title: A simple biological imaging system for  detecting viable human circulating tumor cells.
abstract: The presence of circulating tumor cells (CTCs) in the peripheral blood is associated with short survival, making the detection of CTCs clinically useful as a prognostic factor of disease outcome and/or a surrogate marker of treatment response. Recent technical advances in immunocytometric analysis and quantitative real-time PCR have made it possible to detect a few CTCs in the blood; however, there is no sensitive assay to specifically detect viable CTCs. Here, we report what we believe to be a new approach to visually detect live human CTCs among millions of peripheral blood leukocytes, using a telomerase-specific replication-selective adenovirus expressing GFP. First, we constructed a GFP-expressing attenuated adenovirus, in which the telomerase promoter regulates viral replication (OBP-401; TelomeScan). We then used OBP-401 to establish a simple ex vivo method that was able to detect viable human CTCs in the peripheral blood. The detection method involved a 3-step procedure, including the lysis of rbc, the subsequent addition of OBP-401 to the cell pellets, and an automated scan using fluorescence microscopy. OBP-401 infection increased the signal-to-background ratio as a tumor-specific probe, because the fluorescent signal was amplified only in viable, infected human tumor cells, by viral replication. This GFP-expressing virus-based method is remarkably simple and allows precise enumeration of CTCs.
authors.affiliation: Division of Surgical Oncology, Department of Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Kojima
authors.forename: Yuuri
authors.initials: Y
authors.lastname: Hashimoto
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Kagawa
authors.forename: Futoshi
authors.initials: F
authors.lastname: Uno
authors.forename: Shinji
authors.initials: S
authors.lastname: Kuroda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tazawa
authors.forename: Satoru
authors.initials: S
authors.lastname: Kyo
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mizuguchi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Urata
authors.forename: Noriaki
authors.initials: N
authors.lastname: Tanaka
authors.forename: Toshiyoshi
authors.initials: T
authors.lastname: Fujiwara
mesh_terms: D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D003952:Diagnostic Imaging / Q000295:instrumentation / Q000379:methods*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008856:Microscopy, Fluorescence / Q000295:instrumentation / Q000379:methods; D009360:Neoplastic Cells, Circulating
chemical_list: D049452:Green Fluorescent Proteins