Quiescin sulfhydryl oxidase1 (QSOX1) is a sulfhydryl oxidase that is overexpressed in several malignancies and as such is a potential biomarker for multiple cancer types as well as acute decompensated heart failure (ADHF). Since its discovery, QSOX1 has been identified as a key player in the facilitation of tumor cell migration, creating a significant potential for use as a prognostic indicator of metastasis. There are two major forms of QSOX1, a short isoform that is 604 amino acids and a long isoform that is 747 amino acids. The differentiation of the two major isoforms may prove useful in distinguishing various disease states, aiding in the development of advanced treatment strategies. However, to reach its full potential, mechanisms for detecting and distinguishing QSOX1 and its isoforms are needed.
Researchers at Arizona State University and Mayo Clinic have developed tandem antigen capture ELISAs for the quantification of both short and long isoforms of QSOX1 in serum and plasma samples. Three distinct anti-QSOX1 monoclonal antibodies (mAbs), 2F1, 3A10, and 56-3, were generated to accurately measure the levels of QSOX1 across a wide range of donor sera and plasma. By pairing 56-3 with 2F1, the long isoform of QSOX1 can be detected. Total QSOX1 can be detected using 2F1 paired with 3A10. Then the levels of the long isoform of QSOX1 can be subtracted from the total QSOX1 to provide levels of the short isoform of QSOX1. These assays could serve as a valuable diagnostic tool for physicians in oncology and cardiology.
Because of their high sensitivity and ability to distinguish and quantify the two different QSOX1 isoforms, these tandem antigen capture ELISAs could prove highly useful as clinically relevant quantitative assays in detecting cancer or ADHF.
Potential Applications
- Diagnostic, prognostic or monitoring tool for oncologists and cardiologists
- Drug screening
- Quantification of both short and long isoforms of QSOX1
- QSOX1 biomarker studies
Benefits and Advantages
- Quantitative and accurate
- Successful detection of QSOX1-L in both serum and plasma samples
- Detection of QSOX1 at a wide range of concentrations
- Only assay for detecting the long isoform of QSOX1
- The mAb 56-3 can discriminate the long from the short QSOX1 isoform
- This ELISA is unaffected by H2O2 or free thiols in serum or plasma, compared to commercially available kits
- Despite its transmembrane domain, intact QSOX1-L was successfully detected in both serum and plasma samples
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