Kinome profiling identifies MARK3 and STK10 as potential therapeutic targets in uveal melanoma

Most uveal melanoma cases harbor activating mutations in either GNAQ or GNA11. Despite activation of the mitogenactivated protein kinase (MAPK) signaling pathway downstream of G alpha q/11, there are no effective targeted kinase therapies for metastatic uveal melanoma. The human genome encodes numerous understudied kinases, also called the "dark kinome". Identifying additional kinases regulated by G alpha q/11 may uncover novel therapeutic targets for uveal melanoma. In this study, we treated GNAQ-mutant uveal melanoma cell lines with a G alpha q/11 inhibitor, YM-254890, and conducted a kinase signaling proteomic screen using multiplexed-kinase inhibitors followed by mass spectrometry. We observed downregulated expression and/or activity of 22 kinases. A custom siRNA screen targeting these kinases demonstrated that knockdown of microtubule affinity regulating kinase 3 (MARK3) and serine/threonine kinase 10 (STK10) significantly reduced uveal melanoma cell growth and decreased expression of cell cycle proteins. Additionally, knockdown of MARK3 but not STK10 decreased ERK1/2 phosphorylation. Analysis of RNAsequencing and proteomic data showed that G alpha q signaling regulates STK10 expression and MARK3 activity. Our findings suggest an involvement of STK10 and MARK3 in the G alpha q/11 oncogenic pathway and prompt further investigation into the melanoma.