Biology subjects

Butterworth, K. T.

Publications and source records attributed to Butterworth, K. T..

4 recordsLinked to original sources

bioRxiv2026

Fractionated proton and photon FLASH irradiation mitigates radiation-induced lymphopenia through kinetic sparing of circulating lymphocytes

Background and purpose: Radiation-induced lymphopenia is associated with adverse outcomes in thoracic malignancies. FLASH radiotherapy delivers radiation over a timescale of hundreds of milliseconds, potentially reducing the fraction of irradiated circulating lymphocytes. In this study, we investigated whether FLASH mitigates lymphopenia after thoracic irradiation delivered with protons or photons. Materials and methods: C57BL/6 mice received three 13.5-Gy whole-heart fractions at 48-hour intervals using FLASH or standard dose-rate proton irradiation at the University of Pennsylvania (n=15), with photon validation at Queen's University Belfast (n=72). Leukocytes and CD4 T cells, CD8 T cells, B cells, and NK cells were quantified by hemocytometer and flow cytometry. A continuous-time Markov model simulated lymphocyte trafficking, dose accumulation, and post-irradiation recovery. Results: FLASH attenuated leukocyte depletion across both proton and photon irradiation modalities. In the proton cohort, white blood cell counts were significantly higher after FLASH at D1, D3, D7, and D14; CD4 T cells and NK cells were preserved through D14, while CD8 T cell sparing persisted through D21. Photon FLASH preserved CD45 leukocytes at D1, D3, D7, and D21, with sustained CD8 sparing at D21. Modeling showed that FLASH shifted the lymphocyte dose distribution toward lower exposures, increasing the proportion of lymphocytes receiving <1 Gy from 2.4% to 16.4%, and reduced the proportion of lymphocytes repeatedly irradiated across all three fractions from 36.3% at standard dose rate to 9.18%, despite similar median cumulative doses. The spleen contributed substantially to cumulative lymphocyte dose, and marrow-entering lymphocytes displayed a more high-dose-enriched distribution after FLASH irradiation. Conclusion: FLASH consistently mitigated radiation-induced lymphopenia for proton and photon modalities, with durable CD8 T cell preservation. These findings support a kinetic mechanism and provide a rationale for combining FLASH radiotherapy with immune-sparing planning and immunotherapy.

cell biology↗

bioRxiv2026

GIGYF2/4EHP-Mediated Translational Attenuation Maintains Cellular Homeostasis Following Ionizing Radiation

Translational regulation is a critical component of the cellular response to environmental stress. Ionizing radiation (IR) exists naturally at low doses (e.g., cosmic rays and radioactive materials) but is applied at much higher doses in clinical settings, where accelerated photons (X-rays) and particle beams (protons, ions etc) are utilized for the treatment of cancer. While the effects of IR on DNA damage and cell cycle are well established, its impacts on cellular RNA metabolism remains less understood. In particular, the role of the mRNA translation machinery in shaping the early cellular response to IR is largely unexplored. Here, we demonstrate that IR induces an acute and persistent translational repression. This acute repression is independent of the mTOR and Integrated Stress Response pathways, which are known regulators of mRNA translation in response to environmental cues. Instead, we discovered that the translational repression is, at least partially, mediated by the GIGYF2/4EHP translational repressor complex. We show that GIGYF2/4EHP recruitment to the mRNAs upon IR exposure is driven by rapidly enhanced interactions with RNA-binding proteins such as ZFP36 and components of the miRNA-Induced Silencing Complex (miRISC) that are poised on their target mRNAs. Importantly, the presence of the GIGYF2/4EHP complex is required for the maintenance of proteostasis and cell viability following irradiation. Together, our results establish mRNA translational control as a key determinant of cellular response to IR and identify GIGYF2/4EHP as a critical component of this adaptive mechanism.

cell biology↗

bioRxiv2025

Regional Vulnerability of Cardiac Chambers to Radiotherapy: A Multi-Omics Perspective

The heart is highly vulnerable to radiotherapy (RT)-induced injury, leading to molecular and structural remodeling collectively termed radiation-induced cardiac toxicity (RICT). Although several biological pathways have been implicated, the regional, cardiac-specific molecular responses to radiation exposure remain incompletely understood. Here, a multi-omics approach was adopted to longitudinally characterise the unique responses to radiation of the heart base (including ventricular base and right atrium), or the heart apex. Ventricular base irradiation induced a cardiomyopathy phenotype, with pronounced molecular perturbations in metabolism and electrical conduction, while changes related to tissue structure were predominant following apex-directed RT. In the right atrium, irradiation drives fibrotic tissue remodelling, leading to an increased propensity for atrial fibrillation, underpinned by changes in sarcomere organisation. This study represents a comprehensive characterisation of differential spatiotemporal radiation effects in the heart and highlights biological and functional pathways that are potentially clinically actionable for cardiac radioprotection and monitoring.

cell biology↗

bioRxiv2020

Targeting CXCR1 and CXCR2 to overcome radiotherapy resistance in PTEN-deficient prostate carcinoma

ABSTRACTFunctional impairment of the tumour-suppressor PTEN is common in primary-prostate cancer and has been linked to relapse post-radiotherapy (RT). Pre-clinical modelling supports elevated CXC-chemokine signaling as a critical mediator of PTEN-depleted disease progression and therapeutic resistance. We assessed the correlation of PTEN-deficiency with CXC-chemokine signaling and its association with clinical outcomes. Gene expression analysis characterized a PTENLOW/CXCR1HIGH/CXCR2HIGH cluster of tumors that associates with earlier time-to-biochemical recurrence (HR 5.87 and HR 2.65 respectively) and development of systemic metastasis (HR 3.51). In vitro, CXCL-signaling was further amplified following exposure of PTEN-deficient prostate cancer cell lines to ionizing radiation (IR). Inhibition of CXCR1/2-signaling in PTEN-depleted cell-based models increased IR-sensitivity. In vivo, administration of a CXCR1/2-targeted pepducin (x1/2pal-i3), or CXCR2-specific antagonist (AZD5069), in combination with IR to PTEN-deficient xenografts attenuated tumor growth and progression compared to control or IR alone. Post-mortem analysis confirmed that x1/2pal-i3 administration attenuated IR-induced CXCL-signaling and anti-apoptotic protein expression. Interventions targeting CXC-chemokine signaling may provide an effective strategy to combine with radiotherapy, in both locally-advanced and oligometastatic-prostate cancers, with known presence of PTEN-deficient foci.

cancer biology↗