Multipotential behaviour of cloned rat mesothelioma cells with epithelial phenotype

Our plain-English summary of Multipotential behaviour of cloned rat mesothelioma cells with epithelial phenotype, by D.G. Brown, N.F. Johnson, M.M. Wagner (British Journal of Cancer, 1985).

The study

• Authors: D.G. Brown, N.F. Johnson, M.M. Wagner
• Journal: British Journal of Cancer
• Published: 1985;51(2):245-52
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Reference cultures derived from a transplantable rat mesothelioma were obtained by cloning cells three times in soft agar. Each line, designated "CARM-Lines", was selected on the basis of their epithelial or fibroblastic phenotype, and their uniform morphology. Three epithelial lines were used for more detailed in vitro studies comparing morphological and biological criteria at early and late passages. All three lines exhibited both epithelial and fibroblastic elements after 10-14 passages in vitro, demonstrating that the dimorphic histology of these tumours could be derived from a single aberrant cell. Morphology and growth characteristics of these cells were density-dependent. Anchorage dependent and independent clonogenic assays did not correlate. Anchorage dependent colony formation was the only parameter which differed markedly from the original parent line in the assays described. In vivo evidence of chondrogenesis and attempted ossification support the concept of a multipotential cell contributing to the diverse primary tumour morphology by cellular modulation or differentiation.

In plain English

This was a laboratory study of rat tumour cells, not of people. The authors had caused mesotheliomas in PVG/c Norwegian Hooded rats by injecting 20 mg of UICC crocidolite asbestos into the chest (pleural) cavity. They used one tumour from a female rat that had a mixed appearance. They cloned its cells three times in soft agar to obtain lines of uniform appearance, 17 of them epithelial. Ten of twelve epithelial lines injected back into rats produced tumours at 30 days, and three lines were studied in detail. All three later showed both epithelial and fibroblast-like cells after repeated growth in culture. Eight lines formed solid tumours. Most cells in these looked epithelial, but five tumours contained cartilage and one other showed bone formation. Cells doubled more slowly when sparse (69.0 hours) than when crowded (41.9 hours). The authors concluded that the uniform cloned cells changed form in culture and differentiated in animals. They noted that the cells' mesothelial origin had not been unequivocally determined.

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 cell-culture study (cloning of tumour cells) with transplantation of the cloned cells back into rats
• Who was studied: cells from one asbestos-induced mesothelioma (tumour Me9/TG3) from a female PVG/c Norwegian Hooded rat; 17 epithelial cloned lines (CARM-L1 to L17) were derived, 12 were injected into rats, and 3 lines were studied in detail
• Exposure: the original tumour was induced by an intrapleural injection of 20 mg of UICC crocidolite; the study itself examined the behaviour of the tumour cells, not the effects of exposure
• Main results:
  • The three epithelial lines studied in detail all came to show both epithelial and fibroblastic elements after repeated growth in culture
  • Of 12 epithelial cloned lines injected into rats, 10 produced tumours at 30 days
  • Eight lines formed solid tumours in which most cells looked epithelial; areas of cartilage were seen in five of these tumours
  • Of the three remaining tumours, none showed cartilage formation, and one showed bone formation only
  • Population doubling time in sub-confluent (sparse) cultures was a mean of 69.0 hours (s.d. 7.3, n=12), compared with 41.9 hours (s.d. 2.4, n=12) in confluent cultures
  • Anchorage-dependent colony formation was the most variable measure; lines 1 and 12 formed more colonies after several passages than the parent line
  • Plating efficiency differed between early and late passages for the three cloned lines and the parent line (paired t test, t=6.26, P less than 0.01)
  • Anchorage-independent colony formation did not vary significantly between the epithelial cloned lines and the parent line
• The authors' conclusion: The authors concluded that the thrice-cloned, uniform cells changed form in culture and differentiated in animals. They proposed that the epithelial lines may represent a multipotential sub-population of cells.
• Limitations the authors state:
  • The authors stated that the mesothelial origin of the cloned cells had not been unequivocally determined
  • Confluent cultures were harder to count accurately because the cells clumped together

Topics

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

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

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