MR molecular imaging of tumors based on an optimal hTERT promoter tyrosinase expression system.
The early diagnosis and treatment of tumors is of vital significance to increase patient survival. Therefore, we constructed a lentiviral vector expressing tyrosinase (TYR) driven by an optimized human telomerase reverse transcriptase (hTERT) promoter or a cytomegalovirus(CMV) promoter in the hopes of performing noninvasive and real-time tumor-specific imaging. First, hTERT-TYR and CMV-TYR were constructed to infect cancer cell lines (telomerase-negative cell line: U2OS; telomerase-positive cell lines: SGC-7901, SW480 and HepG2). Subsequently, stable tyrosinase-expressing cell lines were sorted by flow cytometry out of these infected cancer cell lines. Then, the mRNA and protein levels of tyrosinase were analyzed. Thetyrosinase activity, melanin production and ferric ion adsorption were measured followed by an MR scan. Consequently the results showed that tyrosinase was only expressed in telomerase-positive tumor cells infected by hTERT-TYR, whereas tyrosinase was expressed in both telomerase-negative and telomerase-positive tumor cells infected by CMV-TYR. Finally, we performed in vivo tumor MR using a clinical 3T MR scanner and found increased signals at T1W1 from telomerase-positive cells infected by hTERT-TYR, which revealed that MR scanning could distinguish cells with hTERT -positive cells from hTERT-negative cells infected with the optimized lentivirus. The mechanism underlying this effect is that tyrosinase promotes melanin production and ferric ion adsorption only in hTERT-expressing cells. Taken together, these data show that this optimized hTERT promoter-driving tyrosinase expression system might be a useful diagnostic tool for the detection of tumors using MR imaging.
Department of Radiology, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China.|Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China.
Chuan
C
Li
Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China.
Chang-Jiang
CJ
Hu
Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China.
Bo
B
Tang
Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China.
Xin
X
Yong
Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China.
Gang
G
Luo
Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China.
Yu-Yun
YY
Wu
Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China.
Su-Min
SM
Wang
Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China.|Department of Oncology, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China.
Song-Tao
ST
Yu
Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, P.R. China.
Shi-Ming
SM
Yang
D000818:Animals; D045744:Cell Line, Tumor; D003587:Cytomegalovirus / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D015316:Genetic Therapy / Q000379:methods; D056945:Hep G2 Cells; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D008543:Melanins / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000000981:diagnostic imaging*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D019098:Telomerase / Q000235:genetics*
D008543:Melanins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014442:Monophenol Monooxygenase; C509186:TERT protein, human; D019098:Telomerase
MR molecular imaging; hTERT promoter; melanin; tyrosinase