Chemical Radioprotection and Radiosensitization of Mammalian Cells Growing<i>in Vitro</i>

Chapman, J. D.; Reuvers, A. P.; Borsa, J.; Greenstock, C.L.

doi:10.1667/rrav18.1

Cited by 115 publications

(7 citation statements)

References 33 publications

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“…Because of the high sensitivity of biological cells to radiation, and the fact that the dose is increasing as the resolution approches smaller values, it is essential to reduce energy input, when using multimodal techniques, especially, when employing scanning methods. ,, Here we study freeze-dried cells, thus largly avoiding the impact of free radicals induced by the radiolysis of water. , These radicals represent 80% of the energy deposition in cells when irradiated. , For example, hydroxyl radicals (·OH) are associated with changes in structural and functional molecules . Alternative techniques using cryo-streams of N 2 at 100 K reduce the diffusion of free radicals very efficiently es well. ,, We combine and correlate two X-ray imaging techniques, ptychography and nanodiffraction. , Ptychography images of the whole cell, as shown in Figure a, serve to localize the sample with respect to the X-ray beam.…”

Section: Resultsmentioning

confidence: 99%

X-rays Reveal the Internal Structure of Keratin Bundles in Whole Cells

et al. 2016

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In recent years, X-ray imaging of biological cells has emerged as a complementary alternative to fluorescence and electron microscopy. Different techniques were established and successfully applied to macromolecular assemblies and structures in cells. However, while the resolution is reaching the nanometer scale, the dose is increasing. It is essential to develop strategies to overcome or reduce radiation damage. Here we approach this intrinsic problem by combing two different X-ray techniques, namely ptychography and nanodiffraction, in one experiment and on the same sample. We acquire low dose ptychography overview images of whole cells at a resolution of 65 nm. We subsequently record high-resolution nanodiffraction data from regions of interest. By comparing images from the two modalities, we can exclude strong effects of radiation damage on the specimen. From the diffraction data we retrieve quantitative structural information from intracellular bundles of keratin intermediate filaments such as a filament radius of 5 nm, hexagonal geometric arrangement with an interfilament distance of 14 nm and bundle diameters on the order of 70 nm. Thus, we present an appealing combined approach to answer a broad range of questions in soft-matter physics, biophysics and biology.

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Section: Resultsmentioning

confidence: 99%

X-rays Reveal the Internal Structure of Keratin Bundles in Whole Cells

et al. 2016

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“…It is possible to image hydrated and even (initially) living cells by scanning nanodiffraction, , but the electron density contrast between sample and environment is low, preventing sufficient photon statistics in the individual diffraction patterns. Moreover, in liquids, the motility of free radicals produced by water radiolysis is very pronounced, leading to severe radiation damage. − Thus, in the past, we have mostly focused on freeze-dried samples providing a comparatively high electron density contrast and reducing the effect of radiation damage. ,, However, radiation damage still remains a challenge, and nanoscale defects caused by the radiation have to be carefully assessed. We have previously shown that such nanoscale changes are observable in average diffraction patterns and in the related power law decay (Porod exponent).…”

Section: Resultsmentioning

confidence: 99%

Following DNA Compaction During the Cell Cycle by X-ray Nanodiffraction

et al. 2016

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X-ray imaging of intact biological cells is emerging as a complementary method to visible light or electron microscopy. Owing to the high penetration depth and small wavelength of X-rays, it is possible to resolve subcellular structures at a resolution of a few nanometers. Here, we apply scanning X-ray nanodiffraction in combination with time-lapse bright-field microscopy to nuclei of 3T3 fibroblasts and thus relate the observed structures to specific phases in the cell division cycle. We scan the sample at a step size of 250 nm and analyze the individual diffraction patterns according to a generalized Porod's law. Thus, we obtain information on the aggregation state of the nuclear DNA at a real space resolution on the order of the step size and in parallel structural information on the order of few nanometers. We are able to distinguish nucleoli, heterochromatin, and euchromatin in the nuclei and follow the compaction and decompaction during the cell division cycle.

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“…Adversely, the apoptosis genes, such as Bax and C-PARP, were upregulated. According to former research, approximately 80% of radiation-induced apoptosis is caused by indirect damage via ROS production [ 16 ]. Consequently, increased oxidative stress has been observed after irradiation, which plays an important role in effective radiotherapy [ 17 , 18 ].…”

Section: Discussionmentioning

confidence: 99%

UBE2C mediated radiotherapy resistance of head and neck squamous cell carcinoma by regulating oxidative-stress-relative apoptosis

Zhou

Zhang

Gong

et al. 2022

Aging

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Purpose: Radiotherapy resistance is the main obstacle in the effective treatment of advanced head and neck squamous cell carcinoma (HNSCC). Increasing scientific opinions present that ubiquitin-conjugating enzyme E2C (UBE2C) might be a target gene acting as an oncogene. Method: TCGA database was used to analyze the expression of UBE2C in HNSCC patients, and the relationship between UBE2C expression and prognosis. Western blot and RT-PCR were used to assess UBE2C expression before and after radiation. Then, cell viability experiment and colony formation were used to evaluate proliferation after 2 Gy radiation. Cell viability experiment, migration, and invasion were evaluated in the condition of UBE2C knock-down. Western blot and RT-PCR were used to assess the expression of apoptosis and ROS relative gene expression. Then, the xenograft model was used to evaluate the efficacy of radiation combined with UBE2C suppression. Result: The expression of UBE2C was high in tumors of patients with HNSCC and relatives with poor prognoses. Si-UBE2C cells showed proliferation inhibited and apoptosis enhanced after radiation. Furthermore, the mechanism of UBE2C in HNSCC radioresistance was explored. We performed RT-PCR to find the 4-HNE, which increases oxidative-stress-relative apoptosis in Si-UBE2C cells after radiation. Conclusions: Through the RT-PCR, WB, cell viability experiment, migration, invasion, and in vivo experiment, UBE2C was confirmed to downregulate oxidative-stress-relative apoptosis induced by radiation and promote the development of malignant tumor cells.

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Chemical Radioprotection and Radiosensitization of Mammalian Cells Growingin Vitro

Cited by 115 publications

References 33 publications

X-rays Reveal the Internal Structure of Keratin Bundles in Whole Cells

X-rays Reveal the Internal Structure of Keratin Bundles in Whole Cells

Following DNA Compaction During the Cell Cycle by X-ray Nanodiffraction

UBE2C mediated radiotherapy resistance of head and neck squamous cell carcinoma by regulating oxidative-stress-relative apoptosis

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