Interphase cytogenetics on paraffin sections of malignant pleural mesothelioma. A comparison to conventional karyotyping and flow cytometric studies

Our plain-English summary of Interphase cytogenetics on paraffin sections of malignant pleural mesothelioma. A comparison to conventional karyotyping and flow cytometric studies, by M. Tiainen, A. Hopman, O. Moesker, et al (Cancer Genetics and Cytogenetics, 1992).

The study

• Authors: M. Tiainen, A. Hopman, O. Moesker, F. Ramaekers, M. Wessman, A. Laasonen, S. Pyrhönen, L. Tammilehto, K. Mattson, S. Knuutila
• Journal: Cancer Genetics and Cytogenetics
• Published: 1992;62(2):171-9
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We performed in situ hybridization (ISH) studies of malignant pleural mesotheliomas to detect numerical aberrations of chromosomes 1 and 7 in interphase nuclei of paraffin sections of 13 cases that had been analyzed previously by conventional karyotyping and flow cytometry. The hybridizations were performed with the biotin-labeled probes recognizing repetitive DNA sequences in the (peri)centromeric regions of chromosomes 1 (1q12) and 7(7cen). Application of histologic sections allowed us to analyze the tumor cells only. Comparison of the karyotype and ISH studies showed that the same chromosome copy numbers were detectable by both methods in 13 (chromosome 1) and in 12 (chromosome 7) cases evaluable by ISH. DNA indexes determined in the paraffin-embedded tumor material corresponded with the ISH findings. As compared with karyotype analysis, ISH showed a larger heterogeneity in chromosome copy numbers. The results can be divided into three groups: 1) Monosomy or disomy of chromosomes 1 and 7 was detected by both methods in two cases; 2) in four cases, disomy of both chromosome 1 and 7 was observed in most of the cells by ISH analysis, and karyotype analysis had shown clear polyploidization in three of these cases; 3) in seven cases, supernumerary copies of chromosomes 1 and/or 7 were present in an evident fraction (27-80%) of the cells analyzed by ISH, and karyotype analysis confirmed the aberrant copy numbers in five of these cases. On the other hand, ISH showed copy numbers not detected by karyotype analysis in six of the seven cases. Thus, by combining karyotype and interphase cytogenetic studies, complementary information about chromosomal aberrations in mesothelioma is obtained.

In plain English

This laboratory study re-examined stored tumor tissue from 13 patients with malignant pleural mesothelioma. Their tumors had earlier been studied by karyotyping (examining chromosomes of dividing cells) and flow cytometry (measuring DNA content). The authors used in situ hybridization, a staining technique, on paraffin sections to count copies of chromosomes 1 and 7 in tumor cells. Among evaluable patients, both methods found the same copy numbers for chromosome 1 in 13 patients and for chromosome 7 in 12. The new technique, however, showed more variation between cells. In seven patients, extra copies of chromosomes 1 and/or 7 appeared in 27-80% of cells, and karyotyping had shown these in five. In six patients the new technique found cell groups that karyotyping had not detected. DNA content measurements agreed with the new findings. The study did not examine asbestos exposure, though one patient had occupational asbestos exposure. The authors concluded that both methods together give complementary information. They noted that the probes detected only regions at or near the centromeres of chromosomes 1 and 7, and that sectioning tissue can distort counts.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory study comparing in situ hybridization on archival paraffin tumor sections with earlier karyotyping and flow cytometry results
• Who was studied: Tumor samples from 13 patients with malignant pleural mesothelioma, chosen from 35 tumors previously analyzed by karyotyping. Hybridizations were done in Helsinki, Finland, and for nine tumors also in Nijmegen, Netherlands. Study dates were not given.
• Exposure: Asbestos exposure was not studied. The only mention is that one newly reported patient (patient 40, a 43-year-old man) had occupational asbestos exposure. No fiber type or dose was given.
• Main results:
  • Karyotyping and in situ hybridization detected the same chromosome copy numbers in 13 patients for chromosome 1 and 12 patients for chromosome 7, among those evaluable by in situ hybridization. In situ hybridization showed more heterogeneity.
  • In seven patients (group III), extra copies of chromosomes 1 and/or 7 were found in 27-80% of cells by in situ hybridization.
  • Karyotype analysis had shown the extra copy numbers in five of these seven patients.
  • Copy numbers not detected by karyotyping ("new clones") were found by in situ hybridization in six patients.
  • In two patients (group I), one or two copies of chromosomes 1 and/or 7 were found in most cells by both methods.
  • In three of the four patients whose karyotypes showed polyploidization (group II), polyploidization was not readily detectable by in situ hybridization.
  • DNA indexes measured by flow cytometry on the paraffin-embedded tumor material agreed with the in situ hybridization findings.
  • In four patients, in situ hybridization found an imbalance between the copy numbers of chromosome 1 and chromosome 7.
• The authors' conclusion: The authors concluded that performing both karyotype analysis and interphase cytogenetic studies gives complementary information about numerical chromosome aberrations in mesothelioma.
• Limitations the authors state:
  • The probes gave information only on regions at or near the centromeres of chromosomes 1 and 7 (the chromosome 1 probe recognized a pericentromeric region, the chromosome 7 probe a centromeric region), not on other parts of these chromosomes.
  • Cutting nuclei during tissue sectioning makes copy numbers appear more varied and may cause the proportion of cells with high copy numbers to be underestimated.
  • In two patients, many nuclei showed only one signal (54-66%), which the authors attributed to suboptimal pretreatment.
  • The in situ hybridization and karyotype studies may have examined different parts of the tumor.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Mesothelioma.

Related studies

• Abnormalities of chromosomes 7 and 22 in human malignant pleural mesothelioma: correlation between Southern blot and cytogenetic analyses — M. Tiainen, J. Kere, et al. (1992)
• Malignant mesothelioma: clinical characteristics, asbestos mineralogy and chromosomal abnormalities of 41 patients — L. Tammilehto, T. Tuomi, et al. (1992)
• Flow cytometric analysis of ploidy in immunohistochemically confirmed examples of malignant epithelial mesothelioma — H.F. Frierson, S.E. Mills, et al. (1988)
• Induction of micronuclei, hyperdiploidy and chromosomal breakage affecting the centric/pericentric regions of chromosomes 1 and 9 in human amniotic fluid cells after treatment with asbestos and ceramic fibers — E. Dopp, M. Schuler, et al. (1997)
• Genomic changes of chromosomes 8p23.1 and 1q21: Novel mutations in malignant mesothelioma — G. Serio, L. Vimercati, et al. (2018)
• Cytogenetic analysis of malignant mesothelioma — A. Hagemeijer, M.A. Versnel, et al. (1990)

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