title: Oseltamivir phosphate monotherapy ablates tumor neovascularization, growth, and metastasis in mouse model of human triple-negative breast adenocarcinoma.
abstract: BACKGROUND
  Triple-negative breast cancers (TNBCs) lack the estrogen, progesterone, and epidermal growth factor (EGF) receptor-2 (HER2/neu) receptors. Patients with TNBC have typical high grading, more frequent relapses, and exhibit poorer outcomes or prognosis compared with the other subtypes of breast cancers. Currently, there are no targeted therapies that are effective for TNBC. Preclinical antitumor activity of oseltamivir phosphate (OP) therapy was investigated to identify its role in tumor neovascularization, growth, invasiveness, and long-term survival in a mouse model of human TNBC.
  
  
  METHODS
  Live cell sialidase, water soluble tetrazolium, WST-1 cell viability, and immunohistochemistry assays were used to evaluate sialidase activity, cell survival, and the expression levels of tumor E-cadherin, N-cadherin, and host endothelial CD31+/PECAM-1 cells in archived paraffin-embedded TNBC MDA-MB-231 tumors grown in RAGxCγ double mutant mice.
  
  
  RESULTS
  OP, anti-Neu1 antibodies, and matrix metalloproteinase-9-specific inhibitor blocked Neu1 activity associated with EGF-stimulated TNBC MDA-MB-231 cells. OP treatment of MDA-MB-231 and MCF-7 cells and their long-term tamoxifen-resistant clones reproducibly and dose-dependently reduced the sialidase activity associated with EGF-stimulated live cells and the cell viability after 72 hours of incubation. Combination of 1 μM cisplatin, 5-FU, paclitaxel, gemcitabine, or tamoxifen with OP dosages ≥300 μg/mL significantly reduced cell viability at 24, 48, and 72 hours when compared to the chemodrug alone. Heterotopic xenografts of MDA-MB-231 tumors developed robust and bloody tumor vascularization in RAG2xCγ double mutant mice. OP treatment at 30 mg/kg daily intraperitoneally reduced tumor vascularization and growth rate as well as significantly reduced tumor weight and spread to the lungs compared with the untreated cohorts. OP treatment at 50 mg/kg completely ablated tumor vascularization, tumor growth and spread to the lungs, with significant long-term survival at day 180 postimplantation, tumor shrinking, and no relapses after 56 days off-drug. OP 30 mg/kg cohort tumors expressed significantly reduced levels of human N-cadherins and host CD31+ endothelial cells with concomitant significant expression of E-cadherins compared to the untreated cohorts.
  
  
  CONCLUSIONS
  OP monotherapy may be the effective treatment therapy for TNBC.
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada.
authors.forename: Fiona
authors.initials: F
authors.lastname: Haxho
authors.affiliation: Department of Chemical Engineering, Queen's University, Kingston, ON, Canada.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Allison
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada ; The King Fahd Armed Forces Hospital, Serology, Jeddah, Saudi Arabia.
authors.forename: Farah
authors.initials: F
authors.lastname: Alghamdi
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada.
authors.forename: Lacey
authors.initials: L
authors.lastname: Brodhagen
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada.
authors.forename: Victoria El
authors.initials: VE
authors.lastname: Kuta
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada ; Department of Molecular Genetics, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Samar
authors.initials: S
authors.lastname: Abdulkhalek
authors.affiliation: Department of Chemical Engineering, Queen's University, Kingston, ON, Canada.
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Neufeld
authors.affiliation: Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada.
authors.forename: Myron R
authors.initials: MR
authors.lastname: Szewczuk
keywords: chemoresistance; triple-negative breast cancer