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Technical Modification of the Balb/c 3T3 Cell Transformation Assay: The use of Serum-reduced Medium to Optimise the Practicability of the Protocol

Technical Modification of the Balb/c 3T3 Cell Transformation Assay: The use of Serum-reduced... The two-stage Balb/c 3T3 model of cell transformation can mimic the two-stage carcinogenicity bioassay, and has been recognised as a screening method for detecting potential tumour initiators and promoters. A technical modification to the original protocol (which involved the use of M10F medium, consisting of MEM plus 10% fetal bovine serum [FBS]) has been previously proposed, in order to increase its efficacy, namely: the introduction of enriched, serum-reduced medium (DF2F medium, comprising DMEM/F12 plus 2% FBS and other supplements). The aim of this study was to further modify the protocol, so as to attain higher practicability for the assay. The protocol was further optimised by: a) reducing the number of plates required, through the use of larger plates; b) reducing the cost of the assay by retaining the reduced serum concentration and by using 2μg/ml insulin, rather than the more-complex insulin–transferrin–ethanolamine–sodium selenite (ITES) supplement (i.e. DF2F2I medium); and c) extending the culture period from 24–25 days to 31–32 days, resulting in clearer foci (the number of medium changes did not increase, as less-frequent medium changes were performed during the extended culture period). Growth curve construction revealed that variations in the saturation densities of the parental Balb/c 3T3 cell line and its three transformed clones were highest when M10F medium was replaced with DF2F2I medium just before cells reached confluence. We applied this newly-optimised protocol to the assessment of: a) the tumour initiating activity of 3-methylcholanthrene (MCA), N-methyl-N’-nitro-N-nitrosoguanidine, mitomycin C, methylmethane sulphonate, CdCl2 and phenacetin, combining a post-treatment of 100ng/ml 12-O-tetradecanoylphorbol-13-acetate at the promotion stage; and b) the tumour promoting activity of insulin, lithocholic acid, CdCl2 and phenobarbital, with pre-treatment of 0.2μg/ml MCA at the initiation stage. In the present study, only phenobarbital was negative when tested by using the modified protocol. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Alternatives to Laboratory Animals SAGE

Technical Modification of the Balb/c 3T3 Cell Transformation Assay: The use of Serum-reduced Medium to Optimise the Practicability of the Protocol

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References (23)

Publisher
SAGE
Copyright
© 2008 Fund for the Replacement of Animals in Medical Experiments
ISSN
0261-1929
eISSN
2632-3559
DOI
10.1177/026119290803600609
Publisher site
See Article on Publisher Site

Abstract

The two-stage Balb/c 3T3 model of cell transformation can mimic the two-stage carcinogenicity bioassay, and has been recognised as a screening method for detecting potential tumour initiators and promoters. A technical modification to the original protocol (which involved the use of M10F medium, consisting of MEM plus 10% fetal bovine serum [FBS]) has been previously proposed, in order to increase its efficacy, namely: the introduction of enriched, serum-reduced medium (DF2F medium, comprising DMEM/F12 plus 2% FBS and other supplements). The aim of this study was to further modify the protocol, so as to attain higher practicability for the assay. The protocol was further optimised by: a) reducing the number of plates required, through the use of larger plates; b) reducing the cost of the assay by retaining the reduced serum concentration and by using 2μg/ml insulin, rather than the more-complex insulin–transferrin–ethanolamine–sodium selenite (ITES) supplement (i.e. DF2F2I medium); and c) extending the culture period from 24–25 days to 31–32 days, resulting in clearer foci (the number of medium changes did not increase, as less-frequent medium changes were performed during the extended culture period). Growth curve construction revealed that variations in the saturation densities of the parental Balb/c 3T3 cell line and its three transformed clones were highest when M10F medium was replaced with DF2F2I medium just before cells reached confluence. We applied this newly-optimised protocol to the assessment of: a) the tumour initiating activity of 3-methylcholanthrene (MCA), N-methyl-N’-nitro-N-nitrosoguanidine, mitomycin C, methylmethane sulphonate, CdCl2 and phenacetin, combining a post-treatment of 100ng/ml 12-O-tetradecanoylphorbol-13-acetate at the promotion stage; and b) the tumour promoting activity of insulin, lithocholic acid, CdCl2 and phenobarbital, with pre-treatment of 0.2μg/ml MCA at the initiation stage. In the present study, only phenobarbital was negative when tested by using the modified protocol.

Journal

Alternatives to Laboratory AnimalsSAGE

Published: Dec 1, 2008

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