Metabolic Dysfunction of Adipocytes Promotes the Secretion of Inflammatory TGFβ with Pro-Migratory Activity in Pancreatic Cancer

Visceral fat mass is associated with a condition of chronic inflammation and can predispose the overweight to an increased cancer risk. Although it is known that adipocytes are active producers of the pro-inflammatory transforming growth factor β (TGFβ), the causes of their excessive synthesis are not clear. In this study, we reproduced two metabolic stress conditions frequently occurring in vivo, namely hypoxia and the fatty acid-driven metabolic uncoupling, and we characterized the response of an in vitro model of 3T3-L1 mouse adipocytes. For the first time, we demonstrated that the mitochondrial dysmetabolism of differentiated adipocytes induced the secretion of TGFβ. The paracrine activity of the secreted cytokine was then tested on two human pancreatic cancer cell lines. Cancer cells responded to the stimulation by increasing mitochondrial respiration, switching on the epithelial–mesenchymal transition (EMT) program and enhancing their motility. The data obtained in this proof-of-concept research show that TGFβ can be produced by dysmetabolic adipocytes, linking the altered metabolism with pro-tumorigenic inflammation. The novel observations of this study identify in metabolic stress a still unexplored cause of inflammation and cancer progression and pave the way to more detailed in vitro and clinical studies on pancreatic cancer.