Peripheral Blood Mononuclear Cell Expression Profile of Proliferation-, Ferroptosis-, and Immune-Related Targets in Breast Cancer

Background and Objectives: This study evaluated eight targets related to proliferation (miR-21, miR-210, PTEN, and mTOR), ferroptosis regulation (SLC7A11, GPX4, and miR-214), and immune regulation (STAT3) in bulk (unfractionated) peripheral blood mononuclear cells (PBMCs) from patients with breast cancer. Their exploratory discriminative performance and associations with clinicopathological characteristics, including immunohistochemical parameters, were also examined. Materials and Methods: Target expression was quantified by qRT-PCR in PBMCs from 41 patients with histopathologically confirmed breast cancer and 30 healthy controls. Immunohistochemistry-defined surrogate subtypes (hereafter, IHC-defined subtypes) were assigned according to ER, PR, HER2 and Ki-67 status. Between-group comparisons were performed using the independent-samples t-test or the Mann–Whitney U test; multiple comparisons were corrected using the Benjamini–Hochberg false discovery rate (BH-FDR) method. Exploratory discriminative performance was determined by ROC analysis with 2000-iteration bootstrap confidence intervals. Directional consistency was examined in two independent PBMC GEO datasets (GSE27562, GSE47862); this was a directional comparison rather than formal external validation.