title: Bioluminescent monitoring of NIS-mediated (131)I ablative effects in MCF-7 xenografts.
abstract: Optical imaging has made it possible to monitor response to anticancer therapies in tumor xenografts. The concept of treating breast cancers with (131)I is predicated on the expression of the Na(+)/I- symporter (NIS) in many tumors and uptake of I- in some. The pattern of (131)I radioablative effects were investigated in an MCF-7 xenograft model dually transfected with firefly luciferase and NIS genes. On Day 16 after tumor cell implantation, 3 mCi of (131)I was injected. Bioluminescent imaging using d-luciferin and a cooled charge-coupled device camera was carried out on Days 1, 2, 3, 7, 10, 16, 22, 29, and 35. Tumor bioluminescence decreased in (131)I-treated tumors after Day 3 and reached a nadir on Day 22. Conversely, bioluminescence steadily increased in controls and was 3.85-fold higher than in treated tumors on Day 22. Bioluminescence in (131)I-treated tumors increased after Day 22, corresponding to tumor regrowth. By Day 35, treated tumors were smaller and accumulated 33% less (99m)TcO(4)(-) than untreated tumors. NIS immunoreactivity was present in <50% of (131)I-treated cells compared to 85-90% of controls. In summary, a pattern of tumor regression occurring over the first three weeks after (131)I administration was observed in NIS-expressing breast cancer xenografts.
authors.affiliation: Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Malavika
authors.initials: M
authors.lastname: Ghosh
authors.forename: Sanjiv Sam
authors.initials: SS
authors.lastname: Gambhir
authors.forename: Abhijit
authors.initials: A
authors.lastname: De
authors.forename: Kent
authors.initials: K
authors.lastname: Nowels
authors.forename: Michael
authors.initials: M
authors.lastname: Goris
authors.forename: Irene
authors.initials: I
authors.lastname: Wapnir
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002999:Clone Cells; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007457:Iodine Radioisotopes / Q000008:administration & dosage* / Q000627:therapeutic use; D008163:Luminescent Measurements; D008164:Luminescent Proteins / Q000096:biosynthesis; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D027981:Symporters / Q000502:physiology*; D014183:Transplantation, Heterologous; D000099209:Sodium-Iodide Symporters
chemical_list: D007457:Iodine Radioisotopes; D008164:Luminescent Proteins; D027981:Symporters; D000099209:Sodium-Iodide Symporters