Reversing-or Rewiring-Lineage Plasticity? Lessons from EZH2 Loss in Prostate Cancer.
Enhancer of zeste homolog 2 (EZH2) inhibitors have been proposed to counteract lineage plasticity (LP) in prostate cancer and thereby resensitize tumors to androgen receptor (AR) inhibition. In this issue of Cancer Research, Jacobi and colleagues provide new mechanistic insights into EZH2 biology across prostate cancer progression using a genetically engineered mouse model that recapitulates the transition toward a neuroendocrine (NE) phenotype. Unexpectedly, genetic deletion of Ezh2 did not reverse LP but instead promoted the diversification of transcription factor (TF) programs driving NE differentiation. In particular, the loss of EZH2 activated members of the KLF TF family, which contributed to this transcriptional diversification. Moreover, EZH2 deletion altered the chromatin-binding landscape of AR, redirecting it toward KLF-associated genomic sites. Collectively, these results refine our understanding of EZH2 function in prostate cancer: Rather than simply reversing LP, EZH2 loss rewires transcriptional networks and reshapes the AR cistrome. These findings are timely given the growing number of clinical trials testing EZH2 inhibitors in metastatic prostate cancer and highlight the need to define when and how to deploy EZH2 inhibition to exploit its effects on tumor lineage dynamics. See related article by Jacobi et al., p. 889.