Expression of growth factor and growth factor receptor RNA in rat pleural mesothelial cells in culture

Our plain-English summary of Expression of growth factor and growth factor receptor RNA in rat pleural mesothelial cells in culture, by E. Bermudez, J. Everitt, C. Walker (Experimental Cell Research, 1990).

The study

• Authors: E. Bermudez, J. Everitt, C. Walker
• Journal: Experimental Cell Research
• Published: 1990;190(1):91-8
• Cited by: 52 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Mineral fiber-induced pleural mesothelioma in the rat is a suitable model for asbestos-induced mesothelioma in humans. A proposed mechanism for the genesis of mesotheliomas is the initiation of an autocrine pathway leading to unregulated growth of the mesothelium. To understand if changes in the expression of mRNA of critical growth factors and receptors occur in target mesothelial cells, it is first necessary to characterize the pattern of expression of these genes in normal mesothelial cells. Rat mesothelial cells were isolated from the parietal pleura and strains of these cells were propagated in vitro. The cells were diploid, had epithelial gross morphology and ultrastructure, and coexpressed keratins and vimentin. Northern blot analysis demonstrated that the cells expressed transforming growth factor beta 1 and fibroblast growth factor. Transcripts for transforming growth factor alpha, platelet-derived growth factor A-chain, and platelet-derived growth factor B-chain were not detected. Receptors for platelet-derived growth factor, epidermal growth factor, and insulin were detected. Although normal mesothelial cells express receptors for these growth factors, no production of their corresponding ligands by these cells could be detected, suggesting that autocrine stimulation of growth via the production of such factors may be specific to transformed mesothelial cells.

In plain English

This was a laboratory study of cells, not of people, and no asbestos or other fibers were applied to the cells. The authors noted that fiber-induced pleural mesothelioma in rats is used as a model for asbestos-induced mesothelioma in humans. They set out to describe which growth factor and growth factor receptor genes are active in normal rat mesothelial cells, as a baseline. They took cells from the parietal pleura of male Fischer-344 rats and grew two cell strains, M12C1 and M12C2, both from the same rat. The cells resembled mesothelial cells and made keratins and vimentin. The authors described their chromosomes as normal, with most cells having 42. The cells showed gene activity for basic fibroblast growth factor, at a very low level for transforming growth factor beta 1 in M12C2, and for receptors for platelet-derived growth factor, epidermal growth factor and insulin. Activity for platelet-derived growth factor A-chain was not detected. A human mesothelial cell line showed low levels of transforming growth factor alpha. The authors concluded that self-stimulation of growth by such factors may be specific to transformed mesothelial cells.

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 (in vitro) cell culture study of normal rat mesothelial cells; no fiber exposure
• Who was studied: Mesothelial cells from the parietal pleura of male Fischer-344 rats (Charles River Laboratories, Raleigh, NC). Two strains, M12C1 and M12C2, came from the same rat. They were compared with a rat visceral pleura cell line (RM4) and a human mesothelial cell line from ascites fluid (LP9).
• Exposure: None. Cells were not exposed to asbestos or other fibers. The study measured growth factor and receptor messenger RNA in normal cells, as a basis for later study of fiber-induced rat mesothelioma.
• Main results:
  • Strain M12C1: of 100 metaphases examined, 78% had 42 chromosomes, 13% had 43 and 9% had 84. Strain M12C2: 93% had 42 and 7% had 43. The authors described the cells as normal, with a modal chromosome number of 42.
  • Average population doubling time was 36 hours for M12C1 and 33 hours for M12C2.
  • Staining showed that the cultured rat cells contained acidic and basic keratins.
  • Receptors for platelet-derived growth factor, epidermal growth factor and insulin were detected in the rat mesothelial cells.
  • Basic fibroblast growth factor was expressed in both the rat and the human mesothelial cells.
  • Platelet-derived growth factor A-chain messenger RNA was found at very low levels in the human LP9 cells but was not detected in any of the rat mesothelial cultures.
  • Unlike the rat cells, the human LP9 cells expressed low but detectable transforming growth factor alpha.
  • Growth factor receptor expression was qualitatively similar across the cell strains examined.
• The authors' conclusion: The authors concluded that, because normal mesothelial cells have these receptors but no production of the matching growth factors was detected, self-stimulation (autocrine) of growth through such factors may be specific to transformed mesothelial cells.
• Limitations the authors state:
  • No specific marker for mesothelial cells exists, so the authors relied on several cell characteristics to support the mesothelial origin of the strains.
  • Diffuse background staining was sometimes seen with the platelet-derived growth factor A-chain probe. Because there were no discrete bands, the rat cells were scored as negative.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelial Cells, Mineral Fiber, Pleural Mesothelioma, Mesothelioma, Mesothelium, Parietal Pleura, Fibroblast, Platelet-Derived Growth Factor (PDGF).

Related studies

• Proliferation of rat pleural mesothelial cells in response to hepatocyte and keratinocyte growth factors — I.Y. Adamson, J. Bakowska, et al. (2000)
• Increased expression of epidermal growth factor receptor in rat pleural mesothelial cells correlates with carcinogenicity of mineral fibres — S.P. Faux, C.E. Houghton, et al. (2000)
• Differential responses to growth factors by normal human mesothelial cultures from individual donors — J.F. Lechner, M.A. LaVeck, et al. (1989)
• Chrysotile asbestos upregulates gene expression and production of alpha-receptors for platelet-derived growth factor (PDGF-AA) on rat lung fibroblasts — J.C. Bonner, A.L. Goodell, et al. (1993)
• Asbestos upregulates expression of the urokinase-type plasminogen activator receptor on mesothelial cells — R.C. Perkins, V.C. Broaddus, et al. (1999)
• Growth factor responses and protooncogene expression of murine mesothelial cell lines derived from asbestos-induced mesotheliomas — L.A. Goodglick, C.A. Vaslet, et al. (1997)

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