preprints.org > medicine and pharmacology > reproductive medicine > doi: 10.20944/preprints202409.0368.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 4 September 2024 / Approved: 4 September 2024 / Online: 5 September 2024 (02:44:28 CEST)

The stress-inducible heat shock protein 70 (Hsp70), which functions as a molecular chaperone and is frequently overexpressed in different cancer cell types, is presented on the cell surface of tumor cells and is actively released into the circulation in free and extracellular lipid vesicle-associated forms. Since the exact pathomechanism of endometriosis has not yet been elucidated but has been associated with the development of endometrial and ovarian cancer, we asked whether extracellular Hsp70 and circulating endometriotic cells (CECs) reflects the presence and development of endometriosis. Therefore, circulating levels of free and lipid microvesicle-associated Hsp70 were measured using the Hsp70-exo ELISA, and the presence of circulating CECs in the peripheral blood of patients with endometriosis was determined using membrane Hsp70 (mHsp70) and EpCAM monoclonal antibody (mAb)-based bead isolation approaches. Isolated CECs were further characterized by immunofluorescence using reagents directed against cytokeratin (epithelial), CD45 (leukocyte), CD105/CD44 (mesenchymal-stemness) and by comparative RNA analysis. Similar to the situation in patients with cancer, levels of circulating Hsp70 were elevated in the blood of patients with histologically proven endometriosis compared to a healthy control cohort, with the highest Hsp70 level in a patient with lymph node endometriosis. Moreover, CECs could be isolated using the cmHsp70.1 mAb- and to a lesser extent EpCAM mAb-based bead approaches in all patients with endometriosis. The longevity in cell culture and the expression of cytokeratin, CD105 and CD44, together with differentially expressed genes related to EMT reveals similarities of mHsp70 expressing CECs with circulating tumor cells (CTCs) and suggest a mesenchymal-stemness origin. These findings may support the involvement of mHsp70 positive, stem cell-like cells in the development of endometriotic lesions. In summary, elevated levels of Hsp70 in the blood and CECs could serve as liquid biopsy markers for endometriosis and help to elucidate the underlying pathomechanism of the disease.

endometriosis; mesenchymal-stemness biomarker; heat shock protein 70 (Hsp70)

Medicine and Pharmacology, Reproductive Medicine

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