Poster Presentation 27th Lorne Cancer Conference 2015

Genome-wide RNAi Screen for Synthetic Lethal Interactions with the Inhibition of RNA Polymerase I in Ovarian Cancer (#319)

Shunfei YAN 1 2 , Keefe Chan 2 3 , Katherine M. Hannan 2 3 , Kaylene J. Simpson 1 4 , Ross D. Hannan 1 2 3 5 , Richard B. Pearson 1 2 3 5
  1. Sir Peter MacCallum Department of Oncology, University Of Melbourne, Parkville, Victoria , Australia
  2. Division of Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
  3. Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria, Australia
  4. Victorian Centre for Functional Genomics, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
  5. Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia

More than 1400 Australian women are diagnosed with ovarian cancer (OVCA) every year, which makes ovarian cancer the second most prevalent gynaecological cancer in Australia. Unfortunately, therapeutic options for OVCA patients are still limited. Consequently more than 900 deaths occur per annum1.  

Cancer is characterised by unregulated cell growth and proliferation, both of which are dependent on hyperactivation of ribosome biogenesis. Inhibition of ribosome biogenesis using the specific inhibitor of RNA polymerase I (Pol I) dependent transcription of the rDNA genes, CX-5461 has already been reported to have therapeutic potential in a mouse model of MYC driven B-cell lymphoma2. However its therapeutic potential in OVCA is yet to be determined. 

Our preliminary data utilising a panel of 36 OVCA cell lines suggests that CX-5461 treatment mediates cell cycle arrest in the majority of cells. We hypothesise that identification of genes that can be targeted to cooperate with CX-5461 and induce cell death will define potential drug combinations for the improved treatment of OVCA. Therefore we are performing a genome-wide genetic screen, based on siRNA knockdown, to identify genes that cause synthetic lethal effects with CX-5461 in the high-grade serous ovarian cancer (the most common and malignant subtype) cell line OVCAR4. The primary screen will be performed in presence of CX5461 in 384 well format with SMARTpool reagents (targeting over 18,100 genes) while using cell death (determined by DAPI staining) as a read out. Validated candidates will then be assessed in normal ovarian cell lines for cytotoxicity using cell growth assay (SRB or MTT). Candidates selectively killing cancer cells will be further assessed in vitro and then in xenograft assays for synergy in combination with CX-5461. 

  1. Australian Cancer Incidence and Mortality (ACIM) Books – Ovarian cancer for Australia (ICD10 C56). http://www.aihw.gov.au/acim-books/
  2. Bywater, M., et al Pearson, R.B., McArthur, G.A. and Hannan, R.D. Inhibition of RNA polymerase I as a therapeutic strategy to promote cancer-specific activation of p53 (2012) Cancer Cell 22, 51–65.