GDF-15 contributes to proliferation and immune escape of malignant gliomas

Growth and differentiation factor (GDF)-15 is a member of the transforming growth factor (TGF)-beta family. GDF-15 is necessary for the maintenance of pregnancy but has also been linked to other physiologic and pathologic conditions.

siRNA Technology in Kidney Transplantation: Current Status and Future Potential

Kidney transplantation is one of the most common transplantation operations in the world, accounting for up to 50 % of all transplantation surgeries. To curtail the damage to transplanted organs that is caused by ischemia-reperfusion injury and the recipient's immune system, small interfering RNA (siRNA) technology is being explored. Importantly, the kidney as a whole is a preferential site for non-specific systemic delivery of siRNA. To date, most attempts at siRNA-based therapy for transplantation-related conditions have remained at the in vitro stage, with only a few of them being advanced into animal models. Hydrodynamic intravenous injection of naked or carrier-bound siRNAs is currently the most common route for delivery of therapeutic constructs. To our knowledge, no systematic screens for siRNA targets most relevant for kidney transplantation have been attempted so far. A majority of researchers have arrived at one or another target of interest by analyzing current literature that dissects pathological processes taking place in transplanted organs. A majority of the genes that make up the list of 53 siRNA targets that have been tested in transplantation-related models so far belong to either apoptosis- or immune rejection-centered networks. There is an opportunity for therapeutic siRNA combinations that may be delivered within the same delivery vector or injected at the same time and, by targeting more than one pathway, or by hitting the same pathways within two different key points, will augment the effects of each other.

BubR1 is required for the mitotic block induced by combretastatin-A4 and a novel cis-restricted ß-lactam analogue in human cancer cells

BubR1 is a well-defined guardian of the mitotic spindle, initiating mitotic arrest in response to the lack of tension and/or chromosome alignment across the mitotic plate. However, the role of BubR1 in combretastatin-induced cell death remains unknown. In this study, we describe the effects of combretastatin A-4 (CA-4) and a synthetic cis-restricted 3,4-diaryl-2-azetidinone (ß-lactam) analogue (CA-432) on the modulation and phosphorylation of BubR1 in human cervical cancer-derived cells. We demonstrate that CA-4 and CA-432 depolymerise the microtubular network of human cervical carcinoma-derived cells. Both compounds induced the disassembly of the microtubules and the loss of microtubule tension led to the early phosphorylation of BubR1 and the late cleavage of BubR1. The phosphorylation of BubR1 correlated with the onset of G2M cell cycle arrest whilst the cleavage of BubR1 coincided with apoptosis induced by the combretastatins. The combretastatin-induced apoptosis and the BubR1 cleavage were caspase-dependent. In vitro enzyme digests demonstrated that combretastatin-activated BubR1 is a substrate for caspase-3. Gene silencing of BubR1 with small interfering RNA severely compromised combretastatin-induced G2M cell cycle arrest with a corresponding increase in the formation of polyploid cells in both cervical and breast cancer-derived cells. In summary, BubR1 is required to maintain the G2M arrest and limit the formation of polyploid cells in response to continued combretastatin exposure. Moreover, substitution of the ethylene bridge with 3,4-diaryl-2-azetidinone did not alter the tubulin depolymerising properties or the subsequent mitotic spindle checkpoint response to CA-4 in human cancer cells.

BubR1 is required for a sustained mitotic spindle checkpoint arrest in human cancer cells treated with tubulin-targeting pyrrolo-1,5-benzoxazepines

Intrinsic or acquired resistance to chemotherapy is a major clinical problem that has evoked the need to develop innovative approaches to predict and ultimately reverse drug resistance. A prolonged G(2)M arrest has been associated with apoptotic resistance to various microtubule-targeting agents (MTAs). In this study, we describe the functional significance of the mitotic spindle checkpoint proteins, BubR1 and Bub3, in maintaining a mitotic arrest after microtubule disruption by nocodazole and a novel series of MTAs, the pyrrolo-1,5-benzoxazepines (PBOXs), in human cancer cells. Cells expressing high levels of BubR1 and Bub3 (K562, MDA-MB-231, and HeLa) display a prolonged G(2)M arrest after exposure to MTAs. On the other hand, cells with low endogenous levels of mitotic spindle checkpoint proteins (SK-BR-3 and HL-60) transiently arrest in mitosis and undergo increased apoptosis. The phosphorylation of BubR1 correlated with PBOX-induced G(2)M arrest in four cell lines tested, indicating an active mitotic spindle checkpoint. Gene silencing of BubR1 by small interfering RNA interference reduced PBOX-induced G(2)M arrest without enhancing apoptotic efficacy. Further analysis demonstrated that PBOX-treated BubR1-depleted cells were both mononucleated and multinucleated with a polyploid DNA content, suggesting a requirement for BubR1 in cytokinesis. Taken together, these results suggest that BubR1 contributes to the mitotic checkpoint induced by the PBOXs.

