Liau S.-S.,Hepatopancreatobiliary Unit |
Liau S.-S.,Medical Research Council MRC Cancer Cell Unit |
Qureshi M.S.,Hepatopancreatobiliary Unit |
Praseedom R.,Hepatopancreatobiliary Unit |
Huguet E.,Hepatopancreatobiliary Unit
Journal of Gastrointestinal Surgery | Year: 2013
Introduction: Hepatic adenomas (HAs) are benign tumors of the liver, which can be solitary or multiple, and have a definite risk of malignant degeneration. Discussion: The pathogenesis and natural history of this disease entity were previously unknown. Recent research into the molecular pathogenesis of this condition has provided evidence for the malignant transformation of some of these adenomas. In the current article, we discuss the current evidence on the molecular biology underlying malignant transformation of hepatic adenomas and the implications for the surgical management of this disease. © 2013 The Society for Surgery of the Alimentary Tract.
Bolderson E.,Queensland Institute of Medical Research |
Bolderson E.,Queensland University of Technology |
Savage K.I.,Queensland Institute of Medical Research |
Savage K.I.,Queens University of Belfast |
And 7 more authors.
Journal of Biological Chemistry | Year: 2012
The DNA damage response encompasses a complex series of signaling pathways that function to regulate and facilitate the repair of damaged DNA. Recent studies have shown that the repair of transcriptionally inactive chromatin, named heterochromatin, is dependent upon the phosphorylation of the co-repressor, Krüppel-associated box (KRAB) domain-associated protein (KAP-1), by the ataxia telangiectasia-mutated (ATM) kinase. Co-repressors, such as KAP-1, function to regulate the rigid structure of heterochromatin by recruiting histone-modifying enzymes, such HDAC1/2, SETDB1, and nucleosome-remodeling complexes such as CHD3. Here, we have characterized a phosphorylation site in the HP1-binding domain of KAP-1, Ser-473, which is phosphorylated by the cell cycle checkpoint kinase Chk2. Expression of a nonphosphorylatable S473A mutant conferred cellular sensitivity to DNA-damaging agents and led to defective repair of DNA double-strand breaks in heterochromatin. In addition, cells expressing S473A also displayed defective mobilization of the HP1-β chromodomain protein. The DNA repair defect observed in cells expressing S473A was alleviated by depletion of HP1-β, suggesting that phosphorylation of KAP-1 on Ser-473 promotes the mobilization of HP1-β from heterochromatin and subsequent DNA repair. These results suggest a novel mechanism of KAP-1-mediated chromatin restructuring via Chk2-regulated HP1-β exchange from heterochromatin, promoting DNA repair. © 2012 by The American Society for Biochemistry and Molecular Biology, Inc.
Gaboriau D.C.A.,National University of Ireland |
Gaboriau D.C.A.,Medical Research Council MRC Cancer Cell Unit |
Rowling P.J.E.,Medical Research Council MRC Cancer Cell Unit |
Rowling P.J.E.,University of Cambridge |
And 4 more authors.
Biochemical Journal | Year: 2015
Mutations in breast cancer susceptibility gene BRCA1 (breast cancer early-onset 1) are associated with increased risk of developing breast and ovarian cancers. BRCA1 is a large protein of 1863 residues with two small structured domains at its termini: a RING domain at the N-terminus and a BRCT (BRCA1 C-terminus domain) repeat domain at the C-terminus. Previously, we quantified the effects of missense mutations on the thermodynamic stability of the BRCT domains, and we showed that many are so destabilizing that the folded functional state is drastically depopulated at physiological temperature. In the present study, we ask whether and how reduced thermodynamic stability of the isolated BRCT mutants translates into loss of function of the full-length protein in the cell. We assessed the effects of missense mutants on different stages of BRCA1-mediated DNA repair by homologous recombination using chicken lymphoblastoid DT40 cells as a model system. We found that all of the mutations, regardless of how profound their destabilizing effects, retained some DNA repair activity and thereby partially rescued the chicken BRCA1 knockout. By contrast, the mutation R1699L, which disrupts the binding of phosphorylated proteins (but which is not destabilizing), was completely inactive. It is likely that both protein context (location of the BRCT domains at the C-terminus of the large BRCA1 protein) and cellular environment (binding partners, molecular chaperones) buffer these destabilizing effects such that at least some mutant protein is able to adopt the folded functional state. ©The Authors Journal compilation © 2015 Biochemical Society.
