Antibodies neutralizing hepsin protease activity do not impact cell growth but inhibit invasion of prostate and ovarian tumor cells in culture.
Hepsin is a type II transmembrane serine protease that is expressed in normal liver, and at lower levels in kidney, pancreas, and testis. Several studies have shown that hepsin mRNA is significantly elevated in most prostate tumors, as well as a significant fraction of ovarian and renal cell carcinomas and hepatomas. Although the overexpression of mRNA in these tumors has been extensively documented, there has been conflicting literature on whether hepsin plays a role in tumor cell growth and progression. Early literature implied a role for hepsin in human tumor cell proliferation, whereas recent studies with a transgenic mouse model for prostate cancer support a role for hepsin in tumor progression and metastases. To evaluate this issue further, we have expressed an activatable form of hepsin, and have generated a set of monoclonal antibodies that neutralize enzyme activity. The neutralizing antibodies inhibit hepsin enzymatic activity in biochemical and cell-based assays. Selected neutralizing and nonneutralizing antibodies were used in cell-based assays with tumor cells to evaluate the effect of antibodies on tumor cell growth and invasion. Neutralizing antibodies failed to inhibit the growth of prostate, ovarian, and hepatoma cell lines in culture. However, potent inhibitory effects of the antibodies were seen on invasion of ovarian and prostate cells in transwell-based invasion assays. These results support a role for hepsin in tumor cell progression but not in primary tumor growth. Consistent with this, immunohistochemical experiments with a mouse monoclonal antibody reveal progressively increased staining of prostate tumors with advanced disease, and in particular, extensive staining of bone metastatic lesions.
Department of Cancer Research, Berlex Biosciences, 2600 Hilltop Drive, Richmond, CA 94806, USA.
Jian-Ai
JA
Xuan
Doug
D
Schneider
Pam
P
Toy
Rick
R
Lin
Alicia
A
Newton
Ying
Y
Zhu
Silke
S
Finster
David
D
Vogel
Bob
B
Mintzer
Harald
H
Dinter
David
D
Light
Renate
R
Parry
Mark
M
Polokoff
Marc
M
Whitlow
Qingyu
Q
Wu
Gordon
G
Parry
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008969:Molecular Sequence Data; D009361:Neoplasm Invasiveness; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000276:immunology / Q000494:pharmacology*
D000911:Antibodies, Monoclonal; D011994:Recombinant Proteins; D015842:Serine Proteinase Inhibitors; D012697:Serine Endopeptidases; C055645:hepsin