Poster Presentation 27th Lorne Cancer Conference 2015

3D and monolayer culture systems highlight ABCA1 as a promoter of aggressive characteristics in epithelial ovarian cancer (#308)

Rebekka Williams 1 , Amanda Russell 1 , Angelika Bongers 1 , Claudia Flemming 1 , Wendy Jessup 2 , Anna DeFazio 3 , Georgia Chenevix-Trench 4 , Michelle Haber 1 , Murray Norris 1 , Michelle Henderson 1
  1. Children’s Cancer Institute Australia for Medical Research, Randwick, NSW, Australia
  2. Atherosclerosis Laboratory, ANZAC Research Institute, Concord, NSW, Australia
  3. Department of Gynaecological Oncology and Westmead Institute for Cancer Research, Westmead Millennium Institute, Sydney, NSW, Australia
  4. Cancer Genetics Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia

Epithelial ovarian cancer (EOC) is a devastating disease and accounts for a large proportion of gynaecological cancer-related deaths. Poor survival is largely due to late diagnosis of the disease which typically presents with peritoneal dissemination. In order to achieve reduced tumour burden and improve survival, it is imperative to identify prognostic markers and potential therapeutic targets. Recent work by our group identified high ATP- Binding Cassette A1 (ABCA1) transporter expression as being associated with poor outcome in EOC (Hedditch et al., 2014). ABCA1 has been widely studied as a cholesterol transporter, however there is little research investigating its potential roles in cancer biology. The aim of this work was to ascertain whether ABCA1 may promote aggressive characteristics in EOC. siRNA-mediated suppression of ABCA1 in EOC cell lines led to reduced colony forming ability, growth and migration as compared to controls. By culturing EOC cell lines (Skov3, 27/87 and HEY) in a 3-dimensional spheroid model, we have shown that ABCA1 suppression significantly reduced overall spheroid volume (p = ≤0.0003, ANOVA with Dunnett’s multiple comparison test). In Skov3 and 27/87 spheroids, reduced volume was associated with cell death; however in HEY spheroids, ABCA1 suppression significantly reduced cell numbers in the absence of  detectable cell death (p = ≤0.0002, ANOVA with Dunnett’s multiple comparison test). Remarkably, whilst HEY cells formed a tightly compacted spheroid with a prominent necrotic core, both of these processes were distinctly impaired by ABCA1 suppression. These compacted and necrotic attributes of ABCA1-positive spheroids are suggestive of a more contractile behaviour and a hypoxic environment, both key characteristics of more aggressive, chemo-resistant and recurrent tumours (Liao et al., 2014, Sodek et al., 2009). Collectively this data may implicate ABCA1 in regulating multiple processes associated with aggressive and invasive characteristics of EOC, highlighting ABCA1 as a potential therapeutic target.

  1. HEDDITCH, E. L., et al., (2014) ABCA transporter gene expression and poor outcome in epithelial ovarian cancer. J Natl Cancer Inst, 106.
  2. LIAO, J. Q., et al., (2014) Ovarian Cancer Spheroid Cells with Stem Cell-Like Properties Contribute to Tumor Generation, Metastasis and Chemotherapy Resistance through Hypoxia-Resistant Metabolism. PLoS One, 9
  3. SODEK, K. L., et al., (2009) Compact spheroid formation by ovarian cancer cells is associated with contractile behavior and an invasive phenotype. Int J Cancer, 124, 2060-70.