Induction of the metastatic phenotype by transfection of a benign rat mammary epithelial cell line with the gene for p9Ka, a rat calcium-binding protein, but not with the oncogene EJ-ras-1.
The rat mammary epithelial cell line, Rama 37, yields benign, non-metastasizing adenomatous tumours in syngeneic Wistar-Furth rats. Transfection of this line with a drug resistance plasmid containing both the gene for resistance to Geneticin (neo) and the gene for p9Ka (pSV2neo-p9Ka), a rat calcium-binding protein, or with a similar plasmid containing neo and the oncogene EJ-ras-1 (pSV2neo-ras) yields drug-resistant transformants that express high levels of the p9Ka or EJ-ras-1 mRNAs and proteins. These transfected cells all produce tumours when injected at subcutaneous sites with a shorter median latent period than the tumours produced by the parental untransfected Rama 37 cells in syngeneic hosts. Cells transfected with pSV2neo-p9Ka yield a higher incidence of tumours than untransfected Rama 37 cells, many of which metastasize to lungs and/or lymph nodes in syngeneic rats. However, cells transfected with pSV2-neo-ras or pSV2neo plasmid alone yield tumours that fail to metastasize. Immunofluorescent studies suggest an association of p9Ka with the cytoskeleton, as depicted by F-actin staining with the reagent phalloidin. It is suggested that the transfection of copies of the gene for the rat calcium-binding protein p9Ka can enhance the tumorigenic potential and induce the metastatic phenotype in this rat mammary model, whereas transfection of control plasmid DNA or the oncogene EJ-ras-1 fails to induce the metastatic phenotype, although EJ-ras-1 transfectants, like those containing p9Ka, possess increased growth properties in vivo.
Davies
B R
BR
Biochemistry Department, University of Liverpool, UK.
Davies
M P
MP
Gibbs
F E
FE
Barraclough
R
R
Rudland
P S
PS
D000818:Animals; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D004847:Epithelial Cells; D015870:Gene Expression; D005796:Genes; D011905:Genes, ras; D066298:In Vitro Techniques; D008321:Mammary Glands, Animal / Q000166:cytology; D009362:Neoplasm Metastasis; D009374:Neoplasms, Experimental / Q000473:pathology* / Q000503:physiopathology; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011994:Recombinant Proteins; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; D014162:Transfection
D002135:Calcium-Binding Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; C499412:S100a4 protein, rat; D016283:Proto-Oncogene Proteins p21(ras)