PIAS1 is increased in human prostate cancer and enhances proliferation through inhibition of p21

Prostate cancer development and progression are associated with alterations in expression and function of elements of cytokine networks, some of which can activate multiple signaling pathways. Protein inhibitor of activated signal transducers and activators of transcription (PIAS)1, a regulator of cytokine signaling, may be implicated in the modulation of cellular events during carcinogenesis. This study was designed to investigate the functional significance of PIAS1 in models of human prostate cancer. We demonstrate for the first time that PIAS1 protein expression is significantly higher in malignant areas of clinical prostate cancer specimens than in normal tissues, thus suggesting a growth-promoting role for PIAS1. Expression of PIAS1 was observed in the majority of tested prostate cancer cell lines. In addition, we investigated the mechanism by which PIAS1 might promote prostate cancer and found that down-regulation of PIAS1 leads to decreased proliferation and colony formation ability of prostate cancer cell lines. This decrease correlates with cell cycle arrest in the G0/G1 phase, which is mediated by increased expression of p21(CIP1/WAF1). Furthermore, PIAS1 overexpression positively influences cell cycle progression and thereby stimulates proliferation, which can be mechanistically explained by a decrease in the levels of cellular p21. Taken together, our data reveal an important new role for PIAS1 in the regulation of cell proliferation in prostate cancer.

MT1-MMP regulates urothelial cell invasion via transcriptional regulation of Dickkopf-3

Membrane type-1 matrix metalloproteinase (MT1-MMP) is a zinc-binding endopeptidase, which plays a crucial role in tumour growth, invasion and metastasis. We have shown previously that MT1-MMP has higher expression levels in the human urothelial cell carcinoma (UCC) tissue. We show here that siRNA against MT1-MMP blocks invasion in UCC cell lines. Invasion is also blocked by broad-spectrum protease and MMP inhibitors including tissue inhibitor of metalloproteinase-1 and -2. Membrane type-1-MMP can also regulate transcription. We have used expression arrays to identify genes that are differentially transcribed when siRNA is used to suppress MT1-MMP expression. Upon MT1-MMP knockdown, Dickkopf-3 (DKK3) expression was highly upregulated. The stability of DKK3 mRNA was unaffected under these conditions, suggesting transcriptional regulation of DKK3 by MT1-MMP. Dickkopf-3 has been previously shown to inhibit invasion. We confirm that the overexpression of DKK3 leads to decreased invasive potential as well as delayed wound healing. We show for the first time that the effects of MT1-MMP on cell invasion are mediated in part through changes in DKK3 gene transcription.

A role for neurotensin in bicalutamide resistant prostate cancer cells

BACKGROUND: Anti-androgens are administered as a principal treatment for prostate cancer. Aggressive hormone refractory disease is characterized in some cases by the development of a neuroendocrine phenotype. However little attention has been paid to resistance pathways selected for by long-term treatment with non-steroidal anti-androgens.

METHODS: Using a resistant sub-line, LNCaP-Bic, we performed a comparative gene expression profiling using cDNA microarrays and target validation by qRT-PCR. Targets were then explored using cell proliferation, cell cycle analysis and in vitro invasion assays using siRNA technology.

RESULTS: Neurotensin/Neuromedin N (NTS) was upregulated in the LNCaP-Bic line at both the transcript and protein level. The resistant line was found to have an increased proliferation rate, more rapid cell cycle progression and increased invasiveness through Matrigel. Each phenotypic difference could be reduced using siRNA knockdown of NT.

