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Acquired resistance to BRAF inhibition induces epithelial-to-mesenchymal transition in BRAF (V600E) mutant thyroid cancer by c-Met-mediated AKT activation.

ABSTRACT: Previously, the authors have identified that c-Met mediates reactivation of the PI3K/AKT pathway following BRAF inhibitor treatment in BRAF (V600E) mutant anaplastic thyroid cancer, thereby contributing to the acquired drug resistance. Therefore dual inhibition of BRAF and c-Met led to sustained treatment response, thereby maximizing the specific anti-tumor effect of targeted therapy. The present study goes one step further and aims to investigate the effect of acquired resistance of BRAF inhibitor on epithelial-to-mesenchymal transition (EMT) in BRAF mutant thyroid cancer cells and the effect of dual inhibition from combinatorial therapy. Two thyroid cancer cell lines, 8505C and BCPAP were selected and treated with BRAF inhibitor, PLX4032 and its effect on EMT were examined and compared. Further investigation was carried out in orthotopic xenograft mouse models. Unlike BCPAP cells, the BRAF inhibitor resistant 8505C cells showed increased expressions of EMT related markers such as vimentin, ?-catenin, and CD44. The combinatorial treatment of PLX4032 and PHA665752, a c-Met inhibitor reversed EMT. Similar results were confirmed in vivo. c-Met-mediated reactivation of the PI3K/AKT pathway contributes to the drug resistance to PLX4032 in BRAF (V600E) mutant anaplastic thyroid cancer cells and further promotes tumor cell migration and invasion by upregulated EMT mechanism. Dual inhibition of BRAF and c-Met leads to reversal of EMT, suggesting a maximal therapeutic response.

SUBMITTER: Byeon HK

PROVIDER: S-EPMC5352181 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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Acquired resistance to BRAF inhibition induces epithelial-to-mesenchymal transition in BRAF (V600E) mutant thyroid cancer by c-Met-mediated AKT activation.

Byeon Hyung Kwon HK Na Hwi Jung HJ Yang Yeon Ju YJ Ko Sooah S Yoon Sun Och SO Ku Minhee M Yang Jaemoon J Kim Jae Wook JW Ban Myung Jin MJ Kim Ji-Hoon JH Kim Da Hee DH Kim Jung Min JM Choi Eun Chang EC Kim Chang-Hoon CH Yoon Joo-Heon JH Koh Yoon Woo YW

Oncotarget 20170101 1

Previously, the authors have identified that c-Met mediates reactivation of the PI3K/AKT pathway following BRAF inhibitor treatment in BRAF (V600E) mutant anaplastic thyroid cancer, thereby contributing to the acquired drug resistance. Therefore dual inhibition of BRAF and c-Met led to sustained treatment response, thereby maximizing the specific anti-tumor effect of targeted therapy. The present study goes one step further and aims to investigate the effect of acquired resistance of BRAF inhibi ...[more]

PMID: 27880942

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Project description:Cystic fibrosis (CF) is a monogenetic disease resulting from mutations in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene encoding an anion channel. Recent evidence indicates that CFTR plays a role in other cellular processes, namely in development, cellular differentiation and wound healing. Accordingly, CFTR has been proposed to function as a tumour suppressor in a wide range of cancers. Along these lines, CF was recently suggested to be associated with epithelial-mesenchymal transition (EMT), a latent developmental process, which can be re-activated in fibrosis and cancer. However, it is unknown whether EMT is indeed active in CF and if EMT is triggered by dysfunctional CFTR itself or a consequence of secondary complications of CF. In this study, we investigated the occurrence of EMT in airways native tissue, primary cells and cell lines expressing mutant CFTR through the expression of epithelial and mesenchymal markers as well as EMT-associated transcription factors. Transepithelial electrical resistance, proliferation and regeneration rates, and cell resistance to TGF-β1induced EMT were also measured. CF tissues/cells expressing mutant CFTR displayed several signs of active EMT, namely: destructured epithelial proteins, defective cell junctions, increased levels of mesenchymal markers and EMT-associated transcription factors, hyper-proliferation and impaired wound healing. Importantly, we found evidence that the mutant CFTR triggered EMT was mediated by EMT-associated transcription factor TWIST1. Further, our data show that CF cells are over-sensitive to EMT but the CF EMT phenotype can be reversed by CFTR modulator drugs. Altogether, these results identify for the first time that EMT is intrinsically triggered by the absence of functional CFTR through a TWIST1 dependent mechanism and indicate that CFTR plays a direct role in EMT protection. This mechanistic link is a plausible explanation for the high incidence of fibrosis and cancer in CF, as well as for the role of CFTR as tumour suppressor protein.

Dataset Information

Acquired resistance to BRAF inhibition induces epithelial-to-mesenchymal transition in BRAF (V600E) mutant thyroid cancer by c-Met-mediated AKT activation.

Publications

Acquired resistance to BRAF inhibition induces epithelial-to-mesenchymal transition in BRAF (V600E) mutant thyroid cancer by c-Met-mediated AKT activation.

Similar Datasets

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