Genome-wide AR and H3K27Ac binding profiles in DSRCT cells, xenograft and PDX mouse tumors
DSRCT is an aggressive, often fatal, sarcoma subtype that usually present in post-pubertal adolescents and young adults. Though the pathognomonic EWSR1-WT1 fusion protein is responsible for tumorigenesis, the androgen receptor (AR) has been suggested as a key contributor to tumor survival and growth. Reverse-phase protein lysate arrays (RPPA) were used to identify new drug targets in DSRCT not present in Ewing sarcoma, a close molecular cousin that shares an EWSR1 N-terminus chimeric partner. Among the 151 proteins analyzed, the AR protein was the most differentially expressed protein, which led to follow-on studies to investigate its role in DSRCT survival and growth in cell lines, xenografts, and patient-derived tumor explants (PDXs), which retain the best fidelity to their human tumor counterparts. Modern-day 2nd-generation AR antagonists were tested for preclinical antitumor activity, in addition to novel AR-directed antisense oligonucleotides that rapidly suppress post-transcriptional activity. Our research demonstrates an important role for the AR in promoting tumor growth and survival in preclinical DSRCT models. Given the widespread availability of safe, orally administered FDA-approved agents used for prostate cancer, such as abiraterone or enzalutamide that potently block AR steroidogenesis or intracellular AR signaling, one could quickly evaluate their effect in DSRCT in phase 2 trials. Overall design: Examination of AR and H3K27Ac binding in DHT stimulated or unstimulated DSRCT cell lines, xenograft and PDX mouse tumors