Explore the vast range of titles available.

Astrocytes, once believed to serve only as “glue” for the structural support of neurons, have been demonstrated to serve critical functions for the maintenance and protection of neurons, especially under conditions of acute or chronic injury. There are at least seven distinct mechanisms by which astrocytes protect neurons from damage; these are (1) protection against glutamate toxicity, (2) protection against redox stress, (3) mediation of mitochondrial repair mechanisms, (4) protection against glucose-induced metabolic stress, (5) protection against iron toxicity, (6) modulation of the immune response in the brain, and (7) maintenance of tissue homeostasis in the presence of DNA damage. Astrocytes support these critical functions through specialized responses to stress or toxic conditions. The detoxifying activities of astrocytes are essential for maintenance of the microenvironment surrounding neurons and in whole tissue homeostasis. Improved understanding of the mechanisms by which astrocytes protect the brain could lead to the development of novel targets for the development of neuroprotective strategies.

Both cancer patients receiving radiotherapy and civilians in a mass casualty nuclear event may suffer from radiation induced damage to organ systems. Radiation induced liver disease (RILD) can cause acute and long-term organ dysfunction that potentially leads to death. The objective of this study was to ascertain the validity of a liver quad-culture chip, a micro-physiological system comprising primary human hepatocytes and non-parenchymal cells (NPCs), including liver sinusoidal endothelial cells, hepatic stellate cells (HSCs), and Kupffer cells, as a model for RILD. The radiation exposure to the chip model resulted in DNA damage and cellular senescence of hepatocytes and NPCs. We observed metabolic dysfunction, inflammation, endothelial dysfunction, and HSCs activation. Whole genome sequencing revealed gene alterations in pathways relevant to RILD, as well as the potential efficacy of N -acetylcysteine amide (NACA) against RILD. NACA exhibited the capacity to mitigate DNA damage and cellular senescence and decreased the impact of radiation exposure on other pathophysiological changes. CDKN1A and miR-34a-5p were validated as useful radiation response and treatment efficacy biomarkers. These findings highlight the potential of the liver quad-culture chip as an effective model for investigating the microenvironment in RILD and for evaluating the efficacy of therapeutic countermeasures and biomarkers.

Background Radiation therapy is integral to effective thoracic cancer treatments, but its application is limited by sensitivity of critical organs such as the heart. The impacts of acute radiation-induced damage and its chronic effects on normal heart cells are highly relevant in radiotherapy with increasing lifespans of patients. Biomarkers for normal tissue damage after radiation exposure, whether accidental or therapeutic, are being studied as indicators of both acute and delayed effects. Recent research has highlighted the potential importance of RNAs, including messenger RNAs (mRNAs), microRNAs (miRNAs), and long non-coding RNAs (lncRNAs) as biomarkers to assess radiation damage. Understanding changes in mRNA and non-coding RNA expression will elucidate biological pathway changes after radiation. Methods To identify significant expression changes in mRNAs, lncRNAs, and miRNAs, we performed whole transcriptome microarray analysis of mouse heart tissue at 48 h after whole-body irradiation with 1, 2, 4, 8, and 12 Gray (Gy). We also validated changes in specific lncRNAs through RT-qPCR. Ingenuity Pathway Analysis (IPA) was used to identify pathways associated with gene expression changes. Results We observed sustained increases in lncRNAs and mRNAs, across all doses of radiation. Alas2 , Aplnr, and Cxc3r1 were the most significantly downregulated mRNAs across all doses. Among the significantly upregulated mRNAs were cell-cycle arrest biomarkers Gdf15, Cdkn1a, and Ckap2. Additionally, IPA identified significant changes in gene expression relevant to senescence, apoptosis, hemoglobin synthesis, inflammation, and metabolism. LncRNAs Abhd11os, Pvt1, Trp53cor1 , and Dino showed increased expression with increasing doses of radiation. We did not observe any miRNAs with sustained up- or downregulation across all doses, but miR-149-3p, miR-6538, miR-8101, miR-7118-5p, miR-211-3p, and miR-3960 were significantly upregulated after 12 Gy. Conclusions Radiation-induced RNA expression changes may be predictive of normal tissue toxicities and may indicate targetable pathways for radiation countermeasure development and improved radiotherapy treatment plans.

