About the Project
Head and neck squamous cell carcinomas (HNSCCs) are the sixth most common malignancy worldwide, with around 600,000 new cases annually. Radiotherapy (RT) is the main treatment, however many patients do not respond to RT while suffering the severe side-effects. Hypoxia in tissues has been recognised as a major cause of radioresistance, and hypoxia drives several biological processes in cancer cells. However, very little is known about the effects of hypoxia on tumour microenvironment (TME). TME is highly heterogeneous and significantly influences tumour behaviour and treatment response. Cancer-associated fibroblasts (CAFs) are one of the main TME components with critical roles in cancer progression and therapy failure. CAFs display extreme phenotypic heterogeneity and functional diversity. Intratumoral hypoxia induces a pro-tumorigenic and pro-metastatic CAF phenotype [1].
CAFs regulate cancer stem cells (CSCs) in different types of solid tumours through secreting proteins and exosomes that activate a wide array of CSC-related signalling pathways [2]. CSCs drive tumour growth and metastasis, and act as a reservoir of treatment-resistant cancer cells that drive relapse after surgery and radiation. Data from our group and others has shown CSCs in HNSCC respond to hypoxia by undergoing increased epithelial-mesenchymal transition (EMT) [3]; these EMT-CSCs have heightened metastatic and radioresistance features [3]. CSCs also induce the proliferation and further activation of CAFs to promote their CSC-supporting activities, thus completing the loop of CAF-CSC crosstalk [4].
In this project, the fellow will test the hypothesis that the TME plays a vital mechanistic role in the tumour hypoxic response and is required for the generation of radioresistant EMT-CSCs in response to hypoxia. The information obtained will open new avenues to develop treatment strategies to overcome radioresistance.
Project plan
1. Investigation of expression of CAF associated genes (ACTA2, FAP, FSP, TGF-Beta), and genes regulating stem cell properties (NOTCH, Oct-4, Nanog, Sox-2, Sox-9) by RT-PCR and immunohistochemistry in a panel of HNSCC tumour tissues with known RT response. Hypoxia will be determined by staining with hypoxia markers HIF1 and CAIX and candidates from our recently identified hypoxia gene signature [5]. These will be correlated with our recently-identified markers of EMT-CSCs in HNSCC [6].
2. Hyperion imaging mass cytometry (CyTOF) for high dimensional and unbiased examination of the TME. These studies will be done in collaboration with Dr Shahram Kordasti (KCL), in a joint recent project we have successfully used this technology to simultaneously detect multiple TME markers in FFPE tissue samples from HNSCC patients.
3. Underlying biological processes will be studied using our large panel of HPV negative and positive HNSCC cell lines, 3D tumour spheroids and HNSCC organoid models (jointly with Dr Anthony Kong, KCL). These will all be cultured +/- CAFs under hypoxic/normoxic conditions to analyse RT response using our hypoxia chamber. Jointly, with Prof Moshe Elkabets, Ben Guerin University, Israel, we have established mouse HNSCC models which will be used for assessing TME and hypoxia in combination with hypoxia-targeting drugs.
The candidate is expected to have a first degree in biological sciences related fields or a medical degree. Comprehensive training will be provided in the intellectual and technical aspects.
Potential research placements
1. Tavassoli’s lab: Centre for Host Microbiome Interaction, Guy’s Campus, KCL. Experience in working with and testing cell lines and 3D models and perform assays for tumour progression and invasion. Training in using irradiation facilities and general techniques in cell and molecular biology.
2. Biddle’s lab: Blizard Institute,QMUL. Characterisation of CSC phenotypes, and identification of the EMT-CSC phenotype in both HNSCC cell lines and patient tissue.
3. Kordasti’s lab: School of Cancer and Pharmaceutical Sciences, KCL. Specialised training for the use of CyTOF and imaging equipment will be provided. The PhD candidate will also be trained in the bioinformatics learning to use packages needed for the analysis of CyTOF data.
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. Chiavarina, B. et al. HIF1-alpha functions as a tumor promoter in cancer associated fibroblasts, and as a tumor suppressor in breast cancer cells: Autophagy drives compartment-specific oncogenesis. Cell Cycle. Sep 1;9(17):3534-51. doi: 10.4161/cc.9.17.12908. (2010)
2. Kalluri, R. The biology and function of fibroblasts in cancer. Nat Rev Cancer. Aug 23;16(9):582-98. doi: 10.1038/nrc.2016.73. (2016)
3. Gammon, L. et al. Sub-sets of cancer stem cells differ intrinsically in their patterns of oxygen metabolism. PLoS One. Apr 30;8(4): e62493. doi: 10.1371/journal.pone.0062493. (2013)
4. Huang, T.X. et al. Therapeutic targeting of the crosstalk between cancer-associated fibroblasts and cancer stem cells. Am J Cancer Res. Sep 1;9(9):1889-1904. (2019)
5. Suh, Y. et al. Association between hypoxic volume and underlying hypoxia-induced gene expression in oropharyngeal squamous cell carcinoma. Br J Cancer 116, 1057–1064 https://doi.org/10.1038/bjc.2017.66 (2017)
6. Youssef, G. et al. Disseminating cells in human tumours acquire an EMT stem cell state that is predictive of metastasis. BioRxiv; doi: https://doi.org/10.1101/2020.04.07.029009 (2020)