The expression of P-glycoprotein and multidrug resistance proteins 1 and 2 (MRP1 and MRP2) in human malignant mesothelioma

Our plain-English summary of The expression of P-glycoprotein and multidrug resistance proteins 1 and 2 (MRP1 and MRP2) in human malignant mesothelioma, by Y. Soini, K. Järvinen, R. Kaarteenaho-Wiik, et al (Annals of Oncology, 2001).

The study

• Authors: Y. Soini, K. Järvinen, R. Kaarteenaho-Wiik, V. Kinnula
• Journal: Annals of Oncology
• Published: 2001;12(9):1239-45
• Cited by: 37 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Malignant mesothelioma is a malignancy with a primary resistance to chemo- and radiotherapies for reasons which are still unclear. Multidrug resistance proteins might explain the observed resistance, but no studies have assessed their expression in mesothelioma.

Patients And Methods: Immunohistochemical expression of P-glycoprotein (P-gp), and the multidrug resistance proteins 1 and 2 (MRP1 and MRP2) were investigated in 36 cases of malignant mesothelioma and in samples from normal mesothelium.

Results: P-gp immunopositivity was found in 61%, MRP1 immunopositivity in 58% and MRP2 positivity in 33% of the cases. Normal mesothelium did not express these multidrug-resistant proteins. There was a significant association between P-gp and MRP2 (P = 0.022) expression. No or weak P-gp, MRP1 or MRP2 immunostaining was significantly more frequent in sarcomatoid mesothelimas than in epithelial or biphasic mesotheliomas (P = 0.031, P = 0.034 and P = 0.024, respectively). There was no significant association between patient survival and expression of the multidrug-resistant proteins.

Conclusions: The results show that P-gp, MRP1 and MRP2 are induced and expressed in malignant mesothelial cells. Regardless of their expression no association with survival of the patients was seen, suggesting that the primary resistance of malignant mesotheliomas is not solely dependent on their expression or function.

In plain English

This laboratory study examined tumor tissue from 36 patients with malignant mesothelioma, drawn from the pathology files of Oulu University Hospital in Finland for 1976 to 1999, along with six samples of non-cancerous pleural tissue. The authors used antibody staining to look for three proteins that can carry cancer drugs out of cells: P-glycoprotein (P-gp), MRP1 and MRP2. P-gp was found in 22 of 36 tumors (61%), MRP1 in 21 of 36 (58%) and MRP2 in 12 of 36 (33%). No MRP2-positive tumor stained moderately or strongly. The normal tissue did not show these proteins. Sarcomatoid mesotheliomas showed no or weak staining more often than epithelial or biphasic ones. Expression of the proteins was not significantly associated with how long patients survived. The authors concluded that mesothelioma's resistance to treatment does not depend solely on these proteins. They noted that four patients had chemotherapy or radiotherapy before biopsy, that treatment was not standardized, and that other related proteins were not studied. The study did not examine 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 (immunohistochemical) study of archived tumor tissue samples, with survival analysis
• Who was studied: Tumor samples from 36 patients with malignant mesothelioma (30 men, 6 women, aged 33 to 79) from the pathology files of Oulu University Hospital, Finland, 1976 to 1999, plus six samples of non-neoplastic pleural tissue
• Exposure: Not studied. The article reports no asbestos exposure information; it measured multidrug resistance proteins (P-gp, MRP1, MRP2) in tumor tissue.
• Main results:
  • P-gp staining was positive in 22 of 36 mesotheliomas (61%): 13 strong, four moderate, five weak
  • MRP1 staining was positive in 21 of 36 mesotheliomas (58%)
  • MRP2 staining was positive in 12 of 36 mesotheliomas (33%), usually weak, with no moderate or strong cases
  • Normal (non-cancerous) mesothelium did not express any of the three proteins
  • Sarcomatoid mesotheliomas more often showed no or weak staining for P-gp, MRP1 and MRP2 than epithelial or biphasic mesotheliomas (P = 0.031, P = 0.034 and P = 0.024 respectively)
  • MRP2 was significantly associated with moderate or strong P-gp staining (P = 0.021)
  • No significant association between patient survival and expression of P-gp (P = 0.135), MRP2 (P = 0.09) or MRP1 (P = 0.88)
• The authors' conclusion: The authors concluded that P-gp, MRP1 and MRP2 are expressed in malignant mesothelioma cells, but because their expression was not associated with survival, the primary treatment resistance of mesothelioma is not solely dependent on them
• Limitations the authors state:
  • Four patients had received chemotherapy or radiotherapy before biopsy, and no systematic treatment protocol was used after diagnosis, so the role of these proteins in drug resistance remains to be evaluated
  • Other members of the MRP protein family were not studied and may play a larger role

Topics

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

Medical terms in this study, explained in our Lexicon: Glycoprotein, Malignant Mesothelioma, Mesothelioma, Mesothelium, Sarcomatoid, Biphasic Mesothelioma, Mesothelial Cells.

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