Targeting eIF4A-dependent translation in soft tissue sarcoma

Well-differentiated and dedifferentiated liposarcoma (WD/DDLS), myxofibrosarcoma (MFS), and undifferentiated pleomorphic sarcoma (UPS) are the most common types of genetically complex sarcoma. There is an urgent need to develop effective targeted therapy for the over 50% of patients who eventually die of disease. Despite their genetic complexity, all four sarcoma types rely on the oncogenic translation of Hippo pathway proteins, which requires the RNA helicase eIF4A (DDX2). Pharmacological inhibition of eIF4A using CR-1-31B effectively suppressed tumor growth and induced apoptosis in DDLS, MFS, and UPS patient-derived cell lines and mouse xenografts. Transcriptome-scale ribosome footprinting identified eIF4A-dependent mRNAs in DDLS, MFS, and UPS cell lines. These include Hippo pathway effectors such as YAP1, WWTR1 (TAZ), and TEAD1. Combined knockdown of YAP and TAZ induced apoptosis in DDLS, MFS, and UPS cell lines, implicating them as critical targets. Hence, DDLS, MFS, and UPS rely on the eIF4A-dependent and CR-1-31B-sensitive translation of Hippo pathway oncogenes such as YAP, TAZ, and TEAD. eIF4A thus represents a new, promising therapeutic target for these incurable forms of soft tissue sarcoma.