Unique features of the basal cells of human prostate epithelium

Abstract

The prostate gland is globally composed of epithelium and stroma. The epithelium plays an important role in the development of both benign and malignant disorders while the stroma is involved in benign prostatic hyperplasia. While the prostatic epithelium of the majority of laboratory animals is well recognized as a pseudostratified columnar, the classification of the human prostatic epithelium is controversial. Moreover, the role of the basal cells of the human prostatic epithelium is still uncertain. These cells have been described as undifferentiated cells, precursors of luminal cells, reserve and myoepithelial cells. The objective of the present study was to assess the similarities and/or differences between the epithelium of the human prostate and that of other laboratory animals and thus derive information about the potential functions of basal cells in the human prostate. In the human, basal cells form a continuous layer of cells resting on the basement membrane and upon which rests a layer of luminal cells. This results in a stratified columnar epithelium of two layers of cells, unlike the sporadic appearance of basal cells observed in other species where it results in a pseudostratified epithelium. In addition, the ratio of basal to luminal cells in the human is about 1:1, while the average ratio in the other animal species examined is about 1:7. Furthermore, the gap junctional proteins connexin 26 and 43, are present between basal and luminal cells in the human, thus suggesting that these cells communicate directly with each other. In addition, the ultrastructure of the human basal cells shows morphological evidence of differentiated but not of undifferentiated cells. Moreover, the presence of junction‐like structures between adjacent basal cells suggests that these cells form a blood‐prostate barrier. In this way, basal cells could prevent substances derived from the blood from directly coming in contact with the luminal cells. Human basal cells could thus regulate functions of the luminal cells by being part of a two‐cell mechanism somewhat analogous to thecal and granulosa cells in the ovary. Microsc. Res. Tech. 51:436–446, 2000. © 2000 Wiley‐Liss, Inc.

Localization of 17β-hydroxysteroid dehydrogenase type 1 mRNA in mouse tissues

“…In the mouse prostatic acini, the majority of epithelial cells are luminal cells, while the basal cells are rather scarce. In fact, the ratio of luminal to basal cells is approximately 10:1 (El-Alfy et al 2000). It can thus be logically assumed that most of the specific labeling is originating from the luminal cells.…”

Prostate cancer susceptibility genes: lessons learned and challenges posed.

“…In normal prostate and in BPH, the epithelium is a stratified columnar structure composed of two layers of cells: a continuous basal layer of low cuboidal cells upon which stands a layer of columnar secretory or luminal cells (El-Alfy et al 2000). Basal cell layer disruption or absence characterizes high-grade PIN and early invasive cancer.…”

Prostatic inflammation enhances basal-to-luminal differentiation and accelerates initiation of prostate cancer with a basal cell origin

“…In comparison, rodent prostates have fewer basal cells that instead usually form a punctuated layer (12). A third type of epithelial cell, neuroendocrine cells, is rare and hence often is not investigated as intensively as the other two lineages (13).…”