A mutagenesis screen identifies tumour suppressors and kinases as potential driver genes of ovarian cancer — The Association Specialists
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A mutagenesis screen identifies tumour suppressors and kinases as potential driver genes of ovarian cancer (316)

Emily K Colvin 1 , Emily Fuller 1 , Jizhou Cheng 1 , Anthony Gill 1 , Deborah J Marsh 1 , Viive M Howell 1
  1. Kolling Institute, St Leonards, NSW, Australia

Background: Inherited mutation of BRCA1 is the best known risk factor for serous epithelial ovarian cancer (SEOC) and somatic mutation of TP53 is the most common molecular change in SEOC. However these changes individually or in combination do not result in SEOC in the mouse, suggesting additional unknown genetic factors are required for ovarian carcinogenesis.

Aims: To increase our understanding of the molecular aetiology of ovarian cancer by utilising Sleeping Beauty (SB) insertional mutagenesis.

Methods: The following genetically engineered mice were interbred: homozygous floxed SB (STOCK Rosa26-LsL-DSB11; T2/Onc2,TG6113), homozygous floxed Brca1 knock-out (C57BL/6.Brca1tm2Brn) and Tp53 mutant (C57BL/6-Trp53tm1Tyj/J). Adenoviral CRE recombinase was surgically injected under the ovarian bursal membrane of mature female mice to delete Brca1 and activate SB mutagenesis in the ovarian surface epithelium. Tumours were assessed for SB transposase activity by immunohistochemistry. DNA was extracted from paraffin embedded sections of ovarian tumours and underwent high-throughput sequencing for T2/Onc2 insertion sites (Illumina, University of Iowa).

Results: Ovarian tumours were observed at low penetrance starting 30 weeks post-surgery in SBflox/+Tp53mut/+ mice (6%, 3/48) and SBflox/+Brca1flox/flox p53mut/+ mice (8%, 4/50). No ovarian tumours were observed in SBflox/+Brca1flox/flox (n=38) or SBflox/+Brca1flox/+ mice (n=26). Sequencing of insertion sites identified several genes of which 67 were altered in 10 - 30% of cases in TCGA SEOC dataset (N = 316). This gene-set was enriched for kinases including Fgfr2, Dyrk1a and Gsk3b, and small GTPase regulators including Smap2, Trio and Dock10. Other genes of interest included tumour suppressor genes Arid1b, Cdh4 and Wwox and the E3 ubiquitin ligase Ube3a.  

Conclusions: This screen identified a number of novel potential driver genes of ovarian cancer. In addition, genes previously associated with ovarian cancer were identified, providing proof of principle for this approach. Investigation of these novel genes may lead to further insights into the pathogenesis of ovarian cancer.