Analysis of changes in the phenotypic profile and frequencies of peripheral blood myeloid-derived suppressor cells in patients with endometrial cancer before and after surgical treatment.

Endometrial cancer (EC) is one of the most frequent gynecologic cancers worldwide. Therapeutic interventions, including surgery, are known to alter immune cell populations and the tumor microenvironment. Among these, Myeloid-derived suppressor cells (MDSC), a heterogeneous population of immature myeloid cells with potent immunosuppressive activity, play an important role in cancer progression. The present study analyzed the frequencies of monocytic MDSC (M-MDSC), early-stage MDSC (e-MDSC), and polymorphonuclear (PMN-MDSC) subsets in PBMC using flow cytometry and quantified Arginase-1 serum levels by ELISA. Our results showed that M-MDSC and PMN-MDSC frequencies were increased in patients compared with healthy donors and decreased following surgery, whereas no changes were observed in e-MDSC percentages. Across MDSC subtypes, the percentages of SIRP-α-, CD73-, PD-L1-, and Galectin-9-positive cells were higher in pre- and post-surgery EC samples than in healthy donors. Notably, in the case of Galectin-9, M-MDSC and PMN-MDSC positive to this receptor were increased before surgery and decreased after surgery, parallel to the changes in M-MDSC and PMN-MDSC frequencies, suggesting a possible role for Galectin-9 in MDSC proliferation. Arginase-1 serum levels also decreased after surgery. In conclusion, our results demonstrate that endometrial cancer patients exhibit differential percentages of MDSC and receptor expression, which are influenced by surgical intervention. It is important to highlight Galectin-9 expression, as it may have a postoperative prognostic role. Future studies are warranted to clarify the prognostic utility of these molecules in endometrial cancer patients.