Zebrafish Rhabdomyosarcoma Models

Rhabdomyosarcoma (RMS) is the most common soft tissue tumor in children, with the phenotype and biology of embryonic skeletal muscle. RMS in children can be divided into two categories: embryonal and alveolar. Embryonic rhabdomyosarcoma is the most common subtype, accounting for about 60% of cases in children. Alveolar rhabdomyosarcoma is generally more aggressive than the embryonal form. However, patients with high-risk features or metastases have poor prognosis regardless of subtype.

Currently, in vivo models of RMS have been shown to help understand the development of devastating pediatric sarcomas. Both vertebrate and invertebrate model systems have been developed to study tumor biology of RMS. The generation of mouse models is expensive and time-consuming, requiring complex breeding protocols to develop reproducible RMS models. In contrast, zebrafish are amenable to large-scale genetic screening due to their high fecundity, ease of in vitro manipulation from embryonic to adulthood, short tumor developmental latency, and biological and pathological similarities to human malignancies. The zebrafish RMS model is particularly suitable for high-throughput studies to identify drug targeting pathways due to its short tumor latency, ease of in vitro manipulation, and conserved tumor biology.

Fig.1 Mosaic transgenic approaches to develop RAS-induced embryonal rhabdomyosarcoma.

Our Zebrafish Rhabdomyosarcoma Models

Creative Biogene has developed a stable zebrafish model of rhabdomyosarcoma. Morphologically, zebrafish rhabdomyosarcomas resemble human rhabdomyosarcomas, exhibiting a spindle cell morphology with occasional primitive circular blue cell nests reproducing different stages of embryonic muscle development. Similar to human rhabdomyosarcoma, zebrafish tumors express myogenic markers commonly used to diagnose human disease, including desmin, myoid, and myogenin. Self-renewing populations of tumor-initiating cells can be observed in this model, which is conducive to further research on the mechanism of tumor self-renewal and the exploration of therapeutic targets for genes involved in self-renewal.

We can not only induce rhabdomyosarcoma in zebrafish, but also identify tumor-proliferating embryonal rhabdomyosarcoma cell subsets and different approaches to uncover cancer-conserved pathways using genomic resources and bioinformatics approaches. We aim to leverage the unique strengths of the zebrafish model organism and the rich cellular and molecular tools currently available to provide a powerful in vivo system for studying RMS tumorigenesis.

Species	Approach	Histologic Subtype	Tumor Onset
Zebrafish	Mosaic Transgenic Approach (rag2- kRASG12D injection at 1-cell stage)	Embryonal	Embryonal
Zebrafish	Heat Shock-inducible Cre-Lox approach (beta-actin-LoxP- EGFP-pA-LoxP- kRASG12D line × hsp70-Cre line)	Embryonal	Heatshocked: Average 35 days Non heatshocked: Average 65 days
Zebrafish	Tol2 gene trap system with transgene expressing constitutively active human H-RASV12	Costello syndrome	60 to 365 days

Advantages

• High similarity in biology and pathology to human malignancies
• Large scale genetic screening
• Enables tumor visualization to image tumor growth over time
• Rapid identification of key genes in the disease process

References

1. Chen EY, Langenau DM. Zebrafish models of rhabdomyosarcoma. Methods Cell Biol. 2011, 105:383-402.
2. Phelps M, Chen E. Zebrafish Rhabdomyosarcoma. Adv Exp Med Biol. 2016, 916:371-389.

For research use only. Not intended for any clinical use.