An optimized telomerase-specific lentivirus for optical imaging of tumors.
Advances in medical imaging techniques, such as ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography, have made great progress in detecting tumors. However, these imaging techniques are unable to differentiate malignant tumors from benign ones. Recently developed optical imaging of tumors in small animals provides a useful method to distinguish malignant tumors from their surrounding normal tissues. Human telomerase reverse transcriptase (hTERT) is normally inactivated in most somatic cells, whereas it is commonly reactivated in many cancer cells. In this study, we constructed a lentiviral vector that expresses green fluorescent protein (GFP) driven by an optimized hTERT promoter to create a noninvasive tumor-specific imaging methodology. The activity of this optimized hTERT promoter was found to be equal to the activity of SV40 and cytomegalovirus promoters. In vitro experiments showed that GFP was only expressed in telomerase-positive tumor cells infected with this lentivirus, whereas there was no GFP expression in telomerase-negative tumor cells or normal somatic cells. We also found that subcutaneous telomerase-positive tumors could be visualized 24 hours after an intratumoral injection with this lentivirus by using a charge-coupled device (CCD) camera. In contrast, telomerase-negative tumors could not be imaged after an intratumoral injection even for 30 days. These results suggest that infection with lentivirus containing this optimized hTERT promoter might be a useful diagnostic tool for the real-time visualization of macroscopically invisible tumor tissues using a highly sensitive CCD imaging system.
Yu
Song-Tao
ST
Institute of Gastroenterology, Southwest Hospital and Institute of Combined Injure, College of Preventive Medicine, Third Military Medical University, Chongqing, People's Republic of China.
Yang
Yin-Bing
YB
Liang
Guang-Ping
GP
Li
Chuan
C
Chen
Ling
L
Shi
Chun-Meng
CM
Tang
Xu-Dong
XD
Li
Chang-Zhu
CZ
Li
Ling
L
Wang
Guo-Zheng
GZ
Wu
Yu-Yun
YY
Yang
Shi-Ming
SM
Fang
Dian-Chun
DC
D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D005822:Genetic Vectors / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D016086:Lentivirus / Q000235:genetics*; D008156:Luciferases / Q000032:analysis / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009369:Neoplasms / Q000175:diagnosis* / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D011401:Promoter Regions, Genetic; D019098:Telomerase / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection; D051598:Whole Body Imaging / Q000379:methods*
D049452:Green Fluorescent Proteins; D008156:Luciferases; D019098:Telomerase