1,2,3-trichloropropane

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: gene mutation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

DNA was isolated from paraffin-embedded tumor sections (obtained from the forestomach of mice of the NTP bioassay on 1,2,3-trichloropropane, see chapter 7.7), amplified by polymerase chain reaction, and analyzed by direct sequencing for mutations in the ras-genes

GLP compliance:

no

Type of assay:

other: PCR analysis of nature of H-ras and K-ras mutations in tumors

Test material

Test material information

Constituent 1

Reference substance name:

1,2,3-trichloropropane

EC Number:

202-486-1

EC Name:

1,2,3-trichloropropane

Cas Number:

96-18-4

Molecular formula:

C3H5Cl3

IUPAC Name:

1,2,3-trichloropropane

Test animals

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

see chapter 7.7 "National Toxicology Program (1993) / Mouse"

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- corn oil
- see chapter 7.7 "National Toxicology Program (1993) / Mouse"

Details on exposure:

see chapter 7.7 "National Toxicology Program (1993) / Mouse"

Duration of treatment / exposure:

2 years, see chapter 7.7 "National Toxicology Program (1993) / Mouse"

Frequency of treatment:

daily 5 d/wk

Post exposure period:

non

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 6, 20 and 60 mg/kg
Basis:
actual ingested
gavage

No. of animals per sex per dose:

60

Control animals:

yes, concurrent vehicle

Examinations

Tissues and cell types examined:

paraffin-embedded tumor sections from the forestomach

Details of tissue and slide preparation:

DNA was isolated from paraffin-embedded tumor sections (obtained from the forestomach of mice of the NTP bioassay on 1,2,3-trichloropropane, see chapter 7.7), amplified by polymerase chain reaction, and analyzed by direct sequencing for mutations in the ras-genes

Results and discussion

Additional information on results:

- 10 of 16 analysed tumors had a highly specific H-ras or K-ras mutation.
- 6 of the 10 had a H-ras mutation at codon 61 with 5 of the 6 showing a AT to TA transversion in base 1.
- 4 of the 10 had a K-ras mutation at codon 13 all of which showed a GC to CG transversion in base 1.
- These transversions aremost probably not caused by S-[1-(hydroxymethyl)-2-(N7- guanypethyl]glutathione which is the major DNA adduct that was found after 1,2,3-trichloropropane treatment.
- Based on preliminary results that are not further specified in the abstract, the authors propose that the found mutations are rather caused through etheno DNA adducts (1,N6-ethenodeoxyadenosine and 3,N4-ethenodeoxycytidine) which stem from lipid peroxidation.
- Their explanation is that the depletion of glutathion in cells that are exposed to 1,2,3-trichloropropane cause an increase in lipid peroxidation and thereby lead to the detrimental transversion mutations that were found in the ras-genes.

Applicant's summary and conclusion

Conclusions:

Interpretation of results: positive
DNA was isolated from paraffin-embedded tumor sections (obtained from the forestomach of mice of the NTP bioassay on 1,2,3-trichloropropane, see chapter 7.7), amplified by polymerase chain reaction, and analyzed by direct sequencing for mutations in the ras-genes.
Based on these results it is confirmed that 1,2,3-trichloropropane induces mutations, but a alternative mode of action is proposed: 1,2,3-trichloropropane exposure leads to glutathion depletion in cells, lipid peroxidation increases and etheno DNA adducts are formed that lead to transversion mutations.

Executive summary:

The present abstract to a poster presentation (Ito, 1996) reports the analysis of mouse forestomach tumor tissues via PCR. DNA was isolated from paraffin-embedded tumor sections (obtained from the forestomach of mice of the NTP bioassay on 1,2,3-trichloropropane, see chapter 7.7), amplified by polymerase chain reaction, and analyzed by direct sequencing for mutations in the ras-genes.

10 of 16 analysed tumors had a highly specific H-ras or K-ras mutation. 6 of the 10 had a H-ras mutation at codon 61 with 5 of the 6 showing a AT to TA transversion in base 1. 4 of the 10 had a K-ras mutation at codon 13 all of which showed a GC to CG transversion in base 1. These transversions are most probably not caused by S-[1-(hydroxymethyl)-2-(N7- guanypethyl]glutathione which is the major DNA adduct that was found after 1,2,3-trichloropropane treatment.

Based on preliminary results that are not further specified in the abstract, the authors propose that the found mutations are rather caused through etheno DNA adducts (1,N6-ethenodeoxyadenosine and 3,N4-ethenodeoxycytidine) which stem from lipid peroxidation. The proposed explanation is that the depletion of glutathion in cells that are exposed to 1,2,3-trichloropropane causes an increase in lipid peroxidation and thereby lead to the detrimental transversion mutations that were found in the ras-genes.