title: Demonstration of dose dependent cytotoxic activity in SW480 colon cancer cells by ¹⁷⁷Lu-labeled siRNA targeting IGF-1R.
abstract: OBJECTIVE
  The radiolabeling of targeting biomolecules with gamma emitter radionuclides for tracing and beta emitters for therapy involves the conjugation of such biomolecules to the chelating agents to form complexes with the radionuclide of interest. In this study, radioconjugate of IGF-1R siRNA with lutetium-177 ((177)Lu) was produced, and the anti-proliferation and apoptosis effects elicited by this (177)Lu-siRNA complex in the SW480 colon cancer cells were evaluated.
  
  
  METHODS
  IGF-1R and Luciferase siRNAs were conjugated with p-SCN-Bn-DTPA, and then radiolabeled with (177)Lu. The effects of labeled and non-labeled IGF-1R siRNAs on IGF-1R expression were assessed with RT-PCR analysis and ELISA assay. IGF-1R siRNAs induced cell death and apoptosis were investigated using MTT assay and Annexin-V/propidium iodide (PI) double staining, respectively.
  
  
  RESULTS
  Combined purification using Vivaspin and PD-10 columns resulted in a radiochemical purity of 97.32% ± 1.97%. Knockdown effect of the labeled IGF-1R siRNA was not significantly different from the non-labeled duplex of the same sequence (P<0.05), but it was significant compared to the Luciferase siRNAs (P<0.001). Proliferation decreased significantly, but apoptosis increased in the cells treated with the (177)Lu-IGF-1R siRNA in comparison with either (177)Lu or IGF-1R siRNA (P<0.001).
  
  
  CONCLUSIONS
  Radioconjugate of IGF-1R siRNA, p-SCN-Bn-DTPA and (177)Lu was successfully produced and characterized as radiopharmaceutical. The present study demonstrates the involvement of (177)Lu-labeled IGF-1R siRNA in the inhibition of cell growth and induction of apoptosis in colon cancer cells.
authors.affiliation: Department of Clinical Biochemistry, Faculty of Medical Sciences, Tarbiat Modares University, PO Box 14115-331, Tehran, Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Fathi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Taghikhani
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ghannadi-Maragheh
authors.forename: Kamal
authors.initials: K
authors.lastname: Yavari
mesh_terms: D001483:Base Sequence; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000528:radiation effects; D003110:Colonic Neoplasms / Q000235:genetics / Q000473:pathology* / Q000532:radiotherapy; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007553:Isotope Labeling; D008187:Lutetium / Q000627:therapeutic use*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics*; D011836:Radiation Tolerance / Q000235:genetics / Q000528:radiation effects; D011854:Radiochemistry; D011868:Radioisotopes / Q000627:therapeutic use*; D017526:Receptor, IGF Type 1 / Q000172:deficiency* / Q000235:genetics* / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011868:Radioisotopes; D008187:Lutetium; D017526:Receptor, IGF Type 1