title: Src inhibitors in suppression of papillary thyroid carcinoma growth.
abstract: BACKGROUND
  Papillary thyroid carcinoma is the most common thyroid malignancy. Most papillary thyroid carcinomas contain BRAF mutations or RET/PTC rearrangements, thus providing targets for biologic therapy. Our previous studies had suggested papillary thyroid carcinomas (PTCs) with a BRAF mutation and the RET/PTC1 rearrangement have different sensitivities to MEK1/2 inhibitors, suggesting different signaling transduction pathways were involved.
  
  
  METHODS
  Src signaling transduction pathway in PTC cells was examined using Src inhibitors (PP2, SU6656, or dasatinib) and si-Src RNA in vitro by Western blot analysis and proliferation analysis. An orthotopic xenograft mouse model was used for the in vivo studies using dasatinib.
  
  
  RESULTS
  In PTC cells, Src inhibitors suppressed p-Src and p-FAK and inhibited cell growth. In addition, significant suppression and extension of the p-ERK1/2 dephosphorylation were detected in RET/PTC1-rearranged cells in combination with an MEK inhibitor (CI-1040). The Src family kinase/ABL inhibitor, dasatinib, significantly decreased tumor volume in mice inoculated with PTC cells carrying the RET/PTC1 rearrangement. In BRAF-mutated PTC cells, Src inhibitors effectively suppressed p-Src expression and dasatinib significantly decreased tumor volume with twice daily treatment.
  
  
  CONCLUSIONS
  Src inhibitors effectively inhibited the Src signaling transduction pathway in PTC cells in vitro and dasatinib suppressed tumor growth in vivo. These results suggested that Src signaling transduction pathway plays an important role in regulating growth in PTC cells. Combination of Src and MEK1/2 inhibitors extended the dephosphorylation of extracellular signal-regulated kinase (ERK)1/2 in PTCs carrying the RET/PTC1 rearrangement suggesting that combination therapy with complementary inhibitors of other signaling transduction pathways may be needed to effectively suppress growth and induce apoptosis in these cells.
authors.affiliation: Department of Head and Neck Surgery, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Ying C
authors.initials: YC
authors.lastname: Henderson
authors.forename: Rafael
authors.initials: R
authors.lastname: Toro-Serra
authors.forename: Yunyun
authors.initials: Y
authors.lastname: Chen
authors.forename: Junsun
authors.initials: J
authors.lastname: Ryu
authors.forename: Mitchell J
authors.initials: MJ
authors.lastname: Frederick
authors.forename: Ge
authors.initials: G
authors.lastname: Zhou
authors.forename: Gary E
authors.initials: GE
authors.lastname: Gallick
authors.forename: Stephen Y
authors.initials: SY
authors.lastname: Lai
authors.forename: Gary L
authors.initials: GL
authors.lastname: Clayman
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000235:genetics / Q000473:pathology*; D002291:Carcinoma, Papillary; D049109:Cell Proliferation; D000069439:Dasatinib; D004195:Disease Models, Animal; D007211:Indoles / Q000627:therapeutic use; D051379:Mice; D008815:Mice, Inbred Strains; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors*; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D011743:Pyrimidines / Q000008:administration & dosage / Q000627:therapeutic use; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D013449:Sulfonamides / Q000627:therapeutic use; D013844:Thiazoles / Q000008:administration & dosage / Q000627:therapeutic use; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000235:genetics / Q000473:pathology*; D014407:Tumor Cells, Cultured; D019061:src-Family Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics
chemical_list: C412373:AG 1879; D007211:Indoles; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; C416927:SU 6656; D013449:Sulfonamides; D013844:Thiazoles; D019061:src-Family Kinases; D019950:Mitogen-Activated Protein Kinase 1; D000069439:Dasatinib
keywords: CI-1040; PP2; SU6656; dasatinib; papillary thyroid carcinoma