Genomic Science Program
U.S. Department of Energy | Office of Science | Biological and Environmental Research Program

Molecular and Cellular Responses of Human Endothelial Cells to Low-Dose Radiation

Authors:

Rebecca Weinberg1* (rweinberg@anl.gov), Sara Forrester1, Justin Podowski2, Abraham Stroka2, Thomas S. Brettin3, Dan Schabacker1, Rick Stevens3

Institutions:

1Biosciences Division, Argonne National Laboratory; 2Data Sciences and Learning Division, Argonne National Laboratory; 3Computing, Environment, and Life Sciences Directorate, Argonne National Laboratory

Goals

The biological impact of low-dose radiation exposure remains an important open question in radiation biology research, with significant implications for human health risk assessment, policy, and regulations. This project is leveraging advances in AI, high throughput experimental technologies, and multiscale modeling and simulation to advance scientific understanding of the molecular and cellular processes involved in low-dose radiation and cancer risk, accelerate discovery, and connect insights across scales.

Abstract

Radiation exposure has a wide spectrum of impacts on human health, notably in carcinogenesis but also in neurological and cardiovascular disorders. While acute toxicity from high doses of radiation is well-characterized, understanding the range of outcomes following exposure to low-dose radiation is more challenging. This project is establishing new experimental workflows that will enable high throughput experiments across molecular and cellular scales to facilitate more comprehensive modeling.

In a pilot study, a monolayer of Human Umbilical Vessel Endothelial Cells (HUVECs) was exposed to a point source of 137Cs at a low-dose rate of 6 milligrays (mGy) per hour. Cells were exposed for one week in culture (i.e., 1,008 mGy total dose) and then harvested for RNA or replated for Cell Painting staining.

Cell Painting is a streamlined multi-parameter approach to fluorescence microscopy that provides rich feature data of cell structure and function. A major advantage of Cell Painting is a robust publicly available dataset spanning thousands of small molecular and genomic perturbations produced by the collaborative JUMP Consortium. The scale of characterized phenotypes has facilitated development of predictive models that incorporate chemical structural information, biological mechanism of action, and gene expression, which will be expanded into the realm of radiation exposure.

With Cell Painting, features can be extracted based on staining of the nuclear and endoplasmic reticulum plasma membranes and cellular Golgi, actin, nucleoli, and mitochondria. Principle component analysis of control and irradiated cells provided a proof-of-principle demonstration that Cell Painting enables detection of features impacted by irradiation. Transcriptome analysis revealed that in endothelial cells, radiation robustly induced cell response pathways integral to cytokine and chemokine pathways, such as the Tumor Necrosis Factor (TNF) pathway.

Underscoring the relevancy of HUVECs to cardiovascular disease, pathways associated with “lipid” and “atherosclerosis” were also activated. Two Kyoto Encyclopedia of Genes and Genomes terms shed light on the molecular mechanisms of these processes, namely the HIF-1 and NF-kappa B signaling pathways.

To compare these results to previous studies of low-dose radiation exposure, data were compared with gene expression datasets from the RadBioBase, a publicly available comprehensive transcriptome repository of irradiated mammalian samples. Datasets that used human cells and doses below 0.5 Gy were selected to identify 235 genes impacted by radiation across four published datasets. Of these, 35 genes were also seen in the data, notably the inflammatory cytokines IL6 and IL1B, as well as the genes PTGS2 (COX2) and CXCL12, which are involved in inflammatory processes underlying cardiovascular disease.

To overcome the limitations (e.g, variable dose field, high activity) of the point radiation source in the pilot study, a major goal of the next project phase is to prototype and deploy new source geometries in a 96-well plate format for high-throughput experimental exposures. New source geometries will require minimal activity, provide uniform dose fields, and enable multiple dose rate exposures in parallel. The impact of low-dose radiation will then be assessed with molecular (e.g., multi-omic) and cellular (e.g., Cell Painting) assays to develop advanced multi-scale models of low-dose radiation impacts.

Funding Information

Argonne National Laboratory’s work on the Low-dose Understanding, Cellular Insights, and Molecular Discoveries (LUCID) program was supported by the DOE Office of Science, BER Program, under Contract DE-AC02-06CH11357.