title: Effects of tamoxifen and retinoic acid on cell growth and c-myc gene expression in human breast and cervical cancer cells.
abstract: The effects of estradiol, tamoxifen, and retinoic acid on the proliferation of breast and cervical cancer cells were investigated. Estrogen stimulated only MCF-7 cell growth, whereas tamoxifen and retinoic acid inhibited the proliferation of all cells studied. Northern blot analysis indicated that estradiol up-regulates c-myc mRNA level in all cell lines studied regardless of the estrogen receptor status in the cells. On the contrary, tamoxifen inhibits c-myc gene expression in all cell lines studied except in MCF-7 cells where the c-myc transcript was not affected. The inhibitory effect of tamoxifen on c-myc gene expression and cell proliferation in estrogen receptor-negative cells suggest an estrogen receptor-independent mechanism. The results also suggest that different mechanisms are involved in the regulation of cell growth and c-myc gene expression in different cancer cells by estrogen and tamoxifen.
authors.affiliation: Department of Medical Research, Veterans General Hospital, Taipei, Taiwan, R.O.C.
authors.forename: L C
authors.initials: LC
authors.lastname: Tsai
authors.forename: M W
authors.initials: MW
authors.lastname: Hung
authors.forename: C C
authors.initials: CC
authors.lastname: Yuan
authors.forename: P L
authors.initials: PL
authors.lastname: Chao
authors.forename: S Y
authors.initials: SY
authors.lastname: Jiang
authors.forename: G G
authors.initials: GG
authors.lastname: Chang
authors.forename: T C
authors.initials: TC
authors.lastname: Chang
mesh_terms: D001943:Breast Neoplasms; D002455:Cell Division / Q000187:drug effects*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D016259:Genes, myc / Q000187:drug effects*; D006801:Humans; D007700:Kinetics; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis; D013629:Tamoxifen / Q000494:pharmacology*; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects*; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D002583:Uterine Cervical Neoplasms
chemical_list: D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D013629:Tamoxifen; D004958:Estradiol; D014212:Tretinoin