Time filter

Source Type

Craigavon, United Kingdom

Fonville J.M.,Imperial College London | Bylesjo M.,Almac Diagnostics | Coen M.,Imperial College London | Nicholson J.K.,Imperial College London | And 3 more authors.
Analytica Chimica Acta | Year: 2011

Linear multivariate projection methods are frequently applied for predictive modeling of spectroscopic data in metabonomic studies. The OPLS method is a commonly used computational procedure for characterizing spectral metabonomic data, largely due to its favorable model interpretation properties providing separate descriptions of predictive variation and response-orthogonal structured noise. However, when the relationship between descriptor variables and the response is non-linear, conventional linear models will perform sub-optimally. In this study we have evaluated to what extent a non-linear model, kernel-based orthogonal projections to latent structures (K-OPLS), can provide enhanced predictive performance compared to the linear OPLS model. Just like its linear counterpart, K-OPLS provides separate model components for predictive variation and response-orthogonal structured noise. The improved model interpretation by this separate modeling is a property unique to K-OPLS in comparison to other kernel-based models. Simulated annealing (SA) was used for effective and automated optimization of the kernel-function parameter in K-OPLS (SA-K-OPLS).Our results reveal that the non-linear K-OPLS model provides improved prediction performance in three separate metabonomic data sets compared to the linear OPLS model. We also demonstrate how response-orthogonal K-OPLS components provide valuable biological interpretation of model and data. The metabonomic data sets were acquired using proton Nuclear Magnetic Resonance (NMR) spectroscopy, and include a study of the liver toxin galactosamine, a study of the nephrotoxin mercuric chloride and a study of Trypanosoma brucei brucei infection. Automated and user-friendly procedures for the kernel-optimization have been incorporated into version 1.1.1 of the freely available K-OPLS software package for both R and Matlab to enable easy application of K-OPLS for non-linear prediction modeling. © 2011 Elsevier B.V. Source

Maxwell P.J.,Queens University of Belfast | Coulter J.,Queens University of Belfast | Walker S.M.,Queens University of Belfast | McKechnie M.,Queens University of Belfast | And 6 more authors.
European Urology | Year: 2013

Background: Inflammation and genetic instability are enabling characteristics of prostate carcinoma (PCa). Inactivation of the tumour suppressor gene phosphatase and tensin homolog (PTEN) is prevalent in early PCa. The relationship of PTEN deficiency to inflammatory signalling remains to be characterised. Objective: To determine how loss of PTEN functionality modulates expression and efficacy of clinically relevant, proinflammatory chemokines in PCa. Design, setting, and participants: Experiments were performed in established cell-based PCa models, supported by pathologic analysis of chemokine expression in prostate tissue harvested from PTEN heterozygous (Pten +/-) mice harbouring inactivation of one PTEN allele. Interventions: Small interfering RNA (siRNA)- or small hairpin RNA (shRNA)-directed strategies were used to repress PTEN expression and resultant interleukin-8 (CXCL8) signalling, determined under normal and hypoxic culture conditions. Outcome measurements and statistical analysis: Changes in chemokine expression in PCa cells and tissue were analysed by real-time polymerase chain reaction (PCR), immunoblotting, enzyme-linked immunosorbent assay (ELISA), and immunohistochemistry; effects of chemokine signalling on cell function were assessed by cell cycle analysis, apoptosis, and survival assays. Results and limitations: Transient (siRNA) or prolonged (shRNA) PTEN repression increased expression of CXCL8 and its receptors, chemokine (C-X-C motif) receptor (CXCR) 1 and CXCR2, in PCa cells. Hypoxia-induced increases in CXCL8, CXCR1, and CXCR2 expression were greater in magnitude and duration in PTEN-depleted cells. Autocrine CXCL8 signalling was more efficacious in PTEN-depleted cells, inducing hypoxia-inducible factor-1 (HIF-1) and nuclear factor kappa-light-chain- enhancer of activated B cells (NF-κB) transcription and regulating genes involved in survival and angiogenesis. Increased expression of the orthologous chemokine KC was observed in regions displaying atypical cytologic features in Pten+/- murine prostate tissue relative to normal epithelium in wild-type PTEN (PtenWT) glands. Attenuation of CXCL8 signalling decreased viability of PCa cells harbouring partial or complete PTEN loss through promotion of G1 cell cycle arrest and apoptosis. The current absence of clinical validation is a limitation of the study. Conclusions: PTEN loss induces a selective upregulation of CXCL8 signalling that sustains the growth and survival of PTEN-deficient prostate epithelium. © 2012 European Association of Urology. Source

Huang M.,Dana-Farber Cancer Institute | Kennedy R.,Almac Diagnostics | Ali A.M.,University of Cincinnati | Moreau L.A.,Dana-Farber Cancer Institute | And 4 more authors.
DNA Repair | Year: 2011

