title: Evaluation of (99m)Tc-HYNIC-TMTP1 as a tumor-homing imaging agent targeting metastasis with SPECT.
abstract: BACKGROUND
  TMTP1 (NVVRQ) is a novel tumor-homing peptide, which specifically targets tumor metastases, even at the early stage of occult metastasis foci. Fusing TMTP1 to therapeutic peptides or proteins can increase its anti-cancer efficacy both in vivo and in vitro. Here, we labeled TMTP1 with (99m)Tc to evaluate its targeting properties in an ovarian cancer xenograft tumor mouse model and a gastric cancer xenograft mouse model.
  
  
  METHODS
  The invasion ability of SKOV3 and highly metastatic SKOV3.ip cell lines were performed by the Transwell Invasion Assays, and then Rhodamine-TMTP1 was used to detect its affinity to these two cells. Using the co-ligand ethylenediamine-N, N'-diacetic acid (EDDA) and the bifunctional chelator 6-hydrazinonicotinic acid (HYNIC), the TMTP1 peptide was labeled with (99m)Tc. A cell-binding assay was performed by incubating cancer cells with (99m)Tc-HYNIC-TMTP1 with or without an excess dose of cold HYNIC-TMTP1. To evaluate the probe in vivo, nude mice bearing SKOV3, SKOV3.ip and MNK-45 tumor cells were established and subjected to SPECT imaging after injection with (99m)Tc-HYNIC-TMTP1. Ex vivo γ-counting of dissected tissues from the mice was used to evaluate its biodistribution.
  
  
  RESULTS
  (99m)Tc-HYNIC-TMTP1 was successfully synthesized. The radiotracer also exhibited high hydrophilicity and excellent stability in vitro and in vivo. It has strong affinity to highly metastatic cancer cell lines but not to poorly metastatic cell lines. After mice were injected with (99m)Tc-HYNIC-TMTP1, non-invasive SPECT imaging detected SKOV3.ip and MNK-45 xenograft tumors but not SKOV3 xenograft tumors. This result can be inhibited by excess HYNIC-TMTP1. The uptake of (99m)Tc-HYNIC-TMTP1 in SKOV3.ip xenograft tumors was 0.182±0.017% ID/g at 2h p.i. with high renal uptake (74.32±15.05% ID/g at 2h p.i.).
  
  
  CONCLUSIONS
  (99m)Tc-HYNIC-TMTP1 biodistribution and SPECT imaging demonstrated its ability to target highly metastatic tumors. Therefore, metastasis can be non-invasively investigated by SPECT imaging using (99m)Tc-HYNIC-TMTP1. Meanwhile, this radiotracer has some shortages in the low % ID/g of tumors and high accumulation in the kidney.
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Teng
authors.initials: T
authors.lastname: Cheng
authors.affiliation: Department of Nuclear Medicine,Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Qingjian
authors.initials: Q
authors.lastname: Dong
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wei
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Zhenzhong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Danfeng
authors.initials: D
authors.lastname: Luo
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Xiangyi
authors.initials: X
authors.lastname: Ma
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Shixuan
authors.initials: S
authors.lastname: Wang
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Qinglei
authors.initials: Q
authors.lastname: Gao
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China.
authors.forename: Ding
authors.initials: D
authors.lastname: Ma
authors.affiliation: Department of Nuclear Medicine,Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China. Electronic address: evazhu@vip.sina.com.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Cancer Biology Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, Hubei 430030, People's Republic of China. Electronic address: lxi@tjh.tjmu.edu.cn.
authors.forename: Ling
authors.initials: L
authors.lastname: Xi
mesh_terms: D000818:Animals; D001692:Biological Transport; D045744:Cell Line, Tumor; D004355:Drug Stability; D006801:Humans; D006834:Hydrazines / Q000737:chemistry*; D007553:Isotope Labeling; D051379:Mice; D009362:Neoplasm Metastasis; D009539:Nicotinic Acids / Q000737:chemistry*; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism / Q000493:pharmacokinetics; D011854:Radiochemistry; D013667:Technetium; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: C120392:6-hydrazinopyridine-3-carboxylic acid; D006834:Hydrazines; D009539:Nicotinic Acids; D009842:Oligopeptides; C531959:asparagyl-valyl-valyl-arginyl-glutamine; D013667:Technetium
keywords: (99m)Tc-HYNIC-TMTP1; Metastasis; Ovarian cancer; SPECT imaging; TMTP1; Tumor imaging