title: Cyclin D1 is a direct target of JAG1-mediated Notch signaling in breast cancer.
abstract: The Notch ligand, JAG1 is associated with breast cancer recurrence. Herein, we report on a genomics approach to elucidate mechanisms downstream of JAG1 that promote breast cancer growth. In a survey of 46 breast cancer cell lines, we found that triple negative (TN; basal and mesenchymal ER-, PR-, and Her2-negative) lines express JAG1 at significantly higher levels than do HER2(+) or luminal (ER(+)) Her2(-) cell lines. In contrast to the luminal lines tested (T47D and MCF7), TN breast cancer cell lines (HCC1143 and MDA MB231) display high-level JAG1 expression and growth inhibition with RNA interference-induced JAG1 down-regulation. We used microarray profiling of TN tumor cells transfected with JAG1 siRNA to identify JAG1-regulated genes (P <or= 0.005; fold change >or=1.5). Among JAG1-regulated genes identified, cyclin D1 was found to be a direct target of NOTCH1 and NOTCH3. We show that JAG1 down-regulation reduces direct binding of Notch to the cyclin D1 promoter, reduced cyclin D1 expression and inhibition of cell cycle progression through the cyclin D1-dependant G1/S checkpoint. Furthermore, we show that cyclin D1 and JAG1 expression correlate in TN breast cancer expression datasets. These data suggest a model whereby JAG1 promotes cyclin D1-mediated proliferation of TN breast cancers.
authors.affiliation: Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, Toronto, Canada.
authors.forename: Brenda
authors.initials: B
authors.lastname: Cohen
authors.forename: Mamiko
authors.initials: M
authors.lastname: Shimizu
authors.forename: Julia
authors.initials: J
authors.lastname: Izrailit
authors.forename: Nancy F L
authors.initials: NF
authors.lastname: Ng
authors.forename: Yuri
authors.initials: Y
authors.lastname: Buchman
authors.forename: James G
authors.initials: JG
authors.lastname: Pan
authors.forename: Judy
authors.initials: J
authors.lastname: Dering
authors.forename: Michael
authors.initials: M
authors.lastname: Reedijk
mesh_terms: D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D000072100:Jagged-1 Protein; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D034741:RNA, Small Interfering; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis / Q000235:genetics; D011960:Receptors, Estrogen / Q000096:biosynthesis / Q000235:genetics; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000072099:Serrate-Jagged Proteins; D015398:Signal Transduction / Q000235:genetics*; D014162:Transfection
chemical_list: D002135:Calcium-Binding Proteins; D019938:Cyclin D1; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D051880:Receptors, Notch; D011980:Receptors, Progesterone; D000072099:Serrate-Jagged Proteins; C000606273:JAG1 protein, human