title: v-myc alters the response of a cloned mouse mammary epithelial cell line to lactogenic hormones.
abstract: Several oncogenes have now been implicated in mammary carcinogenesis. We investigated the phenotypic effects of expressing three representative oncogenes in mammary epithelial cells. v-myc (coding for a nuclear protein), v-Ha-ras (a G-protein homologue) and v-fgr (a tyrosine kinase) genes were introduced into the nontumorigenic clone 14 of the mouse mammary epithelial cell line COMMA-1D. Their effects upon growth and differentiation were determined. Anchorage-independent growth was induced by all three oncogenes with low efficiency. v-Ha-ras and v-fgr induced tumorigenicity in nude mice. The effect of oncogenes upon parameters unique to mammary epithelial cells in vitro was assayed. Both v-myc and v-fgr abolished the ability of clone 14 to grow as three-dimensional branching structures in hydrated collagen gel. v-fgr completely and v-myc partially inhibited the expression of the epithelium specific cytokeratins. Clone 14 can be induced to produce the beta-casein milk protein by the combination of the lactogenic hormones, dexamethasone, insulin, and PRL. Introduction of v-myc into clone 14 cells resulted in an estimated 50-fold increased induction of beta-casein protein and at least a 60-fold increase in beta-casein mRNA. The number of cells stained with anti-beta casein antibodies also showed a 10-fold increase after v-myc introduction. This still required the synergistic action of all three lactogenic hormones. Thus v-myc can alter the normal response of mammary epithelial cells to lactogenic hormones.
authors.affiliation: Ludwig Institute for Cancer Research, Inselspital, Bern, Switzerland.
authors.forename: R K
authors.initials: RK
authors.lastname: Ball
authors.forename: A
authors.initials: A
authors.lastname: Ziemiecki
authors.forename: C A
authors.initials: CA
authors.lastname: Schönenberger
authors.forename: E
authors.initials: E
authors.lastname: Reichmann
authors.forename: S M
authors.initials: SM
authors.lastname: Redmond
authors.forename: B
authors.initials: B
authors.lastname: Groner
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002999:Clone Cells; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000502:physiology*; D051379:Mice; D009857:Oncogenes; D011388:Prolactin / Q000502:physiology*
chemical_list: D011388:Prolactin