The Fanconi Anemia (FA) pathway encodes a DNA damage response activated by DNA damage-stalled replication forks. Current evidence suggests that the FA pathway initiates with DNA damage recognition by the FANCM complex (FANCM/FAAP24/MHF). However, genetic inactivation of FANCM in mouse and DT40 cells causes only a partial defect in the FA pathway activation, suggesting the existence of redundant DNA damage sensors. Here we show that the MutS homologs function in this capacity. A RNAi screen revealed that MSH2 silencing caused defective FA pathway activation, as assessed by damage-induced FANCD2 mono-ubiquitination. A similar FA pathway defect was observed with MSH3 or MSH6 silencing. MSH2 depletion caused cellular phenotypes associated with defective FA pathway, including mitomycin C hypersensitivity and chromosomal instability. Further, silencing of FANCM in MSH2 deficient HEC59 cells caused a more severe FA defect relative to comparable silencing in MSH2 complemented HEC59. +. Chr2 cells, suggesting redundant functions between MSH2 and FANCM. Consistent with this hypothesis, depletion of MSH2 resulted in defective chromatin localization of the FA core complex upon DNA damage. Further, MSH2 was co-purified and co-immunoprecipitated with FA core complex components. Taken together, our results suggest that human MutS homologs and FANCM complexes function as redundant DNA damage sensors of the FA pathway. © 2011 Elsevier B.V. Source

Plebani R.,University of Chieti Pescara | Oliver G.R.,Almac Diagnostics | Trerotola M.,University of Chieti Pescara | Trerotola M.,Thomas Jefferson University | And 9 more authors.
Neoplasia (United States) | Year: 2012

mRNA chimeras from chromosomal translocations often play a role as transforming oncogenes. However, cancer transcriptomes also contain mRNA chimeras that may play a role in tumor development, which arise as transcriptional or post-transcriptional events. To identify such chimeras, we developed a deterministic screening strategy for long-range sequence analysis. High-throughput, long-read sequencing was then performed on cDNA libraries from major tumor histotypes and corresponding normal tissues. These analyses led to the identification of 378 chimeras, with an unexpectedly high frequency of expression (≈ 2 × 10-5 of all mRNA). Functional assays in breast and ovarian cancer cell lines showed that a large fraction of mRNA chimeras regulates cell replication. Strikingly, chimeras were shown to include both positive and negative regulators of cell growth, which functioned as such in a cell-type-specific manner. Replication-controlling chimeras were found to be expressed by most cancers from breast, ovary, colon, uterus, kidney, lung, and stomach, suggesting a widespread role in tumor development. © 2012 Neoplasia Press, Inc. All rights reserved. Source

Hadad S.,University of Dundee | Iwamoto T.,University of Texas M. D. Anderson Cancer Center | Jordan L.,University of Dundee | Purdie C.,University of Dundee | And 10 more authors.
Breast Cancer Research and Treatment | Year: 2011

Metformin may reduce the incidence of breast cancer and enhance response to neoadjuvant chemotherapy in diabetic women. This trial examined the effects of metformin on Ki67 and gene expression in primary breast cancer. Non-diabetic women with operable invasive breast cancer received pre-operative metformin. A pilot cohort of eight patients had core biopsy of the cancer at presentation, a week later (without treatment; internal control), then following metformin 500-mg o.d. for 1 week increased to 1-g b.d. for a further week continued to surgery. A further 47 patients had core biopsy at diagnosis were randomized to metformin (the same dose regimen) or no drug, and 2 weeks later had core biopsy at surgery. Ki67 immunohistochemistry, transcriptome analysis on formalin-fixed paraffin-embedded cores and serum insulin determination were performed blinded to treatment. Seven patients (7/32, 21.9%) receiving metformin withdrew because of gastrointestinal upset. The mean percentage of cells staining for Ki67 fell significantly following metformin treatment in both the pilot cohort (P = 0.041, paired t-test) and in the metformin arm (P = 0.027, Wilcoxon rank test) but was unchanged in the internal control or metformin control arms. Messenger RNA expression was significantly downregulated by metformin for PDE3B (phosphodiesterase 3B, cGMP-inhibited; a critical regulator of cAMP levels that affect activation of AMP-activated protein kinase, AMPK), confirmed by immunohistochemistry, SSR3, TP53 and CCDC14. By ingenuity pathway analysis, the tumour necrosis factor receptor 1 (TNFR1) signaling pathway was most affected by metformin: TGFB and MEKK were upregulated and cdc42 downregulated; mTOR and AMPK pathways were also affected. Gene set analysis additionally revealed that p53, BRCA1 and cell cycle pathways also had reduced expression following metformin. Mean serum insulin remained stable in patients receiving metformin but rose in control patients. This trial presents biomarker evidence for anti-proliferative effects of metformin in women with breast cancer and provides support for therapeutic trials of metformin. © 2011 Springer Science+Business Media, LLC. Source

Discover hidden collaborations