Journal Article

Dasatinib reduces FAK phosphorylation increasing the effects of RPI-1 inhibition in a RET/PTC1-expressing cell line

Mondellini, Piera, Casalini, Patrizia, Cassinelli, Giuliana, Miccichè, Francesca, Bongarzone, Italia, Caccia, Dario

2010

Overview

Background TPC-1 is a papillary thyroid carcinoma (PTC)-derived cell line that spontaneously expresses the oncogene RET/PTC1 . TPC-1 treated with the RET/PTC1 inhibitor RPI-1 displayed a cytostatic and reversible inhibition of cell proliferation and a strong activation of focal adhesion kinase (FAK). As dasatinib inhibition of Src results in reduction of FAK activation, we evaluated the effects of TPC-1 treatment with dasatinib in combination with RPI-1. Results Dasatinib (100 nM) strongly reduced TPC-1 proliferation and induced marked changes in TPC-1 morphology. Cells appeared smaller and more contracted, with decreased cell spreading, due to the inhibition of phosphorylation of important cytoskeletal proteins (p130 CAS , Crk, and paxillin) by dasatinib. The combination of RPI-1 with dasatinib demonstrated enhanced effects on cell proliferation (more than 80% reduction) and on the phosphotyrosine protein profile. In particular, RPI-1 reduced the phosphorylation of RET, MET, DCDB2, CTND1, and PLCγ, while dasatinib acted on the phosphorylation of EGFR, EPHA2, and DOK1. Moreover, dasatinib completely abrogated the phosphorylation of FAK at all tyrosine sites (Y576, Y577, Y861, Y925) with the exception of the autoactivation site (Y397). Notably, the pharmacological treatments induced an overexpression of integrin β1 (ITB1) that was correlated with a mild enhancement in phosphorylation of ERK1/2 and STAT3, known for their roles in prevention of apoptosis and in increase of proliferation and survival. A reduction in Akt, p38 and JNK1/2 activation was observed. Conclusions All data demonstrate that the combination of the two drugs effectively reduced cell proliferation (by more than 80%), significantly decreased Tyr phosphorylation of almost all phosphorylable proteins, and altered the morphology of the cells, supporting high cytostatic effects. Following the combined treatment, cell survival pathways appeared to be mediated by STAT3 and ERK activities resulting from integrin clustering and FAK autophosphorylation. EphA2 may also contribute, at least in part, to integrin and FAK activation. In conclusion, these data implicate ITB1 and EphA2 as promising therapeutic targets in PTC.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Biomedical and Life Sciences / Biomedicine / Cancer / Cancer Research / Cell cycle / Cell Line, Tumor / Clinical medicine / Dasatinib / Drug therapy / Enzymes / Experiments / Focal Adhesion Protein-Tyrosine Kinases - metabolism / Genes / Genetic aspects / Health aspects / Humans / Indoles - antagonists & inhibitors / Indoles - metabolism / Integrin beta1 - metabolism / JNK Mitogen-Activated Protein Kinases - metabolism / Kinases / Medical research / Molecular weight / Oncology / p38 Mitogen-Activated Protein Kinases - metabolism / Phosphorylation / Phosphorylation - drug effects / Physiological aspects / Protein Kinase Inhibitors - pharmacology / Protein kinases / Proteins / Proto-Oncogene Proteins c-akt - metabolism / Proto-Oncogene Proteins c-ret - metabolism / Pyrimidines - pharmacology / Receptor, EphA2 - metabolism / STAT3 Transcription Factor - metabolism / Thiazoles - pharmacology / Thyroid cancer / Thyroid Neoplasms - drug therapy / Thyroid Neoplasms - metabolism