Pancreatic cancer is associated with high mortality, and pancreatic ductal adenocarcinoma (PDAC) is its most common subtype. The rapid growth of PDAC is dependent on the non-canonical pathway of glutamine (GIn) utilization, and loss of heterozygosity for Kras(G12D) (Kras(G12D)-LOH) frequently observed in PDAC is associated with an aggressive and invasive phenotype. However, it remains unclear whether Kras(G12D)-LOH contributes to non-canonical GIn metabolism in PDAC. Here, we showed that Kras(G12D)-LOH leads to a substantial increase in non-canonical Gln metabolism in PDAC cells. Importantly, we observed elevated expression of regulated in DNA damage and development 1 (REDD1), which is activated in response to hypoxia and nutrient deprivation, in Kras(G12D)-LOH PDAC, and that REDD1 knockdown efficiently repressed Kras(G12D)-LOH-regulated GIn metabolism and suppressed proliferation, migration, and invasion of Kras(G12D)-LOH PDAC cells. These data provide evidence that REDD1 is a downstream target of Kras(G12D)-LOH and is involved in promoting non-canonical GIn metabolism in PDAC. (C) 2020 The Authors. Published by Elsevier Inc.