Monitoring mitochondrial metabolisms in irradiated human cancer cells with 99mTc-MIBI

Reprint of: Deciphering and simulating models of radiation genotoxicity with CRISPR/Cas9 systems

This short review explores the utility and applications of CRISPR/Cas9 systems in radiobiology. Specifically, in the context of experimentally simulating genotoxic effects of Ionizing Radiation (IR) to determine the contributions from DNA targets and 'Complex Double-Stranded Breaks' (complex DSBs) to the IR response. To elucidate this objective, this review considers applications of CRISPR/Cas9 on nuclear DNA targets to recognize the respective 'nucleocentric' response. The article also highlights contributions from mitochondrial DNA (mtDNA) - an often under-recognized target in radiobiology. This objective requires accurate experimental simulation of IR-like effects and parameters with the CRISPR/Cas9 systems. Therefore, the role of anti-CRISPR proteins in modulating enzyme activity to simulate dose rate - an important factor in radiobiology experiments is an important topic of this review. The applications of auxiliary domains on the Cas9 nuclease to simulate oxidative base damage and multiple stressor experiments are also topics of discussion. Ultimately, incorporation of CRISPR/Cas9 experiments into computational parameters in radiobiology models of IR damage and shortcomings to the technology are discussed as well. Altogether, the simulation of IR parameters and lack of damage to non-DNA targets in the CRISPR/Cas9 system lends this rapidly emerging tool as an effective model of IR induced DNA damage. Therefore, this literature review ultimately considers the relevance of complex DSBs to radiobiology with respect to using the CRISPR/Cas9 system as an effective experimental tool in models of IR induced effects.

Deciphering and simulating models of radiation genotoxicity with CRISPR/Cas9 systems

This short review explores the utility and applications of CRISPR/Cas9 systems in radiobiology. Specifically, in the context of experimentally simulating genotoxic effects of Ionizing Radiation (IR) to determine the contributions from DNA targets and 'Complex Double-Stranded Breaks' (complex DSBs) to the IR response. To elucidate this objective, this review considers applications of CRISPR/Cas9 on nuclear DNA targets to recognize the respective 'nucleocentric' response. The article also highlights contributions from mitochondrial DNA (mtDNA) - an often under-recognized target in radiobiology. This objective requires accurate experimental simulation of IR-like effects and parameters with the CRISPR/Cas9 systems. Therefore, the role of anti-CRISPR proteins in modulating enzyme activity to simulate dose rate - an important factor in radiobiology experiments is an important topic of this review. The applications of auxiliary domains on the Cas9 nuclease to simulate oxidative base damage and multiple stressor experiments are also topics of discussion. Ultimately, incorporation of CRISPR/Cas9 experiments into computational parameters in radiobiology models of IR damage and shortcomings to the technology are discussed as well. Altogether, the simulation of IR parameters and lack of damage to non-DNA targets in the CRISPR/Cas9 system lends this rapidly emerging tool as an effective model of IR induced DNA damage. Therefore, this literature review ultimately considers the relevance of complex DSBs to radiobiology with respect to using the CRISPR/Cas9 system as an effective experimental tool in models of IR induced effects.

The fluorescent bioprobe with aggregation-induced emission features for monitoring to carbon dioxide generation rate in single living cell and early identification of cancer cells

A novel fluorescent probe, tris (2-(dimethylamino) ethyl)-4,4',4″-(1H-pyrrole-1,2,5-triyl) tribenzoate (TPP-TMAE), with aggregation-enhanced emission (AEE) feature showed a simple, highly selective, specific, and instant response to trace amount carbon dioxide (CO2). Because of this special characteristic, TPP-TMAE is ideal to be a biomarker for in-situ monitoring of the CO2 generation rate during the metabolism of single living cell. The rates in single living HeLa cell, MCF-7 cell, and MEF cell were 6.40 × 10(-6)±6.0 × 10(-8) μg/h, 5.78 × 10(-6)±6.0 × 10(-8) μg/h, and 4.27 × 10(-7)±4.0 × 10(-9) μg/h, respectively. The distinct responses of TPP-TMAE to CO2 generated from cancer cells and normal cells suggested TPP-TMAE as a useful tool for deeper understanding metabolism process and distinguishing cancer cells from normal cells during the early diagnosis of cancers.

