S2554
Radiobiology - Microenvironment
ESTRO 2026
[1] Catto, J. W. F., et al. (2023) BJU International,15970[2] Choudhury, A. et al. (2021) Lancet Oncol. 22, 246[3] Guerrero Qiles, C. et al. (2025) Front Oncol. 1616943 Keywords: Bladder cancer, 3D cell culture, Hydrogels Poster Discussion 3846 Characterizing Sex Chromosome Dosage Differences in Head and Neck Squamous Cell Carcinoma Microenvironment Cristina Conde Lopez 1,2 , Divyasree Marripati 3 , Maria J Besso 1 , Mareike Roscher 4 , Rui Han 2 , Wahyu W Hadiwikarta 1,5 , Moshe Elkabets 3,6 , Jochen Hess 2 , Ina Kurth 1,7 1 Radiooncology/Radiobiology, DKFZ, Heidelberg, Germany. 2 Department of Otorhinolaryngology, Head and Neck Surgery, Heidelberg University Hospital, Heidelberg, Germany. 3 The Shraga Segal Department of Microbiology, Immunology, and Genetics, Ben- Gurion University of the Negev, Beer-Sheva, Israel. 4 Service Unit for Radiopharmaceuticals and Preclinical Studies, DKFZ, Heidelberg, Germany. 5 German Cancer Consortium (DKTK), Core Center Heidelberg, Heidelberg, Germany. 6 Faculty of Health Sciences, Ben- Gurion University of the Negev, Beer-Sheva, Israel. 7 German Cancer Consortium (DKTK), DKFZ, Heidelberg, Germany Purpose/Objective: Head and neck squamous cell carcinoma (HNSCC) is a biologically heterogeneous disease with marked sex differences in incidence and prognosis. While clinical disparities between sexes are increasingly acknowledged, the molecular consequences of sex chromosome dosage alterations, such as Loss of Y chromosome (LoY) and Extreme Downregulation of Y- linked genes (EDY), remain poorly understood. This study investigates how these alterations influence tumor biology and reshape the tumor microenvironment (TME), with a focus on fibroblast and immune cell dynamics. Material/Methods: Analysis of TCGA bulk RNA-seq data revealed widespread LoY and EDY events in male patients, predominantly in HPV-negative tumors. These alterations were strongly linked, with LoY acting as a major driver of EDY. Stratification into XX, XY, and XØ (EDY/LoY) groups uncovered distinct transcriptomic and cellular profiles. To enable deeper exploration, a harmonized single-cell HNSCC atlas was constructed, integrating datasets across cohorts to examine gene expression, chromosomal instability, and cell–cell interactions. Y chromosome downregulation was primarily localized to tumor cells and enabled refined patient classification.
Figure 1. MIBC cell lines cultured within SAPHs of varying stiffness. Live cells stained with calcein-AM (green) and dead cells stained with ethidium homodimer III (red). Scale bar: 250 μ m.Distinct survival patterns were observed across cell lines. The T24 cells exhibited robust viability across all stiffness conditions. UMUC3 cells displayed initial cell loss followed by recovery, suggesting adaptation to 3D growth. J82 cells showed variable survival, with increased cell death in stiffer hydrogels.When assessing response to radiotherapy, T24 cells showed a dose-dependent decline in survival following RT, validating the system’s ability to capture differential radiosensitivity (Figure 2). Figure 2. (A) Viability of T24 cells cultured in Alpha 4 (0.1-1.3kPa) 14 days post irradiation. (B) Dose response assessing the proportion of viable cells, normalised to 0 Gy with a Nonlinear fit of data (R2=0.8238).The proportion of viable cells decreased from 1±0.178 at 0Gy to 0.921±0.145 at 2Gy, 0.179±0.0.005at 4Gy, 0.173±0.013 at 6Gy, 0.157±0.007 at 8Gy, and 0.086±0.002 at 10Gy. Conclusion: SAPHs provide a physiologically relevant 3D model for studying MIBC radioresponse, bridging the translational gap between 2D cultures and in vivo systems. This platform enables mechanistic exploration of microenvironment-driven radioresistance and offers a tuneable system for testing novel radiosensitisation strategies aimed at improving therapeutic outcomes for MIBC patients. References:
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