During the eukaryotic cell division cycle, the genome must be precisely duplicated with no sections left unreplicated and no sections replicated more than once. To achieve this, replication origins must be ‘licensed’ before replication starts by binding hexamers of the MCM2-7 proteins. We have shown that many cancer cells have defects in their ability to determine whether licensing has occurred properly. This makes them reliant on newly-discovered backup pathways that ensure the completion of DNA replication (Moreno et al, 2016). It also provides an opportunity for selective killing of cancer cells by inhibiting replication licensing, and we have recently described the first small molecule inhibitors to exploit this (Gardner et al, 2017). The proposed PhD project will involve the improvement of these inhibitors, enhancing their ability to inhibit licensing whilst minimising their off-target side effects. We will use these in chemical biology approaches to probe the licensing checkpoint and to better understand how normal and cancer cells respond to licensing inhibition. These experiments could help provide an entirely new anti-cancer strategy that selectively kills cancer cells whilst leaving normal cells unharmed. The project will involve both biochemical approaches (such as immunoblotting and immunoprecipitation, use of recombinant proteins and small molecule inhibitor assays) and cell biological approaches (such as cell culture, immunofluorescence, FACS, siRNA, CRISPR/CAS).
Recent relevant papers:
Gardner et al, 2017. The high-affinity interaction between ORC and DNA that is required for replication licensing is inhibited by 2-Arylquinolin-4-amines. Cell Chem Biol 24, 981–992.
Moreno et al, 2016. Unreplicated DNA remaining from unperturbed S phases passes through mitosis for resolution in daughter cells. Proc Natl Acad Sci USA 113, E5757-64.