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American Journal of Pathology, 2, 463- 468

Translocation t(2/5) is not a primary event in Hodgkin's disease. Simultaneous immunophenotyping and interphase cytogenetics

K. Weber-Matthiesen, J. Deerberg-Wittram, A. Rosenwald, M. Poetsch, W. Grote, B. Schlegelberger

A number of neoplastic disorders are characterized by recurrent chromosome aberrations. One of these is the translocation t(2;5), which is found in a considerable percentage of large-cell anaplastic lymphomas. This translocation results in the fusion of two genes, alk and npm. The recent discovery of alk/npm mRNA in 11 of 13 cases of Hodgkin's disease has caused a controversial discussion concerning the question of whether t(2;5) is also present in Hodgkin and Reed-Sternberg cells. We tackled this problem on the molecular cytogenetic level by combined CD30 immunophenotyping and interphase cytogenetics. Using a pair of DNA probes flanking both sides of the npm gene breakpoint at 5q35 we were able to prove, at least in 12 of 13 cases of Hodgkin's disease, that all CD30-positive Hodgkin and Reed-Sternberg cells lacked the translocation t(2;5). Fifteen to forty-five Hodgkin/Reed-Sternberg cells were analyzed per case (mean, 27). Our findings indicate that this translocation is not a primary event in the development of Hodgkin's disease.

Blood, 87, 5269- 5278

DNA copy number changes in diffuse large B-cell lymphoma - Comparative genomic hybridization study

O. Monni, H. Joensuu, K. Franssila, S. Knuutila

We studied DNA copy number changes in diffuse large B-cell lymphoma using comparative genomic hybridization analysis on 20 primary tumors and on 12 recurrent tumors excised after chemotherapy or radiotherapy. Twenty-nine (91%) of the cases showed abnormal copy number karyotypes. Chromosomal regions at X (41%), 1q (38%), 7 (31%), 3 (24%), 6p (21%), 11 (21%), 12 (21%), and 18 (21%) were most frequently gained, and the most common losses involved 6q (38%), X (21%), 1p (14%), and 8p (10%). High-level amplifications were observed at 6p23-ter, 10p12-14, 17p1l.2, 18q21-ter, and Xq22-ter, all but 18q appearing only in the recurrent tumors. Gains (median, 2; range, 0 to 10) were more frequent than losses (median, 1; range, 0 to 7; P = .0004). The median number of aberrations found in the recurrent tumors (6.5) was greater than that in the primary tumors (2; P = .01). The copy number changes found in the recurrent tumors were more random than those found in the primary tumors, which were mainly located in the most frequently affected regions. Our findings are in line with those observed using conventional cytogenetic analysis, but especially novel high-level amplifications were detected. Southern blot analysis showed BCL2 amplification, but not translocation t(14;18)(q32;q21), in cases in which a gain at 18q was detected by comparative genomic hybridization, which strongly suggests that, in addition to translocation, gene amplification is another mechanism for the overexpression of the BCL2 protein.

Mutation Research, 334, 97- 102

Automated metaphase finding: an assessment of the efficiency of the METAFER2 system in routine mutagenicity assay

R. Huber, U. Kulka, T. L{\"o}rch, H. Braselmann, M. Bauchinger

The efficiency of the automated metaphase finding system METAFER2 is assessed in a routine mutagenicity assay using an aneuploid rat liver cell line treated with various promutagens. Data sets generated by automated and manual selection of metaphases are compared. It is demonstrated that METAFER2 routinely allows an efficient automatic identification of metaphases not only in lymphocyte preparations, but also in preparations from mammalian cell lines with varying chromosome numbers. Although larger slide areas are required for automated compared to manual metaphase scanning, the automatic system is faster by a factor of about 5. The interactive visual elimination of metaphases of insufficient quality is an easy and fast procedure. METAFER2 allows an unbiased selection of metaphases irrespective of their appearance as homogeneously stained first or harlequin-stained second division cells. Random selection of metaphases is neither influenced by various structural chromosome changes nor by increased frequencies of sister-chromatid exchanges.

