Overexpression of the proto-oncogene/translation factor 4E in breast-carcinoma cell lines.
The expression of the proto-oncogene, translation factor elF-4E, was examined in breast-cell lines: 5 carcinomas and 2 normal. At the protein level, elF-4E was 10 times higher in the carcinoma lines than in normal cells, which is comparable to the level found in breast-cancer biopsies. The elevation appears to be due to increased transcription, since the elF-4E mRNA was correspondingly increased. These results demonstrate that cells isolated from naturally occurring breast carcinomas maintain an elevated expression of the factor. Turnover rates for elF-4E (mRNA and protein) were determined for normal and cancer cells. We found that elF-4e mRNA is relatively stable during an 8-hr incubation with Actinomycin D, but the half-life of the protein is fairly short (approximately 4.5 hr). This suggests that, in proliferating cells, elF-4E may be turning over rapidly, possibly to fine-tune the changes in translation rates which occur during the cell cycle.
Anthony
B
B
Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, Shreveport 71130-3932, USA.
Carter
P
P
De Benedetti
A
A
D001483:Base Sequence; D015153:Blotting, Western; D001940:Breast / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism*; D002478:Cells, Cultured; D004848:Epithelium / Q000378:metabolism; D039561:Eukaryotic Initiation Factor-4E; D005260:Female; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D011233:Precipitin Tests; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012016:Reference Values; D014407:Tumor Cells, Cultured
D039561:Eukaryotic Initiation Factor-4E; C000715470:MAS1 protein, human; D010448:Peptide Initiation Factors; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger