Targeting BRCA1/2-deficient cells and tumours with G-quadruplex-binding compounds

Lead Research Organisation: University of Oxford
Department Name: Oncology

Abstract

Heterozygous BRCA1 and BRCA2 mutations increase the risk of breast and ovarian cancers. Genome profiling studies revealed that 30% of all ovarian tumours and 16% of all breast tumours carry either BRCA1 or BRCA2 gene inactivation, in the form of germline or somatic mutations or BRCA1 promoter methylation. At the molecular level, BRCA1 and BRCA2 proteins play essential roles in DNA replication and double-strand break repair by homologous recombination. Consequently, loss of BRCA1 or BRCA2 function triggers replication arrest and accumulation of unrepaired DNA lesions. The project proposed here aims to exploit the hypersensitivity of BRCA1- and BRCA2-deficient cancers to G-quadruplex (G4)-binding compounds, in particular pyridostatin (Zimmer et al., 2016), for the development of novel, specific therapies.

To elucidate the mechanism of action of pyridostatin, innovative END-seq technology (Canela et al., 2016) will be applied to determine the genome-wide location of DNA double-strand breaks induced by pyridostatin in BRCA2-deficient cells. We will focus on those mapping to actively transcribed genes. Transcriptional deregulation of G4-containing genes has been proposed to mediate pyridostatin toxicity (Rodriguez et al., 2012). We will thus determine the transcription profiles of BRCA2-proficient and -deficient cells treated with pyridostatin using RNA-seq. This will allow identification of genes or gene networks affected by pyridostatin. Integration of gene expression profiles with DNA breaks location determined by END-seq, will enable isolation and characterization of the gene subset whose transcriptional deregulation promotes BRCA2-deficient cell killing by pyridostatin. Alterations in expression of these genes upon pyridostatin treatment will be subsequently monitored in xenograft tumours established in nude mice.

Publications

10 25 50
 
Description In vivo model 
Organisation Regina Elena National Cancer Institute
Country Italy 
Sector Hospitals 
PI Contribution We conducted in vitro experiments with different drugs in order to find concentration ranges and treatment orders that could be effectively recapitulated in a mouse breast cancer model.
Collaborator Contribution Our collaborators have a deep expertise in in vivo models and conducted all the in vivo experiments. They provided key results that helped shaping my project and plan which experiments should be conducted.
Impact In our lab we identified a synergistic effect between two drug that effectively kill BRCA-deficient cancer cells including those that have acquired resistance to a current treatment. This synergistic effect was successfully recapitulated in vivo by our collaborators. This demonstrate the efficiency of such combination in a whole living organism. Such promising results are essential to pave the way toward clinical trial.
Start Year 2017
 
Description Partnership with Merck KGaA 
Organisation Merck
Country Germany 
Sector Private 
PI Contribution We characterized a newly developed inhibitor regarding its in vitro toxicity and specificity in our cell lines. We further identified synergistic effects between this inhibitor and another drug.
Collaborator Contribution Merck KGaA has kindly provided the new inhibitor.
Impact Our work has shown that this new inhibitor seems efficient and selective and are suitable with our in vitro models. This new inhibitor seems to have better pharmacokinetics properties than other widely used inhibitors in the same class, therefore showing a promising potential for clinical purposes.
Start Year 2017
 
Description Public engagement 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact I attended public engagement introductions and lectures conducted at my institute. I then volunteered twice to introduce my research topic (oncology) to pupils and visit our research facilities. They seemed fascinated by the complexity and importance to conduct research in oncology.
Year(s) Of Engagement Activity 2017,2018,2019