Sequencing of melanoma driver genes revealed GNAQ (p.Q209L) mutations in two samples; although it is possible that these samples represent extraocular spread of an occult uveal melanoma.
Recent genomic studies have shown that mutations within components of G protein-coupled receptor (GPCR) signaling are early events associated with approximately 98% of uveal melanomas.<b>Implications:</b> This review discusses the alterations in GPCR signaling components (GNAQ and GNA11), dysregulated GPCR signaling cascades, and viable targeted therapies with the intent to provide insight into new therapeutic strategies in uveal melanoma.<i></i>.
Intriguingly, enforced expression of GNAQ(Q209L) progressively eliminated melanocytes from the interfollicular epidermis in adults, possibly explaining the near absence of GNAQ(Q209) mutations in human epithelial melanomas.
To examine whether GNAQ and GNA11 somatic mutations previously identified in uveal melanomas of Caucasians are associated with uveal melanomas in Chinese patients.
These G-alpha protein mutations occur in the genes GNAQ and GNA11 and are seen at a high frequency in uveal melanomas, those melanomas that begin in the eye.
GNAQ mutations are present in uveal melanocytomas and in a case of transformation to melanoma, implicating GNAQ-dependent mitogen activation signals, in the pathogenesis of uveal melanocytoma.
Deep sequencing studies show that 4.2% of tumours carry activating mutations in GNAS (encoding Gαs), and that oncogenic activating mutations in genes encoding Gαq family members (GNAQ or GNA11) are present in ~66% and ~6% of melanomas arising in the eye and skin, respectively.
The mutations, such as those in NRAS, BRAF, GNAQ and GNA11, promote the growth of melanoma cells in most part through the mitogen-activated protein kinase (MAPK) pathway.
Somatic GNAQ mutations at codon 209 have been identified in approximately 50% of uveal melanomas and have been reported to be oncogenic through activating PLCβ/PKC/Erk1/2 pathways.
The results of this study suggest that GNAQ mutated uveal melanomas do not exhibit a higher deregulation of proliferation or higher activation of the MAPK signalling pathway than uveal melanomas without GNAQ overactivation.