Abstract 6130: Zebrafish: A prominent tool for cancer drug screening and discovery
Authors: Srivastava Saumya , Guo Linlin , Mohanty Atish , Nelson Michael , Armstrong Brian , Kulkarni Prakash , Salgia Ravi 
Published: September 2020

Abstract
Zebrafish xenotransplants have been exploited to study a myriad of cancers. Due to high genetic and physiological similarities with humans, zebrafish represents a powerful and cost-effective animal model. The main advantages of using this model are transparency, easy manipulation, larger sample size, and short testing period. We have utilized this model system to study lung cancer by performing high throughput drug screening, genetic knockout, xenotransplant of human cancer cells, and circulating tumor cells (CTCs). Among the various applications mentioned, we discuss here,1) Cisplatin resistance in NSCLC (Non-small cell lung cancer). 2) CTC growth with single cell sequencing to identify gene signature of CTCs. 1) NSCLC is the most commonly diagnosed form of lung cancer (&gt;85% of cases). Cisplatin resistance remains a major hurdle in treating advanced NSCLC. To understand the mechanistic basis of how drug resistance evolves we studied cancer progression and group behavior of cisplatin sensitive vs cisplatin resistant cancer cells in zebrafish. Cells were stained with DiI Red (H23-sensitive) and DiI Green dyes (H2009-resistant) respectively. Single culture and co-culture microinjections were done with 50-100 cells and the growth of tumor cells was monitored using live imaging for 72 hours at 30°C. In single culture injections we identified that H2009 cells tend to grow in larger groups where 90% of the cells grow in perivitelline space whereas H23 grow as single cells and are able travel farther in the animal faster. For H23 cells some grow in punctate groups in perivitelline space and about 30% of the cells travel to tail region. Next steps are to establish co-culture phenotypes by injecting different ratios (1:1; 1:2; 1:4; 1:8) of two cell types and assay drugs. 2) CTCs are major players of metastasis which leads to progression of cancer at secondary sites. With disease progression and treatment, it is known that the CTC repertoire changes with enrichment of certain populations of CTCs termed sub-clonal evolution. Therefore, monitoring CTC populations to study changes in gene expression profiles, especially in mutation status -before and after treatment, is a great tool to study development of resistance mechanisms. However, isolating a pure CTC population is not trivial due to their extreme rarity in peripheral blood. We utilize the ANGEL Parsotix technology which works on the differences in physical properties of CTCs and blood cells, like size and deformability. But still we retrieve merely 5-10 CTCs from 8ml of blood. Therefore, we allow these CTCs to grow by xenotransplanting them in zebrafish to get enough population of cells for single cell sequencing. Based on this information we plan to study CTC population genotype evolution -before and after treatment and comparison of gene expression profiles/mutation status of CTCs in primary tumor and metastatic lesions.
Citation Format: Saumya Srivastava, Linlin Guo, Atish Mohanty, Michael Nelson, Brian Armstrong, Prakash Kulkarni, Ravi Salgia. Zebrafish: A prominent tool for cancer drug screening and discovery [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6130.