Summary of DNA copy number aberrations identified in twenty C-TL and twelve G-TL.

<p>Copy number variations associated with recombination at the TCRβ, TCRγ, TCRα/δ, Skint, IgH, IgLκ and IgLλ loci are omitted for clarity. Where a locus is listed, the feature was observed within this gene, or the feature included this gene, as noted. Where the feature covered multiple genes and was not clearly associated with any one locus, no locus is listed. Although multiple tumours may be listed for any one feature, the precise nature of each copy number change varied between tumours. Where there is more than one of the same type of feature listed for the same chromosome, each feature represents a distinct chromosomal location.</p><p>Summary of DNA copy number aberrations identified in twenty C-TL and twelve G-TL.</p

Genetic Analysis of T Cell Lymphomas in Carbon Ion-Irradiated Mice Reveals Frequent Interstitial Chromosome Deletions: Implications for Second Cancer Induction in Normal Tissues during Carbon Ion Radiotherapy

<div><p>Monitoring mice exposed to carbon ion radiotherapy provides an indirect method to evaluate the potential for second cancer induction in normal tissues outside the radiotherapy target volume, since such estimates are not yet possible from historical patient data. Here, male and female B6C3F1 mice were given single or fractionated whole-body exposure(s) to a monoenergetic carbon ion radiotherapy beam at the Heavy Ion Medical Accelerator in Chiba, Japan, matching the radiation quality delivered to the normal tissue ahead of the tumour volume (average linear energy transfer = 13 keV.μm^-1) during patient radiotherapy protocols. The mice were monitored for the remainder of their lifespan, and a large number of T cell lymphomas that arose in these mice were analysed alongside those arising following an equivalent dose of ¹³⁷Cs gamma ray-irradiation. Using genome-wide DNA copy number analysis to identify genomic loci involved in radiation-induced lymphomagenesis and subsequent detailed analysis of <i>Notch1</i>, <i>Ikzf1</i>, <i>Pten</i>, <i>Trp53</i> and <i>Bcl11b</i> genes, we compared the genetic profile of the carbon ion- and gamma ray-induced tumours. The canonical set of genes previously associated with radiation-induced T cell lymphoma was identified in both radiation groups. While the pattern of disruption of the various pathways was somewhat different between the radiation types, most notably <i>Pten</i> mutation frequency and loss of heterozygosity flanking <i>Bcl11b</i>, the most striking finding was the observation of large interstitial deletions at various sites across the genome in carbon ion-induced tumours, which were only seen infrequently in the gamma ray-induced tumours analysed. If such large interstitial chromosomal deletions are a characteristic lesion of carbon ion irradiation, even when using the low linear energy transfer radiation to which normal tissues are exposed in radiotherapy patients, understanding the dose-response and tissue specificity of such DNA damage could prove key to assessing second cancer risk in carbon ion radiotherapy patients.</p></div

Lifespan shortening after exposure of mice to gamma-rays or carbon ions during fetal, childhood and adult periods

There are insufficient data at present to inform cancer risk after radiation exposure, during fetal and childhood periods, especially for heavy ions. Using animal models, we studied the age-at-exposure effect of radiation on cancer induction and lifespan shortening, in order to propose age-weighting factors and relative biological effectiveness (RBE) of heavy ions for radiation protection of fetuses and children. Fifty female and male B6C3F1 mice per group were exposed to gamma rays (137Cs) or carbon ions (13 keV/&micro;m) at various ages from fetal to mature adult periods. Mouse ages at the time of irradiation included 3 days post-conception (dpc), 13 dpc, 17 dpc, and 1 week, 3 weeks, 7 weeks and 15 weeks after birth. The doses ranged between 0.2 and 4 Gy for gamma rays and 0.2 and 2 Gy for carbon ions. The mice were observed until moribund and their lifespan and tumor burden were analyzed.Female mice appeared to be more susceptible to radiation-induced lifespan shortening than male mice. The effect of gamma-rays on lifespan shortening was more pronounced when irradiated at 1 week rather than 7 weeks of age. Surprisingly, irradiation with gamma rays at the late fetal stage had little influence on lifespan shortening compared to infant and adult exposures. Carbon ions were more potent in reducing lifespan than gamma rays when 1 week-old mice were exposed. In the case of carbon ions, however, fetuses were still susceptible as infants. The results on lifespan shortening suggest a larger RBE of carbon ions for fetuses compared to later stages. But, if acute non-cancer effects were excluded, the survival curve for fetuses was similar to that for later ages.Heavy Ion in Therapy and Space Radiation Symposium 201

Distribution of large interstitial deletion frequency by irradiation group.

