Effect of mineral dusts on metabolic cooperation between Chinese hamster V79 cells in vitro

Our plain-English summary of Effect of mineral dusts on metabolic cooperation between Chinese hamster V79 cells in vitro, by M. Chamberlain (Environmental Health Perspectives, 1983).

The study

• Author: M. Chamberlain
• Journal: Environmental Health Perspectives
• Published: 1983;51:5-9
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The mode of action of inorganic fibers as carcinogens is unknown. There is conflicting evidence whether they act by inducing lesions in DNA, such as initiating carcinogens, or alternatively act as promoters of carcinogenesis. Recent evidence has suggested that promoters inhibit the process of cell-to-cell chemical communication known as metabolic cooperation. Chinese hamster V79-4 cells in culture exhibit metabolic cooperation which can be blocked by the promoter tetraphorbol-13-acetate (TPA). Three kinds of mineral dust were tested to determine whether or not they could interfere with the intercellular communication. The three dusts studied were: amosite, a fibrous asbestos from the Union Internationale Contre le Cancer (UICC) standard reference series, which is a typical carcinogenic fibrous dust inducing pleural tumors following intrapleural injection into rats; ball-milled amosite, a nonfibrous dust derived from UICC amosite by ball-milling, which has the physical properties characteristic of a noncarcinogenic dust; and Min-U-Sil silica, a widely available sample of fibrogenic quartz which does not induce pleural tumors following intrapleural injection into rats. The results demonstrated that metabolic cooperation between V79-4 cells cannot be reduced by carcinogenic asbestos fibers or by relatively large numbers of nontoxic dust particles. It is concluded that if inorganic fibers promote carcinogenesis, then they do not operate by blocking metabolic cooperation.

In plain English

This laboratory study asked whether asbestos might promote cancer by blocking metabolic cooperation, a chemical communication between touching cells. The author grew V79-4 Chinese hamster lung cells with a drug-resistant line derived from them. Cultures were exposed to UICC amosite asbestos, non-fibrous ball-milled amosite or Min-U-Sil silica, with the known promoter TPA as a positive control. Recovery meant resistant-cell colonies grown with V79-4 cells as a percentage of those grown without them. TPA gave 91.0% recovery (95% confidence limits plus or minus 7.8) against 44.9% (plus or minus 6.6) in its solvent control, meaning cooperation was blocked. None of the three dusts, including amosite at a dose leaving 70% of cells alive, gave significantly greater recovery than their controls (p greater than 0.05). Estimated loads of over 100 milled amosite particles or 23 silica particles per cell did not prevent cooperation. Occasional "giant cells" appeared at higher amosite concentrations. The author concluded that if inorganic fibers promote cancer, they do not do so by blocking metabolic cooperation, without ruling out other mechanisms. The author called the per-cell figures minimum estimates.

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 experiment
• Who was studied: Cultured V79-4 Chinese hamster lung cells and an 8-azaguanine-resistant (AGr) cell line derived from them, studied at the MRC Pneumoconiosis Unit, Llandough Hospital, Penarth, U.K.
• Exposure: UICC amosite asbestos (fibrous) and ball-milled amosite (non-fibrous, milled 4 hours), each at 0.01, 0.1, 1.0 and 5.0 micrograms per mL; Min-U-Sil silica (quartz) at 5, 10, 25 and 50 micrograms per mL; the tumor promoter TPA at 0.01 micrograms per mL as a positive control
• Main results:
  • Recovery was the number of AGr colonies that grew in the presence of V79-4 cells, as a percentage of those that grew without V79-4 cells. With TPA (positive control, 0.01 micrograms per mL), recovery was 91.0 plus or minus 7.8% (95% confidence limits), compared with 44.9 plus or minus 6.6% in the control with solvent (DMSO), showing that metabolic cooperation was blocked
  • None of the three dusts gave significantly greater recovery of AGr colonies than their controls (p greater than 0.05), so none inhibited metabolic cooperation. Recovery was 38.4 plus or minus 6.1% in the medium control, 29.4% to 42.9% with UICC amosite, 40.8% to 52.6% with milled amosite, and 24.9% to 53.8% with Min-U-Sil
  • UICC amosite was also tested at a toxic dose of 5 micrograms per mL (70% cell survival) and still did not inhibit metabolic cooperation
  • Estimated particles settling per cell: UICC amosite at 5 micrograms per mL, 2.15 particles (0.27 fibers longer than 6.5 micrometers); milled amosite at 5 micrograms per mL, 108.6; Min-U-Sil at 50 micrograms per mL, 23.6. These numbers of particles did not prevent metabolic cooperation
  • At the higher concentrations of UICC amosite, occasional "giant cells" were seen in the AGr colonies; milled amosite and Min-U-Sil had no visible effect on cell shape
• The authors' conclusion: The author concluded that if inorganic fibers promote carcinogenesis, they do not do so by blocking metabolic cooperation. The author added that this does not rule out fibers acting as promoters through other mechanisms, such as effects on metabolism.
• Limitations the authors state:
  • The particle-per-cell figures were estimates of minimum doses only, because cells and dust particles can also interact on the Petri dish surface

Topics

Medical terms in this study, explained in our Lexicon: Carcinogenesis, Amosite, UICC, Carcinogenic, Fibrogenic.

Related studies

• The influence of mineral dusts on metabolic co-operation between mammalian cells in tissue culture — M. Chamberlain (1982)
• Cytotoxic action of mineral dusts on CHV 79 cells in vitro: factors affecting toxicity — S.O. Lock, M. Chamberlain (1983)
• Cytotoxic effects of some mineral dusts on Syrian hamster peritoneal macrophages — E. Bey, J.S. Harington (1971)
• Metsovo-tremolite asbestos fibres: in vitro effects on mutation, chromosome aberration, cell transformation and intercellular communication — K. Athanasiou, S.H. Constantopoulos, et al. (1992)
• The cytotoxic effects of asbestos and other mineral dust in tissue culture cell lines — M. Chamberlain, R.C. Brown (1978)
• Amosite, chrysotile and crocidolite asbestos are mutagenic in Chinese hamster lung cells — S.L. Huang (1979)

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