Background
Understanding the molecular pathogenesis of distinct phenotypes in
human benign prostatic hyperplasia (BPH) is essential to improving
therapeutic intervention. Current therapies target smooth muscle and luminal
epithelia for relief of lower urinary tract symptoms (LUTS) due to BPH, but
basal cell hyperplasia (BCH) remains untargeted. The incidence of has been
reported at 8–10%, but a molecular and cellular
characterization has not been performed on this phenotype.
Methods
Using freshly digested tissue from surgical specimens, we performed
RNA-seq analysis of flow cytometry-purified basal epithelia from 3 patients
with and 4 patients without a majority BCH phenotype. qPCR was performed on
28 genes identified as significant from 13 non-BCH and 7 BCH specimens to
confirm transcriptomic analysis. IHC was performed on several non-BCH and
BCH specimens for 3 proteins identified as significant by transcriptomic
analysis.
Results
A total of 141 human BPH specimens were analyzed for the presence of
BCH. Clinical characteristics of non-BCH and BCH cohorts revealed no
significant differences in age, PSA, prostate volume, medical treatment, or
comorbidities. Quantitation of cellular subsets by flow cytometry in 11 BCH
patients vs. 11 non-BCH patients demonstrated a significant increase in the
ratio of basal to luminal epithelia in patients with BCH (P <0.05),
but no significant differences in the total number of leukocytes. RNA-seq
data from flow cytometry isolated basal epithelia from patients with and
without BCH were subjected to gene set enrichment analysis of differentially
expressed genes, which revealed increased expression of members of the
epidermal differentiation complex. Transcriptomic data were complemented by
immunohistochemistry for members of the epidermal differentiation complex,
revealing a morphological similarity to other stratified squamous epithelial
layers.
Conclusions
Increased expression of epidermal differentiation complex members and
altered epithelial stratification resembles the progression of other
metaplastic diseases. These data provide insight into the plasticity of the
human prostate epithelium and suggest a classification of basal cell
hyperplasia as a metaplasia.