Cancer Research, 55, 1334- 1338

Gains and losses of DNA sequences in osteosarcomas by comparative genomic hybridization

M. Tarkkanen, R. Karhu, A. Kallioniemi, I. Elomaa, A.H. Kivioja, J. Nevalainen, T. B{\"o}hling, E. Karaharju, E. Hyytinen, S. Knuutila, O.P. Kallioniemi

Our aim was to identify chromosomal regions that are likely to harbor previously unknown genes with an important role in the genesis of osteosarcoma. Comparative genomic hybridization was used to screen for losses and gains of DNA sequences along all chromosome arms in 11 tumors. Extensive genetic aberrations, with an average of 11 changes/tumor (range, 1-20), were found in 10 of the 11 specimens. High level amplifications of small chromosomal regions were detected in eight tumors. These involved the 12q12-q13 region (known to contain the SAS-MDM2 locus) and several previously unreported amplification sites such as 17p11-p12, 3q26, and Xq12. When all DNA sequence gains were evaluated, the gains at 8q and Xp were most common (45%). The most common losses of DNA sequences were seen at 2q, 6q, 8p, and 10p (36%). In conclusion, despite the very complex pattern of genetic changes in osteosarcomas, certain chromosomal regions appear to be affected more often than others. Most of these regions have not previously been reported to be implicated in osteosarcomas and may thus highlight locations of novel genes with an important role in the development and progression of these tumors.

Mutation Research, 272, 31- 34

Time-saving in biological dosimetry by using the automatic metaphase finder Metafer2

J. Weber, W. Scheid, H. Traut

The amount of time-saving by using the Metafer2 metaphase finder for routine analysis of radiation-induced chromosome aberrations (biological dosimetry) was determined. Metaphases were prepared by standard methods from cultures of human peripheral blood lymphocytes and stained either with Giemsa or with the FPG method. The metaphase finder was used for detecting metaphases on the microscope slides and for automatically processing the evaluation data. In our laboratory, standardized analysis of 1000 metaphases requires at least 3 working days for cell culturing and slide preparation and 51.5 working hours for cytogenetic analysis. When using the metaphase finder the time required for cytogenetic analysis is reduced to 17.3 working hours (time-saving factor: 51.5/17.3 h = 3.0). In our prolonged method, including more than one scoring of each slide and karyotyping of metaphases with chromosome aberrations, the analysis times for 1000 cells are 132 and 70 working hours, respectively (time saving factor: 132/70 h = 1.9).

Chromosome aberrations determined by sFISH and G-banding in lymphocytes from workers with internal deposits of plutonium.

Purpose: To examine the influence of α-particle radiation exposure from internally deposited plutonium on chromosome aberration frequencies in peripheral blood lymphocytes of workers from the Sellafield nuclear facility, UK. Materials and methods: Chromosome aberration data from historical single colour fluorescence in situ hybridization (sFISH) and Giemsa banding (G-banding) analyses, together with more recent sFISH results, were assessed using common aberration analysis criteria and revised radiation dosimetry. The combined sFISH group comprised 29 men with a mean internal red bone marrow dose of 21.0 mGy and a mean external γ-ray dose of 541 mGy. The G-banding group comprised 23 men with a mean internal red bone marrow dose of 23.0 mGy and a mean external γ-ray dose of 315 mGy. Results: Observed translocation frequencies corresponded to expectations based on age and external γ-ray dose with no need to postulate a contribution from α-particle irradiation of the red bone marrow by internally deposited plutonium. Frequencies of stable cells with complex aberrations, including insertions, were similar to those in a group of controls and a group of workers with external radiation exposure only, who were studied concurrently. In a similar comparison there is some suggestion of an increase in cells with unstable complex aberrations and this may reflect recent direct exposure to circulating lymphocytes. Conclusions: Reference to in vitro dose response data for the induction of stable aberrant cells by α-particle irradiation indicates that the low red bone marrow α-particle radiation doses received by the Sellafield workers would not result in a discernible increase in translocations, thus supporting the in vivo findings. Therefore, the greater risk from occupational radiation exposure of the bone marrow resulting in viable chromosomally aberrant cells comes from, in general, much larger γ-ray exposure in comparison to α-particle exposure from plutonium.