title: Color-coded Live Imaging of Heterokaryon Formation and Nuclear Fusion of Hybridizing Cancer Cells.
abstract: OBJECTIVE
  Fusion of cancer cells has been studied for over half a century. However, the steps involved after initial fusion between cells, such as heterokaryon formation and nuclear fusion, have been difficult to observe in real time. In order to be able to visualize these steps, we have established cancer-cell sublines from the human HT-1080 fibrosarcoma, one expressing green fluorescent protein (GFP) linked to histone H2B in the nucleus and a red fluorescent protein (RFP) in the cytoplasm and the other subline expressing RFP in the nucleus (mCherry) linked to histone H2B and GFP in the cytoplasm.
  
  
  METHODS
  The two reciprocal color-coded sublines of HT-1080 cells were fused using the Sendai virus. The fused cells were cultured on plastic and observed using an Olympus FV1000 confocal microscope.
  
  
  RESULTS
  Multi-nucleate (heterokaryotic) cancer cells, in addition to hybrid cancer cells with single-or multiple-fused nuclei, including fused mitotic nuclei, were observed among the fused cells. Heterokaryons with red, green, orange and yellow nuclei were observed by confocal imaging, even in single hybrid cells. The orange and yellow nuclei indicate nuclear fusion. Red and green nuclei remained unfused. Cell fusion with heterokaryon formation and subsequent nuclear fusion resulting in hybridization may be an important natural phenomenon between cancer cells that may make them more malignant.
  
  
  CONCLUSIONS
  The ability to image the complex processes following cell fusion using reciprocal color-coded cancer cells will allow greater understanding of the genetic basis of malignancy.
authors.affiliation: Gifu University Graduate School of Medicine, Gifu, Japan AntiCancer, Inc., San Diego, CA, U.S.A. Department of Surgery, University of California San Diego, San Diego, CA, U.S.A.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suetsugu
authors.affiliation: Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Takuro
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Hasegawa
authors.affiliation: Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kunisada
authors.affiliation: Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Shimizu
authors.affiliation: Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Shigetoyo
authors.initials: S
authors.lastname: Saji
authors.affiliation: Gifu University Graduate School of Medicine, Gifu, Japan.
authors.forename: Hisataka
authors.initials: H
authors.lastname: Moriwaki
authors.affiliation: Department of Surgery, University of California San Diego, San Diego, CA, U.S.A.
authors.forename: Michael
authors.initials: M
authors.lastname: Bouvet
authors.affiliation: AntiCancer, Inc., San Diego, CA, U.S.A. Department of Surgery, University of California San Diego, San Diego, CA, U.S.A. all@anticancer.com.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Hoffman
mesh_terms: D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000473:pathology / Q000648:ultrastructure*; D003593:Cytoplasm / Q000473:pathology / Q000648:ultrastructure*; D005354:Fibrosarcoma / Q000000981:diagnostic imaging* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins; D006657:Histones / Q000302:isolation & purification; D006801:Humans; D018613:Microscopy, Confocal; D009681:Nuclear Fusion
chemical_list: D006657:Histones; D049452:Green Fluorescent Proteins
keywords: Green fluorescent protein; Sendai virus; cell fusion; cell hybrid; dual-color HT-1080; heterokaryon; imaging; nuclear fusion; red fluorescent protein