Evolution of the prostate cancer genome towards resistance

The clinical behavior of prostate cancer is highly heterogeneous, with most patients diagnosed with localized disease that successfully responds to surgery or radiotherapy or that can be followed by active surveillance. However, a fraction of men will relapse after initial treatment and eventually progress to an aggressive resistant form with metastasis spreading and high mortality, a state referred to as castration resistant prostate cancer (CRPC). The technological advances in next generation sequencing have enabled the deep genomic and epigenomic characterization of both the hormone naïve and CRPC states, leading to the definition of molecular subclasses of prostate cancer that could inform the clinicians on therapeutic strategies. These studies also shed light on the mechanisms driving resistance to therapy. CRPCs adapt to androgen receptor (AR) signaling impairment - which follows first-line therapies as androgen deprivation or AR targeting - by restoring the nuclear receptor signaling by means of multiple mechanisms. Alternatively, tumor cells might become resistant to targeted therapies by exploiting lineage plasticity and activating alternative pathways. This review will discuss the main mechanisms leading to the emergence of resistance to therapy in prostate cancer patients in the context of genomic and molecular features of CRPC and on their causal role in the development of resistance.