Rowling P.J.E.,Medical Research Council MRC Cancer Cell Unit |
Cook R.,Medical Research Council MRC Cancer Cell Unit |
Itzhaki L.S.,Medical Research Council MRC Cancer Cell Unit
Journal of Biological Chemistry | Year: 2010
Carriers of germ line mutations in breast cancer susceptibility gene BRCA1 have an increased risk of developing breast and ovarian cancers; missense mutations have, however, been difficult to assess for disease association. Here we have used a biophysical approach to classify these variants. We established an assay for measuring the thermodynamic stability of the BRCA1 BRCT domains and investigated the effects of 36 missense mutations. The mutations show a range of effects. Some do not change the stability, whereas others destabilize the protein by as much as 6 kcal mol-1; one-third of the mutants could not be expressed in soluble form in Escherichia coli, and we conclude that these destabilize the protein by an even greater amount. We tested several computer algorithms for their ability to predict the mutant effects and found that by grouping them into two classes (destabilizing by less than or more than 2.2 kcal mol-1), the algorithms could predict the stability changes. Importantly, with the exception of the few mutants located in the binding site, none showed a significant reduction in affinity for phosphorylated substrate. These results indicate that despite very large losses in stability, the integrity of the structure is not compromised by the mutations. Thus, the majority of mutations cause loss of function by reducing the proportion of BRCA1 molecules that are in the folded state and increasing the proportion of molecules that are unfolded. Consequently, small molecule stabilization of the structure could be a generally applicable preventative therapeutic strategy for rescuing many BRCA1 mutations. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.
Talsma A.K.,Erasmus Medical Center |
Ong C.-A.J.,Medical Research Council MRC Cancer Cell Unit |
Liu X.,Medical Research Council MRC Cancer Cell Unit |
Van Hagen P.,Erasmus Medical Center |
And 7 more authors.
World Journal of Surgery | Year: 2014
Background: The location of positive lymph nodes has been abandoned in the seventh classification of the TNM staging system for esophageal adenocarcinoma. The present study evaluates whether distribution of involved nodes relative to the diaphragm in addition to TNM 7 further refines prediction. Methods: Pathology reports of patients who underwent esophagectomy between 2000 and 2008 for adenocarcinoma of the esophagus were reviewed and staging was performed according to the seventh UICC-AJCC staging system. In addition, lymph node involvement of nodal stations above and below the diaphragm was investigated by endoscopic ultrasonography (EUS) in a separate cohort of patients who were scheduled for esophagectomy between 2008 and 2009 at two institutions. Survival was calculated by the Kaplan-Meier method, and multivariate analysis was performed with a Cox regression model. Results: Some 327 patients who had undergone esophagectomy for cancer were included. Multivariate analysis revealed that patients with from three to six involved lymph nodes in the resection specimen on both sides of the diaphragm had a twofold higher chance of dying compared to patients with the same number of involved lymph nodes on one side of the diaphragm. EUS assessment of lymph node metastases relative to the diaphragm in 102 patients showed that nodal involvement on both sides of the diaphragm was associated with worse survival than when nodes on one side or no nodes are involved [HR (95 % CI) 2.38 (1.15-4.90)]. Conclusions: A combined staging system that incorporates distribution of lymph nodes relative to the diaphragm refines prognostication after esophagectomy as assessed in the resected specimen and pretreatment as assessed by EUS. This improved staging has the potential to have a great impact on clinical decision making as to whether to embark upon potentially curative or palliative treatments. © 2013 Société Internationale de Chirurgie.