CONCLUSION: Increased expression of NT in bicalutamide resistant prostate cancer cells induces cell proliferation and invasion suggesting that this peptide may contribute to the development of bicalutamide resistant prostate cancer.

Interleukin-8 is associated with proliferation, migration, angiogenesis and chemosensitivity in vitro and in vivo in colon cancer cell line models

Interleukin-8 (IL-8), a chemokine with a defining CXC amino acid motif, is known to possess tumorigenic and proangiogenic properties. Overexpression of IL-8 has been detected in many human tumors, including colorectal cancer (CRC), and is associated with poor prognosis. The goal of our study was to determine the role of IL-8 overexpression in CRC cells in vitro and in vivo. We stably transfected the IL-8 cDNA into two human colon cancer cell lines, HCT116 and Caco2, and selected IL-8-secreting transfectants. Real-time RT-PCR confirmed that IL-8 mRNA was overexpressed in IL-8 transfectants with 45- to 85-fold higher than parental cells. The IL-8-transfected clones secreted 19- to 28-fold more IL-8 protein than control and parental cells as detected by ELISA. The IL-8 transfectants demonstrated increased cellular proliferation, cell migration and invasion based on functional assays. Growth inhibition studies showed that IL-8 overexpression lead to a significant resistance to oxaliplatin (p < 0.0001). Inhibition of IL-8 overexpression with small interfering RNA reversed the observed increases in tumorigenic functions and oxaliplatin resistance, suggesting that IL-8 not only provides a proliferative advantage but also promotes the metastatic potential of colon cancer cells. Using a tumor xenograft model, IL-8-expressing cells formed significantly larger tumors than the control cells with increased microvessel density. Together, these findings indicate that overexpression of IL-8 promotes tumor growth, metastasis, chemoresistance and angiogenesis, implying IL-8 to be an important therapeutic target in CRC.

Estudo preliminar do efeito supressor de genes do Citrus tristeza virus (CTV) no silenciamento pós-transcripcional em Nicotiana benthamiana

Dissertação de mest., Engenharia Biológica, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

Cavin 1 and cavin 2 roles on adipocyte cell function

Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina

mRNA metabolism: nonsense mediated mRNA decay as a tool for gene therapy and the role of human DIS3L2 in transcript degradation

Tese de mestrado em Biologia Humana e Ambiente, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2015

Oligodendroglia metabolically support axons and contribute to neurodegeneration.

Oligodendroglia support axon survival and function through mechanisms independent of myelination, and their dysfunction leads to axon degeneration in several diseases. The cause of this degeneration has not been determined, but lack of energy metabolites such as glucose or lactate has been proposed. Lactate is transported exclusively by monocarboxylate transporters, and changes to these transporters alter lactate production and use. Here we show that the most abundant lactate transporter in the central nervous system, monocarboxylate transporter 1 (MCT1, also known as SLC16A1), is highly enriched within oligodendroglia and that disruption of this transporter produces axon damage and neuron loss in animal and cell culture models. In addition, this same transporter is reduced in patients with, and in mouse models of, amyotrophic lateral sclerosis, suggesting a role for oligodendroglial MCT1 in pathogenesis. The role of oligodendroglia in axon function and neuron survival has been elusive; this study defines a new fundamental mechanism by which oligodendroglia support neurons and axons.

Development of techniques for testing the effect of the E1 region on adenovirus integration /