Influence of P-Glycoprotein Inhibition or Deficiency at the Blood-Brain Barrier on (18)F-2-Fluoro-2-Deoxy-D-glucose ( (18)F-FDG) Brain Kinetics

The fluorinated D-glucose analog (18)F-2-fluoro-2-deoxy-D-glucose ((18)F-FDG) is the most prevalent radiopharmaceutical for positron emission tomography (PET) imaging. P-Glycoprotein's (P-gp, MDR1, and ABCB1) function in various cancer cell lines and tumors was shown to impact (18)F-FDG incorporation, suggesting that P-gp function at the blood-brain barrier may also modulate (18)F-FDG brain kinetics. We tested the influence of P-gp inhibition using the cyclosporine analog valspodar (PSC833; 5 μM) on the uptake of (18)F-FDG in standardized human P-gp-overexpressing cells (MDCKII-MDR1). Consequences for (18)F-FDG brain kinetics were then assessed using (i) (18)F-FDG PET imaging and suitable kinetic modelling in baboons without or with P-gp inhibition by intravenous cyclosporine infusion (15 mg kg(-1) h(-1)) and (ii) in situ brain perfusion in wild-type and P-gp/Bcrp (breast cancer resistance protein) knockout mice and controlled D-glucose exposure to the brain. In vitro, the time course of (18)F-FDG uptake in MDR1 cells was influenced by the presence of valspodar in the absence of D-glucose but not in the presence of high D-glucose concentration. PET analysis revealed that P-gp inhibition had no significant impact on estimated brain kinetics parameters K 1, k 2, k 3, V T , and CMRGlc. The lack of P-gp effect on in vivo (18)F-FDG brain distribution was confirmed in P-gp/Bcrp-deficient mice. P-gp inhibition indirectly modulates (18)F-FDG uptake into P-gp-overexpressing cells, possibly through differences in the energetic cell level state. (18)F-FDG is not a P-gp substrate at the BBB and (18)F-FDG brain kinetics as well as estimated brain glucose metabolism are influenced by neither P-gp inhibition nor P-gp/Bcrp deficiencies in baboon and mice, respectively.

Skin perfusion and oxygenation changes in radiation fibrosis

BACKGROUND

Ionizing radiation is known to have deleterious chronic effects on skin, including fibrosis and poor wound healing, hypothesized as mediated by ischemia and hypoxia. Past studies have been unable to simultaneously investigate changes in perfusion and oxygenation as separate parameters. Hyperspectral imaging has emerged as a tool with which to concurrently measure skin perfusion and oxygenation. The authors investigated the use of hyperspectral imaging in a novel murine model of chronic radiation injury.

METHODS

Areas of flank skin (n = 20) on hairless mice were exposed to a 50-Gy dose of beta-radiation. Hyperspectral imaging acquisition was performed at select points through 8 weeks. Immunohistochemical staining and gene expression analysis were performed to evaluate cutaneous vascular density, epidermal cell hypoxia, and angiogenic factors.

RESULTS

All irradiated areas developed a chronic-phase wound by day 28. Hyperspectral imaging demonstrated a 21 percent decline in perfusion on day 56 (p < 0.001), whereas oxygenation levels were unchanged. A 1.7-fold reduction in blood vessel density was measured in irradiated skin compared with control tissue (p < 0.001), but no difference in epidermal cell hypoxia was observed. Vascular endothelial growth factor and related receptor expression were significantly lower in irradiated tissue.

CONCLUSIONS

The authors' analysis does not support the presence of hypoxia in chronic-phase irradiated skin but suggests that hypoperfusion may be a predominant characteristic. The concurrent states of hypoperfusion and normoxia may be explained by the lower metabolic demands of fibrosed tissue.

Differentiation of tumor sensitivity to photodynamic therapy and early evaluation of treatment effect by nuclear medicine techniques

OBJECTIVE

Our final goal is to develop an appropriate method using nuclear medicine technique for monitoring the effect and prediction of Photodynamic Therapy (PDT) on tumors. The aim of this study is to evaluate the effect of PDT on tumor cells in vitro using (18)F-FDG and (99m)Tc-MIBI as tracers.

