Fatemeh Zolghadr1, Nigel Tse1, Dikasya Loka1, George Joun1,2, Sreelakshmi Meppat1, Victor Wan1, Hans Zoellner3, Munira Xaymardan1,2, Camile S Farah4,5, J Guy Lyons6,7, Eric Hau8,9,10, Ellis Patrick9,11, Naisana Seyedasli12,13,14. 1. Discipline of Oral Biosciences, School of Dentistry, Faculty of Medicine and Health, University of Sydney, Westmead Hospital, Westmead, NSW, Australia. 2. School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Westmead Hospital, Westmead, NSW, Australia. 3. Discipline of Oral Surgery, Medicine and Diagnostics, School of Dentistry, Faculty of Medicine and Health, University of Sydney, Westmead Hospital, Westmead, NSW, Australia. 4. Australian Centre for Oral Oncology Research and Education, Nedlands, WA, Australia. 5. Maxillofacial, Oral and Dental Surgery, Fiona Stanley Hospital, Murdoch, WA, Australia. 6. Discipline of Dermatology, Sydney Medical School and Centenary Institute, The University of Sydney, Camperdown, NSW, Australia. 7. Cancer Services, Royal Prince Alfred Hospital, Camperdown, NSW, Australia. 8. Sydney West Radiation Oncology Network, Westmead, NSW, Australia. 9. The Centre for Cancer Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia. 10. Sydney Medical School, Faculty of Medicine and Health, University of Sydney, Westmead Hospital, Westmead, NSW, Australia. 11. School of Mathematics, Faculty of Science, University of Sydney, Camperdown, NSW, Australia. 12. Discipline of Oral Biosciences, School of Dentistry, Faculty of Medicine and Health, University of Sydney, Westmead Hospital, Westmead, NSW, Australia. naisana.seyedasli@sydney.edu.au. 13. School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Westmead Hospital, Westmead, NSW, Australia. naisana.seyedasli@sydney.edu.au. 14. The Centre for Cancer Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia. naisana.seyedasli@sydney.edu.au.
Abstract
BACKGROUND: Dynamic transitions of tumour cells along the epithelial-mesenchymal axis are important in tumorigenesis, metastasis and therapy resistance. METHODS: In this study, we have used cell lines, 3D spheroids and tumour samples in a variety of cell biological and transcriptome analyses to highlight the cellular and molecular dynamics of OSCC response to ionising radiation. RESULTS: Our study demonstrates a prominent hybrid epithelial-mesenchymal state in oral squamous cell carcinoma cells and tumour samples. We have further identified a key role for levels of E-cadherin in stratifying the hybrid cells to compartments with varying levels of radiation response and radiation-induced epithelial-mesenchymal transition. The response to radiation further entailed the generation of a new cell population with low expression levels of E-cadherin, and positive for Vimentin (ECADLow/Neg-VIMPos), a phenotypic signature that showed an enhanced capacity for radiation resistance and invasion. At the molecular level, transcriptome analysis of spheroids in response to radiation showed an initial burst of misregulation within the first 30 min that further declined, although still highlighting key alterations in gene signatures. Among others, pathway analysis showed an over-representation for the Wnt signalling pathway that was further confirmed to be functionally involved in the generation of ECADLow/Neg-VIMPos population, acting upstream of radiation resistance and tumour cell invasion. CONCLUSION: This study highlights the functional significance and complexity of tumour cell remodelling in response to ionising radiation with links to resistance and invasive capacity. An area of less focus in conventional radiotherapy, with the potential to improve treatment outcomes and relapse-free survival.
BACKGROUND: Dynamic transitions of tumour cells along the epithelial-mesenchymal axis are important in tumorigenesis, metastasis and therapy resistance. METHODS: In this study, we have used cell lines, 3D spheroids and tumour samples in a variety of cell biological and transcriptome analyses to highlight the cellular and molecular dynamics of OSCC response to ionising radiation. RESULTS: Our study demonstrates a prominent hybrid epithelial-mesenchymal state in oral squamous cell carcinoma cells and tumour samples. We have further identified a key role for levels of E-cadherin in stratifying the hybrid cells to compartments with varying levels of radiation response and radiation-induced epithelial-mesenchymal transition. The response to radiation further entailed the generation of a new cell population with low expression levels of E-cadherin, and positive for Vimentin (ECADLow/Neg-VIMPos), a phenotypic signature that showed an enhanced capacity for radiation resistance and invasion. At the molecular level, transcriptome analysis of spheroids in response to radiation showed an initial burst of misregulation within the first 30 min that further declined, although still highlighting key alterations in gene signatures. Among others, pathway analysis showed an over-representation for the Wnt signalling pathway that was further confirmed to be functionally involved in the generation of ECADLow/Neg-VIMPos population, acting upstream of radiation resistance and tumour cell invasion. CONCLUSION: This study highlights the functional significance and complexity of tumour cell remodelling in response to ionising radiation with links to resistance and invasive capacity. An area of less focus in conventional radiotherapy, with the potential to improve treatment outcomes and relapse-free survival.