Comparative genomic hybridization study on pooled DNAs from tumors of one clinical-pathological entity.
Knuutila S. Armengol G. Bjorkqvist AM. el-Rifai W. Larramendy ML. Monni O. Szymanska J.
Department of Medical Genetics, Haartman Institute, University of Helsinki, Finland.
Comparative genomic hybridization (CGH) was performed using DNAs pooled from numerous specimens from tumor categories studied case-by-case. The series of six DNA pools consisted of 28 diffuse centroblastic lymphomas (DCL), 28 gastrointestinal stromal tumors (GIST), 21 primary chondrosarcomas (CS), 17 samples from the Ewing family of tumors (ET), 14 liposarcomas (LS), and 14 mesotheliomas (MS). Losses and gains present in at least 50% of the individual specimens were always detected in the pooled DNAs. The loss of the whole p-arm of chromosome 1 was observed even when the affected proportion of individual specimens was only 25%. Gains were also detected at frequencies lower than 50%, but with a high-level amplification in one or more specimens. In conclusion, the present pooled DNA study revealed the following changes: DCL had a gain at 18q22-qter; GIST had losses at 14 and 22q12, and gains at 5p, 8q22-24, 17q22-qter, and 19q13; ET had gains at 1q and 8q13-qter; LS had gains at 1q21-25 and 12q; and MS had a loss at 9p22-pter. No changes were observed in the CS DNA pool. The results from individual specimens also stressed the importance of these chromosomal regions to the tumorigenesis in the corresponding malignancies. This pooled DNA approach can thus be used for fast screening of recurrent DNA copy number in a specific tumor entity.
Genotype configuration in a case of primary gastric lymphoma with T-cell phenotype.
Sueoka N. Inokuchi K. Nishigaki H. Futaki M. Inokuchi M. Sugisaki Y. Dan K. Wakabayashi I.
Department of Internal Medicine, Nippon Medical School, Tokyo, Japan.
T-cell malignant lymphoma of the gastrointestinal tract is rare. The genotype of gastric T-cell lymphoma remains unclear. The aim of this study was to elucidate the pathogenesis of a case of primary gastric T-cell lymphoma by using cytogenetics and molecular biology. Gastric biopsy specimens and lymphoma cells in the ascites were examined by immunocytology, cytogenetic analysis, and Southern blot analysis. The histological diagnosis of the gastric lymphoma was diffuse large cell type. T-cell markers were positive in immunocytochemistry of the gastric lymphoma cells and in FACS analysis of lymphoma cells in the ascites. All lymphoma cells in the ascites had complex abnormal karyotypes containing t(8;14)(q24;q32). Southern blot analysis revealed rearrangement of the IgH and C-MYC genes of the lymphoma cells in both the stomach and the ascites, but no comigration of the C-MYC with the JH locus could be detected. The TCR-beta and -gamma genes were in their germ-line configurations. In this patient, although the phenotype was T-cell lymphoma, the karyotype t(8;14)(q24;q32) and genotype had the characteristics of B-cell lymphoma. The unique B-cell genotype configuration and the C-MYC activation suggested that the cellular origin of this rare case of malignant lymphoma with a T-cell phenotype was quite immature lymphocytes.
Mutation of the 5 noncoding region of the BCL-6 gene in low-grade gastric lymphoma of the mucosa-associated lymphoid tissue.
Liang R. Chan WP. Kwong YL. Chan AC. Xu WS. Srivastava G.
Department of Medicine, University of Hong Kong, Queen Mary Hospital, People's Republic of China.
BCL-6 gene rearrangement and hypermutations were investigated in four Hong Kong Chinese patients with low-grade gastric lymphoma of the mucosa-associated lymphoid tissue (MALToma). The former was studied by Southern analysis and the latter by the technique of polymerase chain reaction and denaturing gradient gel electrophoresis. BCL-6 gene rearrangement was not detectable in any of the four cases. However, mutations at both the E1.11 and E1.12 segments of the 5' noncoding region of the BCL-6 gene were found in two patients. This preliminary observation suggests that the mutations of the 5' noncoding region of the BCL-6 gene rather than gene rearrangement may be playing a more important role in the tumorigenesis of low-grade gastric MALToma. Further confirmation of this finding by studying a larger number of patients will be required.
