The HDL particle composition determines its anti-tumor activity in pancreatic cancer
Despite significant efforts in the last years to improve therapeutic options, pancreatic cancer remains a fatal disease and is expected to become the second leading cause of cancer-related deaths in the next decade. Late diagnosis and a complex, fibrotic tumor microenvironment produces a therapeutically hardly approachable situation with rapidly emerging resistance mechanisms. In response to this hostile microenvironment, previous research identified lipid metabolic pathways to be highly enriched in pancreatic ductal adenocarcinoma (PDAC) cells. Thereby, cholesterol uptake and synthesis was shown to promote a growth advantage to, and chemotherapy resistance for PDAC tumor cells. Here, we demonstrate that efficient, net-cholesterol removal from cancer cells, driven by high-density lipoprotein (HDL) mediated efflux, results in a significant PDAC cell growth reduction, apoptosis and a decreased PDAC tumor development in vivo. This effect is driven by an HDL particle composition-dependent interaction with SR-B1 and ABCA1 on cancer cells, two major lipid flux receptors, which differentially regulate cholesterol transport at the plasma membrane. Eventually, we show that pancreatic cancer patients display reduced plasma levels of HDL-cholesterol, directly translating into a reduced cholesterol efflux capacity of patient-derived plasma samples. We conclude that cholesterol depletion from PDAC cells, together with possible interventions that shunt the import and endogenous synthesis pathways of cholesterol, might represent a promising strategy to increase and complement the currently available treatment options to improve the prognosis of patients suffering from PDAC.