The EGFR mutation status affects the relative biological effectiveness of carbon-ion beams in non-small cell lung carcinoma cells

学位記番号：医博甲1574

Carbon-Ion Beam Irradiation Kills X-Ray-Resistant p53-Null Cancer Cells by Inducing Mitotic Catastrophe

Background and Purpose: To understand the mechanisms involved in the strong killing effect of carbon-ion beam irradiation on cancer cells with TP53 tumor suppressor gene deficiencies.Copyright:Materials and Methods: DNA damage responses after carbon-ion beam or X-ray irradiation in isogenic HCT116 colorectal cancer cell lines with and without TP53 (p53+/ + and p53-/-, respectively) were analyzed as follows: cell survival by clonogenic assay, cell death modes by morphologic observation of DAPI-stained nuclei, DNA doublestrand breaks (DSBs) by immunostaining of phosphorylated H2AX (γH2AX), and cell cycle by flow cytometry and immunostaining of Ser10-phosphorylated histone H3.Results: The p53-/- cells were more resistant than the p53+/+ cells to X-ray irradiation, while the sensitivities of the p53+/+ and p53-/- cells to carbon-ion beam irradiation were comparable. X-ray and carbon-ion beam irradiations predominantly induced apoptosis of the p53+/+ cells but not the p53-/- cells. In the p53-/- cells, carbon-ion beam irradiation, but not X-ray irradiation, markedly induced mitotic catastrophe that was associated with premature mitotic entry with harboring longretained DSBs at 24 h post-irradiation.Conclusions: Efficient induction of mitotic catastrophe in apoptosis-resistant p53- deficient cells implies a strong cancer cell-killing effect of carbon-ion beam irradiation that is independent of the p53 status, suggesting its biological advantage over X-ray treatment

IBS-GEC ESTRO-ABS recommendations for CT based contouring in image guided adaptive brachytherapy for cervical cancer

MR Imaging is regarded asthe gold standardfor Image Gudied Adaptive Brachytherapy (IGABT) for cervical cancer. However, its wide applicability is limited by its availability, logistics and financial implications. Use of alternative imaging like CTand Ultrasound (US) for IGABT has been attempted. In order to arrive at a systematic, uniform and international approach for CT based definition and contouring of target structures, GEC ESTRO, IBS and ABS agreed to jointly develop such recommendations based on the concepts and terms as published in the ICRU Report 89. The minimum requirements are clinical examination & documentation, CT or MR imaging at diagnosis and at a minimum, CT imaging with the applicator in place. The recommendations are based on (i) assessment of the GTV at diagnosis and at brachytherapy, (ii) categorizing the response to external radiation into different clinical remission patterns, (iii) defining various clinico-radiological environments and (iv) definition & delineation of a target on CT imaging at the time of brachytherapy with the applicator in situ. CT based target contouring recommendations based on 4 remission categories within 8 defined environments, aim at improving the contouring accuracy for IGABT using CT, US and MRI as available. For each clinico-radiological environment, there is an attempt to minimize the specific uncertainties in order to arrive at the best possible contouring accuracy. Evaluating feasibility & reproducibility, to achieve a benchmark towards a gold standard MR IGABT and further clinical research including outcomes with CT Based IGABT will become the next steps

Assessment of the confidence interval in the multivariable normal tissue complication probability model for predicting radiation-induced liver disease in primary liver cancer

We developed a confidence interval-(CI) assessing model in multivariable normal tissue complication probability (NTCP) modeling for predicting radiation-induced liver disease (RILD) in primary liver cancer patients using clinical and dosimetric data. Both the mean NTCP and difference in the mean NTCP (Delta NTCP) between two treatment plans of different radiotherapy modalities were further evaluated and their CIs were assessed. Clinical data were retrospectively reviewed in 322 patients with hepatocellular carcinoma (n = 215) and intrahepatic cholangiocarcinoma (n = 107) treated with photon therapy. Dose-volume histograms of normal liver were reduced to mean liver dose (MLD) based on the fraction size-adjusted equivalent uniform dose. The most predictive variables were used to build the model based on multivariable logistic regression analysis with bootstrapping. Internal validation was performed using the cross-validation leave-one-out method. Both the mean NTCP and the mean Delta NTCP with 95% CIs were calculated from computationally generated multivariate random sets of NTCP model parameters using variance-covariance matrix information. RILD occurred in 108/322 patients (33.5%). The NTCP model with three clinical and one dosimetric parameter (tumor type, Child-Pugh class, hepatitis infection status and MLD) was most predictive, with an area under the receiver operative characteristics curve (AUC) of 0.79 (95% CI 0.74-0.84). In eight clinical subgroups based on the three clinical parameters, both the mean NTCP and the mean Delta NTCP with 95% CIs were able to be estimated computationally. The multivariable NTCP model with the assessment of 95% CIs has potential to improve the reliability of the NTCP model-based approach to select the appropriate radiotherapy modality for each patient

Cell cycle profiles of p53^+/+ and p53^-/- HCT116 cells irradiated with X-rays or carbon-ion beams.

<p>Cells were seeded in 35 mm culture plates (a, b) or on glass coverslips (c), incubated overnight, and exposed (or not; 0 h) to X-ray (4 Gy) or carbon-ion beam (1.5 Gy) irradiation. (<b>a, b</b>) Cells irradiated with X-rays (a) or carbon-ion beams (b) were incubated for 0, 12, 24, 48, 72, 96 or 120 h, fixed with ethanol, stained with propidium iodide, and cell cycle status analyzed by flow cytometry. (<b>c</b>) Cells were irradiated with X-rays or carbon-ion beams, incubated for 1 h, and then subjected to immunostaining for pH3, a specific marker for M phase cells. Data are expressed as the mean ± SD. *<i>P</i><0.05 and †<i>P</i><0.01 versus the corresponding controls. IR, irradiation; C-ion, carbon-ion.</p

Mode of cell death induced by X-ray or carbon-ion beam irradiation in isogenic H1299 cells expressing different p53 missense mutations.

<p>Cells were seeded on glass coverslips, incubated overnight, irradiated with X-rays (10.9 Gy, D₁₀ for X-rays; or 3.8 Gy, D₁₀ for carbon-ion beams) or carbon-ion beams (3.8 Gy, D₁₀ for carbon-ion beams), and then stained with DAPI 72 h later. Apoptosis, mitotic catastrophe, and senescence were determined according to the characteristic nuclear morphologies (see “<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115121#s2" target="_blank">Materials and methods</a>” for the definitions). Data are expressed as the mean ± SD. MC, mitotic catastrophe; C-ion, carbon-ion; IR, irradiation. Note that a part of p53-null H1299 panel is the same as that shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115121#pone-0115121-g004" target="_blank">Fig. 4</a> (but the context is now different).</p