ELLIPSIS · Genetic lethal interactions in replication licensing-defective cancer cells

Genetic lethal interactions, which describe the lethal effect of combined perturbations in two or more genetic factors whilst individually have no effect, have emerged as a significant topic in the field of targeted cancer therapy. Despite their promising performance in clinic, current genetic lethality-based therapies focus mainly on digenic interactions restricting the size recipient patients. Complex genetic interactions that involve deregulation of innate mechanisms or cellular responses offer an alternative approach in the development of anti-cancer therapy. Impaired licensing of DNA replication represents a common feature of cancer cells fuelling genomic instability. Cancer cells manage to proliferate and expand under conditions of impaired licensing suggesting that have acquired special mechanisms that are not present in normal cells. Here, my aim is to unveil genetic interactions that induce lethality by investigating the mechanisms that enable the survival of licensing-defective cancer cells. Using colorectal cancer as a model, I will first identify the genes that are overexpressed in tumour cells that exhibit licensing defects. Secondly, I will interrogate the consequences of genes inactivation in the survival of cells by employing a CRISPR/Cas9 screen in a cell system of inducible licensing defects by the overexpression of the licensing factor Cdt1. Finally, the identified hits will be validated through functional experiments in cell systems and model organisms to establish their lethal effect. Our results will identify novel factors that upon inhibition induce the selective cell death of cancer cells and we anticipate that they will be attractive targets for future studies on drug design and development.