Interaction between DNA Polymerase theta inhibition and cGAS/STING activation
Second supervisor: Dr Gonzalo Rodriguez-Berriguete
Emerging evidence suggests that the therapeutic effect of radiotherapy is at least partly dependent upon the induction of an anti-tumour immune response. This response is initiated with the sensing of cytoplasmic DNA by the cGAS/STING pathway and the subsequent induction of Type I interferon (IFN) production by tumour cells. Then, the radiation-induced IFN secreted in the tumour microenvironment stimulates dendritic cell priming and subsequent CD8+ T cell-mediated anti-tumour immunity. We have previously demonstrated that inhibition of DNA Polymerase theta (PolQ), a protein involved in the repair of DNA double strand breaks (DBS), is a feasible strategy to specifically sensitise tumour cells to radiotherapy. Interestingly, PolQ inhibition also potentiates the formation of cytosolic DNA (micronuclei) after irradiation. It has been shown that PolQ inhibition increases micronuclei formation and IFN production specifically in unirradiated cells with BRCA mutations, rendering them more susceptible to immunotherapy. However, little is known about the genetic factors that determine the induction of IFN by PolQ inhibition when combined with radiotherapy. The discovery of such factors may enable the identification of patients more likely to respond to PolQ inhibition and radiotherapy, and who could be eligible for combined immunotherapy treatment. The DPhil candidate will carry out a high-throughput screen to identify genetic mutations that influence irradiation-induced IFN production after the repair of DSBs upon PolQ inhibition. The DPhil candidate will also investigate the mechanism of action by which the genes identified through the screen modulate the induction of the IFN response by PolQ and radiotherapy. To that end, the candidate will employ several molecular and cell biology techniques, including cell cultures, Western blot, high-content fluorescence microscopy, qPCR, flow cytometry, cell signalling assays or cell cycle analysis, amongst others. Furthermore, the student will validate the therapeutic relevance of their findings in in vivo models of cancer and by analysing publicly available patient datasets.
The student will be trained in high throughput screening approaches and hit identification. Specific molecular and cell biology techniques will include, cell culture, Western blot, high-content fluorescence microscopy, qPCR, flow cytometry, cell signalling assays or cell cycle analysis, and the potential to undertake relevant in vivo studies.
Oh, G., Wang, A., Wang, L., Li, J., Werba, G., Weissinger, D., Zhao, E., Dhara, S., Hernandez, R.E., Ackermann, A. and Porcella, S., 2023. POLQ inhibition elicits an immune response in homologous recombination–deficient pancreatic adenocarcinoma via cGAS/STING signaling. The Journal of Clinical Investigation, 133(11).
Rodriguez-Berriguete, G., Ranzani, M., Prevo, R., Puliyadi, R., Machado, N., Bolland, H.R., Millar, V., Ebner, D., Boursier, M., Cerutti, A. and Cicconi, A., 2023. Small-molecule Polθ inhibitors provide safe and effective tumor radiosensitization in preclinical models. Clinical Cancer Research, 29(8), pp.1631-1642.