with significant effects also observed at low doses; i.e. 16-fold lower than the MTD. This study demonstrates that vinflunine expresses both vascular-disrupting and anti-angiogenic activities and induced marked effects against experimental metastases, all properties that support its ongoing clinical development.

Angiogenesis Inhibitors↗

PubMed2005

DNA sequence variations in the prolyl isomerase Pin1 gene and Alzheimer's disease.

Senile plaques and neurofibrillary tangles (NFT) are the prominent lesions in the brain of Alzheimer's disease (AD) patients. NFT are mainly composed of an abnormally phosphorylated form of tau protein, which has lost its function to bind microtubules and promote their assembly. Tau hyperphosphorylation critically decreases tau function and precedes neurodegeneration. The majority of tau phosphorylation sites are Ser/Thr-Pro motifs, which are known to exist in two distinct cis and trans conformations. The prolyl isomerase Pin1 catalyses the conversion of those conformations. Pin1 binds to tau specifically at the Thr231-Pro site and restores tau function, either by inducing conformational changes or facilitating dephosphorylation. It has been shown that Pin1 expression levels inversely correlate with the predicted vulnerability of different brain areas to neurodegeneration and soluble Pin1 is depleted in neurons from AD brains; furthermore, Pin1 knock-out mice develop signs and symptoms of tau-related pathologies late in life. It seems that Pin1 plays an important role in maintaining tau function, thereby preserving neuronal homeostasis and preventing age-dependent neurodegeneration. DNA sequence variations in Pin1 gene may affect its expression level or function and influence the individual risk for developing AD. We screened by denaturing high performance liquid chromatography the genomic DNA of 120 AD subjects and 134 age-matched controls and we found very few and rare sequence variations in the promoter region and in exons 2 and 3. We conclude that Pin1 is a very well conserved gene, whose rare nucleotide variations have no effect on the individual genetic risk for AD.

Aged↗

PubMed2005

Apolipoprotein E haplotyping by denaturing high-performance liquid chromatography.

The apolipoprotein E ( APOE ) gene in humans contains two single-base polymorphisms in exon 4, which result in three common alleles, conventionally named epsilon2 , epsilon3 and epsilon4 . Numerous studies have shown an important association between the epsilon4 variant and an increased risk of Alzheimer's disease; other data suggest a possible linkage of APOE genetic heterogeneity with lipid profile and an increased risk of atherothrombotic stroke and coronary heart disease. APOE genotyping is therefore an increasingly common assay in laboratory medicine. The most widely used technique for APOE genotyping is based upon restriction isotyping, i.e., amplification of the fragment of exon 4 containing the most common sequence variations, followed by enzymatic digestion of the amplicon and fragments analysis by gel electrophoresis. We developed a novel, reliable and fast method that exploits the sensitivity and specificity of denaturing high-performance liquid chromatography in detecting single-nucleotide polymorphisms. We show that, in most cases, with a single chromatographic separation it is possible to correctly identify the six different APOE allelic patterns, without any manipulation after the polymerase chain reaction amplification. When compared to restriction isotyping, our method is much faster, less labor intensive and similarly inexpensive.

Alleles↗

PubMed2003

Association analysis between anterior-pharynx defective-1 genes polymorphisms and Alzheimer's disease.

Recent biological studies indicate the importance of anterior-pharynx defective-1 (APH-1) proteins in Alzheimer's disease (AD) pathogenesis. We scanned APH-1 genes for the presence of sequence variations by denaturing high performance liquid chromatography and analyzed their distribution in an Italian sample of 113 AD patients and 132 controls. We found six different polymorphisms: three of them, all in APH-1b, predict an aminoacid substitution (T27I, V199L and F217L); the others are either silent or in non-coding regions. None of them is significantly associated with the disease; data stratification by the apolipoprotein E epsilon4 carrier status show a trend for coexistence of the transversion c+651T>G (F217L) with the epsilon4 allele. Our data suggest that polymorphisms in APH-1a/b coding regions are not linked with higher risk for sporadic AD in our Italian population sample.

Aged↗

PubMed2003

Vascular-targeting activity of ZD6126, a novel tubulin-binding agent.

The tubulin-binding agent ZD6126 is a novel vascular-targeting agent in clinical development for the treatment of solid tumors. In vivo, ZD6126 is rapidly converted into N-acetylcolchinol (ZD6126 phenol). In this study, we have explored the antivascular property of N-acetylcolchinol in vitro and ZD6126 in vivo. In cell culture, N-acetylcolchinol induced rapid changes in the morphology of human umbilical vein and lung microvessel endothelial cells. Within 40 min, the compound induced endothelial cell contraction, destabilization of the tubulin cytoskeleton, induction of actin stress fibers, and membrane blebbing. These effects occurred at noncytotoxic concentrations and were rapidly reversed on removal of the drug. Nonconfluent endothelial cells were more sensitive than confluent, quiescent cells. Among different cell types, endothelial cells were the most sensitive to the induction of morphological changes, whereas smooth muscle cells were not affected. In vitro, N-acetylcolchinol rapidly disrupted a network of newly formed cords. In vivo, ZD6126 caused shut down of newly formed vessels in the Matrigel plug assay, shortly after injection. This study indicates that rapid alteration of endothelial cell morphology may be responsible for the loss of tumor blood vessel integrity, vessel shut down, and extensive tumor necrosis induced by ZD6126 in experimental tumor models.

Angiogenesis Inhibitors↗

PubMed2002

Antiangiogenic and antitumor activity of IDN 5390, a new taxane derivative.

PURPOSE: We previously reported that paclitaxel, a microtubule-stabilizing drug, inhibited angiogenesis, mainly by inhibiting endothelial cell motility (D. Belotti et al., Clin. Cancer Res., 2: 1843-1849, 1996). The aim of this study was to select a taxane with little cytotoxicity but with antimotility and hence antiangiogenic activity. EXPERIMENTAL DESIGN: Different taxanes, seco derivatives, and 14-beta-hydroxy-10-deacetyl baccatin III derivatives were tested for their effects on the proliferation and motility of human umbilical vein endothelial cells. The antiangiogenic and antineoplastic activities of the compound selected from this screening were further investigated in experimental models in vitro and in vivo. RESULTS: From the screening of different taxanes, we selected IDN 5390, a seco derivative that showed potent antimotility activity and less cytotoxicity than paclitaxel. In comparable experimental conditions, IDN 5390 inhibited endothelial cell migration without affecting proliferation. This compound dose-dependently inhibited the capacity of human umbilical vein endothelial cells plated on Matrigel to organize into a network of cords. In vivo, IDN 5390 significantly inhibited fibroblast growth factor-2-induced angiogenesis in Matrigel implants. Daily treatment with IDN 5390 in mice bearing established lung micrometastases from the B16BL6 murine melanoma caused a reduction in the size of metastases. Finally, IDN 5390 slowed the s.c. growth of the paclitaxel-resistant human ovarian carcinoma, 1A9/PTX22, xenografted in nude mice. CONCLUSIONS: The seco derivative IDN 5390 might represent the prototype of a new class of taxane derivatives with antiangiogenic properties.

Angiogenesis Inhibitors↗