Pancreatic ductal adenocarcinoma (PDAC) relies on hyperactivated protein synthesis. Consistently, human and mouse PDAC lose expression of the translational repressor and mTOR target 4E-BP1. Using genome-wide polysome profiling, we here explore mRNAs whose translational efficiencies depend on the mTOR/4E-BP1 axis in pancreatic cancer cells. We identified a functional enrichment for mRNAs encoding DNA replication and repair proteins, including RRM2 and CDC6. Consequently, 4E-BP1 depletion favors DNA repair and renders DNA replication insensitive to mTOR inhibitors, in correlation with a sustained protein expression of CDC6 and RRM2, which is inversely correlated with 4E-BP1 expression in PDAC patient samples. DNA damage and pancreatic lesions induced by an experimental pancreatitis model uncover that 4E-BP1/2–deleted mice display an increased acinar cell proliferation and a better recovery than WT animals. Targeting translation, independently of 4E-BP1 status, using eIF4A RNA helicase inhibitors (silvestrol derivatives) selectively modulates translation and limits CDC6 expression and DNA replication, leading to reduced PDAC tumor growth. In summary, 4E-BP1 expression loss during PDAC development induces selective changes in translation of mRNA encoding DNA replication and repair protein. Importantly, targeting protein synthesis by eIF4A inhibitors circumvents PDAC resistance to mTOR inhibition.
David Müller, Sauyeun Shin, Théo Goullet de Rugy, Rémi Samain, Romain Baer, Manon Strehaiano, Laia Masvidal-Sanz, Julie Guillermet-Guibert, Christine Jean, Yoshinori Tsukumo, Nahum Sonenberg, Frédéric Marion, Nicolas Guilbaud, Jean-Sébastien Hoffmann, Ola Larsson, Corinne Bousquet, Stéphane Pyronnet, Yvan Martineau
Polysome profiling allows the identification of the mTOR-dependent translatome in human pancreatic cancer cells.