The first case of prostate cancer was identified by histological examination by Adams, a surgeon at The London Hospital, in 1853. In his report, Adams noted that the condition was 'a very rare disease'. Now, over 150 years later, with increased life expectancy and screening, prostate cancer has become one of the most common cancers in men. In the United States alone, nearly 200,000 men are diagnosed with prostate cancer annually and about 33,000 succumb to their disease. Fifty years ago, men were typically diagnosed with prostate cancer in their seventies with disease that had metastasized to the bone and/or soft tissue. Diagnosis at such an advanced stage was a death sentence, with patients dying within 2 years. The pioneering work of Charles Huggins in the 1940s found that metastatic prostate cancer responds to androgen deprivation therapy (ADT), ushering in the rational use of hormone therapies that have irrevocably changed the course of prostate cancer disease management. Medical castration was the first effective systemic targeted therapy for any cancer and, to this day, androgen ablation remains the mainstay of prostate cancer therapy.
Alastair H Davies and Amina Zoubeidi
Amina Zoubeidi and Paramita M Ghosh
In this issue of Endocrine-Related Cancer, we are celebrating the 80th anniversary of hormone ablation as treatment for metastatic prostate cancer. Our understanding has evolved from the observation that androgen withdrawal, either surgical or pharmacological, resulted in prostatic atrophy in animal models, to its application in patients, to investigation of the mysterious way in which prostate cancer escapes androgen dependence. We are now in an era of novel AR pathway inhibitors, the combination of androgen ablation with chemotherapy, PARP inhibitors, immunotherapies, guided radiotherapy, and novel drug application based upon genetic testing of individual tumors. In this special issue, we bring together a collection of eight reviews that cover not only the history of 80 years of progress after the initial identification of androgen ablation as an effective treatment of prostate cancer, but subsequent improvements in the understanding of the biology of the disease, development of novel treatment paradigms, resistance to those treatments and disease progression following that resistance.
Jennifer L Bishop, Alastair Davies, Kirsi Ketola, and Amina Zoubeidi
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.
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.