Morphogenesis of benign prostatic hyperplasia and prostate carcinoma

Enlargement of the prostate is an age-related, physiological process that is unique in human tissue. The prostate gland is the most common site of neoplastic disorders in men. Despite the growing impact of the various prostate diseases in terms of morbidity and mortality, the pathogenesis of benign prostate hyperplasia (BPH) and prostate cancer remains poorly understood. This reflects the complex composition of the gland with different anatomic, cellular and functional compartments that are differentially involved in benign and malignant disease processes. The present review summarizes new concepts on the morphogenesis of normal and abnormal growth in the human prostate. There is increasing evidence that prostatic stem cells are located in the basal cell layer that is basically involved in normal growth and the development of glandular hyperplasia and prostate cancer. High-grade prostatic intraepithelial neoplasia is considered the most likely precursor of clinically important cancer of the peripheral zone. Severe differentiation and proliferation abnormalities occur during malignant transformation of the prostatic epithelium. These premalignant changes are associated with abnormal expression of growth factor receptors, oncogene and suppressor gene products and genetic instability. During the process of stromal invasion the transformed cells lose their basal cell phenotype and produce basement membrane-like matrices. Common prostate cancer is mainly composed of exocrine cell types that remain androgen-responsive even in hormone-independent disease. The frequent occurrence of neuroendocrine differentiation in common prostate cancer reflects the differentiation potency of its stem cells. The endocrine phenotype derives from exocrine tumor cells via intermediate (amphicrine) cell types. Neuroendocrine tumor cells consistently lack the nuclear androgen receptor and represent an androgen-insensitive cell population in prostate cancer.