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Updated: May 12, 2026
A Manual Small Molecule Screen Approaching High-throughput Using Zebrafish Embryos
Published on: November 8, 2014
A novel chemical screening strategy in zebrafish identifies common pathways in embryogenesis and rhabdomyosarcoma
Xiuning Le1, Emily K Pugach, Simone Hettmer
1Stem Cell Program and Division of Hematology/Oncology, Children's Hospital and Dana Farber Cancer Institute, Howard Hughes Medical Institute, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02115, USA.
Abstract:
The zebrafish is a powerful genetic model that has only recently been used to dissect developmental pathways involved in oncogenesis. We hypothesized that operative pathways during embryogenesis would also be used for oncogenesis. In an effort to define RAS target genes during embryogenesis, gene expression was evaluated in Tg(hsp70-HRAS(G12V)) zebrafish embryos subjected to heat shock. dusp6 was activated by RAS, and this was used as the basis for a chemical genetic screen to identify small molecules that interfere with RAS signaling during embryogenesis. A KRAS(G12D)-induced zebrafish embryonal rhabdomyosarcoma was then used to assess the therapeutic effects of the small molecules. Two of these inhibitors, PD98059 and TPCK, had anti-tumor activity as single agents in both zebrafish embryonal rhabdomyosarcoma and a human cell line of rhabdomyosarcoma that harbored activated mutations in NRAS. PD98059 inhibited MEK1 whereas TPCK suppressed S6K1 activity; however, the combined treatment completely suppressed eIF4B phosphorylation and decreased translation initiation. Our work demonstrates that the activated pathways in RAS induction during embryogenesis are also important in oncogenesis and that inhibition of these pathways suppresses tumor growth.
Insights
RAS signaling pathways active during zebrafish embryogenesis are also crucial for cancer development. Inhibiting these pathways, particularly MEK1 and S6K1, suppressed tumor growth in zebrafish and human rhabdomyosarcoma models.
Area of Science:
- Developmental Biology
- Oncology
- Genetics
Background:
- Zebrafish embryos are a novel model for studying oncogenesis.
- RAS signaling pathways are implicated in both development and cancer.
Purpose of the Study:
- To identify RAS target genes during zebrafish embryogenesis.
- To screen for small molecules that inhibit RAS signaling.
- To evaluate the therapeutic potential of these molecules against rhabdomyosarcoma.
Main Methods:
- Gene expression analysis in Tg(hsp70-HRAS(G12V)) zebrafish embryos.
- Chemical genetic screening for RAS signaling inhibitors.
- Assessment of small molecule anti-tumor activity in zebrafish and human rhabdomyosarcoma models.
Main Results:
- DUSP6 was identified as a RAS-activated gene during embryogenesis.
- PD98059 (MEK1 inhibitor) and TPCK (S6K1 inhibitor) showed anti-tumor activity.
- Combined treatment suppressed eIF4B phosphorylation and translation initiation, reducing tumor growth.
Conclusions:
- Embryonic RAS-induced pathways are vital for oncogenesis.
- Targeting MEK1 and S6K1 offers a potential therapeutic strategy for RAS-driven cancers.
- Zebrafish models are effective for discovering cancer therapeutics.
