Activated Ki-ras proto-oncogene in spontaneously transformed and chemical tumor-derived cell lines related to the mouse lung alveologenic carcinoma.
An in vitro cell model of mouse lung alveologenic carcinoma consisting of preneoplastic nonmalignant cells, spontaneously transformed cells, and urethane-induced malignant cells was analyzed for phenotypic and genotypic changes associated with the transition to neoplasia. The polymerase chain reaction (PCR) was used to amplify the cDNA derived from the c-Ki-ras mRNA corresponding to exons 1 and 2 of the proto-oncogene. This approach allowed analysis of the gene transcription product rather than potentially unexpressed DNA. Direct sequencing of the PCR product identified a common single point mutation, alone or together with wild-type mRNA for c-Ki-ras, in all of the malignant clones. An A----G transition in the second base position of codon 61 was common to spontaneously malignant and chemical tumor-derived cell lines and to lines selected for lung metastatic behavior. The absence of the mutation in the nonmalignant cells suggests that the Ki-ras mutation may be a factor in onset or maintenance of the malignant phenotype and, at least in vitro, may be a late event in the transformation process.
Leigh
D A
DA
Carcinogenesis Research Unit, School of Pathology, University of New South Wales, Kensington, Australia.
Ferguson
V
V
Bentel
J M
JM
Miller
J O
JO
Smith
G J
GJ
D002282:Adenocarcinoma, Bronchiolo-Alveolar / Q000235:genetics*; D000236:Adenoma / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D003062:Codon; D008175:Lung Neoplasms / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D009841:Oligonucleotides / Q000737:chemistry; D009857:Oncogenes; D016133:Polymerase Chain Reaction; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D014407:Tumor Cells, Cultured; D014520:Urethane
D003062:Codon; D009841:Oligonucleotides; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D014520:Urethane; D016283:Proto-Oncogene Proteins p21(ras)