The Receptor Tyrosine Kinase RON and Its Isoforms as Therapeutic Targets in Ewing Sarcoma

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• Receptor tyrosine kinase (RTK) RON is implicated in carcinoma metastasis and is a therapeutic target.
• RON's role in sarcomas, particularly pediatric types, is largely uncharacterized.
• RON confers resistance to insulin-like growth factor-1 receptor (IGF1R) targeting in Ewing sarcoma.

Purpose of the Study:

• To investigate the function of RON in pediatric sarcomas, specifically Ewing sarcoma.
• To explore the crosstalk between RON and IGF1R signaling pathways.
• To evaluate the efficacy of targeting RON and IGF1R in preclinical models.

Main Methods:

• Utilized shRNA to silence RON in pediatric sarcoma cell lines and a zebrafish model.
• Employed monoclonal antibodies IMC-RON8 (anti-RON) and IMC-A12 (anti-IGF1R) for targeted inhibition.
• Analyzed signaling pathways and RON isoform expression via RT-PCR and in vivo/in vitro assays.

Main Results:

• RON silencing impaired Ewing sarcoma cell functions in vitro and in vivo, including micrometastatic capacities.
• Demonstrated unidirectional, IGF1-mediated cross-activation of RON.
• Identified expression of a short-form RON isoform in childhood sarcomas, resistant to antibody targeting.
• Observed increased short-form RON expression with DNA methyltransferase inhibitors, unlike in carcinomas.

Conclusions:

• This study establishes a role for RON in the metastatic progression of Ewing sarcoma.
• While RON functions may be conserved across carcinomas and sarcomas, specific isoform regulation necessitates further investigation for effective therapeutic strategies.
• Highlights the need for tailored approaches to target RON effectively in different sarcoma subtypes.