About the Project
Tumour growth is reliant on oxygen supply-supported within a tumour by angiogenesis and vasculogenesis. Insufficiency in these processes results in tumour hypoxia, which renders cancers more aggressive and more likely to evade immune system attacks. Immune evasion in hypoxic tumours has been linked to upregulation of immune checkpoint inhibitors such as CTLA-4 and PD-L1, secretion of immunosuppressive cytokines, and the recruitment of immunosuppressive cell types (e.g. regulatory T-cells, myeloid-derived suppressor cells, tumour associated macrophages). Most notably, tumour hypoxia renders cancers resistant to certain treatments [1]. The Sanz-Moreno lab has found that highly invasive and metastatic cancer cells with high Rho-ROCK activity are immunosuppressive [2], are responsible for both targeted therapy and immunotherapy resistance and harbour a transcriptome indicative of hypoxic signalling [3].This has led to the hypothesis that invasive and metastatic cells may be resistant to more than one type of therapy.
Half of cancer patients undergo radiotherapy treatment. Resistance to radiotherapy is particularly pronounced in hypoxic tumours with hypoxia being a negative predictive factor for response to radiotherapy due to lowering the efficacy of ionizing radiation by a factor of 2-3. Radiotherapy has been shown to increase the migratory potential of cancer cells via Rho-ROCK activation and hypoxia induction. On the other hand, radiotherapy has been shown to exert wide-spread effects on the immune system and the tumour microenvironment (TME) including effects contributing to immune evasion of cancer cells. This led to the rationale of trialling combined radiotherapy with immunotherapy [1]. However, many mechanistic aspects of the interplay between hypoxia, radio-resistance and immune evasion remain elusive as well as strategies how to best combine radio- and immunotherapy.
In this project, the student will aim to define how tumour hypoxia changes the susceptibility to radiotherapy, how persistent these effects are, and what consequences they have on the invasiveness of cancer cells and the immune compartment of such tumours.
Therefore, we will exploit a new in vivo fate-mapping approach [4] that we have modified to identify cancer cells that had experienced hypoxia at any point in their life-courses. Our approach is based on established fluorescence-radionuclide reporters5 exclusively controlled by hypoxia regulator HIF1alpha. The approach enables us to identify, spatiotemporally monitor, and subsequently isolate and analyse cancer cells that had experienced hypoxia in their respective TME and compare them to cancer cells that had not experienced hypoxia while being in the same TME. The student will apply this methodology to the radiotherapy setting with external beam irradiation and apply it to the radiation-resistant and metastatic breast cancer models. Single-cell transcriptomics of isolated cancer cells (distinguished by expression of their different fate-markers reporting on their normoxic/hypoxic pasts) will enable us for the first time to identify phenotypes of radioresistant (and likely pro-invasive) post-hypoxic cancer cells. In addition to in vitro cell biology studies, the isolation and re-establishment of syngeneic tumour models will further reveal how stable such phenotypes are in vivo and how they affect radio-resistance, local tumour spread and the immune microenvironments of such tumours. Importantly, these experiments will enable us to identify and optimize the combination of relevant radio- and immunotherapy regimens and potentially have an impact on metastatic dissemination.
This multi-disciplinary project will employ a range of different techniques including 3D cell culture, mouse tumour models, external beam radiotherapy, imaging (i.e. SPECT/PET-CT, fluorescence microscopy, immunohistochemistry), fluorescence-activated cell sorting, transcriptomics, and tissue histology.
Suitable candidates will have a minimum upper second-class degree in cell biology/biochemistry/immunology or a closely related field, a strong background in cancer biology and a passion for hypothesis-driven research.
Potential research placements
1. Whole-body imaging using radionuclide and optical reporters to enable spatiotemporal detection and monitoring of hypoxic tumour regions. Gilbert Fruhwirth, KCL.
2. Single-cell transcriptomics and associated analyses methods. Francesca Ciccarelli, The Francis Crick Institute.
3. Immunoprofiling by histology and flow cytometry, and in vitro validation in 3D models of invasive growth. Victoria Sanz-Moreno, QMUL .
For further details on how to apply please visit the CRUK CoL PhD training programme web page: https://www.colcc.ac.uk/phd-studentships/
Funding Notes
The funding for this studentship covers students with home tuition fee status only. For more information on home tuition fee status please visit the UKCISA website: https://www.ukcisa.org.uk/Information--Advice/Fees-and-Money/England-fee-status#layer-6082. Please note that we will only be able to offer studentships to candidates that have home tuition fee status or provide evidence that they can fund the international portion of the tuition fee from external sources (i.e. not self-funded).
References
1. Eckert, F. et al. Rationale for Combining Radiotherapy and Immune Checkpoint Inhibition for Patients With Hypoxic Tumors. Front Immunol. 10: 407. doi: 10.3389/fimmu.2019.00407 (2019)
2. Georgouli, M. et al. Regional Activation of Myosin II in Cancer Cells Drives Tumor Progression via a Secretory Cross-Talk with the Immune Microenvironment. Cell 176(4):757-774.e23. doi: 10.1016/j.cell.2018.12.038 (2019)
3. Orgaz, J.L. et al. Myosin II Reactivation and Cytoskeletal Remodeling as a Hallmark and a Vulnerability in Melanoma Therapy Resistance. Cancer Cell 37(1):85-103.e9. doi: 10.1016/j.ccell.2019.12.003 (2020)
4. Godet, I. et al. Fate-mapping post-hypoxic tumor cells reveals a ROS-resistant phenotype that promotes metastasis. Nat Commun. 24;10(1):4862. doi: 10.1038/s41467-019-12412-1 (2019)
5. Fruhwirth, G.O. et al. A whole-body dual-modality radionuclide optical strategy for preclinical imaging of metastasis and heterogeneous treatment response in different microenvironments. J Nucl Med; 55(4):686-94. doi: 10.2967/jnumed.113.127480 (2014)