Comparative proteomics identify HSP90A, STIP1 and TAGLN-2 in serum extracellular vesicles as potential circulating biomarkers for human adenomyosis

Extracellular vesicles (EVs) carry specific proteins involved in intercellular communication. EVs with different protein contents are released into circulation in different diseases. Recent studies have identified proteins in adenomyosis (AM)-derived EVs (AMEVs) from blood as biomarkers for this disease. AM is an extension of endometrial tissue into the uterine myometrium. Magnetic resonance imaging (MRI) is the most accurate imaging tool for identifying adenomyosis. Therefore, the present study aimed to investigate the role of EVs in diagnosing AM. In the present study, tissue AMEVs (T-AMEVs) were isolated from lesion homogenates of patients with adenomyosis, and blood AMEVs (B-AMEVs) were isolated from peripheral blood of patients with AM via differential centrifugation and density gradient centrifugation. T-AMEVs and B-AMEVs were characterized by electron microscopy, western blotting and mass spectrometry and analysed using FunRich3.1.3 software. T-AMEVs (average diameter, 150.9 +/- 102.2 nm) and B-AMEVs (194.1 +/- 66.81 nm) expressed the CD9, CD63 and flotillin-2 EV markers. A total of 211 proteins expressed in T-AMEVs and B-AMEVs overlapped with Vesiclepedia database entries, including 2 epithelial-to-mesenchymal transition (EMT)-associated proteins and 6 invasion-associated proteins. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that these 211 proteins were associated with the 'regulation of cell morphogenesis' and 'cytoskeletal organization' terms, as well as the PPAR and HIF-1 signalling pathways, which are related to the proliferation and metastasis of endometrial cells that cannot invade the myometrium under normal circumstances. Among the 211 proteins, HSP90A, STIP1 and TAGLN-2 were expressed in T-AMEVs and B-AMEVs, but not in serum EVs of women without adenomyosis/endometriosis, and these proteins might be the potential biomarkers for adenomyosis. These findings provide insights into the molecular features of adenomyosis and the new candidate biomarkers for diagnosis.