OBJECTIVE: Tyrosine kinase inhibitors (TKIs) are evaluated for treatment of radioiodine refractory thyroid cancer. Their effects in this setting are based on blockade of proangiogenic signaling mediated by receptors for vascular endothelial growth factors (VEGFs) and platelet-derived growth factors (PDGF). Most TKIs also block other cancer-relevant kinases, such as B-type Raf kinase (BRAF), which are constitutively activated in approximately half of papillary thyroid carcinomas (PTCs), but the impact of these effects is not clear. DESIGN: The aim of our study was to investigate the impact of BRAF(V600E) on proangiogenic gene expression and microvascular features of PTCs. METHODS: mRNA levels for VEGFA, VEGF receptors, and coreceptors (VEGFRs 1, 2, and 3, neuropilin-1), and PDGF receptor β (PDGFRβ or PDGFRB) were measured with real-time PCR in BRAF(V600E) (n=55) and wild-type BRAF (BRAF-wt; n=35) PTCs. VEGF and VEGFR protein expression and microvessel densities (MVD) and lymphatic vessel densities (LVDs) were assessed by immunohistochemistry in 22 of the 90 PTCs (including 11 BRAF(V600E) cases). Angiogenic gene expression was also studied in vitro after induction/silencing of the BRAF(V600E) mutation in thyrocyte lines. RESULTS: Transcript levels of proangiogenic factors were significantly lower in BRAF(V600E) PTCs versus BRAF-wt PTCs (P<0.0001), but MVD and LVDs were not significantly different. VEGFA mRNA levels in thyroid cell lines decreased when BRAF(V600E) mutation was induced (P=0.01) and increased when it was silenced (P=0.01). CONCLUSIONS: Compared with BRAF-wt PTCs, those harboring BRAF(V600E) exhibit downregulated VEGFA, VEGFR, and PDGFRβ expression, suggesting that the presence of BRAF mutation does not imply a stronger prediction of response to drugs targeting VEGF and PDGFB signaling pathways.
OBJECTIVE: Tyrosine kinase inhibitors (TKIs) are evaluated for treatment of radioiodine refractory thyroid cancer. Their effects in this setting are based on blockade of proangiogenic signaling mediated by receptors for vascular endothelial growth factors (VEGFs) and platelet-derived growth factors (PDGF). Most TKIs also block other cancer-relevant kinases, such as B-type Raf kinase (BRAF), which are constitutively activated in approximately half of papillary thyroid carcinomas (PTCs), but the impact of these effects is not clear. DESIGN: The aim of our study was to investigate the impact of BRAF(V600E) on proangiogenic gene expression and microvascular features of PTCs. METHODS: mRNA levels for VEGFA, VEGF receptors, and coreceptors (VEGFRs 1, 2, and 3, neuropilin-1), and PDGF receptor β (PDGFRβ or PDGFRB) were measured with real-time PCR in BRAF(V600E) (n=55) and wild-type BRAF (BRAF-wt; n=35) PTCs. VEGF and VEGFR protein expression and microvessel densities (MVD) and lymphatic vessel densities (LVDs) were assessed by immunohistochemistry in 22 of the 90 PTCs (including 11 BRAF(V600E) cases). Angiogenic gene expression was also studied in vitro after induction/silencing of the BRAF(V600E) mutation in thyrocyte lines. RESULTS: Transcript levels of proangiogenic factors were significantly lower in BRAF(V600E) PTCs versus BRAF-wt PTCs (P<0.0001), but MVD and LVDs were not significantly different. VEGFA mRNA levels in thyroid cell lines decreased when BRAF(V600E) mutation was induced (P=0.01) and increased when it was silenced (P=0.01). CONCLUSIONS: Compared with BRAF-wt PTCs, those harboring BRAF(V600E) exhibit downregulated VEGFA, VEGFR, and PDGFRβ expression, suggesting that the presence of BRAF mutation does not imply a stronger prediction of response to drugs targeting VEGF and PDGFB signaling pathways.
Authors: P G Corrie; A Marshall; P D Nathan; P Lorigan; M Gore; S Tahir; G Faust; C G Kelly; M Marples; S J Danson; E Marshall; S J Houston; R E Board; A M Waterston; J P Nobes; M Harries; S Kumar; A Goodman; A Dalgleish; A Martin-Clavijo; S Westwell; R Casasola; D Chao; A Maraveyas; P M Patel; C H Ottensmeier; D Farrugia; A Humphreys; B Eccles; G Young; E O Barker; C Harman; M Weiss; K A Myers; A Chhabra; S H Rodwell; J A Dunn; M R Middleton; Paul Nathan; Paul Lorigan; Peter Dziewulski; Sonja Holikova; Udaiveer Panwar; Saad Tahir; Guy Faust; Anne Thomas; Pippa Corrie; Bhawna Sirohi; Charles Kelly; Mark Middleton; Maria Marples; Sarah Danson; James Lester; Ernest Marshall; Mazhar Ajaz; Stephen Houston; Ruth Board; David Eaton; Ashita Waterston; Jenny Nobes; Suat Loo; Gill Gray; Helen Stubbings; Martin Gore; Mark Harries; Satish Kumar; Andrew Goodman; Angus Dalgleish; Agustin Martin-Clavijo; Jerry Marsden; Sarah Westwell; Richard Casasola; David Chao; Anthony Maraveyas; Ernest Marshall; Poulam Patel; Christian Ottensmeier; David Farrugia; Alison Humphreys; Bryony Eccles; Renata Dega; Chris Herbert; Christopher Price; Murray Brunt; Martin Scott-Brown; Joanna Hamilton; Richard Larry Hayward; John Smyth; Pamela Woodings; Neena Nayak; Lorna Burrows; Virginia Wolstenholme; John Wagstaff; Marianne Nicolson; Andrew Wilson; Clare Barlow; Christopher Scrase; Timothy Podd; Michael Gonzalez; John Stewart; Martin Highley; Virginia Wolstenholme; Simon Grumett; Andrew Goodman; Toby Talbot; Kannon Nathan; Robert Coltart; Bruce Gee; Martin Gore; David Farrugia; Agustin Martin-Clavijo; Jerry Marsden; Christopher Price; David Farrugia; Kannon Nathan; Robert Coltart; Kannon Nathan; Robert Coltart Journal: Ann Oncol Date: 2018-08-01 Impact factor: 32.976