Conclusions
Inhibition of the Src-FAK complex represents a promising therapeutic strategy for patients with advanced thyroid cancer, and phospho-FAK represents a potential biomarker for response.
Objective
The goal of this study was to determine the role of Src and FAK in the growth and invasion of PTC and ATC. Design: PTC and ATC cells were treated with the oral Src inhibitor, AZD0530, to determine the consequences of Src inhibition using growth and invasion assays. FAK and phospho-FAK levels were analyzed in cell lines as well as in PTC tumor samples.
Results
AZD0530 treatment inhibited the growth and invasion in four of five thyroid cancer cell lines, and inhibition did not correlate with basal levels of phospho-Src. Instead, we show for the first time that FAK, a critical substrate and effector of Src, is phosphorylated at tyrosine residue 861 (pY861) in PTC and ATC cells, and high levels of phospho-FAK correlate with AZD0530 sensitivity. We further showed that pY861-FAK phosphorylation is Src-dependent. Sensitivity to AZD0530 was confirmed using a preclinical three-dimensional culture model. Phospho-ERK1/2 was not affected by AZD0530, indicating that Src signaling does not require MAPK. Finally, FAK and pY861-FAK were expressed in 10 of 10 and five of 10 PTC tumors, respectively. Conclusions: Inhibition of the Src-FAK complex represents a promising therapeutic strategy for patients with advanced thyroid cancer, and phospho-FAK represents a potential biomarker for response.