c-fos, c-jun and c-myc expressions are not growth rate limiting for the human MCF-7 breast cancer cells.
Insulin-like growth factor I (IGF-I) was 3 times more potent in pagating MCF-7 cell proliferation than epidermal growth factor (EGF). IGF-I stimulated c-fos mRNA expression about 5 times less than EGF. Both growth factors were equipotent in inducing c-jun and c-myc mRNA expressions. The protein level of c-Myc correlated with the mRNA level. IGF-I and EGF stimulated the transcriptional activity dependent on the phorbol 12-myristate 13-acetate-responsive element (TRE) to the same extent, when measured by the chloramphenicol acetyl transferase activity of a transiently transfected multiple TRE construct. These results strongly indicate that the expression levels of the measured proto-oncogenes do not correlate with the increase of growth stimulation by IGF-I and EGF and are not growth rate limiting for the human MCF-7 breast cancer cells.
Wosikowski
K
K
Department of Research, University Clinics, Kantonsspital Basel, Switzerland.
Eppenberger
U
U
Küng
W
W
Nagamine
Y
Y
Mueller
H
H
D001943:Breast Neoplasms / Q000378:metabolism*; D002455:Cell Division; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D016762:Genes, fos; D016758:Genes, jun; D016259:Genes, myc; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I