Related Experiment Video
Updated: Aug 6, 2026
In Vivo Modeling of the Morbid Human Genome using Danio rerio
Published on: August 24, 2013
Antisense inhibition of cyclin D1 expression is equivalent to flavopiridol for radiosensitization of zebrafish
Mary Frances McAleer1, Kevin T Duffy, William R Davidson
1Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, PA 19107-5541, USA.
Purpose:
Flavopiridol, a small molecule pan-cyclin inhibitor, has been shown to enhance the radiation response of tumor cells both in vitro and in vivo. The clinical utility of flavopiridol, however, is limited by toxicity, previously attributed to pleiotropic inhibitory effects on several targets affecting multiple signal transduction pathways. Here we used zebrafish embryos to investigate radiosensitizing effects of flavopiridol in normal tissues.
Methods And Materials:
Zebrafish embryos at the 1- to 4-cell stage were treated with 500 nM flavopiridol or injected with 0.5 pmol antisense hydroxylprolyl-phosphono nucleic acid oligomers to reduce cyclin D1 expression, then subjected to ionizing radiation (IR) or no radiation.
Results:
Flavopiridol-treated embryos demonstrated a twofold increase in mortality after exposure to 40 Gy by 96 hpf and developed distinct radiation-induced defects in midline development (designated as the "curly up" phenotype) at higher rates when compared with embryos receiving IR only. Cyclin D1-deficient embryos had virtually identical IR sensitivity profiles when compared with embryos treated with flavopiridol. This was particularly evident for the IR-induced curly up phenotype, which was greatly exacerbated by both flavopriridol and cyclin D1 downregulation.
Conclusions:
Treatment of zebrafish embryos with flavopiridol enhanced radiation sensitivity of zebrafish embryos to a degree that was very similar to that associated with downregulation of cyclin D1 expression. These results are consistent with the hypothesis that inhibition of cyclin D1 is sufficient to account for the radiosensitizing action of flavopiridol in the zebrafish embryo vertebrate model.
Insights
Flavopiridol enhances radiation sensitivity in zebrafish embryos, similar to reducing cyclin D1. This suggests cyclin D1 inhibition may explain flavopiridol's radiosensitizing effects in vertebrates.
Area of Science:
- Developmental Biology
- Radiation Oncology
- Pharmacology
Background:
- Flavopiridol, a pan-cyclin inhibitor, enhances tumor cell radiation response.
- Clinical use of flavopiridol is limited by toxicity due to broad target inhibition.
- Zebrafish embryos offer a model to study flavopiridol's effects on normal tissues.
Purpose of the Study:
- Investigate flavopiridol's radiosensitizing effects in normal zebrafish tissues.
- Determine if cyclin D1 inhibition mediates flavopiridol's radiosensitizing action.
- Assess flavopiridol's impact on radiation-induced developmental defects.
Main Methods:
- Zebrafish embryos (1-4 cell stage) were treated with flavopiridol or cyclin D1 antisense oligomers.
- Embryos were exposed to ionizing radiation (IR) or no radiation.
- Mortality and midline development defects (curly up phenotype) were assessed.
Main Results:
- Flavopiridol treatment increased radiation-induced mortality and curly up phenotype rates.
- Cyclin D1-deficient embryos showed similar IR sensitivity profiles to flavopiridol-treated embryos.
- Both flavopiridol and cyclin D1 downregulation exacerbated radiation-induced defects.
Conclusions:
- Flavopiridol enhances zebrafish embryo radiation sensitivity.
- The radiosensitizing effect is comparable to cyclin D1 downregulation.
- Cyclin D1 inhibition likely accounts for flavopiridol's radiosensitizing action in this model.
