Protein kinase C inhibitor AEB071 targets ocular melanoma harboring GNAQ mutations via effects on the PKC/Erk1/2 and PKC/NF-κB pathways

Abstract

Somatic GNAQ mutations at codon 209 have been identified in approximately 50% of uveal melanomas and have been reported to be oncogenic through activating PLCb /PKC/Erk1/2 pathways. We hypothesized that protein kinase C (PKC) may provide new opportunities for therapeutic targeting of uveal melanoma carrying GNAQ mutations. To test this hypothesis, uveal melanoma cells harboring wild-type or mutant GNAQ were treated with the PKC inhibitor AEB071 (sotrastaurin) or infected with lentivirus-expressing short hairpin RNAs (shRNA) targeting PKC isoforms. Notably, AEB071 at low micromolar concentrations significantly inhibited the growth of uveal melanoma cells harboring GNAQ mutations through induction of G 1 arrest and apoptosis. However, AEB071 had little effect on uveal melanoma cells carrying wild-type GNAQ. AEB071-mediated cell inhibition in the GNAQ-mutated uveal melanoma was accompanied by inhibition of extracellular signal-regulated kinase (Erk)1/2 phosphorylation, NF-κB, decreased expression of cyclin D1, survivin, Bcl-xL, and XIAP, and increased expression of cyclin-dependent kinase inhibitor p27Kip1. AEB071 suppressed the expression of PKC α, β, δ, ε, and θ in GNAQ-mutated uveal melanoma cells. Our findings from shRNA-mediated knockdown studies revealed that these PKC isoforms are functionally important for uveal melanoma cells harboring GNAQ mutations. Furthermore, inhibitors of Erk1/2 and NF-κB pathways reduced viability of uveal melanoma cells. Together, our findings show that AEB071 exerts antitumor action on uveal melanoma cells carrying GNAQ mutations via targeting PKC/Erk1/2 and PKC/NF-κB pathways. Targeted PKC inhibition with drugs such as AEB071 offers novel therapeutic potential for uveal melanoma harboring GNAQ mutations. ©2012 AACR.