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Updated: Nov 16, 2025
Mapping the Structure-Function Relationships of Disordered Oncogenic Transcription Factors Using Transcriptomic Analysis
Published on: June 27, 2020
FOXF1 is required for the oncogenic properties of PAX3-FOXO1 in rhabdomyosarcoma
David Milewski1,2, Samriddhi Shukla1, Berkley E Gryder2
1Division of Pulmonary Biology, The Perinatal Institute of Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
Abstract:
The PAX3-FOXO1 fusion protein is the key oncogenic driver in fusion positive rhabdomyosarcoma (FP-RMS), an aggressive soft tissue malignancy with a particularly poor prognosis. Identifying key downstream targets of PAX3-FOXO1 will provide new therapeutic opportunities for treatment of FP-RMS. Herein, we demonstrate that Forkhead Box F1 (FOXF1) transcription factor is uniquely expressed in FP-RMS and is required for FP-RMS tumorigenesis. The PAX3-FOXO1 directly binds to FOXF1 enhancers and induces FOXF1 gene expression. CRISPR/Cas9 mediated inactivation of either FOXF1 coding sequence or FOXF1 enhancers suppresses FP-RMS tumorigenesis even in the presence of PAX3-FOXO1 oncogene. Knockdown or genetic knockout of FOXF1 induces myogenic differentiation in PAX3-FOXO1-positive FP-RMS. Over-expression of FOXF1 decreases myogenic differentiation in primary human myoblasts. In FP-RMS tumor cells, FOXF1 protein binds chromatin near enhancers associated with FP-RMS gene signature. FOXF1 cooperates with PAX3-FOXO1 and E-box transcription factors MYOD1 and MYOG to regulate FP-RMS-specific gene expression. Altogether, FOXF1 functions downstream of PAX3-FOXO1 to promote FP-RMS tumorigenesis.
Insights
Forkhead Box F1 (FOXF1) drives fusion-positive rhabdomyosarcoma (FP-RMS) tumorigenesis by acting downstream of the PAX3-FOXO1 oncogene. Targeting FOXF1 suppresses tumor growth and promotes differentiation in FP-RMS.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Fusion-positive rhabdomyosarcoma (FP-RMS) is an aggressive cancer driven by the PAX3-FOXO1 fusion protein.
- Identifying downstream targets of PAX3-FOXO1 is crucial for developing new FP-RMS therapies.
Purpose of the Study:
- To investigate the role of Forkhead Box F1 (FOXF1) as a downstream target of PAX3-FOXO1 in FP-RMS.
- To determine if FOXF1 is essential for FP-RMS tumorigenesis and differentiation.
Main Methods:
- Utilized CRISPR/Cas9 to inactivate FOXF1 coding sequences and enhancers.
- Performed gene knockdown and knockout experiments for FOXF1.
- Analyzed FOXF1 binding to chromatin and its cooperation with other transcription factors (MYOD1, MYOG).
Main Results:
- FOXF1 is uniquely expressed in FP-RMS and directly induced by PAX3-FOXO1.
- Inactivation of FOXF1 or its enhancers suppressed FP-RMS tumorigenesis.
- FOXF1 knockdown/knockout induced myogenic differentiation in FP-RMS cells.
- Overexpression of FOXF1 inhibited differentiation in human myoblasts.
Conclusions:
- FOXF1 is a key downstream effector of PAX3-FOXO1, essential for FP-RMS tumorigenesis.
- FOXF1 functions with PAX3-FOXO1 and other factors to regulate FP-RMS-specific gene expression.
- Targeting FOXF1 represents a potential therapeutic strategy for FP-RMS.
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