Discovery of Microbial Natural Products and Their Mechanism of Action using 'FUSION', a Platform for High-Throughput Mechanism of Action Studies

Profound advances in the physical and functional annotation of the protein-coding elements of the human genome are having a transformative impact on discovery science directed at the mechanistic basis of human disease. As a consequence, a challenge for biomedical research is the development of small molecules that target newly discovered disease mechanisms. Natural products have been a tremendous reservoir as small molecule probes and therapeutics, however one of the persistent challenges with natural product-based discovery is determination of mechanism of action and identification of a molecular target. Translating results from phenotypic screens to mechanism currently occurs on an individual compound basis. We have developed an assay that augments phenotypic screening, producing FUnctional SIgnature-based ONtology (FUSION) maps that links bioactive compounds, siRNAs and miRNAs to the molecular target or regulatory network they interact with in a mammalian cell. We have utilized this methodology in combination with our marine bacteria derived collection of natural products for the discovery and biological characterization of novel natural products. A highlighted example will be discoipyrrole A, a potent inhibitor of the discoidin domain receptor 2 (DDR2) pathway. The DDR2 signaling pathway plays a key role in tumor cell migration and proliferation and has recently been identified as promising therapeutic target in cancer. Discoipyrrole A has IC₅₀ values ranging from 150 – 240 nM against a panel of non-small cell lung cancer cell lines with mutations in oncogenic-driver mutations in DDR2.