Gastrointestinal stromal tumor, uncommitted type, with monosomies 14 and 22 as the only chromosomal abnormalities.
Marci V. Casorzo L. Sarotto I. Dogliani N. Milazzo MG. Risio M.
Department of Pathology, Ospedale San Lazzaro, Alba, Italy.
Karyotypic analysis of a gastric stromal tumor with the histologic and immunohistochemical features of a malignant, uncommitted lesion revealed clonal monosomies of chromosomes 14 and 22. Such changes, together with loss of chromosomes 15 and 18, as well as structural rearrangements involved chromosome 1, have been previously reported in gastrointestinal stromal tumors with smooth muscle differentiation. We suggest that monosomies of chromosomes 14 and 22 are early events in the malignant transformation of the mesenchymal cell-originating gastrointestinal stromal tumors.
Cytogenetic findings in an embryonal sarcoma of the liver.
Iliszko M. Czauderna P. Babinska M. Stoba C. Roszkiewicz A. Limon J.
Department of Biology and Genetics, Medical University of Gdansk, Poland.
An undifferentiated embryonal sarcoma (malignant mesenchymoma) of the liver from a 5-year-old girl was found to have near-triploid and near-hexaploid clones with several chromosomal rearrangements. This is the first description of the chromosomal changes in this tumor type.
Fluorescence in situ hybridization reveals trisomy 2q by insertion into 9p in hepatoblastoma.
Balogh E. Swanton S. Kiss C. Jakab ZS. Secker-Walker LM. Olah E.
Department of Pediatrics, University Medical School, Debrecen, Hungary.
Cytogenetics and fluorescence in situ hybridization (FISH) of a hepatoblastoma are presented. The results of standard chromosome analysis were as follows: 47,XY,+2,add(4)(q35),-9,+20. FISH with the use of whole-chromosome paints revealed partial trisomy of the long arm of chromosome 2 by insertion into chromosome 9. Comparison of the G-banded metaphases with metaphase FISH led to a reinterpretation of the karyotype as: 47,XY,add(4)(q35),der(9)ins(9;2)(p22;q?21q?25),+20. This case supports previous observations that the critical region of trisomy 2 lies between 2q21 and 2qter and shows how partial trisomy 2q may evade detection in G-banded metaphases.
Translocation (3;3)(p14;q29) as the primary chromosome abnormality in a peritoneal mesothelioma.
Teixeira MR. Giercksky KE. Ikonomou IM. Heim S.
Department of Genetics, Norwegian Radium Hospital and Institute for Cancer Research, Oslo.
Mesothelioma is a relatively rare malignant neoplasm arising from the serosal lining of the pleural, peritoneal, and pericardial cavities. Mesotheliomas are known to be associated with asbestos exposure. The karyotypes of these tumors have mostly been so complex as to preclude the identification of primary chromosome abnormalities. We present the cytogenetic analysis of two macroscopically distinct abdominal tumors, both diagnosed as peritoneal mesothelioma, occurring in a woman with a history of heavy asbestos exposure. Both tumors contained the same three karyotypically abnormal but cytogenetically related clones, with a balanced t(3;3)(p14;q29) as the primary chromosomal change. The fact that several chromosome abnormalities were common to both tumors strongly indicates that they arose through intraperitoneal spreading of a single neoplastic process; that is, they were not pathogenetically independent lesions. Our findings, taken together with previously published cytogenetic data on peritoneal mesotheliomas, indicate that a proportion of these tumors may be characterized by simple, balanced chromosomal rearrangements. At least a subset of peritoneal mesotheliomas arises through the same pathogenetic mechanisms that are involved in the pleural forms of this disease.