Immunoradiometric assay of pS2 protein in breast cancer cytosols

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 37; no. 10; pp. 1759 - 1762
• Main Authors: Goussard, J, Lechevrel, C, Roussel, G, Cren, H, Bera, O, Sala, M
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.10.1991; American Association for Clinical Chemistry
• Subjects: Biological and medical sciences; Breast Neoplasms - metabolism; Cathepsin D - isolation & purification; Cytosol - metabolism; Female; Host-tumor relations. Immunology. Biological markers; Humans; Immunoradiometric Assay; Medical sciences; Neoplasm Proteins - metabolism; Proteins; Reagent Kits, Diagnostic; Receptors, Estrogen - metabolism; Receptors, Progesterone - metabolism; Trefoil Factor-1; Tumor Cells, Cultured; Tumor Suppressor Proteins; Tumors; Tumoral marker; Mammary gland; Radioimmunoassay; Quantitative analysis
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/37.10.1759

We studied the ELSA-pS2 immunoradiometric kit (CIS Bio International) for pS2 protein assay in breast cancer cytosols according to classic validation methods. In addition, we studied correlations between pS2, steroid receptors, and cathepsin-D assays. Repeatability (CV = 1.5% to 4.8%) and reproducibility (CV = 1.6% to 4.9%) were good. The results were linearly related to pS2 concentrations between 205 and 2200 ng/L; the detection limit was 40 ng/L. The accuracy of the assay was measured by assessing recovery; analytical recoveries were near 100% throughout the standard curve. The use of different compounds for cytosol preparation (Tris 10 mmol/L or phosphate 25 mmol/L, KCl 0.4 mol/L, bovine serum albumin 1 g/L) had no effect on pS2 results. pS2 was assayed in breast tumor cytosols from 197 postmenopausal and 92 premenopausal patients. The mean value was 24 micrograms/g of protein; the median and 25th and 75th percentiles were 6, 1, and 23 micrograms/g protein, respectively. We observed a relation between concentrations of pS2 and those of estrogen and progesterone receptors, but there was no relationship between the concentrations of pS2 and cathepsin-D.