GNAQ and BRAF mutations show differential activation of the mTOR pathway in human transformed cells

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Populo, H (Author) Other; Tavares, S (Author) Other; Faustino, A (Author) Other; Nunes, JB (Author) Other; Lopes, JM (Author) FMUP; Soares, P (Author) FMUP

Journal

Title: PeerJ

Vol. 1

Final page: e104

ISSN: 2167-8359

Publisher: PeerJ

Indexing

ISI Web of Knowledge - 10 Citations

Scopus - 12 Citations

Other information

Authenticus ID: P-008-EV1

DOI: 10.7717/peerj.104

Abstract (EN): Somatic mutations in GNAQ gene were described as being the main oncogenic activation in uveal melanomas, whereas mutations in BRAF gene have been described as a key genetic alteration that contributes to skin melanoma development. We have previously reported differential activation of the MAPK and AKT/mTOR signalling pathways in uveal and skin melanomas harbouring, respectively, GNAQ and BRAF mutations. The aim of this work was to compare the functional effect of GNAQ and BRAF mutations in mTOR and MAPK pathway activation, cell proliferation and apoptosis. In this work, we performed transient transfection of HEK293 cells with BRAF(WT), BRAF(V600E), GNAQ(WT), GNAQ(Q209P) and GNAQ(Q209L) vectors. We treated melanoma cell lines displaying different BRAF and GNAQ mutational status with the mTOR inhibitor RAD001 and with the MEK1/2 inhibitor U0126 and evaluated the effects in the growth of the cell lines and in mTOR and MAPK pathway effectors expression. At variance with the significant increase in the level of pmTOR Ser2448 and pS6 Ser235/236 proteins observed in cells transfected with BRAF vectors, no significant alteration in mTOR pathway effectors was observed in cells transfected with the three GNAQ expressing vectors. Also, GNAQ overexpression enhances Stat3 activation, which might mediate GNAQ oncogenic effects. None of the vectors led to significant differences in proliferation or apoptosis in the transfected cell lines. Cell lines harbouring a BRAF mutation were more sensitive to RAD001 treatment. U0126 leads to the reduction of MAPK and mTOR pathways activation in all cell lines tested. Our results indicate that GNAQ and BRAF activation drive distinct intracellular signalling pathways that may be useful for therapeutic decisions in human melanomas.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16