Prostate cancer (PCa) has become the most common form of cancer in men in the developed world, and it ranks second in cancer-related deaths. Men that succumb to PCa have a disease that is resistant to hormonal therapies that suppress androgen receptor (AR) signaling, which plays a central role in tumor development and progression. Although AR continues to be a clinically relevant therapeutic target in PCa, selection pressures imposed by androgen-deprivation therapies promote the emergence of heterogeneous cell populations within tumors that dictate the severity of disease. This cellular plasticity, which is induced by androgen deprivation, is the focus of this review. More specifically, we address the emergence of cancer stem-like cells, epithelial–mesenchymal or myeloid plasticity, and neuroendocrine transdifferentiation as well as evidence that demonstrates how each is regulated by the AR. Importantly, because all of these cell phenotypes are associated with aggressive PCa, we examine novel therapeutic approaches for targeting therapy-induced cellular plasticity as a way of preventing PCa progression.
Jennifer L Bishop, Alastair Davies, Kirsi Ketola and Amina Zoubeidi
Alastair Davies, Amina Zoubeidi and Luke A Selth
Tumours adapt to increasingly potent targeted therapies by transitioning to alternative lineage states. In prostate cancer, the widespread clinical application of androgen receptor (AR) pathway inhibitors has led to the insurgence of tumours relapsing with a neuroendocrine phenotype, termed neuroendocrine prostate cancer (NEPC). Recent evidence suggests that this lineage reprogramming is driven largely by dysregulation of the epigenome and transcriptional networks. Indeed, aberrant DNA methylation patterning and altered expression of epigenetic modifiers, such as EZH2, transcription factors, and RNA-modifying factors, are hallmarks of NEPC tumours. In this review, we explore the nature of the epigenetic and transcriptional landscape as prostate cancer cells lose their AR-imposed identity and transition to the neuroendocrine lineage. Beyond addressing the mechanisms underlying epithelial-to-neuroendocrine lineage reprogramming, we discuss how oncogenic signaling and metabolic shifts fuel epigenetic/transcriptional changes as well as the current state of epigenetic therapies for NEPC.