Uveal melanoma (UM), a rare cancer of the eye, is characterized by initiating mutations in the genes G-protein subunit alpha Q (<i>GNAQ</i>), G-protein subunit alpha 11 (<i>GNA11</i>), cysteinyl leukotriene receptor 2 (<i>CYSLTR2</i>), and phospholipase C beta 4 (<i>PLCB4</i>) and by metastasis-promoting mutations in the genes splicing factor 3B1 (<i>SF3B1</i>), serine and arginine rich splicing factor 2 (SRSF2), and BRCA1-associated protein 1 (<i>BAP1</i>).
Uveal melanoma (UM) is characterized by mutually exclusive activating mutations in GNAQ, GNA11, CYSLTR2, and PLCB4, four genes in a linear pathway to activation of PLCβ in almost all tumors and loss of BAP1 in the aggressive subset.
We analyzed genomics data from 136 uveal melanoma samples and found a recurrent mutation in CYSLTR2 (cysteinyl leukotriene receptor 2) encoding a p.Leu129Gln substitution in 4 of 9 samples that lacked mutations in GNAQ, GNA11, and PLCB4 but in 0 of 127 samples that harbored mutations in these genes.
Taken together these data suggest that the PLCB4 hotspot mutation is similarly a gain-of-function mutation leading to activation of the same signaling pathway, promoting UM tumorigenesis.