A Molecular Switch from Tumor Suppressor to Oncogene in ER-Positive Breast Cancer: Role of Androgen Receptor, JAK-STAT, and Lineage Plasticity [RNA-seq II]

Due to lack of tumor suppressor-agonists, this hypothesis and mechanisms underlying resistance are not understood. In estrogen receptor (ER)-positive breast cancer (BC), androgen receptor (AR) is a druggable tumor suppressor and offers a promising avenue for this investigation. Spatial genomics suggest that the molecular portrait of AR-expressing BC cells in tumor microenvironment corresponds to better overall patient survival, clinically confirming AR’s role as a tumor suppressor. Ligand-activation of AR-positive BC xenografts reprograms cistromes, inhibits oncogenic pathways, and promotes cellular elasticity towards a more differentiated state, while sustained treatment results in cistromes rearrangement towards transcription factor PROP1, transformation of AR into an oncogene, and activation of the JAK/STAT pathway, all culminating in lineage plasticity to an aggressive resistant subtype. While the molecular profile of AR agonist-sensitive tumors corresponds to better patient survival, the profile represented in the resistant phenotype corresponds to shorter survival. Inhibition of activated oncogenes in resistant tumors reduces growth and re-sensitizes them to AR agonists. Together, these findings indicate that persistent activation of a tumor suppressor is not fail-safe and leads to resistance through lineage plasticity-driven tumor metamorphosis. Our work provides a framework to explore the above phenomenon across multiple cancer types and underscores the importance of factoring the sensitization of tumor suppressor targets while developing agonist-like drugs