Activating mutations of the c-Ha-ras protooncogene in chemically induced hepatomas of the male B6C3 F1 mouse.

Abstract

Activated c-Ha-ras protooncogenes have recently been identified in the DNA of some spontaneous hepatic tumors found in 2-year-old B6C3 F1 mice. Activation of c-Ha-ras has now been demonstrated in DNA from well-differentiated hepatomas initiated by a single dose of carcinogen given to male B6C3 F1 mice at 12 days of age. DNA from each of 25 hepatomas, induced by N-hydroxy-2-acetylaminofluorene, vinyl carbamate, or 1'-hydroxy-2',3'-dehydroestragole, containing transforming activity in the NIH 3T3 transfection assay. Southern analysis of NIH 3T3 cells transformed by DNA from 24 of these hepatomas revealed amplified and/or rear-ranged restriction fragments homologous to a Ha-ras probe. The other tumor contained an activated Ki-ras gene. Immunoprecipitation and NaDodSO4/PAGE analysis of p21 ras proteins in NIH 3T3 transformants derived from a majority of the hepatomas suggested that the activating mutations were localized in the 61st codon of the c-Ha-ras gene. Creation of a new Xba I restriction site by an AT----TA transversion at the second position of codon 61 was detected in DNA from primary tumors and NIH 3T3 cells transformed by DNA from 6 of 7 vinyl carbamate- and 5 of 10 1'-hydroxy-2',3'-dehydroestragole-induced hepatomas. Selective oligonucleotide hybridization demonstrated a CG----AT transversion at the first position of the 61st codon in NIH 3T3 transformants derived from 7 of 7 N-hydroxy-2-acetylaminofluorene-induced hepatomas. By the same criterion, an AT----GC transition at the second position of codon 61 was the activating mutation in 1 of 7 vinyl carbamate- and 5 of 10 1'-hydroxy-2',3'-dehydroestragole-induced tumors. Thus, c-Ha-ras activation is apparently an early event in B6C3 F1 mouse hepatocarcinogenesis that results directly from reaction of ultimate chemical carcinogens with this gene in vivo.

• Authors: R W Wiseman, S J Stowers, E C Miller, M W Anderson, J A Miller
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 83 Issue 16 Pg. 5825-9 (Aug 1986) ISSN: 0027-8424 [Print] United States
• PMID: 3016723 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• DNA, Neoplasm
• DNA Restriction Enzymes

Topics

• Animals
• Base Sequence
• Cells, Cultured
• DNA Restriction Enzymes
• DNA, Neoplasm (isolation & purification)
• Liver Neoplasms, Experimental (genetics)
• Male
• Mice
• Mice, Inbred Strains
• Mutation
• Nucleic Acid Hybridization
• Proto-Oncogenes
• Transfection