title: Regulation of breast cancer stem cell activity by signaling through the Notch4 receptor.
abstract: Notch receptor signaling pathways play an important role not only in normal breast development but also in breast cancer development and progression. We assessed the role of Notch receptors in stem cell activity in breast cancer cell lines and nine primary human tumor samples. Stem cells were enriched by selection of anoikis-resistant cells or cells expressing the membrane phenotype ESA(+)/CD44(+)/CD24(low). Using these breast cancer stem cell populations, we compared the activation status of Notch receptors with the status in luminally differentiated cells, and we evaluated the consequences of pathway inhibition in vitro and in vivo. We found that Notch4 signaling activity was 8-fold higher in stem cell-enriched cell populations compared with differentiated cells, whereas Notch1 signaling activity was 4-fold lower in the stem cell-enriched cell populations. Pharmacologic or genetic inhibition of Notch1 or Notch4 reduced stem cell activity in vitro and reduced tumor formation in vivo, but Notch4 inhibition produced a more robust effect with a complete inhibition of tumor initiation observed. Our findings suggest that Notch4-targeted therapies will be more effective than targeting Notch1 in suppressing breast cancer recurrence, as it is initiated by breast cancer stem cells.
authors.affiliation: Breast Biology Group, School of Cancer, Enabling Sciences and Technology, Paterson Institute for Cancer Research, University of Manchester, Manchester Academic Health Sciences Centre, The Christie NHS Foundation Trust; Department of Medical Oncology, The Christie NHS Foundation Trust, Manchester M20 4BX, United Kingdom.
authors.forename: Hannah
authors.initials: H
authors.lastname: Harrison
authors.forename: Gillian
authors.initials: G
authors.lastname: Farnie
authors.forename: Sacha J
authors.initials: SJ
authors.lastname: Howell
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Rock
authors.forename: Spyros
authors.initials: S
authors.lastname: Stylianou
authors.forename: Keith R
authors.initials: KR
authors.lastname: Brennan
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Bundred
authors.forename: Robert B
authors.initials: RB
authors.lastname: Clarke
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D051927:CD24 Antigen / Q000096:biosynthesis; D045744:Cell Line, Tumor; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis; D008565:Membrane Proteins / Q000096:biosynthesis; D051379:Mice; D018345:Mice, Knockout; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051881:Receptor, Notch1 / Q000378:metabolism; D000074562:Receptor, Notch4; D051880:Receptors, Notch / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D051927:CD24 Antigen; C497889:CD24 protein, human; C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D008565:Membrane Proteins; C497761:NOTCH1 protein, human; C106075:NOTCH4 protein, human; D011518:Proto-Oncogene Proteins; D051881:Receptor, Notch1; D000074562:Receptor, Notch4; D051880:Receptors, Notch; C106354:flotillins