The WFDC1 gene encoding ps20 localizes to 16q24, a region of LOH
in multiple cancers
* Steven J. Ressler,
Michael J. Gerdes,
** Bing Lu,
*** Meg Byron,
Jeanne B. Lawrence,
David R. Rowley
Cell and Molecular Biology Program, Baylor College of Medicine, Houston, Texas 77030, USA
Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
Department of Cell Biology, University of Massachusetts Medical School, 53 Lake Avenue North, Worcester, Massachusetts 01655, USA
Abstract. We previously identified ps20 protein as a secreted
growth inhibitor and purified the protein from fetal rat prostate
urogenital sinus mesenchymal cell conditioned medium. The rat
cDNA was subsequently cloned, and ps20 was found to contain a
WAP-type four-disulfide core motif, indicating it may function as
a protease inhibitor. We now report cloning and characterization of
the mouse ps20 gene (designated Wfdc1), the human homolog
cDNA, and the human gene (designated WFDC1). Both the mouse
and human WFDC1 genes consist of seven exons and encode
respective ps20 proteins sharing 79.1% identity and nearly iden-
tical WAP motifs in exon 2. The WFDC1 gene was mapped by
FISH analysis to human Chromosome (Chr) 16q24, an area of
frequent loss of heterozygosity (LOH) previously identified in
multiple cancers including prostate, breast, hepatocellular, and
Wilms’ tumor. Identification and characterization of the WFDC1
gene may aid in better understanding the potential role of this gene
and ps20 in prostate biology and carcinogenesis.
The rat ps20 protein (prostate stromal protein, 20 kDa) was origi-
nally identified as a secreted growth inhibitor (Rowley 1992; Row-
ley and Tindall 1987) and purified to homogeneity from the con-
ditioned medium of a fetal rat urogenital sinus mesenchymal cell
line (Rowley et al. 1995). We subsequently isolated cDNA encod-
ing rat ps20 and characterized the biological properties of ps20 in
vitro (Larsen et al. 1998). These studies showed that both recom-
binant ps20 protein added exogenously and ps20 expressed in
transfected COS cells is growth inhibitory to the PC-3 prostate
carcinoma and COS cell lines respectively. A putative functional
motif contained within the ps20 amino acid sequence was identi-
fied as a WAP-type four-disulfide core domain, or WAP Signature
motif, a domain composed of eight cysteines forming four disul-
fide bonds at the core of the protein (Bairoch 1991). The WAP
Signature motif functions as a protease inhibitor domain in many
family members, including elafin/ESI/SKALP (Schalkwijk et al.
1991) and SLPI/HUSI-I/ALP (Heinzel et al. 1986), and has been
hypothesized to do the same in ps20 (Larsen et al. 1998). Immu-
nohistochemistry analysis of expression showed ps20 is high in
smooth muscle cells relative to all other cell types, which exhibit
either low or nearly undetectable immunostaining in the adult rat
(Larsen et al. 1998). Immunostaining of ps20 was observed in both
visceral and vascular smooth muscle in multiple tissues (Larsen et
al. 1998). Particularly high expression was noted in adult rat pros-
tate gland stroma relative to other tissues (Larsen et al. 1998) and
in human prostate gland (unpublished data). The full extent of ps20
expression in human tissues and cell types is not yet known. Be-
cause ps20 exhibits both growth regulatory effects and affects cell
phenotypic properties in vitro, it may function as a mediator of
stromal-epithelial interactions and in maintenance of tissue ho-
meostasis (Rowley 1999).
The purpose of the present study was to clone the mouse and
human ps20 genes, characterize intron-exon structure, and to map
the chromosomal location of the human ps20 gene in order to
assess potential significance of ps20 in human disease. The full-
length human ps20 cDNA was cloned from a prostate cDNA li-
brary and used to isolate human ps20 genomic sequences from a
human P1 genomic library. To facilitate future studies of ps20
function in vivo in mouse model systems, we cloned the mouse
ps20 gene and sequenced it to determine its genomic structure. The
human gene encoding ps20 protein was designated WFDC1, or
WAP four-disulfide core-1, and the mouse homolog gene, Wfdc1.
Both the mouse and human WFDC1 genes consisted of seven
exons, suggesting WFDC1 is most similar to the largest gene in the
WAP Signature domain family, the KAL gene, which is geneti-
cally linked to Kallmann syndrome. The amino acid sequences of
mouse, rat, and human ps20 proteins were highly conserved. By
fluorescent in situ hybridization (FISH), we mapped the human
WFDC1 gene to Chr 16q24, a region of loss of heterozygosity
(LOH) in several human cancers, including prostate (Carter et al.
1990; Godfrey et al. 1997; Latil et al. 1997) and breast cancer
(Cleton-Jansen et al. 1994; Sato et al. 1991a; Whitmore et al.
1998), and Wilms’ tumor (Grundy et al. 1998; Maw et al. 1992).
Owing to its location on Chr 16q24, combined with the growth
inhibitory properties of its gene product (ps20), WFDC1 may be a
candidate for further study as a potential tumor suppressor gene.
Materials and methods
Cloning of human ps20 cDNA.
The Human Prostate 5Ј-STRETCH
Lambda gt11 cDNA Library (Clontech, Palo Alto, Calif.) was screened by
moderate stringency hybridization with a partial rat ps20 cDNA clone as
probe. Ten 150-mm plates with approximately 45,000 pfu/plate were pre-
pared. DNA was transferred to Nytran 0.45-mm membranes (Schleicher
and Schuell, Keene, N.H.) and cross-linked by UV irradiation (Stratalinker,
The HUGO Nomenclature approved name for the human gene encoding
ps20 is WDFC1 and for the mouse gene is Wdfc1 (WAP four-disulfide core
domain 1). Sequences described in this manuscript have been deposited
with the GenBank/EMBL libraries. The human ps20 cDNA sequence is
AF169631. The Wfdc1 mouse genomic sequence has been deposited in
two parts: MGLClone1 (upstream sequence and exon 1), AF169632; and
MGLClone2 (exons 2–7), AF170446.
Correspondence to: D.R. Rowley; E-mail: firstname.lastname@example.org
* Present address: NIH/NIDCR/CDBRB, 30 Convent Dr., MSC 4370,
Bethesda, MD 20892-4370, USA.
** Present address: NIH/NCI/LCCTP, 37 Convent Dr., MSC 4255,
Bethesda, MD 20892-4255, USA.
*** Present address: Dupont Pharmaceutical Company, Stine-Haskell Re-
search Center, Bldg. 110, P.O. Box 30, 1094 Elkton Road, Newark, DE
Mammalian Genome 11, 767–773 (2000).
© Springer-Verlag New York Inc. 2000