<p>The number of large interstitial deletions (>250 kb) per tumour is shown for each treatment group as a percentage of the number of tumours examined by array CGH (<i>n</i> = 4–6 per carbon group, <i>n</i> = 12 gamma group). The number of tumours analysed per carbon dose group did not permit pairwise comparisons of rank, but the difference between the pooled carbon group (<i>n</i> = 20) and the gamma group approaches significance (<i>P</i> = 0.053, Mann-Whitney U-Test). Across the four carbon groups the number of TL with at least one large interstitial deletion ranged from 50–75%, while only 25% of G-TL harboured one or more large interstitial deletions (mean of 1.4 large interstitial deletions per C-TL, and 0.5 per G-TL). Interestingly, the single G-TL with 4 large interstitial deletions contained two independent large deletions overlapping over the B cell differentiation gene <i>Pax5</i> (the only TL to have <i>Pax5</i> involvement) and was the only TL to have a rearranged immunoglobulin light chain gene, which together may point towards a distinct tumour phenotype.</p

Patterns of Oncogene Activation and TSG Inactivation.

<p>All 117 tumours are sorted by the presence (1) or absence (0) of specific aberrations in <i>Notch1</i>, <i>Ikzf1</i>, <i>Pten</i>, <i>Trp53</i> and <i>Bcl11b</i>, with (-) denoting an unclear result. Patterns of activation/inactivation are highlighted by letter codes as shown in the key, for <i>Notch1</i> (A-E), <i>Ikzf1</i> (F-H) and <i>Pten</i> (I-K). Almost complete LOH at the <i>Bcl11b</i> locus can be observed, along with high frequency of <i>Notch1</i> aberrations. <i>Pten</i> aberrations, and particularly homozygous <i>Pten</i> mutations, are more frequently associated with tumours not carrying the combined 5′ Deletion and PEST mutation in <i>Notch1</i>.</p

Summary of DNA copy number aberrations identified in twenty C-TL and twelve G-TL.

<p>Copy number variations associated with recombination at the TCRβ, TCRγ, TCRα/δ, Skint, IgH, IgLκ and IgLλ loci are omitted for clarity. Where a locus is listed, the feature was observed within this gene, or the feature included this gene, as noted. Where the feature covered multiple genes and was not clearly associated with any one locus, no locus is listed. Although multiple tumours may be listed for any one feature, the precise nature of each copy number change varied between tumours. Where there is more than one of the same type of feature listed for the same chromosome, each feature represents a distinct chromosomal location.</p><p>Summary of DNA copy number aberrations identified in twenty C-TL and twelve G-TL.</p

Lifespan shortening after exposure of mice to gamma-rays, carbon ions and neutrons during fetal, childhood and adult periods

There are insufficient data at present to inform cancer risk after radiation exposure, during fetal and childhood periods, especially for heavy ions and neutrons. Using animal models, we studied the age-at-exposure effect of radiation on cancer induction and lifespan shortening, in order to propose age-weighting factors and relative biological effectiveness (RBE) of heavy ions for radiation protection of fetuses and children. Fifty female and male B6C3F1 mice per group were exposed to gamma rays (137Cs), carbon ions (13 keV/&micro;m) generated from Heavy Ion Accerelator in Chiba (HIMAC), or neutrons (average energy, 1-2 MeV) from Neutron Exposure Accelerator System for Biological Effect Experiments (NASBEE), at various ages from fetal to mature adult periods. Mouse ages at the time of irradiation included 3 days post-conception (dpc), 13 dpc, 17 dpc, and 1 week, 3 weeks, 7 weeks and 15 weeks after birth. The doses ranged between 0.2 and 4 Gy for gamma rays, 0.2 and 2 Gy for carbon ions, and 0.05 and 1 Gy for neutrons. Mice were observed until moribund and their lifespan and tumor burden were analyzed.Female mice appeared to be more susceptible to radiation-induced lifespan shortening than male mice. The effect of gamma-rays on lifespan shortening was more pronounced when irradiated at 1 week rather than 7 weeks of age. Surprisingly, irradiation with gamma rays at the late fetal stage had little influence on lifespan shortening compared to infant and adult exposures. Carbon ions and neutrons were more potent in reducing lifespan than gamma rays when 1 week-old mice and fetuses were exposed. These results on lifespan shortening suggest the highest RBE value were obtained for neutrons. Currently, pathological examination is undertaken to clarify the cause of life shortening.59ｔｈ　Annual Meeting　of the Radiation Research Societ

Combined DNA copy number information, loss or retention of heterozygosity and mutation screening.

<p>Data for chromosomes 11, 12 and 19, from twelve G-TL and twenty C-TL are shown. Each column represents a single tumour down through all three panels. Columns are ordered manually based on observed groupings. Each row represents either LOH and DNA copy number (CGH) data, DNA copy number data only (<i>Bcl11b</i> locus) or DNA copy number and mutation data (<i>Ikzf1</i>, <i>Trp53</i> and <i>Pten</i> loci). Locations noted in each row are from GRCm38 positioning.</p

Comparative Incidence for Genetic Features found in G-TL and C-TL.

<p><i>P</i> values shown are from Fisher’s Exact Test, with differences significant at the 0.05 level marked (*)</p><p>Comparative Incidence for Genetic Features found in G-TL and C-TL.</p