title: Building bridges toward invasion: tumor promoter treatment induces a novel protein kinase C-dependent phenotype in MCF10A mammary cell acini.
abstract: The potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) alters many cellular processes through activation of its receptor protein kinase C (PKC), including gene expression, cell cycle, and the regulation of cell morphology, raising an important question for developing targeted methods to prevent cancer: which effects of TPA are crucial for carcinogenesis? To address this question, we studied TPA action in the 3-dimensional (3D) MCF10A human breast epithelial cell system, which models important features of in vivo epithelial tissue including growth constraints, structural organization of cells, and establishment of a basement membrane. MCF10A cells, which are immortalized but nontumorigenic, form hollow, spheroid structures in 3D culture referred to as acini. The development of normal acini requires the tight spatiotemporal regulation of cellular proliferation, polarization, apoptosis, and growth arrest. Treatment of MCF10A acini with TPA caused the appearance of multi-acinar structures. Surprisingly, this phenotype did not involve an increase in cell number or major changes in cell death, and polarization. Instead, live cell and confocal microscopy revealed that TPA stimulates MCF10A acini to aggregate. TPA induces the PKC-dependent production of actin-based protrusions, which leads to the formation of cellular bridges between acini, the clustering of acini, and allows cells to move into adjacent acini. During this process, the integrity of the laminin V basement membrane is disrupted, while E-cadherin-based cell-cell contacts remain intact. Altogether, our results show that under the biochemical and structural constraints of epithelial tissue, as modeled by the 3D MCF10A system, TPA induces a novel PKC-dependent phenotype that resembles local invasion. Of the many effects caused by TPA, these studies highlight the aggressive production of actin-based cellular protrusions as a potentially important event along the pathway to carcinogenesis.
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Kristine S
authors.initials: KS
authors.lastname: Klos
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Janel K
authors.initials: JK
authors.lastname: Warmka
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Disa M
authors.initials: DM
authors.lastname: Drachenberg
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Liang
authors.initials: L
authors.lastname: Chang
authors.affiliation: Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: G W Gant
authors.initials: GW
authors.lastname: Luxton
authors.affiliation: Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Cheuk T
authors.initials: CT
authors.lastname: Leung
authors.affiliation: Department of Laboratory Medicine and Pathology and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Schwertfeger
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors.forename: Elizabeth V
authors.initials: EV
authors.lastname: Wattenberg
mesh_terms: D061354:Acinar Cells / Q000201:enzymology* / Q000473:pathology*; D000199:Actins / Q000378:metabolism; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology*; D015820:Cadherins / Q000378:metabolism; D063646:Carcinogenesis / Q000473:pathology*; D002449:Cell Aggregation / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D016764:Cell Polarity / Q000187:drug effects; D005260:Female; D006801:Humans; D007797:Laminin / Q000378:metabolism; D042361:Mammary Glands, Human / Q000473:pathology*; D008938:Mitosis / Q000187:drug effects; D009361:Neoplasm Invasiveness; D010641:Phenotype; D011493:Protein Kinase C / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate; D013997:Time Factors
chemical_list: D000199:Actins; D015820:Cadherins; D007797:Laminin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate