Changes induced by oxidized low-density lipoprotein on prostate stromal cells derived from patients with benign prostatic hyperplasia

Abstract

Abstract: 

Benign Prostatic Hyperplasia (BPH) is a pathology that affects elderly men, being the result of an excessive and uncontrolled cellular proliferative process of both epithelial and stromal prostatic compartments. Novel evidence suggests that dyslipidemias and other factors of the Metabolic Syndrome are associated to BPH progression and aggressiveness. However, little information is available about the pathogenic mechanisms promoting prostatic growth in atherogenic contexts. We, therefore, aimed to analyze in vitro the effects of oxidized low-density lipoprotein (OxLDL) on primary cell cultures. Prostatic stromal cells, surgically harvested from patients with BPH (n=3), were isolated, cultured, and stimulated with OxLDL (20 μM or 100 μM, simulating an atherogenic state) or vehicle for 24 h and 48 h. In this context, OxLDL induced cell proliferation, as assessed by BrdU incorporation and Ki67 immunocytochemistry, mainly at lower concentrations and in a time-dependent manner (p<0.001 vs. vehicle). OxLDL-treated cells also displayed a myofibroblastic phenotype with high metabolic activity, characterized by an increase of cytoplasmic granules, dilated endoplasmic reticulum, and the presence of prominent nucleoli, as evaluated by transmission electron microscopy (TEM). Furthermore, the release and characterization of Extracellular Vesicles (EVs) were determined in supernatants, which were isolated by ultracentrifugation steps and observed by TEM using negative staining. BPH-derived stromal cells showed a very low frequency of secreted EVs, with OxLDL inducing a 10-fold increase, especially in a fraction of 15-20 nm (p<0.001). At ultrastructural level, these vesicles exhibited an artificial concave shape appearance, compatible with exosomes. Taken together, these findings indicate that OxLDL promotes cell proliferation, stimulation, and EVs release in BPH stromal cells, pointing OxLDL as a strong pathogenic factor in atherogenic contexts supporting uncontrolled prostatic growth.