Radio-copper-labeled Cu-ATSM: an indicator of quiescent but clonogenic cells under mild hypoxia in a Lewis lung carcinoma model.
The purpose of this study is to reveal characteristics of (64)Cu-labeled diacetyl-bis(N(4)-methylthiosemicarbazone) ([(64)Cu]Cu-ATSM) during cell proliferation and hypoxia by autoradiography imaging and immunohistochemical staining.


METHODS
The intratumoral distributions of [(64)Cu]Cu-ATSM and [(18)F]-2-fluoro-2-deoxy-D-glucose ([(18)F]FDG) in mice implanted with Lewis lung carcinoma (LLC1) tumor cells according to dual autoradiography were compared with the immunohistochemical staining patterns of proliferating markers [Ki-67 and 5-bromo-2'-deoxyuridine (BrdU)] and a hypoxic marker (pimonidazole). A clonogenic assay was performed using the cells of LLC1 tumor-implanted mice, and it was compared with the distribution of [(64)Cu]Cu-ATSM.


RESULTS
[(64)Cu]Cu-ATSM mainly accumulated at the edge of tumors, whereas [(18)F]FDG was distributed inside the tumor and inside the [(64)Cu]Cu-ATSM accumulation. The number of Ki-67-positive cells/area tended to increase with [(18)F]FDG accumulation and decrease with [(64)Cu]Cu-ATSM accumulation. On the other hand, the number of BrdU-positive cells/area was negatively correlated with [(18)F]FDG accumulation and positively correlated with [(64)Cu]Cu-ATSM accumulation. High [(64)Cu]Cu-ATSM accumulation was found outside the high-[(18)F]FDG-accumulation and pimonidazole-positive regions. Colony formation ability was significantly higher in the tumor cells obtained from high-[(64)Cu]Cu-ATSM-accumulation regions than the cells from the intermediate- and the low-accumulation regions.


CONCLUSIONS
[(64)Cu]Cu-ATSM accumulation regions in tumor cells indicate quiescent but clonogenic tumor cells under mild hypoxia. [(64)Cu]Cu-ATSM could play an important role in planning appropriate tumor radiotherapy.
Department of Otorhinolaryngology, School of Medicine, University of Fukui, Matsuoka Shimoizuki, Eiheiji-cho, Yoshida-gun, Fukui 910-1193, Japan. sampo@u-fukui.ac.jp
Myungmi
M
Oh
Takeshi
T
Tanaka
Masato
M
Kobayashi
Takako
T
Furukawa
Tetsuya
T
Mori
Takashi
T
Kudo
Shigeharu
S
Fujieda
Yasuhisa
Y
Fujibayashi
D000818:Animals; D001345:Autoradiography; D001973:Bromodeoxyuridine / Q000276:immunology; D018827:Carcinoma, Lewis Lung / Q000150:complications* / Q000378:metabolism / Q000473:pathology*; D049109:Cell Proliferation; D003114:Colony-Forming Units Assay; D056831:Coordination Complexes; D003301:Copper Radioisotopes / Q000737:chemistry*; D004195:Disease Models, Animal; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D000860:Hypoxia / Q000150:complications* / Q000378:metabolism / Q000473:pathology*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000276:immunology; D008297:Male; D051379:Mice; D009593:Nitroimidazoles / Q000737:chemistry / Q000276:immunology; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism*; D049268:Positron-Emission Tomography; D013194:Staining and Labeling; D013882:Thiosemicarbazones / Q000737:chemistry / Q000378:metabolism*
D056831:Coordination Complexes; D003301:Copper Radioisotopes; D019394:Ki-67 Antigen; D009593:Nitroimidazoles; D009942:Organometallic Compounds; D013882:Thiosemicarbazones; C089548:copper (II) diacetyl-di(N(4)-methylthiosemicarbazone); D019788:Fluorodeoxyglucose F18; C033815:pimonidazole; D001973:Bromodeoxyuridine