Imaging of nuclear factor κB activation induced by ionizing radiation in human embryonic kidney (HEK) cells

The Use of ProteoTuner Technology to Study Nuclear Factor κB Activation by Heavy Ions

Nuclear factor κB (NF-κB) activation might be central to heavy ion-induced detrimental processes such as cancer promotion and progression and sustained inflammatory responses. A sensitive detection system is crucial to better understand its involvement in these processes. Therefore, a DD-tdTomato fluorescent protein-based reporter system was previously constructed with human embryonic kidney (HEK) cells expressing DD-tdTomato as a reporter under the control of a promoter containing NF-κB binding sites (HEK-pNFκB-DD-tdTomato-C8). Using this reporter cell line, NF-κB activation after exposure to different energetic heavy ions (¹⁶O, 95 MeV/n, linear energy transfer—LET 51 keV/µm; ¹²C, 95 MeV/n, LET 73 keV/μm; ³⁶Ar, 95 MeV/n, LET 272 keV/µm) was quantified considering the dose and number of heavy ions hits per cell nucleus that double NF-κB-dependent DD-tdTomato expression. Approximately 44 hits of ¹⁶O ions and ≈45 hits of ¹²C ions per cell nucleus were required to double the NF-κB-dependent DD-tdTomato expression, whereas only ≈3 hits of ³⁶Ar ions were sufficient. In the presence of Shield-1, a synthetic molecule that stabilizes DD-tdTomato, even a single particle hit of ³⁶Ar ions doubled NF-κB-dependent DD-tdTomato expression. In conclusion, stabilization of the reporter protein can increase the sensitivity for NF-κB activation detection by a factor of three, allowing the detection of single particle hits’ effects.

An in-vitro approach for water quality determination: activation of NF-κB as marker for cancer-related stress responses induced by anthropogenic pollutants of drinking water

Epidemiological studies show that there is a link between urban water pollution and increase in human morbidity and mortality. With the increase in number of new substances arising from the chemical, pharmaceutical, and agricultural industries, there is an urgent need to develop biological test systems for fast evaluation of potential risks to humans and the environmental ecosystems. Here, a combined cellular reporter assay based on the cellular survival and the stress-induced activation of the survival-promoting factor nuclear factor κB (NF-κB) and its use for the detection of cytotoxicity and cancer-related stress responses is presented. A total of 14 chemicals that may be found in trace-amounts in ground water levels are applied and tested with the presented assay. The project is embedded within the joint research project TOX-BOX which aims to develop a harmonized testing strategy for risk management of anthropogenic trace substances in potable water. The assay identified carbendazim as a NF-κB-activating agent in mammalian cells.

Radioprotective effect of mefenamic acid against radiation-induced genotoxicity in human lymphocytes

Purpose

Mefenamic acid (MEF) as a non-steroidal anti-inflammatory drug is used as a medication for relieving of pain and inflammation. Radiation-induced inflammation process is involved in DNA damage and cell death. In this study, the radioprotective effect of MEF was investigated against genotoxicity induced by ionizing radiation in human blood lymphocytes.

Materials and Methods

Peripheral blood samples were collected from human volunteers and incubated with MEF at different concentrations (5, 10, 50, or 100 µM) for two hours. The whole blood was exposed to ionizing radiation at a dose 1.5 Gy. Lymphocytes were cultured with mitogenic stimulation to determine the micronuclei in cytokinesis blocked binucleated lymphocyte.

Results

A significant decreasing in the frequency of micronuclei was observed in human lymphocytes irradiated with MEF as compared to irradiated lymphocytes without MEF. The maximum decreasing in frequency of micronuclei was observed at 100 µM of MEF (38% decrease), providing maximal protection against ionizing radiation.

Conclusion

The radioprotective effect of MEF is probably related to anti-inflammatory property of MEF on human lymphocytes.

In vitro γ-ray-induced inflammatory response is dominated by culturing conditions rather than radiation exposures

The inflammatory pathway has a pivotal role in regulating the fate and functions of cells after a wide range of stimuli, including ionizing radiation. However, the molecular mechanisms governing such responses have not been completely elucidated yet. In particular, the complex activation dynamics of the Nuclear transcription Factor kB (NF-kB), the key molecule governing the inflammatory pathway, still lacks a complete characterization. In this work we focused on the activation dynamics of the NF-kB (subunit p65) pathway following different stimuli. Quantitative measurements of NF-kB were performed and results interpreted within a systems theory approach, based on the negative feedback loop feature of this pathway. Time-series data of nuclear NF-kB concentration showed no evidence of γ-ray induced activation of the pathway for doses up to 5Gy but highlighted important transient effects of common environmental stress (e.g. CO₂, temperature) and laboratory procedures, e.g. replacing the culture medium, which dominate the in vitro inflammatory response.