Ferroptosis is a death program executed via selective oxidation of arachidonic acid–phosphatidylethanolamines (AA-PE) by 15-lipoxygenases. In mammalian cells and tissues, ferroptosis has been pathogenically associated with brain, kidney, and liver injury/diseases. We discovered that a prokaryotic bacterium, Pseudomonas aeruginosa, that does not contain AA-PE can express lipoxygenase (pLoxA), oxidize host AA-PE to 15-hydroperoxy-AA-PE (15-HOO-AA-PE), and trigger ferroptosis in human bronchial epithelial cells. Induction of ferroptosis by clinical P. aeruginosa isolates from patients with persistent lower respiratory tract infections was dependent on the level and enzymatic activity of pLoxA. Redox phospholipidomics revealed elevated levels of oxidized AA-PE in airway tissues from patients with cystic fibrosis (CF) but not with emphysema or CF without P. aeruginosa. We believe that the evolutionarily conserved mechanism of pLoxA-driven ferroptosis may represent a potential therapeutic target against P. aeruginosa–associated diseases such as CF and persistent lower respiratory tract infections.

Background: We hypothesized that the Effective radiation Dose to the Immune Cells (EDIC) in circulating blood is a significant factor for the treatment outcome in patients with locally advanced non-small-cell lung cancer (NSCLC). Methods: This is a secondary study of a phase III trial, NRG/RTOG 0617, in patients with stage III NSCLC treated with radiation-based treatment. The EDIC was computed as equivalent uniform dose to the entire blood based on radiation doses to all blood-containing organs, with consideration of blood flow and fractionation effect. The primary endpoint was overall survival (OS), and the secondary endpoints were progression-free survival (PFS) and local progression-free survival (LPFS). The EDIC–survival relationship was analyzed with consideration of clinical significant factors. Results: A total of 456 patients were eligible. The median EDIC values were 5.6 Gy (range, 2.1–12.2 Gy) and 6.3 Gy (2.1–11.6 Gy) for the low- and high-dose groups, respectively. The EDIC was significantly associated with OS (hazard ratio [HR] = 1.12, p = 0.005) and LPFS (HR = 1.09, p = 0.02) but PFS (HR = 1.05, p = 0.17) after adjustment for tumor dose, gross tumor volume and other factors. OS decreased with an increasing EDIC in a non-linear pattern: the two-year OS decreased first with a slope of 8%/Gy when the EDIC < 6 Gy, remained relatively unchanged when the EDIC was 6–8 Gy, and followed by a further reduction with a slope of 12%/Gy when the EDIC > 8 Gy. Conclusions: The EDIC is a significant independent risk factor for poor OS and LPFS in RTOG 0617 patients with stage III NSCLC, suggesting that radiation dose to circulating immune cells is critical for tumor control. Organ at risk for the immune system should be considered during RT plan.

Background: We determined factors associated with morbidity and outcomes of a series of non-small cell lung cancer (NSCLC) patients treated with dose escalated chemoradiotherapy at the University of Pittsburgh Lung Cancer Program. Methods and Materials: The records of 170 stage III NSCLC patients treated with definitive intent were retrospectively reviewed. All patients received 4D-CT simulation scan and had respiratory gating if tumor movement exceeded 5 mm. Overall survival (OS), locoregional control (LRC), and freedom from distant metastasis (FFDM) were calculated using log rank and Cox regression analysis. Results: For the present series of patients, median follow-up was 36.6 months, median survival 27.4 months, and the 2- and 4-year (OS) was 56.0 and 30.7%, respectively. The 4-year local regional control (LRC) and freedom from distant metastases (FFDM) were 43.9% and 40.7%, respectively. No benefit was associated with irradiation doses above 66 Gy in overall survival (OS) (p=0.586), LRC (p=0.440), or FFDM (p=0.230). On univariate analysis, variables associated with worse survival included: clinical stage IIIB (p=0.037), PTV over 450 cc (p 20% (43.8 vs. 21.3 months, p-0.01) were associated with lower survival. Grade 2 or higher acute lung toxicity and esophagitis were detected in 9.5% and 59.7%, respectively of patients. Grade 2 or higher acute lung toxicity was reduced if lung V5 was < 65 (7.4% vs. 23.8%, p=0.03). Grade 2 or higher acute esophagitis was reduced if V60 < 20% (62% vs. 81.3%, p=0.018). The use of Intensity Modulated Radiation Therapy (IMRT) was more frequent in stage IIIB compared to stage IIIA patients (56.5% vs. 39.5%, p=0.048), and was associated with a higher lung V5 and V10. Conclusions: The outcomes of a program of dose escalated chemoradiotherapy for unresectable stage IIIA and IIB NSCLC patients were consistent with other studies and showed no benefit to radiation doses above 66 Gy. Furthermore, maintaining low esophageal V60 and lung V5 were associated with lower morbidity and mortality.

Unmitigated UV radiation (UVR) induces skin photoaging and multiple forms of cutaneous carcinoma by complex pathways that include those mediated by UV-induced reactive oxygen species (ROS). Upon UVR exposure, a cascade of events is induced that overwhelms the skin’s natural antioxidant defenses and results in DNA damage, intracellular lipid and protein peroxidation, and the dysregulation of pathways that modulate inflammatory and apoptotic responses. To this end, natural products with potent antioxidant properties have been developed to prevent, mitigate, or reverse this damage with varying degrees of success. Mitochondria are particularly susceptible to ROS and subsequent DNA damage as they are a major intracellular source of oxidants. Therefore, the development of mitochondrially targeted agents to mitigate mitochondrial oxidative stress and resulting DNA damage is a logical approach to prevent and treat UV-induced skin damage. We summarize evidence that some existing natural products may reduce mitochondrial oxidative stress and support for synthetically generated mitochondrial targeted cyclic nitroxides as potential alternatives for the prevention and mitigation of UVR-induced skin damage.

Mammalian POLQ (pol θ) is a specialized DNA polymerase with an unknown function in vivo. Roles have been proposed in chromosome stability, as a backup enzyme in DNA base excision repair, and in somatic hypermutation of immunoglobulin genes. The purified enzyme can bypass AP sites and thymine glycol. Mice defective in POLQ are viable and have been reported to have elevated spontaneous and radiation-induced frequencies of micronuclei in circulating red blood cells. To examine the potential roles of POLQ in hematopoiesis and in responses to oxidative stress responses, including ionizing radiation, bone marrow cultures and marrow stromal cell lines were established from Polq / and Polq−/− mice. Aging of bone marrow cultures was not altered, but Polq−/− cells were more sensitive to γ radiation than were Polq / cells. The D0 was 1.38 ± 0.06 Gy for Polq / cells compared to 1.27 ± 0.16 and 0.98 ± 0.10 Gy (P = 0.032) for two Polq−/− clones. Polq−/− cells were moderately more sensitive to bleomycin than Polq / cells and were not hypersensitive to paraquat or hydrogen peroxide. ATM kinase activation appeared to be normal in γ-irradiated Polq−/− cells. Inhibition of ATM kinase activity increased the radiosensitivity of Polq / cells slightly but did not affect Polq−/− cells. Polq−/− mice had more spontaneous and radiation-induced micronucleated reticulocytes than Polq / and /− mice. The sensitivity of POLQ-defective bone marrow stromal cells to ionizing radiation and bleomycin and the increase in micronuclei in red blood cells support a role for this DNA polymerase in cellular tolerance of DNA damage that can lead to double-strand DNA breaks.