The clinical potential of miRNA-based liquid biopsy has been largely limited by the heterogeneous sources in plasma and tedious assay processes. Researchers at Shanghai Jiao Tong University have developed a precise and robust one-pot assay called dual-surface-protein-guided orthogonal recognition of tumor-derived exosomes and in situ profiling of microRNAs (SORTER) to detect tumor-derived exosomal miRNAs and enhance the diagnostic accuracy of prostate cancer (PCa). The SORTER uses two allosteric aptamers against exosomal marker CD63 and tumor marker EpCAM to create an orthogonal labeling barcode and achieve selective sorting of tumor-specific exosome subtypes. Furthermore, the labeled barcode on tumor-derived exosomes initiated targeted membrane fusion with liposome probes to import miRNA detection reagents, enabling in situ sensitive profiling of tumor-derived exosomal miRNAs. With a signature of six miRNAs, SORTER differentiated PCa and benign prostatic hyperplasia with an accuracy of 100%. Notably, the diagnostic accuracy reached 90.6% in the classification of metastatic and nonmetastatic PCa. The researchers envision that the SORTER will promote the clinical adaptability of miRNA-based liquid biopsy.
Schematic illustration of SORTER assay for miRNA profiling of tumor-derived exosomes
(A) The assay workflow consists of three parts. (I) Clinical plasma samples (0.2 μl, 100-fold dilution) were collected from age-matched PCa patients and BPH controls. Exosomes, ectosomes, and free molecules produced by tumor and normal cells coexist in plasma samples and exhibit overlapping compositional features. (II) SORTER assessment of miRNA profiles in tumor-derived exosomes. The SORTER assay is designed to achieve specific recognition and sorting of tumor-derived exosome subtypes and in situ sensitive probing of tumor-derived exosomal miRNA profiles. (III) Data processing and bioinformatic analysis for cancer diagnosis. The linear discriminant analysis (LDA) algorithm is used to identify the best combinations of miRNAs to classify patients with PCa from BPH controls, and the LDA model then evaluates the predicted results. (B) SORTER incorporates multiple parallel processes, including exosome recognition, importing probes, and miRNA profiling, permitting a sensitive and robust one-pot tumor-derived exosomal miRNA assay. (I) Dual-surface-protein-guided orthogonal recognition barcode for the selective labeling of tumor-derived exosomes. (II) Importation of miRNA detection probes into tumor-derived exosomes. (III) In situ sensitive profiling of miRNAs inside tumor-derived exosomes.