Biology subjects

Dok, R.

Publications and source records attributed to Dok, R..

3 recordsLinked to original sources

bioRxiv2025

FLASH or flare: variable intestinal toxicity results in a mouse model following proton pencil beam scanning irradiation on a clinical superconducting synchrocyclotron

Background and aimsUltra-high dose rate (FLASH) irradiation is a promising technique to reduce radiation-induced normal tissue toxicities while preserving antitumor efficacy. We evaluated the feasibility and intestinal sparing potential of FLASH irradiation using a clinical synchrocyclotron-based proton therapy system generating a pulsed beam. Material and methodsC57BL/6J mice received abdominal irradiation (2x2 cm) in transmission mode at FLASH (>60 Gy/s) or conventional (CONV, 0.5 Gy/s) dose rates using a 230 MeV superconducting synchrocyclotron proton pencil beam scanning (PBS) system. Two independent irradiation rounds were performed. Endpoints included 75-day survival, regenerating crypt counts, whole blood counts at day 4, and intestinal wall thickness, cyst-like structures, and cytokine levels at day 75. ResultsIn the first irradiation round, survival after 14.5 Gy FLASH was markedly improved (5/8 survivors) compared to CONV (0/8), whereas in the second round, survival rates were identical (2/7 per group). Overall, pooled data indicated improved survival with 14.5 Gy FLASH. The LD50 was 13.74 Gy in CONV and 14.48 Gy in FLASH mode, corresponding to a FLASH modifying factor of 0.95. FLASH at 14.5 Gy increased regenerating crypt numbers compared to CONV, but only in the first round, supporting survival outcomes. No significant differences were observed in whole blood counts, cytokine profiles, or long-term intestinal structural changes between groups. ConclusionFLASH proton therapy delivered with a clinical synchrocyclotron PBS system can reduce short-term gastrointestinal toxicity in mice. However, inconsistent results across irradiation rounds highlight limitations of this model for reliable FLASH studies.

cancer biology↗

bioRxiv2025

Nanoparticle Metal Mass Uptake Governs Radiosensitizing Efficacy Across 2D, 3D, and In Vivo Models

Despite extensive efforts to develop nanoparticle-based radioenhancers, clinical translation remains limited, partly due to the lack of physiologically relevant in vitro models. To address this gap, we developed a 3D spheroid model of head and neck cancer using FaDu cells and compared it directly to a corresponding in vivo model in a radiotherapy setting. The spheroids exhibited key tumor-like features, including the formation of a hypoxic core and growth kinetics comparable to in vivo tumors. Importantly, the model allowed for long-term monitoring of tumor growth and radiation response. Upon X-ray irradiation, dose-response behavior in spheroids mirrored that observed in vivo. Furthermore, TiO2, HfO2, and Au nanoparticles demonstrated consistent radiosensitization effects in both systems when matched for uptake mass. In contrast, conventional 2D clonogenic assays failed to predict in vivo performance, likely due to their lower radioresistance and unrealistic nanoparticle exposure conditions. This study introduces a robust, scalable, and clinically compatible 3D in vitro platform for preclinical screening of nanoparticle radioenhancers. The system may offer streamlining of development pipelines and support the 3R principles of reduction, replacement, and refinement in radiation oncology research.

cancer biology↗

bioRxiv2023

TIPRL1 and its ATM-dependent phosphorylation promote radiotherapy resistance in head and neck cancer

TIPRL1 (target of rapamycin signaling pathway regulator-like 1) is a known interactor and inhibitor of protein phosphatases PP2A, PP4 and PP6 - all pleiotropic modulators of the DNA Damage Response (DDR). Here, we describe a new role for TIPRL1 in the radiotherapy (RT) response of Head and Neck Squamous Cell Carcinoma (HNSCC). TIPRL1 expression was found increased in tumor versus non- tumor tissue, with high tumoral TIPRL1 expression associating with lower locoregional control and decreased survival of RT-treated patients. TIPRL1 deletion in HNSCC cells resulted in increased RT sensitivity, a faster but prolonged cell cycle arrest, increased micronuclei formation and an altered proteome-wide DDR. Upon irradiation, ATM phosphorylates TIPRL1 at Ser265, contributing to TIPRL1-mediated RT resistance. Mass spectrometry analysis identified DNA-PKcs, RAD51 and nucleosomal histones as novel TIPRL1 interactors. Histone binding, although stimulated by RT, was adversely affected by TIPRL1 Ser265 phosphorylation. Our findings underscore a clinically relevant role for TIPRL1 and its ATM-dependent phosphorylation in RT resistance through modulation of DNA damage checkpoint activation and repair.

cancer biology↗