**1. Introduction**

Prostate cancer (PCa) is the most commonly diagnosed malignancy and the second leading cause of cancer-related death in men in the United States. It is estimated that PCa will afflict approximately 191,930 men and cause nearly 33,330 deaths this year in the United States alone [1]. Notably, PCa incidence and associated mortality are nearly two-thirds and over two times higher, respectively, in African-American (AA) men compared to their Caucasian-American (CA) counterparts [2,3]. PCa follows a defined pattern of cellular progression but exhibits diverse molecular pathobiology making it one of most highly heterogeneous cancers [4,5]. The prostate-specific antigen (PSA) test is the primary detection tool for PCa screening. However, due to the lack of accuracy and specificity, the usefulness of PSA for PCa diagnosis has been questioned [6–8]. Most PCa patients are generally subjected to localized radical prostatectomy, radiation therapy, proton beam therapy, and cryosurgery after the initial diagnosis [9–11]. However, for patients with metastatic disease or recurrent cancer with locoregional and distant metastases, androgen-deprivation therapy (ADT) or castration therapy is considered the primary line of treatment [12]. Unfortunately, despite the initial outstanding therapeutic response, most PCa patients treated with ADT eventually have the relapse of PCa in a highly aggressive and therapy-resistant form leading to poor clinical outcomes [13,14].

To meet the challenges associated with prostate cancer clinical management, research labs across the world have been working tirelessly to understand underlying molecular diversity and biology of PCa. These efforts have resulted in novel therapies that are currently in clinics, while researchers continue to gather more insights to address new hurdles and failures faced in clinical settings. These advances have been possible through the development of several in vitro and in vivo research models, while new models continue to be developed to address the genetic and biological complexities associated with the PCa. In this review, we discuss the cellular and molecular progression of PCa as well as the available in vitro and in vivo models for PCa research. We believe that the information presented herein will be helpful to the researchers, especially those who are new to the field, in understanding the molecular pathobiology of PCa and guide them in choosing the correct model(s) for their laboratory and preclinical research.
