title: Urokinase plasminogen activator is localized in stromal cells in ductal breast cancer.
abstract: Urokinase plasminogen activator (uPA) regulates a proteolytic cascade that facilitates cancer invasion through degradation of the extracellular matrix, and high levels of uPA in human breast cancer tissue correlate with poor prognosis. We previously found that, in ductal breast cancer, uPA mRNA is highly expressed by myofibroblasts surrounding invasively growing cancer cells. However, the localization of uPA protein has not been settled in the published literature. Because uPA is a secreted molecule, it could conceivably be localized differently from its mRNA. We have studied the localization of uPA immunoreactivity in detail. Twenty-five cases of invasive ductal carcinoma were analyzed with three different uPA antibody preparations, all of which gave an essentially identical stromal staining pattern. Using double immunofluorescence, we identified uPA immunoreactivity in myofibroblasts and macrophages in all cases examined. Additionally, in approximately half of the tumors, we saw uPA staining of endothelial cells. In 3 of the 25 cases, a small subpopulation of the cancer cells was uPA-positive. We conclude that uPA immunoreactivity is almost exclusively associated with stromal cells, which thus play a major role in generation of proteolytic activity in ductal breast cancer.
authors.affiliation: Finsen Laboratory, Rigshospitalet, Copenhagen. schnack@finsenlab.dk
authors.forename: B S
authors.initials: BS
authors.lastname: Nielsen
authors.forename: M
authors.initials: M
authors.lastname: Sehested
authors.forename: S
authors.initials: S
authors.lastname: Duun
authors.forename: F
authors.initials: F
authors.lastname: Rank
authors.forename: S
authors.initials: S
authors.lastname: Timshel
authors.forename: J
authors.initials: J
authors.lastname: Rygaard
authors.forename: M
authors.initials: M
authors.lastname: Johnsen
authors.forename: K
authors.initials: K
authors.lastname: Danø
mesh_terms: D000918:Antibody Specificity; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000201:enzymology / Q000473:pathology*; D003902:Detergents; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005404:Fixatives; D005455:Fluorescent Antibody Technique; D005557:Formaldehyde; D006801:Humans; D017403:In Situ Hybridization; D017830:Octoxynol; D016612:Paraffin Embedding; D012333:RNA, Messenger / Q000032:analysis; D017154:Stromal Cells / Q000201:enzymology*; D014357:Trypsin; D014568:Urokinase-Type Plasminogen Activator / Q000032:analysis* / Q000235:genetics / Q000276:immunology
chemical_list: D014408:Biomarkers, Tumor; D003902:Detergents; D005404:Fixatives; D012333:RNA, Messenger; D005557:Formaldehyde; D017830:Octoxynol; D014357:Trypsin; D014568:Urokinase-Type Plasminogen Activator