Genetic epidemiology of breast cancer in CYPRUS: A case -control study of DNA repair genes

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The occurrence of early-onset breast cancer (EOBC) has been associated with germline mutations in the BRCA1 and BRCA2 genes. The first aim of this thesis was to evaluate the frequency and distribution of mutations in these genes, in a group of Cypriot women diagnosed with EOBC. Pathogenic mutations were identified in 6 of the 26 unrelated patients. This study supports a strong correlation between the early onset breast cancer phenotype and the presence of pathogenic BRCA1/2 mutations. It is of interest that pathogenic mutations were detected in patients without a family history of the disease. Based on these results, we recommend that BRCA1/2 screening should be offered to patients with a diagnosis of EOBC irrespective of their family history. The known breast cancer susceptibility genes explain only about 5% of breast cancer cases. Thus, it is likely that other breast cancer susceptibility genes exist. The second aim of the present thesis was to assess whether alterations in DNA repair genes modify breast cancer risk in the Cypriot population. Towards this objective, blood samples were collected and genomic DNA isolated from 1109 Cypriot female breast cancer patients diagnosed between 40-70 years old, and from 1177 age-matched healthy female controls. A total of 79 single nucleotide polymorphisms (SNPs) were genotyped in all samples. Significant associations with breast cancer risk were observed for eight of the SNPs studied. Five SNPs in the BRCA2, MRE11A, MUS81, PBOV1 and XRCC1 genes, were associated with an increased risk for breast cancer, while two SNPs in the NBS1 gene and one SNP in the MRE11A gene appeared to be associated with reduced risk for the disease. The data from this study support the hypothesis that genetic variants in DNA repair genes influence breast cancer risk and provides further evidence for the existence of a polygenic model for breast cancer

Sequences on law and the body

Book synopsis: This handbook sets out an innovative approach to the theory of law reconceptualising legal theory in a material, socially contextualised and politically radical way. The book is made up of original contributions authored by academics at the forefront of research in legal theory so provides a valuable overview of the discipline

Study of the cap structure of (3,3), (4,4) and (5,5)-SWCNTs: application of the sphere-in-contact model

We have applied the sphere-in-contact model supported by hybrid Density Functional Theory (DFT) calculations to elucidate the cap geometry of the sub-nanometer in dimension (3,3), (4,4) and (5,5) single-wall carbon-nanotubes (SWCNTs). Our approach predicts certain cap-geometries that do not comprise of the commonly known for their stability combination of pentagonal and hexagonal carbon rings but also tetragonal, trigonal and all-pentagonal structures. Based on hybrid-DFT calcula-tions carbon atoms in these new cap geometries have similar stability to carbon found in other fullerene-like capped zig-zag and arm-chair nanotubes (i.e., (5,5), (6,6), (9,0) and (10,0)) that are known to be stable and synthetically accessible. We find that the cap structure of the (3,3)-CNTs is a pointy carbon geometry comprised of six pentagonal rings with a single carbon atom at the tip apex. In this tip geome-try the carbon atom at the tip apex does not have the usual sp2 or sp3 geometry but an unusual trigonal pyramidal configuration. DFT calculations of the molecular orbitals and density-of-states of the tip show that this tip structure apart from being stable can be used in scanning probe microscopies such as STM for very high resolution imaging

Cancer cells grown in 3D under fluid flow exhibit an aggressive phenotype and reduced responsiveness to the anti-cancer treatment doxorubicin.

3D laboratory models of cancer are designed to recapitulate the biochemical and biophysical characteristics of the tumour microenvironment and aim to enable studies of cancer, and new therapeutic modalities, in a physiologically-relevant manner. We have developed an in vitro 3D model comprising a central high-density mass of breast cancer cells surrounded by collagen type-1 and we incorporated fluid flow and pressure. We noted significant changes in cancer cell behaviour using this system. MDA-MB231 and SKBR3 breast cancer cells grown in 3D downregulated the proliferative marker Ki67 (P<0.05) and exhibited decreased response to the chemotherapeutic agent doxorubicin (DOX) (P<0.01). Mesenchymal markers snail and MMP14 were upregulated in cancer cells maintained in 3D (P<0.001), cadherin-11 was downregulated (P<0.001) and HER2 increased (P<0.05). Cells maintained in 3D under fluid flow exhibited a further reduction in response to DOX (P<0.05); HER2 and Ki67 levels were also attenuated. Fluid flow and pressure was associated with reduced cell viability and decreased expression levels of vimentin. In summary, aggressive cancer cell behaviour and reduced drug responsiveness was observed when breast cancer cells were maintained in 3D under fluid flow and pressure. These observations are relevant for future developments of 3D in vitro cancer models and organ-on-a-chip initiatives

Argyrin B a non-competitive inhibitor of the human immunoproteasome exhibiting preference for β1i

Inhibitors of the proteasome have found broad therapeutic applications however, they show severe toxicity due to the abundance of proteasomes in healthy cells. In contrast, inhibitors of the immunoproteasome, which is upregulated during disease states, are less toxic and have increased therapeutic potential including against autoimmune disorders. In this project, we report argyrin B, a natural product cyclic peptide to be a reversible, non-competitive inhibitor of the immunoproteasome. Argyrin B showed selective inhibition of the β5i and β1i sites of the immunoproteasome over the β5c and β1c sites of the constitutive proteasome with nearly 20-fold selective inhibition of β1i over the homologous β1c. Molecular modelling attributes the β1i over β1c selectivity to the small hydrophobic S1 pocket of β1i and β5i over β5c to site-specific amino acid variations that enable additional bonding interactions and stabilization of the binding conformation. These findings facilitate the design of immunoproteasome selective and reversible inhibitors that may have a greater therapeutic potential and lower toxicity

Size-dependent bond dissociation enthalpies in single-walled carbon nanotubes

We report the bond dissociation enthalpy (BDE) and the local electronic properties of Single-Walled Carbon Nanotubes (SWCNT) using density functional theory. Our analysis shows that there is a strong size-dependence of the BDE of these SWCNTs, which is inversely proportional to the radius-squared (1/r2) and the length (1/l) of SWCNT. We derive quantitative relationships from which the BDE can be calculated as a function of size and radius of the SWCNT. We find that the BDE of SWCNT outside the size-dependent region is about 480 kJ mol−1, which can be used for thermochemical calculations