Abnormalities of chromosomes 7 and 22 in human malignant pleural mesothelioma: correlation between Southern blot and cytogenetic analyses

Our plain-English summary of Abnormalities of chromosomes 7 and 22 in human malignant pleural mesothelioma: correlation between Southern blot and cytogenetic analyses, by M. Tiainen, J. Kere, L. Tammilehto, et al (Genes, Chromosomes & Cancer, 1992).

The study

• Authors: M. Tiainen, J. Kere, L. Tammilehto, K. Mattson, S. Knuutila
• Journal: Genes, Chromosomes & Cancer
• Published: 1992;4(2):176-82
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Southern blot hybridization studies were performed on 23 mesothelioma primary tumor specimens to detect chromosome 1-, 7-, and 22-specific numerical changes, gene amplifications, and gene rearrangements. The molecular findings were compared with previous cytogenetic findings. No gene rearrangements or amplifications were detected. A numerical abnormality of chromosome 7 was detected by Southern blot analysis in two cases in which no numerical abnormality had been detected by the previous chromosome study. A numerical aberration of chromosome 22 was detected in five cases, which was compatible with the cytogenetic finding of monosomy 22 in these cases. The Southern blot results for the copy numbers of chromosomes 7 and 22 were concordant with the cytogenetic findings in 65%-80% of the cases.

In plain English

This brief laboratory report from Helsinki, Finland, looked at the genetics of tumor tissue from 23 patients with malignant pleural mesothelioma. The authors had already examined these patients' chromosomes under the microscope (cytogenetic analysis). For six patients, that earlier analysis of the tumor had failed, so findings from cells in pleural effusion (fluid around the lung) were used instead. In this study they used a DNA technique, Southern blot (RFLP) analysis, to look for extra or missing copies of chromosomes 7 and 22 and for amplified or rearranged genes on chromosomes 1, 7 and 22. They then compared the two methods. No gene amplifications or rearrangements were found in any of the 23 tumors. For chromosome 7, the DNA results agreed with the earlier chromosome findings in 13 of 20 informative cases (65%). For chromosome 22 they agreed in 12 of 15 informative cases (80%). In two patients, the DNA test showed a change in the number of copies of chromosome 7 that the chromosome study had not shown. The authors concluded that the two methods mostly agreed. Among the limitations they stated, normal DNA from the same patient was missing for most patients. The article did not study asbestos exposure.

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 molecular genetic study (brief communication) using Southern blot / RFLP analysis of tumor DNA, compared with the same group's earlier cytogenetic findings
• Who was studied: Primary tumor specimens from 23 patients with malignant pleural mesothelioma, out of 38 patients studied cytogenetically before, at the University of Helsinki and Helsinki University Central Hospital, Finland. Twenty specimens were taken before any treatment. Dates of collection are not given.
• Main results:
  • In six patients (10, 12, 21, 22, 24 and 25), the chromosome study of the tumor had failed, so the earlier cytogenetic results used for comparison came from pleural effusion cells
  • No gene rearrangements or amplifications were found in any of the 23 mesotheliomas with the probes used (including NRAS, EGFR, MET, PDGFA and PDGFB)
  • For chromosome 7, the DNA analysis agreed with the earlier cytogenetic findings in 13 of 20 informative cases (65%)
  • For chromosome 22, the two methods agreed in 12 of 15 informative cases (80%)
  • In two patients (patients 5 and 36), the DNA analysis showed a numerical abnormality (a change in copy number) of chromosome 7 that the cytogenetic study had not shown. In patient 5, the earlier chromosome study had found a structural change involving chromosome 7, but a normal copy number of the chromosome 7 long arms.
  • For patient 5, the earlier cytogenetic study had recorded a normal copy number of the chromosome 7 long arms
  • In five patients (5, 12, 20, 21 and 29), the chromosome 22 probes gave abnormal results, suggesting a gain or loss of chromosome 22 material. These patients had loss of chromosome 22 (monosomy 22) in the cytogenetic study.
• The authors' conclusion: The authors concluded that the DNA results on extra or missing copies of chromosomes 7 and 22 mostly agreed with the earlier chromosome findings, and that the DNA analysis found two new cases with a chromosome 7 abnormality.
• Limitations the authors state:
  • Normal DNA from the patient was not available for most patients, so some genetic losses could not be told apart from normal inherited variation
  • Normal cells mixed into every tumor sample may have interfered with judging whether chromosome copies were gained or lost
  • Only patients who were heterozygous for the genetic markers (carried two different versions) could be assessed
  • The method cannot detect point mutations, so the negative gene findings do not rule out a role for these genes (NRAS given as an example)
  • In some patients the chromosome results came from pleural effusion fluid rather than the primary tumor used for DNA, which may explain some disagreements
  • Few cells could be analyzed cytogenetically in all the cases where the two methods disagreed

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

• Malignant mesothelioma: clinical characteristics, asbestos mineralogy and chromosomal abnormalities of 41 patients — L. Tammilehto, T. Tuomi, et al. (1992)
• Interphase cytogenetics on paraffin sections of malignant pleural mesothelioma. A comparison to conventional karyotyping and flow cytometric studies — M. Tiainen, A. Hopman, et al. (1992)
• Chromosomal abnormalities and their correlations with asbestos exposure and survival in patients with mesothelioma — M. Tiainen, L. Tammilehto, et al. (1989)
• Chromosomes and chromosomal evolution in human mesotheliomas as reflected in sequential analyses of two cases — G. Stenman, K. Olofsson, et al. (1986)
• Recurring loss involving chromosomes 1, 3, and 22 in malignant mesothelioma: possible sites of tumor suppressor genes — W.L. Flejter, F.P. Li, et al. (1989)
• 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)

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