Allele loss and point mutation in codons 12 and 61 of the c-Ha-ras oncogene in carcinogen-transformed human breast epithelial cells

Mol Carcinog. 1994 Jan;9(1):46-56. doi: 10.1002/mc.2940090109.

Abstract

There is significant evidence that the ras oncogene plays a role in experimental mammary carcinogenesis; the evidence in human breast cancer, however, is more limited. We induced the expression of transformation phenotypes in the human breast epithelial cell line MCF-10F with the chemical carcinogens 7,12-dimethylbenz[a]anthracene, N-methyl-N-nitrosourea, N-methyl-N-nitro-N'-nitrosoguanidine, and benzo[a]pyrene. This work was designed to clarify whether chemically induced neoplastic transformation correlates with alterations in the ras gene. MCF-10F cells have two c-Ha-ras alleles, identified by 1.0-kb and 1.2-kb restriction fragments. Treatment with carcinogens resulted in the loss of one of the alleles (1.0 kb). Polymerase chain reaction-amplified DNA from all carcinogen-treated cells was analyzed for point mutations in c-Ha-ras at codons 12 and 61. All of the carcinogens induced a mutation of the remaining allele at the first position of codon 12 (GGC-->AGC). Another frequent mutation occurred at the first position of codon 61 (CAG-->GAG). The changes in c-Ha-ras were associated with the emergence of colony formation in agar-methocel, but no specific changes in this gene correlated with the emergence of invasiveness or tumorigenesis, indicating that other genes may be involved in the process.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Alleles*
  • Animals
  • Base Sequence
  • Breast / drug effects
  • Breast Neoplasms / chemically induced*
  • Breast Neoplasms / genetics*
  • Carcinogenicity Tests
  • Carcinogens
  • Cell Line
  • Cell Transformation, Neoplastic / genetics*
  • Codon / genetics*
  • DNA Probes
  • DNA, Neoplasm / genetics
  • Epithelium / pathology
  • Epithelium / physiology
  • Female
  • Gene Amplification
  • Gene Deletion*
  • Genes, ras / genetics*
  • Humans
  • Immunoblotting
  • Mice
  • Mice, SCID
  • Molecular Sequence Data
  • Nucleic Acid Hybridization
  • Phenotype
  • Point Mutation / drug effects
  • Point Mutation / genetics*
  • Polymerase Chain Reaction

Substances

  • Carcinogens
  • Codon
  • DNA Probes
  • DNA, Neoplasm