Abstract
Purpose :
Discovery of ocular therapeutics typically relies on reductionist approaches to a small number of targets known to regulate physiological or pathological processes. A preferential approach utilises an unbiased screen of drug libraries to identify drugs that restore/maintain visual function or inhibit disease pathologies as primary phenotypic end-points. Here, we provide a critical analysis of our phenotype-based drug screens in zebrafish which discover drugs improving visual function or inhibiting ocular angiogeneis in vivo.
Methods :
For visual behaviour assays dye mutants are screened as individual larvae in 10 uM library drug using the visualmotor response (VMR) assay. For anti-angiogenic drugs, 5 TG(fli1:EGFP) zebrafish per well are screened iin 10 uM drug and developmental angiogenesis of the vitreo-retinal hyaloid vasculature quantified by fluorescence microscopy. Screening efficiency can be accelerated by horizontal and vertical drug pooling e.g. 80 plate drugs into 18 pools comprising10 uM of each drug.
Results :
Our phenotype-based drugs screens in zebrafish are effective at screening thousands of diverse small molecule drugs. Screens of a Chembridge Diverset library of 5000 randomised chemicals with predicted drug-like properties, an ICCB library of 472 known bioactive drugs, and bespoke PI3K/Akt/mTOR pathway (50) or lysine deacetylase inhibitors (KDACi) libraries have been completed. Important screen outputs include: i) identification of KDAC inhibitors tricostatin A and scriptaid to significantly improve visual function in the dye model of inherited blindness ii) discovery that vitamin D agonists from bioactive library significantly attenuate hyaloid vasculature angiogenesis; iii) identification of combinations of PI3K/Akt/mTOR inhibitors (e.g. NVP-BEZ235 + PI-103) resulting in additive/synergistic inhibition of developmental angiogenesis; and iv) discovery of (2-[(E)-2-(quinolin-2-yl)vinyl] phenol) and resulting novel chemical entities (NCE) inhibiting hyaloid vessel development.
Conclusions :
Phenotype-based drug screening in zebrafish provides exciting opportunities to identify existing drugs which can be re-purposed, or novel first-in-class drugs for development as therapeutics for ocular disease.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.