Radiation injury, either from radiotherapy or a mass-casualty event requires a health care system that can efficiently allocate resources to patients. We conducted a comprehensive transcriptome analysis of whole blood from a nonhuman primate model that received upper thoracic radiation (9.8–10.7 Gy). Blood samples were collected at multiple time points, extending up to 270 days post-irradiation with a minimum n  = 6 for initial time points (Day 3-Day 40) and a total number of n  = 28 primates. No males receiving the higher dose survived to Day 270. Using the Elastic Net model in R we found that pooling biomarkers from Day 3–21 increased our accuracy in discerning survival time, pleural effusion or dose compared to using biomarkers specific to a single day. For survival data, in predicting short term (less than 90 day), medium term (Day 91–269) or long-term survival (Day 270), prediction accuracy using only Day 3 data was 0.14 (95% Confidence Interval (CI) 0.1, 0.19) while pooled data for Male and Female was 0.76 (CI 0.69, 0.82). When pooled data was divided by biological sex, accuracy was 0.7 (CI 0.58, 0.8) for pooled data from Males and 0.84 (CI 0.76, 0.91) for Females. The development of RNA biomarkers as a tool to aid in clinical decision-making could significantly improve patient care in cases of radiation injury, whether from radiotherapy or mass-casualty events. Further validation and clinical translation of these findings could lead to improved patient care and management strategies in cases of radiation exposure.

Radiation injury from medical, accidental, or intentional sources can induce acute and long-term hepatic dysregulation, fibrosis, and cancer. This long-term hepatic dysregulation decreases quality of life and may lead to death. Our goal in this study is to determine acute changes in biological pathways and discover potential RNA biomarkers predictive of radiation injury. We performed whole transcriptome microarray analysis of mouse liver tissue (C57BL/6 J) 48 h after whole-body irradiation with 1, 2, 4, 8, and 12 Gray to identify significant expression changes in mRNAs, lncRNAs, and miRNAs, We also validated changes in specific RNAs through qRT-PCR. We used Ingenuity Pathway Analysis (IPA) to identify pathways associated with gene expression changes. We observed significant dysregulation of multiple mRNAs across all doses. In contrast, miRNA dysregulation was observed upwards of 2 Gray. The most significantly upregulated mRNAs function as tumor suppressors: Cdkn1a , Phlda3 , and Eda2r . The most significantly downregulated mRNAs were involved in hemoglobin synthesis, inflammation, and mitochondrial function including multiple members of Hbb and Hba . The most significantly upregulated miRNA included: miR-34a-5p, miR-3102-5p, and miR-3960, while miR-342-3p, miR-142a-3p, and miR-223-3p were most significantly downregulated. IPA predicted activation of cell cycle checkpoint control pathways and inhibition of pathways relevant to inflammation and erythropoietin. Clarifying expression of mRNA, miRNA and lncRNA at a short time point (48 h) offers insight into potential biomarkers, including radiation markers shared across organs and animal models. This information, once validated in human models, can aid in development of bio-dosimetry biomarkers, and furthers our understanding of acute pathway dysregulation.

In a mass radiation exposure, the healthcare system may rely on differential expression of miRNA to determine exposure and effectively allocate resources. To this end, miRNome analysis was performed on non-human primate serum after whole thorax photon beam irradiation of 9.8 or 10.7 Gy with dose rate 600 cGy/min. Serum was collected up to 270 days after irradiation and sequenced to determine immediate and delayed effects on miRNA expression. Elastic net based GLM methods were used to develop models that predicted the dose vs. controls at 81% accuracy at Day 15. A three-group model at Day 9 achieved 71% accuracy in determining if an animal would die in less than 90 days, between 90 and 269 days, or survive the length of the study. At Day 21, we achieved 100% accuracy in determining whether an animal would later develop pleural effusion. These results demonstrate the potential ability of miRNAs to determine thorax partial-body irradiation dose and forecast survival or complications early following whole thorax irradiation in large animal models. Future experiments incorporating additional doses and independent animal cohorts are warranted to validate these results. Development of a serum miRNA assay will facilitate the administration of medical countermeasures to increase survival and limit normal tissue damage following a mass exposure.

Our laboratory has demonstrated that captopril, an angiotensin converting enzyme inhibitor, mitigates hematopoietic injury following total body irradiation in mice. Improved survival in mice is correlated with improved recovery of mature blood cells and bone marrow, reduction of radiation-induced inflammation, and suppression of radiation coagulopathy. Here we investigated the effects of captopril treatment against radiation injuries in the Göttingen mini pig model of Hematopoietic-Acute Radiation Syndrome (H-ARS). Minipigs were given captopril orally (0.96 mg/kg) twice daily for 12 days following total body irradiation ( 60 Co 1.79 Gy, 0.42–0.48 Gy/min). Blood was drawn over a time course following irradiation, and tissue samples were collected at euthanasia (32–35 days post-irradiation). We observed improved survival with captopril treatment, with survival rates of 62.5% in vehicle treated and 87.5% in captopril treated group. Additionally, captopril significantly improved recovery of peripheral blood mononuclear cells, and a trend toward improvement in recovery of red blood cells and platelets. Captopril significantly reduced radiation-induced expression of cytokines erythropoietin and granulocyte-macrophage colony-stimulating factor and suppressed radiation-induced acute-phase inflammatory response cytokine serum amyloid protein A. Using quantitative-RT-PCR to monitor bone marrow recovery, we observed significant suppression of radiation-induced expression of redox stress genes and improved hematopoietic cytokine expression. Our findings suggest that captopril activities in the Göttingen minipig model of hematopoietic-acute radiation syndrome reflect findings in the murine model.

