Development of G9a-targeted BioPROTACs based on peptides and nanobodies

Abstract

This project arose motivated by the high incidence that neoplastic pathologies have nowadays, and therefore by the need that our society has to find a solution against them. The main objective of this research was to identify specific peptides and nanobodies against G9a methyltransferase, whose role in cancer is to introduce epigenetic modifications to silence tumor suppressor genes. The strategy followed focuses on degrading this enzyme through the Biological Proteolysis Targeting Chimera (BioPROTAC) system, made up of either the aforementioned peptides or nanobodies. A search for these specific molecules was carried out using phage display, to find the most specific candidates against the previously produced and purified G9a. Later, the binding affinity of the selected clones was evaluated, the BioPROTAC construct was designed, and immunocytochemistry (ICQ) was performed to check their cellular internalization. In short, it was possible to select 3 peptide clones and 16 nanobodies with a good affinity for G9a, in addition to designing a system capable of being introduced into the tumor cell. This represents a project of Targeted Protein Degradation (TPD) for drug discovery with its main objectives met. Furthermore, this study will facilitate future investigations aimed at confirming the efficacy of the system to degrade the enzyme, in order to conduct additional testing of its therapeutic effect.