Proliferation and survival molecules implicated in the inhibition of BRAF pathway in thyroid cancer cells harbouring different genetic mutations

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Ana Preto (Author) Other; Joana Gonçalves (Author) Other; Ana P Rebocho (Author) Other; Joana Figueiredo (Author) Other; Ana M Meireles (Author) Other; Ana S Rocha (Author) Other; Helena M Vasconcelos (Author) FFUP; Hugo Seca (Author) Other; Raquel Seruca (Author) Other; Soares, P (Author) FMUP; Manuel Sobrinho-Simões (Author) Other

Journal

Title: BMC Cancer

Vol. 9

Pages: 387-397

ISSN: 1471-2407

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 27 Citations

ISI Web of Science

Scopus - 28 Citations

Scientific classification

FOS: Medical and Health sciences > Other medical sciences

CORDIS: Health sciences > Pharmacological sciences > Pharmacy

Other information

Authenticus ID: P-003-EZ5

Resumo (PT): Background: Thyroid carcinomas show a high prevalence of mutations in the oncogene BRAF which are inversely associated with RAS or RET/PTC oncogenic activation. The possibility of using inhibitors on the BRAF pathway as became an interesting therapeutic approach. In thyroid cancer cells the target molecules, implicated on the cellular effects, mediated by inhibition of BRAF are not well established. In order to fill this lack of knowledge we studied the proliferation and survival pathways and associated molecules induced by BRAF inhibition in thyroid carcinoma cell lines harbouring distinct genetic backgrounds. Methods: Suppression of BRAF pathway in thyroid cancer cell lines (8505C, TPC1 and C643) was achieved using RNA interference (RNAi) for BRAF and the kinase inhibitor, sorafenib. Proliferation analysis was performed by BrdU incorporation and apoptosis was accessed by TUNEL assay. Levels of protein expression were analysed by western-blot. Results: Both BRAF RNAi and sorafenib inhibited proliferation in all the cell lines independently of the genetic background, mostly in cells with BRAFV600E mutation. In BRAFV600E mutated cells inhibition of BRAF pathway lead to a decrease in ERK1/2 phosphorylation and cyclin D1 levels and an increase in p27Kip1. Specific inhibition of BRAF by RNAi in cells with BRAFV600E mutation had no effect on apoptosis. In the case of sorafenib treatment, cells harbouring BRAFV600E mutation showed increase levels of apoptosis due to a balance of the anti-apoptotic proteins Mcl-1 and Bcl-2. Conclusion: Our results in thyroid cancer cells, namely those harbouring BRAFV600Emutation showed that BRAF signalling pathway provides important proliferation signals. We have shown that in thyroid cancer cells sorafenib induces apoptosis by affecting Mcl-1 and Bcl-2 in BRAFV600E mutated cells which was independent of BRAF. These results suggest that sorafenib may prove useful in the treatment of thyroid carcinomas, particularly those refractory to conventional treatment and harbouring BRAF mutations. <br> <br> <a target="_blank" href="http://web.ebscohost.com/ehost/detail?vid=40&hid=15&sid=86acae9e-fb89-49c5-a9c2-4e0d70164b6e%40sessionmgr12&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=a9h&AN=47282622 "> Texto integral </a> <br> <br>

Abstract (EN): Background: Thyroid carcinomas show a high prevalence of mutations in the oncogene BRAF which are inversely associated with RAS or RET/PTC oncogenic activation. The possibility of using inhibitors on the BRAF pathway as became an interesting therapeutic approach. In thyroid cancer cells the target molecules, implicated on the cellular effects, mediated by inhibition of BRAF are not well established. In order to fill this lack of knowledge we studied the proliferation and survival pathways and associated molecules induced by BRAF inhibition in thyroid carcinoma cell lines harbouring distinct genetic backgrounds. Methods: Suppression of BRAF pathway in thyroid cancer cell lines (8505C, TPC1 and C643) was achieved using RNA interference (RNAi) for BRAF and the kinase inhibitor, sorafenib. Proliferation analysis was performed by BrdU incorporation and apoptosis was accessed by TUNEL assay. Levels of protein expression were analysed by western-blot. Results: Both BRAF RNAi and sorafenib inhibited proliferation in all the cell lines independently of the genetic background, mostly in cells with BRAFV600E mutation. In BRAFV600E mutated cells inhibition of BRAF pathway lead to a decrease in ERK1/2 phosphorylation and cyclin D1 levels and an increase in p27Kip1. Specific inhibition of BRAF by RNAi in cells with BRAFV600E mutation had no effect on apoptosis. In the case of sorafenib treatment, cells harbouring BRAFV600E mutation showed increase levels of apoptosis due to a balance of the anti-apoptotic proteins Mcl-1 and Bcl-2. Conclusion: Our results in thyroid cancer cells, namely those harbouring BRAFV600Emutation showed that BRAF signalling pathway provides important proliferation signals. We have shown that in thyroid cancer cells sorafenib induces apoptosis by affecting Mcl-1 and Bcl-2 in BRAFV600E mutated cells which was independent of BRAF. These results suggest that sorafenib may prove useful in the treatment of thyroid carcinomas, particularly those refractory to conventional treatment and harbouring BRAF mutations. <br> <br> <a target="_blank" href="http://web.ebscohost.com/ehost/detail?vid=40&hid=15&sid=86acae9e-fb89-49c5-a9c2-4e0d70164b6e%40sessionmgr12&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=a9h&AN=47282622 "> Texto integral </a> <br> <br>

Language: English

Type (Professor's evaluation): Scientific