Cap-dependent translation blockade and fixed dose-rate gemcitabine: Interaction in an in vitro bioreactor system

Translation initiation commences with the binding of eIF-4F to the mRNA 5′-end cap. eIF-4F binds the cap structure via its eIF-4E subunit, which is the rate-limiting step for the initiation of translation. This pathway can be inhibited by 4E-binding proteins (4E-BPs). The present study investigated prolonged gemcitabine infusion in combination with reduced eIF-4E function on NSCLC cell viability in an in vitro bioreactor system. To assess attachment to the hollow fibers, cells with dominant active 4E-BP1 were first analyzed by scanning electron microscopy. Cells were treated with 0.5- or 2.5 h (fixed dose rate) infusion (same total dose), simulating human plasma gemcitabine concentration-time profiles. An interaction was observed between fixed dose rate infusion gemcitabine and presence of dominant active 4E-BP1. We conclude that cap-dependent translation blockade and fixed dose rate infusion gemcitabine treatment results in a significant interaction affecting cell viability in vitro.