MYCN expression induces replication stress and sensitivity to PARP inhibition in neuroblastoma

Abstract

// David King 1 , * , Xiao Dun Li 2 , # , * , Gilberto S. Almeida 3 , 4 , Colin Kwok 2 , Polly Gravells 1 , Daniel Harrison 1 , Saoirse Burke 1 , Albert Hallsworth 2 , Yann Jamin 3 , 4 , Sally George 2 , Simon P. Robinson 3 , 4 , Christopher J. Lord 5 , Evon Poon 2 , Daniel Yeomanson 6 , Louis Chesler 2 and Helen E. Bryant 1 1 Academic Unit of Molecular Oncology, Sheffield Institute for Nucleic Acids (SInFoNiA), Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK 2 Divisions of Clinical Studies and Cancer Therapeutics, The Institute of Cancer Research, Sutton, UK 3 Divisions of Radiotherapy & Imaging, The Institute of Cancer Research, Sutton, UK 4 The Children and Young People’s Unit, The Royal Marsden NHS Trust, Sutton, UK 5 CRUK Gene Function Laboratory and Breast Cancer Now Research Centre, The Institute of Cancer Research, London, UK 6 Sheffield Children’s Hospital, Western Bank, Sheffield, UK # Present address: Medical Research Council Cancer Unit, Hutchison/Medical Research Council Research Centre, University of Cambridge, Cambridge, UK * These authors contributed equally to this work Correspondence to: Helen E. Bryant, email: [email protected] Louis Chesler, email: [email protected] Keywords: PARP inhibitor; neuroblastoma; MYCN; replication stress; replication fork stalling Received: September 24, 2019     Accepted: October 03, 2019     Published: June 09, 2020 ABSTRACT This study investigates the influence expression of the MYCN oncogene has on the DNA damage response, replication fork progression and sensitivity to PARP inhibition in neuroblastoma. In a panel of neuroblastoma cell lines, MYCN amplification or MYCN expression resulted in increased cell death in response to a range of PARP inhibitors (niraparib, veliparib, talazoparib and olaparib) compared to the response seen in non-expressing/amplified cells. MYCN expression slowed replication fork speed and increased replication fork stalling, an effect that was amplified by PARP inhibition or PARP1 depletion. Increased DNA damage seen was specifically induced in S-phase cells. Importantly, PARP inhibition caused a significant increase in the survival of mice bearing MYCN expressing tumours in a transgenic murine model of MYCN expressing neuroblastoma. Olaparib also sensitized MYCN expressing cells to camptothecin- and temozolomide-induced cell death to a greater degree than non-expressing cells. In summary, MYCN expression leads to increased replication stress in neuroblastoma cells. This effect is exaggerated by inhibition of PARP, resulting in S-phase specific DNA damage and ultimately increased tumour cell death. PARP inhibition alone or in combination with classical chemotherapeutics is therefore a potential therapeutic strategy for neuroblastoma and may be more effective in MYCN expressing tumours.

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