Poster Presentation 25th Annual Lorne Proteomics Symposium 2020

A High Throughput approach to identifying compound inhibitors of mRNA processing and export (#96)

Kirstyn Carey 1 , Tobias Williams 1 , Vihandha Wickramasinghe 1
  1. Peter Maccallum cancer centre, Parkville, VICTORIA, Australia

Once considered to be a constitutive step of the gene expression pathway, work from our laboratory has demonstrated that export of mRNA from the nucleus to the cytoplasm can be highly selective, giving priority to some mRNAs over others. Perturbations in this pathway result in dysregulated cellular proliferation and genome instability, demonstrating that selective mRNA export regulates processes known to be drivers of malignant transformation. There is accumulating evidence that mRNA export dysregulation contributes to cancer development. Furthermore, transcriptionally driven cancers are heavily reliant on the gene expression pathway to ensure production of oncogenic protein isoforms and to sustain proliferative growth. This creates novel vulnerabilities in cancer cells that can be therapeutically exploited using compounds that affect the gene expression pathway, such as nuclear export of mRNA. Compounds inhibiting all other steps of the gene expression pathway are promising therapeutic candidates, and many have reached clinical trials. Thus, development of RNA export inhibitors offers a unique opportunity to develop innovative, targeted cancer therapeutics.

 We have developed and optimised a sensitive, high-throughput assay to screen 25,000 natural, “drug-like” compounds examining their effects on cell death and RNA localisation within breast cancer cells. Coupled with advanced image analysis, it is possible to reproducibly detect and quantify perturbations of mRNA processing and export. We have demonstrated the first ever compounds inhibiting mRNA export. Immunofluorescence analysis demonstrates compounds disrupt normal localisation of mRNA export machinery components. Furthermore, many compounds show selective toxicity to cancer cells over non-transformed cells in vitro.

 Future work focuses on mechanistic characterisation of compounds and target identification, integrating chemical biology and proteomic strategies. Comprehensive characterisation of these compounds will facilitate our understanding of mRNA processing and export and will hopefully lead to development of pharmacologically relevant compounds which can eventually advance to clinical trials as cancer therapeutics.