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Inhibition of mammalian cell proliferation by genetically selected peptide aptamers that functionally antagonize E2F
E Fabbrizio1, L Le Cam, J Polanowska
1Institut de Génétique Moléculaire, UMR 5535 CNRS, Montpellier, France.
Abstract:
The p16-cyclin D-pRB-E2F pathway is frequently deregulated in human tumors. This critical regulatory pathway controls the G1/S transition of the mammalian cell cycle by positive and negative regulation of E2F-responsive genes required for DNA replication. To assess the value of the transcription factors E2Fs as targets for antiproliferative strategies, we have initiated a program aiming to develop inhibitors targeting specifically these proteins in vitro and in vivo. The cellular activity of E2F is the result of the heterodimeric association of two families of proteins, E2Fs and DPs, which then bind DNA. Here, we use a two hybrid approach to isolate from combinatorial libraries peptide aptamers that specifically interact with E2Fs DNA binding and dimerization domains. One of these is a potent inhibitor of E2F binding activity in vitro and in mammalian fibroblasts, blocks cells in G1, and the free variable region from this aptamer has the same effect. Our experiments argue that the variable region of this aptamer is structured, and that it functions by binding E2F with a motif that resembles a DP heterodimerization region, and blocking E2F's association with DP. These results show that cell proliferation can be inhibited using genetically-selected synthetic peptides that specifically target protein-protein interaction motifs within cell cycle regulators. These results also emphasize the critical role of the E2F pathway for cell proliferation and might allow the design of novel antiproliferative agents targeting the cyclin/CDK-pRB-E2F pathway.
Insights
Researchers developed peptide aptamers to inhibit the E2F transcription factor, a key regulator of cell cycle progression. This targeted inhibition effectively blocks cell proliferation, offering a potential new strategy for cancer therapy.
Area of Science:
- Molecular Biology
- Cell Cycle Regulation
- Cancer Biology
Background:
- The p16-cyclin D-pRB-E2F pathway is crucial for controlling the cell cycle's G1/S transition.
- Deregulation of this pathway is common in human tumors.
- E2F transcription factors are essential for DNA replication and cell proliferation.
Purpose of the Study:
- To develop novel antiproliferative strategies by targeting E2F transcription factors.
- To identify specific inhibitors of E2F DNA binding and dimerization activities.
- To assess the therapeutic potential of inhibiting the E2F pathway.
Main Methods:
- Utilized a yeast two-hybrid approach to screen combinatorial libraries for peptide aptamers.
- Isolated peptide aptamers that specifically interact with E2F DNA binding and dimerization domains.
- Tested aptamer efficacy in vitro and in mammalian fibroblasts to assess cell cycle effects.
Main Results:
- Identified a potent peptide aptamer that inhibits E2F binding activity.
- Demonstrated that this aptamer blocks mammalian fibroblasts in the G1 phase of the cell cycle.
- The aptamer's variable region, structured to mimic a DP heterodimerization motif, inhibits E2F-DP association.
Conclusions:
- Genetically-selected synthetic peptides can inhibit cell proliferation by targeting protein-protein interactions in cell cycle regulators.
- The E2F pathway plays a critical role in cell proliferation.
- These findings support the development of novel antiproliferative agents targeting the cyclin/CDK-pRB-E2F pathway for cancer treatment.