Reduced chromosome aberration complexity in normal human bronchial epithelial cells exposed to low-LET γ-rays and high-LET α-particles

This article is made available through the Brunel Open Access Publishing Fund.Copyright © 2013 The Author(s). Purpose: Cells of the lung are at risk from exposure to low and moderate doses of ionizing radiation from a range of environmental and medical sources. To help assess human health risks from such exposures, a better understanding of the frequency and types of chromosome aberration initially-induced in human lung cell types is required to link initial DNA damage and rearrangements with transmission potential and, to assess how this varies with radiation quality. Materials and methods: We exposed normal human bronchial lung epithelial (NHBE) cells in vitro to 0.5 and 1 Gy low-linear energy transfer (LET) γ-rays and a low fluence of high-LET α-particles and assayed for chromosome aberrations in premature chromosome condensation (PCC) spreads by 24-color multiplex-fluorescence in situ hybridization (M-FISH). Results: Both simple and complex aberrations were induced in a LET and dose-dependent manner; however, the frequency and complexity observed were reduced in comparison to that previously reported in spherical cell types after exposure to comparable doses or fluence of radiation. Approximately 1–2% of all exposed cells were categorized as being capable of transmitting radiation-induced chromosomal damage to future NHBE cell generations, irrespective of dose. Conclusion: One possible mechanistic explanation for this reduced complexity is the differing geometric organization of chromosome territories within ellipsoid nuclei compared to spherical nuclei. This study highlights the need to better understand the role of nuclear organization in the formation of exchange aberrations and, the influence three-dimensional (3D) tissue architecture may have on this in vivo.Department of Health, UK (Contract RRX115)

Relative proximity of chromosome territories influences chromosome exchange partners in radiation-induced chromosome rearrangements in primary human bronchial epithelial cells

Copyright © 2013 The Authors. This article is made available through the Brunel Open Access Publishing Fund. This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.Copyright © 2013 The Authors. It is well established that chromosomes exist in discrete territories (CTs) in interphase and are positioned in a cell-type specific probabilistic manner. The relative localisation of individual CTs within cell nuclei remains poorly understood, yet many cancers are associated with specific chromosome rearrangements and there is good evidence that relative territorial position influences their frequency of exchange. To examine this further, we characterised the complexity of radiation-induced chromosome exchanges in normal human bronchial epithelial (NHBE) cells by M-FISH analysis of PCC spreads and correlated the exchanges induced with their preferred interphase position, as determined by 1/2-colour 2D-FISH analysis, at the time of irradiation. We found that the frequency and complexity of aberrations induced were reduced in ellipsoid NHBE cells in comparison to previous observations in spherical cells, consistent with aberration complexity being dependent upon the number and proximity of damaged CTs, i.e. lesion proximity. To ask if particular chromosome neighbourhoods could be identified we analysed all radiation-induced pair-wise exchanges using SCHIP (statistics for chromosome interphase positioning) and found that exchanges between chromosomes (1;13), (9;17), (9;18), (12;18) and (16;21) all occurred more often than expected assuming randomness. All of these pairs were also found to be either sharing similar preferred positions in interphase and/or sharing neighbouring territory boundaries. We also analysed a human small cell lung cancer cell line, DMS53, by M-FISH observing the genome to be highly rearranged, yet possessing rearrangements also involving chromosomes (1;13) and (9;17). Our findings show evidence for the occurrence of non-random exchanges that may reflect the territorial organisation of chromosomes in interphase at time of damage and highlight the importance of cellular geometry for the induction of aberrations of varying complexity after exposure to both low and high-LET radiation.Department of Healt

Genomic imbalances are confined to non-proliferating cells in paediatric patients with acute myeloid leukaemia and a normal or incomplete karyotype

Copyright @ 2011 Ballabio et al.Leukaemia is often associated with genetic alterations such as translocations, amplifications and deletions, and recurrent chromosome abnormalities are used as markers of diagnostic and prognostic relevance. However, a proportion of acute myeloid leukaemia (AML) cases have an apparently normal karyotype despite comprehensive cytogenetic analysis. Based on conventional cytogenetic analysis of banded chromosomes, we selected a series of 23 paediatric patients with acute myeloid leukaemia and performed whole genome array comparative genome hybridization (aCGH) using DNA samples derived from the same patients. Imbalances involving large chromosomal regions or entire chromosomes were detected by aCGH in seven of the patients studied. Results were validated by fluorescence in situ hybridization (FISH) to both interphase nuclei and metaphase chromosomes using appropriate bacterial artificial chromosome (BAC) probes. The majority of these copy number alterations (CNAs) were confirmed by FISH and found to localize to the interphase rather than metaphase nuclei. Furthermore, the proliferative states of the cells analyzed by FISH were tested by immunofluorescence using an antibody against the proliferation marker pKi67. Interestingly, these experiments showed that, in the vast majority of cases, the changes appeared to be confined to interphase nuclei in a non-proliferative status.This work was supported by a grant from Leukaemia Research UK (grant no. 0253). SJLK and RR were supported by the NIHR Biomedical Research Centre, Oxford, with funding from the Department of Health’s NIHR Biomedical Research Centres funding schemeThis article is available through the Brunel Open Access Publishing Fund