Adenoviral vectors are currently the most widely used gene therapeutic vectors, but their inability to integrate into host chromosomal DNA shortened their transgene expression and limited their use in clinical trials. In this project, we initially planned to develop a technique to test the effect of the early region 1 (E1) on adenovirus integration by comparing the integration efficiencies between an E1-deleted adenoviral vector (SubE1) and an Elcontaining vector (SubE3). However, we did not harvest any SubE3 virus, even if we repeated the transfection and successfully rescued the SubE1 virus (2/4 transfections generated viruses) and positive control virus (6/6). The failure of rescuing SubE3 could be caused by the instability of the genomic plasmid pFG173, as it had frequent intemal deletions when we were purifying It. Therefore, we developed techniques to test the effect of E1 on homologous recombination (HR) since literature suggested that adenovirus integration is initiated by HR. We attempted to silence the E1 in 293 cells by transfecting E1A/B-specific small interfering RNA (siRNA). However, no silenced phenotype was observed, even if we varied the concentrations of E1A/B siRNA (from 30 nM to 270 nM) and checked the silencing effects at different time points (48, 72, 96 h). One possible explanation would be that the E1A/B siRNA sequences are not potent enough to Induce the silenced phenotype. For evaluating HR efficiencies, an HR assay system based on bacterial transfonmatJon was designed. We constmcted two plasmids ( designated as pUC19-dl1 and pUC19-dl2) containing different defective lacZa cassettes (forming white colonies after transformation) that can generate a functional lacZa cassette (forming blue colonies) through HR after transfecting into 293 cells. The HR efficiencies would be expressed as the percentages of the blue colonies among all the colonies. Unfortunately, after transfonnation of plasmid isolated from 293 cells, no colony was found, even at a transformation efficiency of 1.8x10^ colonies/pg pUC19, suggesting the sensitivity of this system was low. To enhance the sensitivity, PCR was used. We designed a set of primers that can only amplify the recombinant plasmid fomied through HR. Therefore, the HR efficiencies among different treatments can be evaluated by the amplification results, and this system could be used to test the effect of E1 region on adenovirus integration. In addition, to our knowledge there was no previous studies using PCR/ Realtime PCR to evaluate HR efficiency, so this system also provides a PCR-based method to carry out the HR assays.

Chemical synthesis of glycosylated oligoribonucleotides for siRNA development

In this study, an efficient methodology for the preparation of carbohydrate-RNA conjugates was established, which involved the use of 3,4~diethoxy-3-cyclobutene-l,2- dione (diethyl squarate) as the linking reagent. First, a glycan moiety containing an amino group reacted with diethyl squarate to form an activated glycan, which further reacted with an amino modified oligoribonucleotide to form a glycoconjugate under slightly basic conditions. The effect of glycosylation on the stability of RNA molecules was evaluated on two glycoconjugates, monomannosyl UlO-mer and dimannosyl UlO-mer. In the synthesis of aromatic fluorescent ribosides, perbenzylated ribofuranosyl pyrene and phenanthrene were synthesized from perbenzylated ribolactone. Deprotection of benzyl-protected ribofuranosyl phenanthrene and pyrene by boron tribromide gave ribofuranosyl phenanthrene and ribopyranosyl pyrene, respectively. UV/vis and fluorescent properties of the ribosides were characterized.

Identification des canaux TRPC impliqués dans la potentialisation à long terme des interneurones de la région CA1 de l'hippocampe chez le rat

Le réseau neuronal de l’hippocampe joue un rôle central dans la mémoire en modifiant de façon durable l’efficacité de ses synapses. Dans les interneurones de la couche oriens/alveus (O/A), l’induction de la potentialisation à long terme (PLT) requiert les courants postsynaptiques excitateurs évoqués par les récepteurs métabotropes du glutamate de sous-type 1a (CPSEmGluR1a) et l’entrée subséquente de Ca2+ via des canaux de la famille des transient receptor potential (TRP). Le but de ce projet était d’identifier les canaux TRP responsables des CPSEmGluR1a et d’explorer les mécanismes moléculaires régulant leur ouverture. Nous avons déterminé par des enregistrements électrophysiologiques que les CPSEmGluR1a étaient spécifiques aux interneurones O/A et qu’ils étaient indépendants de la phospholipase C. Nous avons ensuite examiné l’expression des TRPC et leur interaction avec mGluR1a par les techniques de RT-PCR, d’immunofluorescence et de co-immunoprécipitation. Nos résultats montrent que TRPC1 et mGluR1a s’associent dans l’hippocampe et que ces deux protéines sont présentes dans les dendrites des interneurones O/A. En revanche, TRPC4 ne semble s’associer à mGluR1a qu’en système recombinant et leur colocalisation paraît limitée au corps cellulaire. Finalement, nous avons procédé à des enregistrements d’interneurones dans lesquels l’expression des TRPC a été sélectivement supprimée par la transfection d’ARN interférant et avons ainsi démontré que TRPC1, mais non TRPC4, est une sous-unité obligatoire du canal responsable des CPSEmGluR1a. Ces travaux ont permis de mieux comprendre les mécanismes moléculaires à la base de la transmission synaptique des interneurones O/A et de mettre en évidence un rôle potentiel de TRPC1 dans la PLT.