Translation is an essential cellular process whose deregulation is associated with alterations in cell growth, cell cycle progression, and cell death responses. The initiation phase of translation is a key target for regulation when cells are exposed to various environmental cues (e.g. - insulin, amino acid starvation, mitogenic stimulation, hypoxia, etc). As well, this process is deregulated in many human cancers. Over-expression of certain translation factors can lead to malignant transformation and many of the components of the translational apparatus are over-expressed in human cancers. Several tumor suppressor genes directly influence the translation process and recently, chemoresistance in vivo has been linked to deregulated translation initiation. In a transformed setting, where translation can be inhibited by a small molecule modulator (e.g. rapamycin), decreased translation rates are associated with reversal of chemoresistance, possibly by inhibition of (a) pro-survival or resetting of (a) pro-apoptotic program(s). These results validate translation initiation, and in particular eIF4F, a heterotrimeric complex involved in the ribosome/mRNA recruitment phase, as a potential chemotherapeutic target.
The Specific Aims of the current application are to implement a High Throughput Screen (HTS) at the MLSCN in order to identify small molecules that alter eIF4F complex integrity, by disrupting the association between two of its subunits, eIF4E and eIF4G. Following the initial identification of compounds that show activity in the HTS assay, false-positives will be identified and eliminated using a counterscreen designed to identify non-specific effects of compounds on the TR-FRET assay or on protein-protein interaction (for example, denaturants or chemically reactive compounds). The activity of compounds that are not eliminated in the counterscreen will then be confirmed in a secondary assay that monitors the interaction between eIF4E and eIF4G, but utilizes a different readout. Follow-up studies with optimized compounds will be performed to characterize their biological properties in vitro and in vivo. Should any of the optimized hits show activity in vivo, relative cytotoxicities will be determined in lymphomas of defined genotypes generated from a mechanism-based mouse cancer model. ? ? ?
| Cencic, Regina; Desforges, Marc; Hall, David R et al. (2011) Blocking eIF4E-eIF4G interaction as a strategy to impair coronavirus replication. J Virol 85:6381-9 |
| Cencic, Regina; Hall, David R; Robert, Francis et al. (2011) Reversing chemoresistance by small molecule inhibition of the translation initiation complex eIF4F. Proc Natl Acad Sci U S A 108:1046-51 |