Constitutional mismatch repair deficiency (CMMRD) presenting with high-grade glioma, multiple developmental venous anomalies and malformations of cortical development-a multidisciplinary/multicentre approach and neuroimaging clues to clinching the diagnosis

Constitutional mismatch repair deficiency syndrome (CMMRD) is a rare cancer-predisposition syndrome associated with a high risk of developing a spectrum of malignancies in childhood and adolescence, including brain tumours. In this report, we present the case of an 8-year-old boy with acute headache, vomiting and an episode of unconsciousness in whom brain imaging revealed a high-grade glioma (HGG). The possibility of an underlying diagnosis of CMMRD was suspected radiologically on the basis of additional neuroimaging findings, specifically the presence of multiple supratentorial and infratentorial developmental venous anomalies (DVAs) and malformations of cortical development (MCD), namely, heterotopic grey matter. The tumour was debulked and confirmed to be a HGG on histopathology. The suspected diagnosis of CMMRD was confirmed on immunohistochemistry and genetic testing which revealed mutations in PMS2 and MSH6. The combination of a HGG, multiple DVAs and MCD in a paediatric or young adult patient should prompt the neuroradiologist to suggest an underlying diagnosis of CMMRD. A diagnosis of CMMRD has an important treatment and surveillance implications not only for the child but also the family in terms of genetic counselling

A case series of Diffuse Glioneuronal Tumours with Oligodendroglioma-like features and Nuclear Clusters (DGONC).

In this study, we report three paediatric cases of Diffuse Glioneuronal Tumours with Oligodendroglioma-like features and Nuclear Clusters (DGONC)

Language impairment in a case of a complex chromosomal rearrangement with a breakpoint downstream of FOXP2

BACKGROUND: We report on a young female, who presents with a severe speech and language disorder and a balanced de novo complex chromosomal rearrangement, likely to have resulted from a chromosome 7 pericentromeric inversion, followed by a chromosome 7 and 11 translocation. RESULTS: Using molecular cytogenetics, we mapped the four breakpoints to 7p21.1-15.3 (chromosome position: 20,954,043-21,001,537, hg19), 7q31 (chromosome position: 114,528,369-114,556,605, hg19), 7q21.3 (chromosome position: 93,884,065-93,933,453, hg19) and 11p12 (chromosome position: 38,601,145-38,621,572, hg19). These regions contain only non-coding transcripts (ENSG00000232790 on 7p21.1 and TCONS_00013886, TCONS_00013887, TCONS_00014353, TCONS_00013888 on 7q21) indicating that no coding sequences are directly disrupted. The breakpoint on 7q31 mapped 200 kb downstream of FOXP2, a well-known language gene. No splice site or non-synonymous coding variants were found in the FOXP2 coding sequence. We were unable to detect any changes in the expression level of FOXP2 in fibroblast cells derived from the proband, although this may be the result of the low expression level of FOXP2 in these cells. CONCLUSIONS: We conclude that the phenotype observed in this patient either arises from a subtle change in FOXP2 regulation due to the disruption of a downstream element controlling its expression, or from the direct disruption of non-coding RNAs

Relative proximity of chromosome territories influences chromosome exchange partners in radiation-induced chromosome rearrangements in primary human bronchial epithelial cells and in a small cell lung cancer cell line

It is well established that chromosomes exist in discrete territories (CTs) in interphase and are positioned in a cell-type specific probabilistic manner. The relative localisation of individual CTs within cell nuclei remains poorly understood, yet many cancers are associated with specific chromosome rearrangements and there is good evidence that relative territorial position influences their frequency of exchange. To examine this further, we characterised the complexity of radiation-induced chromosome exchanges in normal human bronchial epithelial (NHBE) cells by M-FISH analysis of PCC spreads and correlated the exchanges induced with their preferred interphase position, as determined by 1/2-colour 2D-FISH analysis, at the time of irradiation. We found that the frequency and complexity of aberrations induced were reduced in ellipsoid NHBE cells in comparison to previous observations in spherical cells, consistent with aberration complexity being dependent upon the number and proximity of damaged CTs, i.e. lesion proximity. To ask if particular chromosome neighbourhoods could be identified we analysed all radiation-induced pair-wise exchanges using SCHIP (statistics for chromosome interphase positioning) and found that exchanges between chromosomes (1;13), (9;17), (9;18), (12;18) and (16;21) all occurred more often than expected assuming randomness. All of these pairs were also found to be either sharing similar preferred positions in interphase and/or sharing neighbouring territory boundaries. We also analysed a human small cell lung cancer cell line, DMS53, by M-FISH observing the genome to be highly rearranged, yet possessing rearrangements also involving chromosomes (1;13) and (9;17). Our findings show evidence for the occurrence of non-random exchanges that may reflect the territorial organisation of chromosomes in interphase at time of damage and highlight the importance of cellular geometry for the induction of aberrations of varying complexity after exposure to both low and high-LET radiation. © 2013 The Authors