Estimation of pS2 protein level in human body fluids by a sensitive two-site enzyme immunoassay.
A sensitive two-site enzyme immunoassay (EIA) system was established for human pS2 protein, a small estrogen-inducible secretory protein of unknown function originally identified in MCF-7 human breast cancer cells. Our EIA system is based on the sandwiching of antigen between anti-recombinant (r) pS2 antibody IgG coated on a polystyrene plate and biotinylated anti-rpS2 antibody IgG. The amount of pS2 protein was quantified by measurement of the bound enzyme activity of subsequently added streptavidin-linked beta-D-galactosidase (beta-D-galactosidase, EC 3.2.1.23). pS2 protein purified from MCF-7 culture supernatants was detectable at a concentration as low as 3 pg/ml (corresponding to 60 fg/well). This EIA system revealed that the amount of pS2-like immunoreactivity (LI) in human urine was 13.6 ng/mg creatinine (median, n = 416) and that there was no correlation between the pS2-LI concentration in urine and sex or aging. pS2-LI levels in plasma and sera of the normal subjects were 392 pg/ml (median, n = 14) and 494 pg/ml (median, n = 12), respectively. The serum level of the patients with breast cancer (528 pg/ml; median, n = 67) was not statistically different from that of normal subjects, although high levels of pS2 protein in breast cancer tissues had been reported.
Miyashita
S
S
Department of Molecular Biology, Gifu Pharmaceutical University, Japan.
Nomoto
H
H
Konishi
H
H
Hayashi
K
K
D000918:Antibody Specificity; D001426:Bacterial Proteins; D001943:Breast Neoplasms / Q000097:blood / Q000737:chemistry; D004967:Estrogens; D005260:Female; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007124:Immunoenzyme Techniques / Q000706:statistics & numerical data; D007074:Immunoglobulin G; D008297:Male; D009363:Neoplasm Proteins / Q000032:analysis* / Q000097:blood / Q000652:urine; D011506:Proteins; D011994:Recombinant Proteins; D012016:Reference Values; D019809:Streptavidin; D000071163:Trefoil Factor-1; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D001616:beta-Galactosidase
D001426:Bacterial Proteins; D004967:Estrogens; D007106:Immune Sera; D007074:Immunoglobulin G; D009363:Neoplasm Proteins; D011506:Proteins; D011994:Recombinant Proteins; C051838:TFF1 protein, human; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins; D019809:Streptavidin; D001616:beta-Galactosidase