title: Targeting BRAFV600E with PLX4720 displays potent antimigratory and anti-invasive activity in preclinical models of human thyroid cancer.
abstract: OBJECTIVE
  B-Raf(V600E) may play a role in the progression from papillary thyroid cancer to anaplastic thyroid cancer (ATC). We tested the effects of a highly selective B-Raf(V600E) inhibitor, PLX4720, on proliferation, migration, and invasion both in human thyroid cancer cell lines (8505c(B-RafV600E) and TPC-1(RET/PTC-1 and wild-type B-Raf)) and in primary human normal thyroid (NT) follicular cells engineered with or without B-Raf(V600E).
  
  
  METHODS
  Large-scale genotyping analysis by mass spectrometry was performed in order to analyze >900 gene mutations. Cell proliferation and migration/invasion were performed upon PLX4720 treatment in 8505c, TPC-1, and NT cells. Orthotopic implantation of either 8505c or TPC-1 cells into the thyroid of severe combined immunodeficient mice was performed. Gene validations were performed by quantitative polymerase chain reaction and immunohistochemistry.
  
  
  RESULTS
  We found that PLX4720 reduced in vitro cell proliferation and migration and invasion of 8505c cells, causing early downregulation of genes involved in tumor progression. PLX4720-treated NT cells overexpressing B-Raf(V600E) (heterozygous wild-type B-Raf/B-Raf(V600E)) showed significantly lower cell proliferation, migration, and invasion. PLX4720 treatment did not block cell invasion in TPC-1 cells with wild-type B-Raf, which showed very low and delayed in vivo tumor growth. In vivo, PLX4720 treatment of 8505c orthotopic thyroid tumors inhibited tumor aggressiveness and significantly upregulated the thyroid differentiation markers thyroid transcription factor 1 and paired box gene 8.
  
  
  CONCLUSIONS
  Here, we have shown that PLX4720 preferentially inhibits migration and invasion of B-Raf(V600E) thyroid cancer cells and tumor aggressiveness. Normal thyroid cells were generated to be heterozygous for wild-type B-Raf/B-Raf(V600E), mimicking the condition found in most human thyroid cancers. PLX4720 was effective in reducing cell proliferation, migration, and invasion in this heterozygous model. PLX4720 therapy should be tested and considered for a phase I study for the treatment of patients with B-Raf(V600E) ATC.
authors.affiliation: Harvard Medical School, Massachusetts General Hospital, Boston, MA 02115, USA.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Nucera
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Nehs
authors.forename: Sushruta S
authors.initials: SS
authors.lastname: Nagarkatti
authors.forename: Peter M
authors.initials: PM
authors.lastname: Sadow
authors.forename: Michal
authors.initials: M
authors.lastname: Mekel
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Fischer
authors.forename: Paul S
authors.initials: PS
authors.lastname: Lin
authors.forename: Gideon E
authors.initials: GE
authors.lastname: Bollag
authors.forename: Jack
authors.initials: J
authors.lastname: Lawler
authors.forename: Richard A
authors.initials: RA
authors.lastname: Hodin
authors.forename: Sareh
authors.initials: S
authors.lastname: Parangi
mesh_terms: D000818:Animals; D048708:Cell Growth Processes / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D016513:Mice, SCID; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics*; D013449:Sulfonamides / Q000494:pharmacology*; D013964:Thyroid Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
chemical_list: D007211:Indoles; C528407:PLX 4720; D013449:Sulfonamides; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3