title: cJun overexpression in MCF-7 breast cancer cells produces a tumorigenic, invasive and hormone resistant phenotype.
abstract: We have previously demonstrated decreased Jun/AP-1 activity in the breast cancer cell line MCF-7 when compared to normal or immortalized mammary epithelial cells. In this paper, we overexpress Jun in MCF-7 cells (MCF7Jun) and demonstrate that it results in diverse biologic and biochemical changes, which mimic those seen clinically in breast cancer. Overexpression of Jun causes significant alterations in the composition of AP-1, decreased junB and increased fra-1 expression and results in an increased biologic aggressiveness. MCF7Jun cells exhibit increased cellular motility, increased expression of a matrix degrading enzyme MMP-9, increased in vitro chemoinvasion and tumor formation in nude mice in the absence of exogenous estrogens. Furthermore, MCF7Jun cells are unresponsive to the growth stimulating effects of estrogen and growth inhibitory effects of tamoxifen. Analysis of the estrogen receptor (ER) expression and activity showed that the MCF7Jun cells have no detectable ER. MCF-7 cells overexpressing mutant forms of cJun were responsive to the growth stimulatory effects of estrogen indicating that full-length cJun is required to acquire the estrogen-independent phenotype in breast cancer cells.
authors.affiliation: Department of Cell and Cancer Biology, Medicine Branch, National Cancer Institute, NIH, Rockville, Maryland, MD 20850, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Smith
authors.forename: S C
authors.initials: SC
authors.lastname: Wise
authors.forename: D T
authors.initials: DT
authors.lastname: Hendricks
authors.forename: A L
authors.initials: AL
authors.lastname: Sabichi
authors.forename: T
authors.initials: T
authors.lastname: Bos
authors.forename: P
authors.initials: P
authors.lastname: Reddy
authors.forename: P H
authors.initials: PH
authors.lastname: Brown
authors.forename: M J
authors.initials: MJ
authors.lastname: Birrer
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology*; D002465:Cell Movement / Q000235:genetics; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D016762:Genes, fos; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D009361:Neoplasm Invasiveness; D010641:Phenotype; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics* / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D013629:Tamoxifen / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014746:Vimentin / Q000235:genetics / Q000378:metabolism; D000099169:Fos-Related Antigen 1
chemical_list: D004965:Estrogen Antagonists; D004967:Estrogens; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011960:Receptors, Estrogen; D013629:Tamoxifen; D018808:Transcription Factor AP-1; D014746:Vimentin; D000099169:Fos-Related Antigen 1