Temporal clustering analysis of endothelial cell gene expression following exposure to a conventional radiotherapy dose fraction using Gaussian process clustering

Profiling mRNA, miRNA and lncRNA expression changes in endothelial cells in response to increasing doses of ionizing radiation

Recent and past research have highlighted the importance of the endothelium in the manifestation of radiation injury. Our primary focus is on medical triage and management following whole body or partial-body irradiation. Here we investigated the usability of endothelial cells' radiation response for biodosimetry applications. We profiled the transcriptome in cultured human endothelial cells treated with increasing doses of X-rays. mRNA expression changes were useful 24 h and 72 h post-radiation, microRNA and lncRNA expression changes were useful 72 h after radiation. More mRNA expressions were repressed than induced while more miRNA and lncRNA expressions were induced than repressed. These novel observations imply distinct radiation responsive regulatory mechanisms for coding and non-coding transcripts. It also follows how different RNA species should be explored as biomarkers for different time-points. Radiation-responsive markers which could classify no radiation (i.e., '0 Gy') and dose-differentiating markers were also predicted. IPA analysis showed growth arrest-related processes at 24 h but immune response coordination at the 72 h post-radiation. Collectively, these observations suggest that endothelial cells have a precise dose and time-dependent response to radiation. Further studies in the laboratory are examining if these differences could be captured in the extracellular vesicles released by irradiated endothelial cells.

Deep models of integrated multiscale molecular data decipher the endothelial cell response to ionizing radiation

The vascular endothelium is a hot spot in the response to radiation therapy for both tumors and normal tissues. To improve patient outcomes, interpretable systemic hypotheses are needed to help radiobiologists and radiation oncologists propose endothelial targets that could protect normal tissues from the adverse effects of radiation therapy and/or enhance its antitumor potential. To this end, we captured the kinetics of multi-omics layers-i.e. miRNome, targeted transcriptome, proteome, and metabolome-in irradiated primary human endothelial cells cultured in vitro. We then designed a strategy of deep learning as in convolutional graph networks that facilitates unsupervised high-level feature extraction of important omics data to learn how ionizing radiation-induced endothelial dysfunction may evolve over time. Last, we present experimental data showing that some of the features identified using our approach are involved in the alteration of angiogenesis by ionizing radiation.

X‑irradiation induces acute and early term inflammatory responses in atherosclerosis‑prone ApoE‑/‑ mice and in endothelial cells

Thoracic radiotherapy is an effective treatment for many types of cancer; however it is also associated with an increased risk of developing cardiovascular disease (CVD), appearing mainly ≥10 years after radiation exposure. The present study investigated acute and early term physiological and molecular changes in the cardiovascular system after ionizing radiation exposure. Female and male ApoE^‑/‑ mice received a single exposure of low or high dose X‑ray thoracic irradiation (0.1 and 10 Gy). The level of cholesterol and triglycerides, as well as a large panel of inflammatory markers, were analyzed in serum samples obtained at 24 h and 1 month after irradiation. The secretion of inflammatory markers was further verified in vitro in coronary artery and microvascular endothelial cell lines after exposure to low and high dose of ionizing radiation (0.1 and 5 Gy). Local thoracic irradiation of ApoE^‑/‑ mice increased serum growth differentiation factor‑15 (GDF‑15) and C‑X‑C motif chemokine ligand 10 (CXCL10) levels in both female and male mice 24 h after high dose irradiation, which were also secreted from coronary artery and microvascular endothelial cells in vitro. Sex‑specific responses were observed for triglyceride and cholesterol levels, and some of the assessed inflammatory markers as detailed below. Male ApoE^‑/‑ mice demonstrated elevated intercellular adhesion molecule‑1 and P‑selectin at 24 h, and adiponectin and plasminogen activator inhibitor‑1 at 1 month after irradiation, while female ApoE^‑/‑ mice exhibited decreased monocyte chemoattractant protein‑1 and urokinase‑type plasminogen activator receptor at 24 h, and basic fibroblast growth factor 1 month after irradiation. The inflammatory responses were mainly significant following high dose irradiation, but certain markers showed significant changes after low dose exposure. The present study revealed that acute/early inflammatory responses occurred after low and high dose thoracic irradiation. However, further research is required to elucidate early asymptomatic changes in the cardiovascular system post thoracic X‑irradiation and to investigate whether GDF‑15 and CXCL10 could be considered as potential biomarkers for the early detection of CVD risk in thoracic radiotherapy‑treated patients.

Radiation-induced Adaptive Response: New Potential for Cancer Treatment

Radiotherapy is highly effective due to its ability to physically focus the treatment to target the tumor while sparing normal tissue and its ability to be combined with systemic therapy. This systemic therapy can be utilized before radiotherapy as an adjuvant or induction treatment, during radiotherapy as a radiation "sensitizer," or following radiotherapy as a part of combined modality therapy. As part of a unique concept of using radiation as "focused biology," we investigated how tumors and normal tissues adapt to clinically relevant multifraction (MF) and single-dose (SD) radiation to observe whether the adaptations can induce susceptibility to cell killing by available drugs or by immune enhancement. We identified an adaptation occurring after MF (3 × 2 Gy) that induced cell killing when AKT-mTOR inhibitors were delivered following cessation of radiotherapy. In addition, we identified inducible changes in integrin expression 2 months following cessation of radiotherapy that differ between MF (1 Gy × 10) and SD (10 Gy) that remain targetable compared with preradiotherapy. Adaptation is reflected across different "omics" studies, and thus the range of possible molecular targets is not only broad but also time, dose, and schedule dependent. While much remains to be studied about the radiation adaptive response, radiation should be characterized by its molecular perturbations in addition to physical dose. Consideration of the adaptive effects should result in the design of a tailored radiotherapy treatment plan that accounts for specific molecular changes to be targeted as part of precision multimodality cancer treatment.