ABSTRACT
Activated cap-dependent translation promotes cancer by stimulating translation of mRNAs encoding malignancy-promoting proteins. The nucleoside monophosphate Protide, 4Ei-10, undergoes intracellular uptake and conversion by Hint1 to form 7-Cl-Ph-Ethyl-GMP. 7-Cl-Ph-Ethyl-GMP is an analog of cap and inhibits protein translation by binding and sequestering eIF4E thus blocking eIF4E from binding to the mRNA cap. The effects of inhibiting translation initiation by disruption of the eIF4F complex with 4Ei-10 were examined in malignant mesothelioma (MM). In a cell-free assay system, formation of the eIF4F complex was disabled in response to exposure to 4Ei-10. Treatment of MM with 4Ei-10 resulted in decreased cell proliferation, increased sensitivity to pemetrexed and altered expression of malignancy-related proteins. In light of these findings, suppression of translation initiation by small molecule inhibitors like 4Ei-10 alone or in combination with pemetrexed represents an encouraging strategy meriting further evaluation in the treatment of MM.
Subject(s)
Antineoplastic Agents/pharmacology , Carcinogenesis/genetics , Cell Proliferation/drug effects , Cell Proliferation/genetics , Lung Neoplasms/drug therapy , Lung Neoplasms/genetics , Mesothelioma/drug therapy , Mesothelioma/genetics , Carcinogenesis/drug effects , Cell Line, Tumor , Eukaryotic Initiation Factor-4F/genetics , Humans , Mesothelioma, Malignant , Pemetrexed/pharmacology , RNA, Messenger/genetics , Small Molecule Libraries/pharmacologyABSTRACT
Deranged cap-mediated translation is implicated in the genesis, maintenance and progression of many human cancers including mesothelioma. In this study, disrupting the eIF4F complex by antagonizing the eIF4E-mRNA-cap interaction is assessed as a therapy for mesothelioma. Mesothelioma cells were treated with 4Ei-1, a membrane permeable prodrug that when converted to the active drug, 7-benzyl guanosine monophosphate (7Bn-GMP) displaces capped mRNAs from the eIF4F complex. Colony formation was measured in mesothelioma treated with 4Ei-1 alone or combined with pemetrexed. Proliferation was examined in cells treated with 4Ei-1. Binding to a synthetic cap-analogue was used to study the strength of eIF4F complex activation in lysates exposed to 4Ei-1. 4Ei-1 treatment resulted in a dose dependent decrease in colony formation and cell viability. Combination therapy of 4Ei-1 with pemetrexed further reduced colony number. Formation of eIF4F cap-complex decreased in response to 4Ei-1 exposure. 4Ei-1 is a novel prodrug that reduces proliferation, represses colony formation, diminishes association of eIF4F with the mRNA cap, and sensitizes mesothelioma cells to pemetrexed.
