Background. Hippostasin is a kallikrein-like protease (PRSS20/KLK11), which
is expressed preferentially in the hippocampus and prostate. We have repor
ted that alternative splicing variants of human hippostasin are regulated i
n a tissue-specific manner. Brain-type hippostasin consists of 250 amino ac
ids including a typical signal sequence, and is expressed in the brain and
prostate. The prostate-type hippostasin, which has 32 extra amino acids at
the N-terminal end, is expressed only in the prostate.
Methods. We analyzed the expression and localization of hippostasin in norm
al prostate tissue, BPH tissue, and prostate cancer cell lines. We performe
d northern blotting, in situ hybridization, immunohistochemistry, and RT-PC
R.
Results. Hippostasin mRNA is expressed preferentially in the normal prostat
e and weakly in the testis. It was detected in prostate secretory epitheliu
m. Hippostasin protein was localized in the prostate secretory epithelium,
and western blotting showed that hippostasin was present in semen. All test
ed prostate cancer cell lines, including PSA-negative cell lines, expressed
hippostasin. Interestingly, all the prostate cancer cell lines expressed o
nly brain-type but not prostate-type hippostasin, while normal prostate and
BPH expressed both types of hippostasin.
Conclusions. Our results suggest the possibility that hippostasin may be a
useful marker by which prostate cancer and BPH can be distinguished Prostat
e 49: 72-78, 2001. (C) 2001 Wiley-Liss, Inc.