Anterior gradient 2 (AGR2) is an endoplasmic reticulum -resident protein belonging to the disulfide isomerase family. AGR2 contributes to protein quality control and unfolded protein response (UPR). In addition to its canonical intracellular role, AGR2 also exists in an extracellular form (eAGR2), which is strongly associated with tumour progression and cancer aggressiveness. The objective was to develop a novel approach for identifying and quantifying AGR2 from a broad range of biological fluids (cell lysates, extracellular medium, serum). Therefore, an amplified luminescent proximity homogeneous assay (EnLIGHT OMEGA ™) was established using a proximity method based on the principles of fluorescence resonance energy transfer and antigen–antibody specific binding. This method is sensitive, rapid, performed without washing, and can detect 0.02–300 ng/mL of AGR2. In conclusion, our study establishes a simple, sensitive, and rapid method for eAGR2 detection in oncology applications, including cancer drug resistance and metastatic progression.
Gosset et al. (2026) studied this question.