The efficacy of molecular targeted therapy depends on expression and enzymatic activity of the target molecules. As radiotherapy modulates gene expression and protein phosphorylation dependent on dose and fractionation, we analyzed the long-term effects of irradiation on the post-radiation efficacy of molecular targeted drugs. We irradiated prostate cancer cells either with a single dose (SD) of 10 Gy x-ray or a multifractionated (MF) regimen with 10 fractions of 1 Gy. Whole genome arrays and reverse phase protein microarrays were used to determine gene expression and protein phosphorylation. Additionally, we evaluated radiation-induced pathway activation with the Ingenuity Pathway Analysis software. To measure cell survival and sensitivity to clinically used molecular targeted drugs, we performed colony formation assays. We found increased activation of several pathways regulating important cell functions such as cell migration and cell survival at 24 h after MF irradiation or at 2 months after SD irradiation. Further, cells which survived a SD of 10 Gy showed a long-term upregulation and increased activity of multiple molecular targets including AKT, IGF-1R, VEGFR2, or MET, while HDAC expression was decreased. In line with this, 10 Gy SD cells were more sensitive to target inhibition with Capivasertib or Ipatasertib (AKTi), BMS-754807 (IGF-1Ri), or Foretinib (VEGFR2/METi), but less sensitive to Panobinostat or Vorinostat (HDACi). In summary, understanding the molecular short- and long-term changes after irradiation can aid in optimizing the efficacy of multimodal radiation oncology in combination with post-irradiation molecularly-targeted drug treatment and improving the outcome of prostate cancer patients.

Abstract Radiotherapy is a common modality for treatment of brain cancers, but it can induce long-term physiological and cognitive deficits. The responses of normal human brain cells to radiation is not well understood. Astrocytes have been shown to have a variety of protective mechanisms against oxidative stress and have been shown to protect neurons. We investigated the response of cultured normal human astrocytes (NHAs) to X-ray irradiation. Following exposure to 10 Gy X-irradiation, NHAs exhibited DNA damage as indicated by the formation of γ-H2AX foci. Western blotting showed that NHAs displayed a robust increase in expression of non-homologous end joining DNA repair enzymes within 15 min post-irradiation and increased expression of homologous recombination DNA repair enzymes ~2 h post-irradiation. The cell cycle checkpoint protein p21/waf1 was upregulated from 6–24 h, and then returned to baseline. Levels of DNA repair enzymes returned to basal ~48 h post-irradiation. NHAs re-entered the cell cycle and proliferation was observed at 6 days. In contrast, normal human mesenchymal stem cells (MSCs) failed to upregulate DNA repair enzymes and instead displayed sustained upregulation of p21/waf1, a cell cycle checkpoint marker for senescence. Ectopic overexpression of Ku70 was sufficient to protect MSCs from sustained upregulation of p21/waf1 induced by 10 Gy X-rays. These findings suggest that increased expression of Ku70 may be a key mechanism for the radioresistance of NHAs, preventing their accelerated senescence from high-dose radiation. These results may have implications for the development of novel targets for radiation countermeasure development.

The expression of immune-related genes in cancer cells can alter the anti-tumor immune response and thereby impact patient outcomes. Radiotherapy has been shown to modulate immune-related genes dependent on the fractionation regimen. To identify long-term changes in gene expression after irradiation, PC3 (p53 deleted) and LNCaP (p53 wildtype) prostate cancer cells were irradiated with either a single dose (SD, 10 Gy) or a fractionated regimen (MF) of 10 fractions (1 Gy per fraction). Whole human genome arrays were used to determine gene expression at 24 h and 2 months after irradiation. Immune pathway activation was analyzed with Ingenuity Pathway Analysis software. Additionally, 3D colony formation assays and T-cell cytotoxicity assays were performed. LNCaP had a higher basal expression of immunogenic genes and was more efficiently killed by cytotoxic T-cells compared to PC3. In both cell lines, MF irradiation resulted in an increase in multiple immune-related genes immediately after irradiation, while at 2 months, SD irradiation had a more pronounced effect on radiation-induced gene expression. Both immunogenic and immunosuppressive genes were upregulated in the long term in PC3 cells by a 10 Gy SD irradiation but not in LNCaP. T-cell-mediated cytotoxicity was significantly increased in 10 Gy SD PC3 cells compared to the unirradiated control and could be further enhanced by treatment with immune checkpoint inhibitors. Irradiation impacts the expression of immune-related genes in cancer cells in a fractionation-dependent manner. Understanding and targeting these changes may be a promising strategy for primary prostate cancer and recurrent tumors.