Mt. Nevalainen et al., PROLACTIN AND PROLACTIN RECEPTORS ARE EXPRESSED AND FUNCTIONING IN HUMAN PROSTATE, The Journal of clinical investigation, 99(4), 1997, pp. 618-627
Prolactin is widely expressed in different tissues, and it is presumed
to have both local and systemic actions. In males it is known to infl
uence reproductive functions but the significance and mechanisms of pr
olactin action in male accessory reproductive tissues are poorly under
stood. Here we show that prolactin acts as a direct growth and differe
ntiation factor for human prostate, as measured by changes in DNA synt
hesis and epithelial morphology of organ cultures. Furthermore, we rep
ort the expression in human prostate of a short prolactin receptor for
m in addition to the long form, based upon ligand cross-linking studie
s and RT-PCR analysis of mRNA expression, The highest density of prola
ctin receptors was detected in the secretory epithelial cells by immun
ohistochemistry. Finally, we report that prolactin is locally produced
in human prostate epithelium, as evidenced by marked prolactin immuno
reactivity in a significant portion of prostate epithelial cells, with
parallel expression of prolactin mRNA in human prostate. Collectively
, these data provide significant support for the existence of an autoc
rine/paracrine loop of prolactin in the human prostate and may shed ne
w tight on the involvement of prolactin in the etiology and progressio
n of neoplastic growth of the prostate.