Impairment of Cytoplasmic eIF6 Activity Restricts Lymphomagenesis and Tumor Progression without Affecting Normal Growth

SummaryEukaryotic Initiation Factor 6 (eIF6) controls translation by regulating 80S subunit formation. eIF6 is overexpressed in tumors. Here, we demonstrate that eIF6 inactivation delays tumorigenesis and reduces tumor growth in vivo. eIF6+/− mice resist to Myc-induced lymphomagenesis and have prolonged tumor-free survival and reduced tumor growth. eIF6+/− mice are also protected by p53 loss. Myc-driven lymphomas contain PKCβII and phosphorylated eIF6; eIF6 is phosphorylated by tumor-derived PKCβII, but not by the eIF4F activator mTORC1. Mutation of PKCβII phosphosite of eIF6 reduces tumor growth. Thus, eIF6 is a rate-limiting controller of initiation of translation, able to affect tumorigenesis and tumor growth. Modulation of eIF6 activity, independent from eIF4F complex, may lead to a therapeutical avenue in tumor therapy.

► eIF6 is rate limiting for Myc-induced lymphomagenesis and tumor growth ► eIF6 phosphorylation is mTOR independent and PKC dependent ► Cells with eIF6S235A overexpression transform in vitro, but do not grow in vivo ► eIF6 is a potential mTOR-independent translational target for cancer therapy