METHODS

Five tumor cell lines (A431, DU145, H1650, LS180, SHIN3) with varied characteristics were irradiated after incubating for 24 h with several doses of Photofrin (PF). Singlet oxygen was monitored by the near-IR emission detection system during irradiation and generated (1)O2 was calculated. PDT effects were rapidly evaluated by nuclear medicine techniques (uptake of (18)F-FDG and (99m)Tc-MIBI) and traditional methods for cell viability (MTT and trypan blue assays) at 3 h after PDT. Intracellular PF concentration was measured by absorption spectrometer and cell protein content was measured by the Lowry method. (18)F-FDG uptake, (99m)Tc-MIBI uptake, singlet oxygen, and intracellular PF concentration were standardized by protein content. Decrease % of (18)F-FDG and (99m)Tc-MIBI, MTT, and trypan blue was normalized to the control group.

RESULTS

Decrease % of (18)F-FDG was exponentially related to decrease % of MTT (R (2) = 0.650, P < 0.01) while decrease % of (99m)Tc-MIBI was linearly related to that of MTT (R (2) = 0.719, P < 0.01). The decrease % of MTT was more sensitive than that of trypan blue. However, neither (1)O2 nor PF uptake was correlated with sensitivity to PDT. In addition, (18)F-FDG uptake before PDT was linearly related to decrease % of MTT (R (2) = 0.800, P < 0.05).

CONCLUSIONS

Our findings in in vitro studies suggest that (99m)Tc-MIBI is better than (18)F-FDG for early evaluation of PDT effect, but (18)F-FDG uptake may be used to predict PDT sensitivity before therapy.

Protection of mitochondrial system by Hippophae rhamnoides L. against radiation-induced oxidative damage in mice

The whole extract of the fresh berries of Hippophae rhamnoides L. (RH−3), which has been reported to provide protection to whole mice, various tissues, cells and cell organelles against lethal irradiation, was further investigated for its effects on mitochondria isolated from mouse liver. Superoxide anion, reduced (GSH) and oxidized glutathione (GSSG) levels, NADH-ubiquinone oxidoreductase (complex I), NADH-cytochrome c oxidoreductase (complex I/II), succinate-cytochrome c oxidoreductase (complex II/III), mitochondrial membrane potential (MMP), lipid peroxidation (LPx) and protein oxidation (PO) were determined for RH-3-mediated radioprotective manifestation. Pre-irradiation treatment of mice with RH-3 (30 mg kg−1, i.p.; single dose; −30 min) significantly inhibited the radiation-induced increase in superoxide anions, GSSG, thiobarbituric acid reactive substances (TBARS), complex I, complex I/III activity and MMP maximally at 4 h (P &lt; 0.05). This treatment inhibited the oxidation of proteins (P &lt; 0.05) at all the time periods studied here. This study suggests that pre-irradiation treatment of mice with RH-3 protects the functional integrity of mitochondria from radiation-induced oxidative stress.

Oncocytic modifications in rectal adenocarcinomas after radio and chemotherapy

The purpose of the study is to highlight oncocytic modifications in rectal adenocarcinomas and evaluate a possible correlation with preoperative radiochemotherapy (RCT). Twenty-eight cases of advanced rectal carcinoma, treated preoperatively by 5-fluorouracil (200-225 mg/m(2)) and 44-46 Gy in 22-23 fractions, were studied. All patients underwent biopsy before RCT. Surgery was performed within 6 weeks after RCT. In all cases oncocytic modifications were searched for on hematoxylin and eosin (H&E) and at immunohistochemistry using an antimitochondrial antibody. In addition, in two cases, both pre- and post-RCT tissues were examined at electron microscopy. All tumors were adenocarcinomas. In pre-RCT biopsies, oncocytic changes were difficult to find on H&E, while the antimitochondrial antibody strongly stained numerous neoplastic cells (mean 48.4%). In post-RCT surgical specimens, oncocytic changes were detected in 24 out of 28 cases on H&E and the antimitochondrial antibody stained most of the residual neoplastic cells (mean 76.7%). Ultrastructural examination revealed large and bizarre mitochondria inside tumor cells both in pre- and post-RCT tissues. In conclusion, the present data suggest that rectal adenocarcinomas are "mitochondrion-rich" tumors. After preoperative RCT, residual neoplastic cells acquire a definite oncocytic phenotype.