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Flow cytometry analysis of single‐strand DNA damage in neuroblastoma cell lines using the F7‐26 monoclonal antibody
Author(s) -
Grigoryan Rita S.,
Yang Bo,
Keshelava Nino,
Barnhart Jerry R.,
Reynolds C. Patrick
Publication year - 2007
Publication title -
cytometry part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.316
H-Index - 90
eISSN - 1552-4930
pISSN - 1552-4922
DOI - 10.1002/cyto.a.20458
Subject(s) - fenretinide , propidium iodide , tunel assay , flow cytometry , apoptosis , microbiology and biotechnology , dna damage , comet assay , cytotoxicity , chemistry , reactive oxygen species , monoclonal antibody , programmed cell death , biology , dna , biochemistry , antibody , immunology , in vitro , retinoid , retinoic acid , gene
The F7‐26 monoclonal antibody (Mab) has been reported to be specific for single‐strand DNA damage (ssDNA) and to also identify cells in apoptosis. We carriedout studies to determine if F7‐26 binding measured by flow cytometry was able to specifically identify exogenous ssDNA as opposed to DNA damage from apoptosis. Neuroblastoma cells were treated with melphalan (L‐PAM), fenretinide, 4‐hydroperoxycyclophosphamide (4‐HC) ± pan‐caspase inhibitor BOC‐d‐fmk, topotecan or with 10Gy γ radiation ± hydrogen peroxide (H 2 O 2 ) and fixed immediately postradiation. Cytotoxicity was measured by DIMSCAN digital imaging fluorescence assay. The degree of ssDNA damage was analyzed by flow cytometry using Mab F7‐26, with DNA visualized by propidium iodide counterstaining. Flow cytometry was used to measure apoptosis detected by terminal deoxynucleotidyltransferase (TUNEL) assay and reactive oxygen species (ROS) by carboxy‐dichlorofluorescein diacetate. Irradiated and immediately fixed neuroblastoma cells showed increased ssDNA, but not apoptosis by TUNEL (TUNEL‐negative). 4‐HC or L‐PAM ± BOC‐d‐fmk increased ssDNA (F7‐26‐positive), but BOC‐d‐fmk prevented TUNEL staining. Fenretinide increased apoptosis by TUNEL but not ssDNA damage detected with F7‐26. Enhanced ssDNA in neuroblastoma cells treated with radiation + H 2 O 2 was associated with increased ROS. Topotecan increased both ssDNA and cytotoxicity in 4‐HC‐treated cells. These data demonstrate that Mab F7‐26 recognized ssDNA due to exogenous DNA damage, rather than apoptosis. This assay should be useful to characterize the mechanism of action of antineoplastic drugs. © 2007 International Society for Analytical Cytology