María Elena Hernández-Aguilar

Rehabilitating a brain with Alzheimer's: a proposal.

Alzheimer’s disease (AD) is the most common neurodegenerative disorder, originating sporadically in the population aged over 65 years, and advanced age is the principal risk factor leading to AD development. In spite of the large amount of research going on around the globe and all the information now available about AD, there is still no origin or triggering process known so far. Drugs approved for the treatment of AD include tacrine, donepezil, rivastigmine, galantamine, and memantine. These may delay or slow down the degenerative process for a while, but they can neither stop nor reverse its progression. Because that this might be due to a lack of effect of these drugs on degenerating neurons, even when they are able to potentiate the brain in nondegenerative conditions, we propose here an alternative therapy consisting of initial repair of neuronal membranes followed by conventional drug therapies. The rehabilitation of neurons in a degeneration process would enable the drugs to act more effectively on them and improve the effects of treatment in AD patients.

A strategy focused on MAPT, APP, NCSTN and BACE1 to build blood classifiers for Alzheimer׳s disease

BACKGROUND Although Alzheimers disease (AD) is a brain disorder, a number of peripheral alterations have been found in these patients, including differences in leukocyte gene expression; however, the key genes involved in plaque and tangle formation have shown a relatively small potential as diagnostic markers. We focused on MAPT, APP, NCSTN and BACE1 as the basis to build and compare blood classifiers for AD. METHODS We used a combined model to build disease classifiers, using measures of blood pressure and serum glucose, cholesterol and triglyceride levels as well as RT-PCR expression levels of APP, NCSTN and BACE1 in peripheral blood mononuclear cells (PBMCs) from an independent cohort of 36 individuals of cognitively-normal controls, AD and other neuropathologies. Also, a set of genes was carefully selected by molecular interactions with MAPT, APP, NCSTN and BACE1 to test an expression-based classifier in a public microarray dataset of 40 samples (AD and controls). A series of discriminant analyses and classification and regression trees (C&RTs) were used to perform classification tasks. RESULTS Using C&RTs, the combined model showed potential to differentially diagnose AD with up to 94.4% accuracy and 100% specificity for our independent sample. Furthermore, a subset of 16 genes showed the best diagnostic potential using a minimum number of expression variables, correctly classifying up to 100% of samples in the public dataset. CONCLUSIONS Our unique method of variable selection proves that even elements showing no significant differences between controls and AD, but that have somehow been linked to AD or AD-related elements, still hold a potential to be used in its diagnosis. Sample size and inherent methodological limitations of this study need to be kept in mind. Our classifiers require careful further testing in larger cohorts. Nonetheless, we believe these results provide evidence for the utility of our innovative method, which contributes a different approach to generate promising diagnostic tools for neuropsychiatric disorders.

Abeta(1-42) induces abnormal alternative splicing of tau exons 2/3 in NGF-induced PC12 cells

Protein tau plays a pivotal role in the pathophysiology of Alzheimers disease, where its hyperphos-phorylation promotes aggregation and microtubule destabilization. Tau undergoes alternative splicing which generates six isoforms in the human brain, due to inclusion/exclusion of exons 2, 3 and 10. Dysregulation of the splicing process of tau exon 10 is sufficient to cause tauopathy and has shown to be influenced by beta-amyloid peptides, but splicing of other exons is less studied. We studied the effects of beta-amyloid(42) in the alternative splicing of tau exons 2/3 and 6, using untreated and Nerve Growth Factor-induced PC12 cells. Beta-amyloid exposure caused formed cell processes to retract in differentiated cells and altered the expression of exons 2/3 in both undifferentiated and differentiated cells. Expression of exon 6 was repressed in undifferentiated cells only. Our results suggest that beta-amyloid interferes with the splicing process of exons 2/3, favoring their exclusion and thus the expression of immature tau isoforms that are less efficient in stabilizing microtubules and may also be more prone to hyperphosphorylation. The molecular mechanism for this amyloid-tau interaction remains to be determined, but may have potential implications for the understanding of the underlying neuropathological processes in Alzheimers disease.

Molecular dynamics and virtual screening analysis of lanosterol derivatives from Ganoderma medicinal mushrooms (agaricomycetes) as selective ligands of human androgen receptor

Male sex hormones such as testosterone and dihydrotestosterone play important roles in several physiological and pathological processes. The biological activities of the aforementioned metabolites are mediated by the multidomain androgen receptor (AR), which is therefore a well-studied drug target. Ganoderma mushroom lanostanoid extracts have previously been shown to exert antiandrogenic activity; therefore, this work aims to identify which lanostane derivatives might act as selective ligands for AR. Because protein flexibility is of paramount importance for ligand binding, different conformations of AR were sampled to account for binding modes within a ligand binding site, then subjected to virtual screening against a metabolite library. Fifteen Ganoderma lanostanoids were selected as AR ligands, according to their calculated binding affinity to this nuclear receptor. The results show the relevance of certain structural and chemical aspects of our ligands, such as the presence of a ketonic group on C-3, which influences the process through which they bind to AR.

Abstract B50: Antiproliferative activity of the polar extract of Justicia spicigera on LNCaP cells

Justicia spicigera is a Mexican plant employed in traditional medicine for treatment of anemia, stomach illness and skin diseases. Furthermore, it has been suggested that this plant has anticancer properties on leukemia patients and in other types of cancer. However, the scientific evidence supporting these properties is not sufficient. The aim of this study was to evaluate the effect of Justicia spicigera on proliferation and viability of the androgen-dependent human prostate cancer cell line, LNCaP.A polar extract was obtained by exhaustive maceration with water and ethanol (v/v) of the air parts of the plant. The phytochemical analysis by the color test and thin layer chromatography (TLC) showed the presence of antioxidant compounds like coumarins, flavonoids and anthocyanins, which was corroborated by Nuclear Magnetic Resonance (H1 NMR). At the same time, the extract showed the presence of polyphenolic compounds detected by the Folin-Ciocalteu9s reagent. The reducing power and the free radical scavenging capacity, was not too high in comparison with other less polar extracts of this plant, this could be explained by the high rate of glycosylation of the compounds in the sample. In the other hand, the polar extract of Justicia spicigera showed an antiproliferative activity on LNCaP cells since 500 g/ml of extract, measured by the MTT assay and direct cell account. Interestingly, cell morphology was not affected under these conditions. Likewise, the same extract did not show a relevant citotoxic effect (MTT assay) or an affectation on cellular viability (trypan blue assay) of LNCaP cells. Our study showed an antiproliferative effect of the polar extract of Justicia spicigera on LNCaP cells suggesting a potential use as anticancer agent. Further studies should focus on the characterization of compounds responsible of the effects observed on LNCaP cells, as well as in the definition of the mechanisms by which they affect the growth of these cells. Citation Information: Cancer Prev Res 2010;3(12 Suppl):B50.