Enzyme immunoassay of immunoreactive progastrin-releasing peptide(31- 98) as tumor marker for small-cell lung carcinoma: development and evaluation

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 41; no. 4; pp. 537 - 543
• Main Authors: Aoyagi, K, Miyake, Y, Urakami, K, Kashiwakuma, T, Hasegawa, A, Kodama, T, Yamaguchi, K
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.04.1995; American Association for Clinical Chemistry
• Subjects: Amino Acid Sequence; Antibodies, Monoclonal; Base Sequence; Biological and medical sciences; Biomarkers, Tumor - blood; Biotin; Carcinoma, Small Cell - blood; Enzyme-Linked Immunosorbent Assay - statistics & numerical data; Humans; Lung Neoplasms - blood; Medical sciences; Microchemistry; Molecular Sequence Data; Peptide Fragments - blood; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptides - blood; Peptides - chemistry; Peptides - genetics; Pneumology; Recombinant Proteins - analysis; Recombinant Proteins - blood; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Reference Values; Sensitivity and Specificity; Tumors of the respiratory system and mediastinum; Human; Biological fluid; Lung disease; Peptide hormone; Biological marker; Malignant tumor; Gastrin releasing peptide; Clinical biology; Serum; Biosynthesis precursor; Hormone releasing factor; ELISA assay; Quantitative analysis
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/41.4.537

Previously, using recombinant human progastrin-releasing peptide (ProGRP)(31-98), we developed a RIA for ProGRP(31-98) and demonstrated that the determination of serum ProGRP(31-98) was a reliable marker for small-cell lung carcinoma (SCLC) (Miyake et al., Cancer Res 1994;54:2136-40). Aiming for a more convenient assay system, we have now developed and evaluated a highly sensitive and specific ELISA for ProGRP(31-98). Only 50 microL of nonextracted serum is needed, and results are obtained in only 2 h. Intraassay and between-day CVs were 1.7-4.6% and 4.2-6.8%, respectively. The log-log calibration curve was linear to 1000 ng/L, and analytical recovery was 91.5-108.7%. The detection limit of this assay, 1.9 ng/L, means that basal concentrations of ProGRP(31-98) were detectable in all healthy subjects. The cutoff value, based on the mean + 3 SD of concentrations in 247 healthy subjects, was set to 45.1 ng/L. Serum concentrations exceeded this value in 18 of 25 SCLC patients, similar to the frequency of increased values found by RIA previously. In contrast, the frequency of increased serum ProGRP(31-98) in patients with nonmalignant pulmonary diseases or non-SCLC was quite low: 0% and 5.0%, respectively. Such results may justify a clinical trial for evaluating this ELISA for the diagnosis and monitoring of SCLC patients.