Résumé
Early detection is key to reduce the burden of cancer on human life. More specifically, ovarian cancer is the deadliest gynaecological cancer as most patients are diagnosed at a late stage, where survival rate drops below 40%. This survival rate could potentially be improved with a non-invasive, early stage detection. Towards this end, we selected high-affinity aptamers for the detection of an ovarian cancer biomarker in urine. We targeted urine Human Epididymis protein 4 (HE4). HE4 is protein overexpressed in ovarian cancers, and a validated biomarker in serum for ROMA score (Ovarian Malignancy Risk Algorithm) and in recurring ovarian cancers. The selection for high-affinity aptamers against HE4 was performed in artificial urine, using a modified version of Hi-Fi SELEX (High-Fidelity SELEX Systematic Evolution of Ligands by EXponential enrichment) using digital droplet PCR (Polymerase Chain Reaction).Next-Generation Sequencing and bioinformatics analysis were carried out to identify potential HE4 binders. The interactions between the target HE4 and several aptamers were characterized in artificial urine. We successfully identified HE4-binding aptamers in urine. These sequences perform with higher affinity and specificity in urine that previously published sequences in the literature. The potential of urine-selected aptamers was investigated in the development of prospective tests such as ELONA and turbidity based assays at level relevant to HE4 concentrations in healthy and different stages (early I/II and III/IV late ) of ovarian cancer. These results are a proof of concept for the detection of HE4 in non-invasive body fluid samples. Due to their specificity and high-affinity, the selected anti-HE4 DNA aptamers offer a cheap alternative to conventional antibodies towards diagnostic tests. Therefore, they could be used as molecular probe in the development of biosensors or Point-of-care testing (POCT) diagnostic devices for ovarian cancers early detection.