Identification of a novel complex between human kallikrein 2 and protease inhibitor-6 in prostate cancer tissue.
Human kallikrein (hK) 2 is an arginine-selective serine protease expressed predominantly in the prostate that has an 80% sequence identity with prostate-specific antigen. Expression of hK2 is elevated in the tumor epithelium compared to benign prostate tissue. We have purified, sequenced, and identified a novel hK2 complex in prostate tissue consisting of hK2 and a serine protease inhibitor known as protease inhibitor-6 (PI-6). This 64-kDa SDS-PAGE stable complex is elevated in the tumor and is approximately 10% of total hK2. No comparable complex of prostate-specific antigen was detected. PI-6, also known as cytoplasmic antiprotease, has been characterized as an intracellular inhibitor of trypsin and chymotrypsin-like proteases, which has high homology to plasminogen activator inhibitor 1 and 2. The physiological role of PI-6 in the prostate and its relationship to hK2 and prostate cancer are under investigation.
Mikolajczyk
S D
SD
Hybritech Inc., San Diego, California 92121, USA. sdmikolajczyk@beckman.com
Millar
L S
LS
Marker
K M
KM
Rittenhouse
H G
HG
Wolfert
R L
RL
Marks
L S
LS
Charlesworth
M C
MC
Tindall
D J
DJ
D014408:Biomarkers, Tumor; D003593:Cytoplasm / Q000378:metabolism; D006801:Humans; D007610:Kallikreins / Q000378:metabolism*; D008297:Male; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D011485:Protein Binding; D015842:Serine Proteinase Inhibitors / Q000378:metabolism; D015843:Serpins / Q000378:metabolism*; D020840:Tissue Kallikreins
D014408:Biomarkers, Tumor; D015842:Serine Proteinase Inhibitors; D015843:Serpins; C094472:serpin B6; D007610:Kallikreins; D020840:Tissue Kallikreins