FKBPL:a marker of good prognosis in breast cancer

FK506-binding protein-like (FKBPL) has established roles as an anti-tumor protein, with a therapeutic peptide based on this protein, ALM201, shortly entering phase I/II clinical trials. Here, we evaluated FKBPL’s prognostic ability in primary breast cancer tissue, represented on tissue microarrays (TMA) from 3277 women recruited into five independent retrospective studies, using immunohistochemistry (IHC). In a meta-analysis, FKBPL levels were a significant predictor of BCSS; low FKBPL levels indicated poorer breast cancer specific survival (BCSS) (hazard ratio (HR) = 1.30, 95% confidence interval (CI) 1.14–1.49, p < 0.001). The prognostic impact of FKBPL remained significant after adjusting for other known prognostic factors (HR = 1.25, 95% CI 1.07–1.45, p = 0.004). For the sub-groups of 2365 estrogen receptor (ER) positive patients and 1649 tamoxifen treated patients, FKBPL was significantly associated with BCSS (HR = 1.34, 95% CI 1.13–1.58, p < 0.001, and HR = 1.25, 95% CI 1.04–1.49, p = 0.02, respectively). A univariate analysis revealed that FKBPL was also a significant predictor of relapse free interval (RFI) within the ER positive patient group, but it was only borderline significant within the smaller tamoxifen treated patient group (HR = 1.32 95% CI 1.05–1.65, p = 0.02 and HR = 1.23 95% CI 0.99–1.54, p = 0.06, respectively). The data suggests a role for FKBPL as a prognostic factor for BCSS, with the potential to be routinely evaluated within the clinic

The contribution of reactive nitrogen species to the cytotoxicity of nitric oxide generating therapy

Nitric oxide (NO) has become increasingly recognized throughout the past decade for its role in many patho-physiologies. NO delivery has been investigated as a potential therapeutic strategy against solid tumours, using both NO donor drugs and gene therapy strategies. This project aims to study the importance of oxygen concentration and the possible role of key reaction products involved in NO induced cytotoxicity. Utilising the NO donor drug, DETA/NO the effects of oxygen tension on the cytotoxicity was investigated in vitro. The find ings presented in this study indicate that the DETA/NO mediated cytotoxic effects in all the tumour cell lines tested was significantly more toxic under severe hypoxia. This effect was most evident at drug concentrations greater than 10 ~M. Both the intrinsic and extrinsic apoptotic pathways were activated fo llowing DETA/NO treatment, and cleavage of apoptotic proteins was enhanced under hypoxia. DETA/NO treatment under hypoxia significantly destabilized hypoxia inducible factor (HIF-1a) and resulted in the accumulation of p53 protein. Investigations into the contribution of reactive nitrogen species to NO' cytotoxicity revealed that neither peroxynitrite (ONOO-) nor Nitroxyl (HNO) was generated. Fluorometric analysis in the presence of dinitrogen trioxide (N,O,) scavengers suggests for the first time that N,O, may be responsible for the cytotoxicity with DETA/NO. Compelling evidence is provided to suggest that S-nitrosylation is the key molecular mechanism involved in NO signalling. This is the fi rst study that shows significant Snitrosothiol formation in cancer cells when exposed to high levels of NO irrespective of oxygen concentration. Further investigations revealed that both nuclear p53, and GAPDH proteins are targets for S-nitrosylation following treatment with DETA/NO, and may possibly play a key role in DETA/NO-mediated apoptosis and cytotoxicity.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigation of the Pharmacological Inhibition of HDAC6 with Ricolinostat

The histone deacetylase 6 (HDAC6) protein is a unique member of the HDAC superfamily of deacetylating enzymes. At 1225 amino acids, it is a large multidomain protein uniquely consisting of 2 catalytic domains. Unlike other HDAC proteins, HDAC6 deacetylates several cytoplasmic proteins and HDAC6 functions are widely reported to contribute to tumorigenesis. Moderate to strong HDAC6 IHC expression has been associated with favourable outcomes in breast cancer that may be associated with the improved survival of estrogen positive breast cancers. Here we explore the anticancer activity of HDAC6i therapy in triple negative breast cancer and high grade serous ovarian cancer cells because TP53 altered cell lines have an increased dependency upon HDAC6. In western blot analysis of TNBC cell lines HDAC6 is upregulated compared to normal cells and further upregulated in cells mutated for BRCA1. The selective inhibition of HDAC6 with ricolinostat inhibited HDAC6 deacetylation of α-tubulin, resulting in a sustained accumulation of acetylated α-tubulin up to 24 hours. However, this did not translate to robust inhibition of HDAC6 protein function. Inhibition of cancer cell proliferation and migration required significantly higher and non-selective doses of ricolinostat than those required to eliminate its enzymatic activity. Molecular modelling of ricolinostat was performed to understand ricolinostat binding interactions with human HDAC6. Our data demonstrates the functional activity of both catalytic domains in living cells in which inhibition of both catalytic domains would be required for complete inhibition of HDAC6. Molecular dynamic simulations confirm that ricolinostat is capable of binding both catalytic domains and also indicates the potential for ricolinostat to bind multiple HDACs at higher concentrations. In conclusion, selective HAC6 inhibition has limited efficacy as a monotherapy in the treatment of solid tumours