Unraveling the Role of Metabolic Endotoxemia in Accelerating Breast Tumor Progression

Background: Obese women have a significantly higher risk of bearing breast tumors that are resistant to therapies and are associated with poorer prognoses/treatment outcomes. Breast cancer-promoting action of obesity is often attributed to elevated levels of insulin, glucose, inflammatory mediators, and misbalanced estrogen production in adipose tissue under obese conditions. Metabolic endotoxemia, characterized by chronic presence of extremely low levels of bacterial endotoxin (lipopolysaccharide [LPS]) in the circulation, is a less explored obesity-associated factor. Results: Here, utilizing in vitro and in vivo models of breast carcinoma (BC), we report that subclinical levels of LPS typical for metabolic endotoxemia enhance the malignant phenotype of breast cancer cells and accelerate breast tumor progression. Conclusions: Our study, while focusing primarily on the direct effects of metabolic endotoxemia on breast tumor progression, also suggests that metabolic endotoxemia can contribute to obesity-breast cancer link. Thus, our findings add novel mechanistic insights into how obesity-associated metabolic changes, particularly metabolic endotoxemia, modulate the biological and clinical behavior of breast carcinoma. In turn, understanding of the mechanistic aspects underlying the association between obesity and breast cancer could help inform better strategies to reduce BC risk in an increasingly obese population and to suppress the breast cancer-promoting consequences of excess adiposity.