Molecular inhibitors of DNA repair: searching for the ultimate tumor killing weapon

DNA repair (DR) inhibitors are small molecules that interact with DR proteins in order to disrupt their function and induce a strike' to the high fidelity of the mammalian DNA repair systems. Many anticancer therapies aim to harm the DNA of the usually highly proliferative cancer cell, causing it to undergo apoptosis. In response to this, cancer cells attempt to fix the induced lesion and reconstitute its genomic integrity, in turn reducing the efficacy of treatment. To overcome this, DR inhibitors suppress DNA repair proteins' function, increasing the potency and tumor killing effect of chemotherapy or radiotherapy. In this review, we discuss clinically applied novel inhibitors under translational investigation and we apply bioinformatic tools in order to identify repair proteins implicated in more than two phenomenically distinct DNA repair pathways (e.g., base excision repair and nonhomologous end joining), that is, the concept of synthetic lethality'. Our study can aid towards the optimization of this therapeutic strategy and, therefore, maximizing treatment effectiveness like in the case of radiation therapy.