Targeting EYA3 in Ewing Sarcoma Retards Tumor Growth and Angiogenesis

Area of Science:

• Oncology
• Molecular Biology
• Cancer Therapeutics

Background:

• The EWSR1/FLI1 fusion gene, prevalent in Ewing sarcoma, elevates Eyes Absent 3 (EYA3) expression.
• EYA3 functions as a transactivator-phosphatase protein, potentially influencing tumor progression.

Purpose of the Study:

• To elucidate the molecular and cellular mechanisms by which EYA3 promotes Ewing sarcoma growth.
• To assess the therapeutic potential of targeting EYA3 tyrosine phosphatase activity.

Main Methods:

• Genetic and pharmacologic modulation of EYA3 in cell line-based xenografts.
• In vivo and in vitro analyses of tumor tissue and multicellular tumor spheroids.
• Evaluation of EYA3 substrate (H2AX-pY142) levels and VEGFA regulation.

Main Results:

• Loss of EYA3 or inhibition of its tyrosine phosphatase activity significantly reduces Ewing sarcoma tumor growth and angiogenesis.
• EYA3 regulates VEGFA levels and enhances DNA damage repair and survival in Ewing sarcoma cells.
• Benzarone treatment and EYA3 loss increase H2AX-pY142 levels, confirming target engagement.
• Efficacy confirmed in a patient-derived tumor xenograft model.

Conclusions:

• EYA3 is validated as a therapeutic target for Ewing sarcoma.
• Inhibition of EYA3's tyrosine phosphatase activity offers a promising strategy.
• Combining EYA3 inhibition with chemotherapy may enhance treatment outcomes.