title: Knockdown of IGF-IR by RNAi inhibits SW480 colon cancer cells growth in vitro.
abstract: OBJECTIVE
  Colon cancer is the second leading cause of death due to cancer worldwide. Elevated expression of IGF-IR is a frequent genetic abnormality seen in this malignancy. The aim of the study was to examine the anti-growth effects elicited by a decrease in the protein level of IGF-IR by RNA interference (RNAi) in SW480 cells.
  
  
  METHODS
  A plasmid-based polymerase III promoter system was used to deliver and express short interfering RNA (siRNA) targeting IGF-IR to reduce its expression in SW480 cells. The expression of IGF-1R protein was detected by Western blot. We assessed the effects of IGF-IR silencing on cancer cell growth by a growth curve.
  
  
  RESULTS
  We prepared a type of IGF-IR short hairpin RNA (shRNA) expression vector that could efficiently inhibit the expression of IGF-IR in SW480 cells. At 48 h after transfection, the expression inhibition rate was 92 +/- 2% at mRNA level detected by RT-PCR analysis. Western blotting detected a similar inhibition of IGF-IR protein levels in cells transfected with pkD-shRNA-IGF-IR-V2. Downregulation of IGF-IR resulted in significant inhibition of cancer cell growth in vitro. The cell growth inhibition rates at 24, 48, and 72 h after pkD-shRNA-IGF-IR-V2 transfection were 32.06, 47.61, and 35.36%, respectively.
  
  
  CONCLUSIONS
  Our data show that decreasing the IGF-IR protein level in SW480 cells by RNAi could significantly inhibit tumor growth in vitro, implying the therapeutic potential of RNAi on the treatment of colon cancer by targeting overexpression oncogenes such as IGF-IR. IGF-IR may be a potential therapeutic target for human colon cancer.
authors.affiliation: Department of Clinical Biochemistry, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: Kamal
authors.initials: K
authors.lastname: Yavari
authors.forename: Mohammad
authors.initials: M
authors.lastname: Taghikhani
authors.forename: Mohammad Ghannadi
authors.initials: MG
authors.lastname: Maragheh
authors.forename: Seyed A
authors.initials: SA
authors.lastname: Mesbah-Namin
authors.forename: Mohammad Hosein
authors.initials: MH
authors.lastname: Babaei
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000473:pathology*; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006801:Humans; D034741:RNA, Small Interfering / Q000235:genetics*; D017526:Receptor, IGF Type 1 / Q000037:antagonists & inhibitors* / Q000235:genetics*; D014162:Transfection
chemical_list: D034741:RNA, Small Interfering; D017526:Receptor, IGF Type 1