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ASTM E1262-24

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Standard Guide for Performance of Chinese Hamster Ovary Cell/Hypoxanthine Guanine Phosphoribosyl Transferase Gene Mutation Assay

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1.1 This guide highlights some of the more relevant biological concepts as they are currently understood, and summarizes the critical technical aspects for acceptable bioassay performances as they currently are perceived and practiced. The Chinese hamster ovary cell/hypoxanthine guanine phosphoribosyl transferase (CHO/HGPRT) assay (1)2 has been widely applied to the toxicological evaluation of industrial and environmental chemicals. The method is limited to detection of small-scale genetic interactions. Therefore, when this method is used for genotoxicity assessment it is recommended that an in vitro clastogenicity assay (for example, chromosomal aberration, micronucleus) is considered to detect large-scale (for example, chromosomal) DNA damage.

1.2 This guide concentrates on the practical aspects of cell culture, mutagenesis procedures, data analysis, quality control, and testing strategy. The suggested approach represents a consensus of the panel members for the performance of the assay. It is to be understood, however, that these are merely general guidelines and are not to be followed without the use of sound scientific judgement. Users of the assay should evaluate their approach based on the properties of the substances to be tested and the questions to be answered.

1.3 Deviation from the guidelines based on sound scientific judgement should by no means invalidate the results obtained.

1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.


2.1 The CHO/HGPRT assay detects forward mutations of the X-linked hypoxanthine-guanine phosphoribosyl transferase (hgprt) locus (coding for the enzyme, HGPRT) in Chinese hamster ovary (CHO) cells. Cells originally derived from Chinese hamster ovary tissue are exposed to a test article and, following an appropriate cell culture regimen, descendants of the original treated population are monitored for the loss of functional HGPRT, presumably due to mutations. Resistance to a purine analogue, 6-thioguanine (6TG) (or less desirably, 8-azaguanine (8AG)), is employed as the genetic marker. HGPRT catalyzes the conversion of the nontoxic 6TG to its toxic ribophosphorylated derivative. Loss of the enzyme or its activity therefore leads to cells resistant to 6TG.

2.2 Because HGPRT is an enzyme of the purine nucleotide salvage pathway, loss of the enzyme is not a lethal event. Different types of mutational events (base substitutions, frame shifts, deletions, and so forth) can be detectable at the hgprt locus. The assay does not appear to detect large-scale chromosomal damage. The CHO/HGPRT assay has been used to study a wide range of mutagens, including radiations (2-4), and a wide variety of chemicals (1) and complex chemical mixtures (5).

SDO ASTM: ASTM International
Document Number E1262
Publication Date Dec. 1, 2024
Language en - English
Page Count 5
Revision Level 24
Supercedes
Committee F04.16
Publish Date Document Id Type View
Dec. 1, 2024 E1262-24 Revision
Feb. 1, 2018 E1262-88R18 Reaffirmation
Oct. 1, 2013 E1262-88R13 Reaffirmation
Aug. 1, 2008 E1262-88R08 Reaffirmation
Sept. 10, 2003 E1262-88R03 Reaffirmation
Jan. 1, 1996 E1262-88R96 Reaffirmation