title: Targeted delivery of polyamidoamine-paclitaxel conjugate functionalized with anti-human epidermal growth factor receptor 2 trastuzumab.
abstract: BACKGROUND
  Antibody-dendrimer conjugates have the potential to improve the targeting and release of chemotherapeutic drugs at the tumor site while reducing adverse side effects caused by drug accumulation in healthy tissues. In this study, trastuzumab (TMAB), which binds to human epidermal growth factor receptor 2 (HER2), was used as a targeting agent in a TMAB-polyamidoamine (PAMAM) conjugate carrying paclitaxel (PTX) specifically to cells overexpressing HER2.
  
  
  METHODS
  TMAB was covalently linked to a PAMAM dendrimer via bifunctional polyethylene glycol (PEG). PTX was conjugated to PAMAM using succinic anhydride as a cross-linker, yielding TMAB-PEG-PAMAM-PTX. Dynamic light scattering and transmission electron microscopy were used to characterize the conjugates. The cellular uptake and in vivo biodistribution were studied by fluorescence microscopy, flow cytometry, and Carestream In Vivo FX, respectively.
  
  
  RESULTS
  Nuclear magnetic resonance spectroscopy demonstrated that PEG, PTX, fluorescein isothiocyanate, and cyanine7 were conjugated to PAMAM. Ultraviolet-visible spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that TMAB was conjugated to PEG-PAMAM. Dynamic light scattering and transmission electron microscopy measurements revealed that the different conjugates ranged in size between 10 and 35 nm and had a spherical shape. In vitro cellular uptake demonstrated that the TMAB-conjugated PAMAM was taken up by HER2-overexpressing BT474 cells more efficiently than MCF-7 cells that expressed lower levels of HER2. Co-localization experiments indicated that TMAB-conjugated PAMAM was located in the cytoplasm. The in vitro cytotoxicity of TMAB-conjugated PAMAM was lower than free PTX due to the slow release of PTX from the conjugate. In vivo targeting further demonstrated that TMAB-conjugated PAMAM accumulated in the BT474 tumor model more efficiently than non-conjugated PAMAM.
  
  
  CONCLUSIONS
  TMAB can serve as an effective targeting agent, and the TMAB-conjugated PAMAM can be exploited as a potential targeted chemotherapeutic drug delivery system for tumors that overexpress HER2.
authors.affiliation: School of Pharmacy, Yantai University, Yantai, Shandong Province, People's Republic of China.
authors.forename: Pengkai
authors.initials: P
authors.lastname: Ma
authors.affiliation: School of Pharmacy, Yantai University, Yantai, Shandong Province, People's Republic of China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Long-acting and Targeting Drug Delivery System, Yantai, Shandong Province, People's Republic of China.
authors.forename: Ling
authors.initials: L
authors.lastname: Ni
authors.affiliation: State Key Laboratory of Long-acting and Targeting Drug Delivery System, Yantai, Shandong Province, People's Republic of China.
authors.forename: Jinming
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Pharmacy, Yantai University, Yantai, Shandong Province, People's Republic of China.
authors.forename: Fengpu
authors.initials: F
authors.lastname: Zhang
authors.affiliation: School of Pharmacy, Yantai University, Yantai, Shandong Province, People's Republic of China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: School of Pharmacy, Yantai University, Yantai, Shandong Province, People's Republic of China.
authors.forename: Shengnan
authors.initials: S
authors.lastname: Lian
authors.affiliation: School of Pharmacy, Yantai University, Yantai, Shandong Province, People's Republic of China.
authors.forename: Kaoxiang
authors.initials: K
authors.lastname: Sun
mesh_terms: D050091:Dendrimers / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D061986:MCF-7 Cells; D053758:Nanoparticles / Q000737:chemistry*; D017239:Paclitaxel / Q000737:chemistry / Q000493:pharmacokinetics; D014018:Tissue Distribution; D000068878:Trastuzumab / Q000737:chemistry*
chemical_list: D050091:Dendrimers; C104700:PAMAM Starburst; D000068878:Trastuzumab; D017239:Paclitaxel
keywords: HER2; PAMAM; active targeting; paclitaxel; trastuzumab
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