Pathways to implementation of serum proteomics for cancer.

Proteomic and genomic technologies have been developed that can simultaneously detect large panels of cancer biomarkers in body fluids such as serum, plasma, sputum, saliva or urine. These approaches provide great promise for the early detection of cancer, but have thrust the field into the era of diagnostic multianalyte-based cancer tests with few, if any, models for the implementation of such tests. These multianalyte tests may be based on the detection of serum antibodies to tumor antigens, the presence of cancer-related proteins in serum or the presence of tumor-specific genomic changes that appear in plasma as free DNA. The application of noninvasive diagnostic approaches to detect early stage cancer will provide the physician with greater presymptomatic periods for clinical intervention, but it is uncertain how the various forces will impact their implementation in a patient care setting. Utilization will be balanced by medical follow-up pathways, commercial/reimbursement factors and regulatory issues that influence implementation of new devices in the marketplace.

Quantification of 20-hydroxyeicosatetraenoic acid by colorimetric competitive enzyme linked immunosorbent assay.

Analysis of 20-hydroxyeicosatetraenoic acid (20-HETE), a potent vasoconstrictor produced by the cytochrome P450 pathway, presently requires high-performance liquid chromatography (HPLC) and gas chromatography/ mass spectrometry (GC/MS). To simplify 20-HETE analysis, competitive ELISAs were developed using polyclonal anti-20-HETE coated ELISA plates to which free 20-HETE and 20-HETE conjugated to horseradish peroxidase (HRP) or alkaline phosphatase (AP) were added. Assays were developed with and without a pro prietary enhancer solution which allows for the extraction-free measurement of 20-HETE in urine samples. The bound 20-HETE-HRP or 20-HETE-AP was detected using 3,3 ,5,5, -tetramethylbenzidine and p-nitrophenyl phosphate, respectively. Sensitivities expressed as 80% B/B0, were 0.1 ng/ml for the HRP assay, and 0 5 ng/ml for the AP assay, with r2 = 0 99 for both formats. Of the 17 lipids tested for cross-reactivity, arachidonic acid showed the highest (0.32%) followed by racemic 5-HETE (0.07%) and 8,9-dihydroxyeicosatrienoic acid (DHET) (0.04%). Preliminary validation experiments examining serum and urine concentrations of 20-HETE yield values that fall within the ranges established by GC/MS in the literature. These ELISAs provide simple and inexpensive methods for the analysis of 20-HETE in biological samples.