p53, p21 and metallothionein immunoreactivities in patients with malignant pleural mesothelioma: correlations with the epidemiological features and prognosis of mesotheliomas with environmental asbestos exposure

Our plain-English summary of p53, p21 and metallothionein immunoreactivities in patients with malignant pleural mesothelioma: correlations with the epidemiological features and prognosis of mesotheliomas with environmental asbestos exposure, by R. Isik, M. Metintas, A.R. Gibbs, et al (Respiratory Medicine, 2001).

The study

• Authors: R. Isik, M. Metintas, A.R. Gibbs, S. Metintas, B. Jasani, U. Oner, E. Harmanci, S. Demircan, S. Işiksoy
• Journal: Respiratory Medicine
• Published: 2001;95(7):588-93
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The aim of this study is to investigate immunoreactivity for p53, p21 and metallothionein in diffuse malignant pleural mesothelioma (DMPM) and to determine the relationships between the age, sex, asbestos exposure time, survival of DMPM patients with environmental asbestos exposure and immunoreactivity to p53, p21 and metallothionein. Sixty-seven histopathologically-confirmed DMPMs, 38 of whom had environmental and 29 had occupational asbestos exposure, were included. The tumour tissue samples were immunostained with antibodies against p53, p21 and metallothionein. Epidemiological data and the survival times for the DMPM patients with environmental asbestos exposures were obtained from hospital records. Thirty-three per cent of the DMPMs were positive for p53, 35% for p21 and 52% for metallothionein. There was no statistical difference between the histological subtypes of DMPM in terms of immunoreactivity for p53, p21 and metallothionein. For p21 and metallothionein there was a statistically significant difference between the exposure characteristics: patients with environmental asbestos exposure had shown more immunopositivity. There were statistically significant differences between age groups and between asbestos exposure times for metallothionein, and between asbestos exposure times and p21. The patients with positive immunostaining had longer exposure times and were older than those having negative immunostaining. The differences between survival of the patients were not statistically significant in terms of the immunohistochemical results for p53, p21 and metallothionein.

In plain English

The authors stained tissue from 67 patients with diffuse malignant pleural mesothelioma for p53 and metallothionein (66 tumours) and p21 (65 tumours). Thirty-eight patients from Eskisehir, Turkey, had been exposed to asbestos from birth through 'white-soil' used on their houses, reported to contain mainly tremolite or tremolite–chrysotile. The other 29, from Cardiff, U.K., had occupational exposure to commercial amphiboles. Positive results were 22 of 66 (33%) for p53, 23 of 65 (35%) for p21 and 34 of 66 (52%) for metallothionein. Positivity did not differ significantly between tumour subtypes. Environmentally exposed patients were significantly more often positive for p21 (19 of 37 versus 4 of 28 occupationally exposed) and metallothionein (24 of 38 versus 10 of 28). In the Turkish group, those positive for p21 or metallothionein had significantly longer exposure times, and metallothionein-positive patients were older. Median survival among 36 Turkish patients with survival data was 9 months. Patients with negative staining survived longer, but not statistically significantly; the authors suggested the limited number of cases as a possible reason, and called their metallothionein explanation speculative.

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 (immunohistochemical) study of stored tumour biopsy tissue, with survival analysis from hospital records for the environmentally exposed patients
• Who was studied: 67 patients with histologically confirmed diffuse malignant pleural mesothelioma. Thirty-eight were diagnosed and followed up at Osmangazi University, Eskisehir, Turkey (19 men, 19 women; mean age 56.6 years, median 56.5 years). The other 29 were diagnosed at Llandough Hospital, Cardiff, U.K. Sixty-six tumours were stained for p53 and metallothionein and 65 for p21. Study years are not given.
• Exposure: The 38 Turkish patients had environmental exposure from birth to asbestos-contaminated white-soil used for whitewashing and roof insulation. Earlier cited work found tremolite or tremolite–chrysotile in this soil, or at a lower rate combinations of actinolite, anthophyllite or chrysotile. Their mean exposure time was 34.9 years (median 31.0 years). The 29 Cardiff patients had occupational exposure to commercial amphiboles.
• Main results:
  • Of all tumours tested, 22 of 66 (33%) were positive for p53, 23 of 65 (35%) for p21 and 34 of 66 (52%) for metallothionein.
  • Positivity for the three proteins did not differ significantly between histological subtypes (25 epithelial, 20 mixed, 20 sarcomatoid, two transitional).
  • p53 positivity did not differ significantly between occupationally exposed patients (9 of 28, 32%) and environmentally exposed patients (13 of 38, 34%).
  • Environmentally exposed patients were more often positive than occupationally exposed patients for p21 (19 of 37, 51%, versus 4 of 28, 14%). They were also more often positive for metallothionein (24 of 38, 63%, versus 10 of 28, 36%). Both differences were statistically significant (P less than 0.05).
  • Among the 38 environmentally exposed patients, p53 results were not related to age, sex or exposure time. p21-positive patients had significantly longer asbestos exposure times than p21-negative patients (mean 39.4 versus 31.4 years).
  • Among the 38 environmentally exposed patients, metallothionein-positive patients were significantly older than metallothionein-negative patients (mean 59.9 versus 50.2 years). They also had longer exposure times (mean 41.2 versus 22.7 years, P less than 0.001). There was no difference by sex.
  • Survival times were available for 36 of the 38 environmentally exposed patients for the p53 and metallothionein analyses, and for 35 for p21. In these patients median survival was 9 months and mean survival 13.7 months (36 patients). Positive versus negative median survival was 8.0 versus 12.0 months for p53 (log-rank P=0.28), 8.0 versus 12.0 months for p21 (P=0.34) and 8.0 versus 9.0 months for metallothionein (P=0.48). None of these differences was statistically significant.
• The authors' conclusion: The authors suggested that metallothionein expression may increase with longer exposure, to protect cells from asbestos-related toxic substances. They called this speculative. They said they could not precisely explain the relations between p21 and metallothionein staining and the epidemiological features, and that further studies are warranted.
• Limitations the authors state:
  • The number of patients was limited, which the authors said may explain why the survival differences were not significant.
  • Some staining results are missing because the biopsies were small and some sections lacked enough tumour.

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, Prognosis, Mesothelioma, Asbestos Exposure, Histological Subtype.

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