Obesity is an established risk factor for pancreatic ductal
adenocarcinoma (PDA). Despite recent identification of metabolic alterations in this lethal
malignancy, the metabolic dependencies of
obesity-associated PDA remain unknown. Here we show that
obesity-driven PDA exhibits accelerated growth and a striking transcriptional enrichment for pathways regulating
nitrogen metabolism. We find that the mitochondrial form of
arginase (ARG2), which hydrolyzes
arginine into
ornithine and
urea, is induced upon
obesity, and silencing or loss of ARG2 markedly suppresses PDA. In vivo infusion of 15N-glutamine in obese mouse models of PDA demonstrates enhanced
nitrogen flux into the
urea cycle and infusion of 15N-arginine shows that Arg2 loss causes significant
ammonia accumulation that results from the shunting of
arginine catabolism into alternative
nitrogen repositories. Furthermore, analysis of PDA patient
tumors indicates that ARG2 levels correlate with body mass index (BMI). The specific dependency of PDA on ARG2 rather than the principal hepatic
enzyme ARG1 opens a therapeutic window for
obesity-associated
pancreatic cancer.Obesity is an established risk factor for pancreatic ductal
adenocarcinoma (PDA). Here the authors show that
obesity induces the expression of the mitochondrial form of
arginase ARG2 in PDA and that ARG2 silencing or loss results in
ammonia accumulation and suppression of
obesity-driven PDA
tumor growth.