title: A pilot study of fluorescent imaging of colorectal tumors using a γ-glutamyl-transpeptidase-activatable fluorescent probe.
abstract: Backgrounds/Aim: Colorectal laterally spreading tumors (LSTs) are sometimes difficult to visualize even with image-enhanced endoscopy. γ-Glutamyl-transpeptidase (GGT) is a cell surface-associated enzyme that is overexpressed in various types of human cancers. Furthermore, GGT expression is higher in colorectal cancer cells than in normal colorectal mucosa. γ-Glutamyl hydroxymethyl rhodamine green (gGlu-HMRG), an activatable fluorescent probe, is nonfluorescent under a neutral pH and normal cellular environment; however, it turns highly fluorescent upon reaction with GGT. We evaluated ex vivo fluorescent imaging of colorectal LSTs using this GGT-activatable fluorescent probe.
  
  
  METHODS
  Between March 2013 and March 2014, 30 endoscopically resected colorectal LSTs were prospectively included in this study. Each was analyzed by first taking a baseline image before spraying, then spraying with gGlu-HMRG onto the freshly resected specimen, and finally taking fluorescent images 15 min after spraying with a dedicated imaging machine.
  
  
  RESULTS
  Of the LSTs, 67% rapidly showed positive fluorescent activity. These activities were shown in adenoma (54%) and carcinoma in adenoma (76%), and in LST-granular type (80%) and LST-nongranular type (40%).
  
  
  CONCLUSIONS
  Topically spraying gGlu-HMRG enabled rapid and selective fluorescent imaging of colorectal tumors owing to the upregulated GGT activity in cancer cells.
authors: Endoscopy Division, National Cancer Center Hospital, Tokyo, Japan.
authors: Chiko
authors: C
authors: Sato
authors: Seiichiro
authors: S
authors: Abe
authors: Yutaka
authors: Y
authors: Saito
authors: Eriko
authors: E
authors: So Tsuruki
authors: Hiroyuki
authors: H
authors: Takamaru
authors: Makomo
authors: M
authors: Makazu
authors: Yoshinori
authors: Y
authors: Sato
authors: Hayato
authors: H
authors: Sasaki
authors: Hirohito
authors: H
authors: Tanaka
authors: Nobuaki
authors: N
authors: Ikezawa
authors: Masayoshi
authors: M
authors: Yamada
authors: Taku
authors: T
authors: Sakamoto
authors: Takeshi
authors: T
authors: Nakajima
authors: Takahisa
authors: T
authors: Matsuda
authors: Ryoji
authors: R
authors: Kushima
authors: Mako
authors: M
authors: Kamiya
authors: Shin
authors: S
authors: Maeda
authors: Yasuteru
authors: Y
authors: Urano
mesh_terms: D000287:Administration, Topical; D000368:Aged; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000201:enzymology; D005260:Female; D005456:Fluorescent Dyes / Q000008:administration & dosage / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011446:Prospective Studies; D011859:Radiography; D015854:Up-Regulation / Q000187:drug effects; D005723:gamma-Glutamyltransferase / Q000493:pharmacokinetics
chemical_list: D005456:Fluorescent Dyes; D005723:gamma-Glutamyltransferase