Poster Presentation 25th Lorne Cancer Conference 2013

Novel small molecules that target the dimer interface of 14-3-3 proteins as a basis for possible anti-cancer therapeutics. (#406)

Joanna Woodcock 1 , Carl Coolen 1 , Urmi Dhagat 2 , Jess Holien 2 , Robert Bittman 3 , Stuart Pitson 1 , Michael Parker 2 , Angel Lopez 1
  1. Centre for Cancer Biology, Adelaide, SA, Australia
  2. ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Melbourne, Vic, Australia
  3. Queen's College, City University of New York , New York, USA

The 14-3-3 proteins are a family of highly conserved, ubiquitously expressed dimeric phospho-serine binding proteins that play a key role in protecting cells against apoptosis through interacting with and regulating pro-apoptotic proteins such as BAD and Ask-1. 14-3-3 protein expression is up-regulated in many human cancers and associated with enhanced survival of cancer cells, cancer chemo-resistance and poor patient prognosis, identifying14-3-3 proteins potential targets for cancer therapy. The anti-apoptotic functions of 14-3-3 are entirely dependent on the dimeric state of the protein and our findings show that through binding to 14-3-3 proteins, sphingosine and analogs render the dimeric proteins phosphorylatable, which in turn disrupts the dimeric state of the 14-3-3 proteins, leading to induction of apoptosis. Thus, this provides us with a novel mechanism to harness for potential therapeutic effect. Using our knowledge of 14-3-3 dimerisation and understanding of the lipid chemistry required for interaction with 14-3-3, we have taken two independent approaches to identify novel 14-3-3 inhibitors that harness the sphingosine-triggered 14-3-3 regulation pathway to develop 14-3-3 inhibitors. We have also used an in silico approach to identify novel small molecules that interact with 14-3-3 at the dimer interface and by screening for their ability to render 14-3-3 phosphorylatable, identified a family of small molecule hits with 14-3-3 dimer destabilizing properties that potently induce mitochondrial apoptosis. These small molecules are being further characterised to determine their molecular effects on 14-3-3 dimers. In the second approach we have rationally designed novel synthetic lipid molecules akin to sphingosine that are capable of rendering 14-3-3 phosphorylatable and similarly induce mitochondrially-mediated cell death. These novel lipids induce apoptosis in human lung cancer cells and synergise with conventional chemotherapy and importantly reduce xenograft growth in nude mice.