J Cancer 2014; 5(2):115-124. doi:10.7150/jca.8084 This issue

Research Paper

An Ultra-Sensitive Immunoassay for Quantifying Biomarkers in Breast Tumor Tissue

Carol B. Fowler1, Yan-Gao Man2, Jeffrey T. Mason1✉

1. Laboratory of Proteomics and Protein Science, Baltimore Veterans Affairs Medical Center, Baltimore, MD, USA;
2. Bon Secours Cancer Institute, Bon Secours Health System, Richmond, VA, USA.

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Fowler CB, Man YG, Mason JT. An Ultra-Sensitive Immunoassay for Quantifying Biomarkers in Breast Tumor Tissue. J Cancer 2014; 5(2):115-124. doi:10.7150/jca.8084. Available from https://www.jcancer.org/v05p0115.htm

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Urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type-1 (PAI-1) have been validated at the highest level of evidence as clinical biomarkers of prognosis in breast cancer. The American Society of Clinical Oncology recommends using uPA and PAI-1 levels in breast tumors for deciding whether patients with newly diagnosed node-negative breast cancer can forgo adjuvant chemotherapy. The sole validated method for quantifying uPA and PAI-1 levels in breast tumor tissue is a colorimetric ELISA assay that takes 3 days to complete and requires 100-300 mg of fresh or frozen tissue. In this study we describe a new assay method for quantifying PAI-1 levels in human breast tumor tissue. This assay combines pressure-cycling technology to extract PAI-1 from breast tumor tissue with a highly sensitive liposome polymerase chain reaction immunoassay for quantification of PAI-1 in the tissue extract. The new PAI-1 assay method reduced the total assay time to one day and improved assay sensitivity and dynamic range by >100, compared to ELISA.

Keywords: breast cancer, plasminogen activator inhibitor type-1, tissue biomarkers, high-pressure tissue extraction, immunoliposome-PCR, immunoassay