title: Development of mammary tumors by conditional expression of GLI1.
abstract: A diverse set of cellular defects, presumably elicited by multiple genetic alterations, underlies cancer development. Aberrant Hedgehog (Hh) signaling has recently been implicated in the development and maintenance of breast cancer. However, evidence conclusively showing that activated Hh signaling can induce mammary tumors is lacking. We now show that transgenic expression of the Hh effector protein GLI1 under the regulation of the mouse mammary tumor virus promoter, expressed in the mouse mammary gland, is associated with the appearance of hyperplastic lesions, defective terminal end buds, and tumor development. The GLI1-induced tumors are histologically heterogeneous and involve the expansion of a population of epithelial cells expressing the progenitor cell markers keratin 6 and Bmi-1. Moreover, tumor cells express genes involved in proliferation, cell survival, and metastasis. GLI1-induced tumors do not fully regress following transgene deinduction, indicating that some tumors develop and are maintained autonomously, independent of sustained transgenic GLI1 expression. The data strongly support a role of Hh/GLI signaling in breast cancer development and suggest that inhibition of this signaling pathway represents a new therapeutic opportunity for limiting tumorigenesis and early tumorigenic progression.
authors.affiliation: Center for Biosciences, Department of Biosciences, Karolinska Institutet,Novum, SE-141 57 Huddinge, Sweden.
authors.forename: Marie
authors.initials: M
authors.lastname: Fiaschi
authors.forename: Björn
authors.initials: B
authors.lastname: Rozell
authors.forename: Asa
authors.initials: A
authors.lastname: Bergström
authors.forename: Rune
authors.initials: R
authors.lastname: Toftgård
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002277:Carcinoma / Q000196:embryology / Q000235:genetics* / Q000473:pathology; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D005260:Female; D015870:Gene Expression; D053823:Hedgehog Proteins / Q000502:physiology; D051741:Kruppel-Like Transcription Factors / Q000235:genetics*; D008297:Male; D008321:Mammary Glands, Animal / Q000473:pathology; D015674:Mammary Neoplasms, Animal / Q000196:embryology / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D009361:Neoplasm Invasiveness; D009928:Organ Specificity / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013234:Stem Cells / Q000378:metabolism; D000071676:Zinc Finger Protein GLI1
chemical_list: D015415:Biomarkers; C498520:Gli1 protein, mouse; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; D000071676:Zinc Finger Protein GLI1