TRIB3 silencing promotes the downregulation of Akt pathway and PAX3-FOXO1 in high-risk rhabdomyosarcoma

Fusion protein; RhabdomyosarcomaProteïna de fusió; RabdomiosarcomaProteína de fusión; RabdomiosarcomaRhabdomyosarcoma (RMS), such as other childhood tumors, has witnessed treatment advancements in recent years. However, high-risk patients continue to face poor survival rates, often attributed to the presence of the PAX3/7-FOXO1 fusion proteins, which has been associated with metastasis and treatment resistance. Despite efforts to directly target these chimeric proteins, clinical success remains elusive. In this study, the main aim was to address this challenge by investigating regulators of FOXO1. Specifically, we focused on TRIB3, a potential regulator of the fusion protein in RMS. Our findings revealed a prominent TRIB3 expression in RMS tumors, highlighting its correlation with the presence of fusion protein. By conducting TRIB3 genetic inhibition experiments, we observed an impairment on cell proliferation. Notably, the knockdown of TRIB3 led to a decrease in PAX3-FOXO1 and its target genes at protein level, accompanied by a reduction in the activity of the Akt signaling pathway. Additionally, inducible silencing of TRIB3 significantly delayed tumor growth and improved overall survival in vivo. Based on our analysis, we propose that TRIB3 holds therapeutic potential for treating the most aggressive subtype of RMS. The findings herein reported contribute to our understanding of the underlying molecular mechanisms driving RMS progression and provide novel insights into the potential use of TRIB3 as a therapeutic intervention for high-risk RMS patients.This research was funded by grants from Institut Català d’Oncologia (ICO), Instituto de Salud Carlos III (PI21/00640), Fundació la Marató de TV3, Fundació BOSCH, Iniciativa Tot per tu, Fundació Amics Joan Petit, Fundación Inocente, and Mi compañero de viaje

Additional file 1 of TRIB3 silencing promotes the downregulation of Akt pathway and PAX3-FOXO1 in high-risk rhabdomyosarcoma

Additional file 1. Materials and Methods. Table S1: Western blot antibodies conditions. Figure S1: TRIB3 is overexpressed in FP-RMS cell lines, and its genetic inhibition leads to impaired cell survival and increased apoptosis. Figure S2: Gene expression levels determination and band intensity quantification of WB results from Figure 1e. Figure S3: Scheme of the in vivo experimental design and band intensity quantification for mice samples sacrificed at 7, 11, and 14 days