Purpose: To compare the proteomic profiles of two categories of primary uveal melanoma tissue samples; those from patients who have subsequently developed metastatic disease and those who have not.
Methods: Two-dimensional difference gel electrophoresis (2D DIGE) was performed on 25 uveal melanoma tissue specimens (minimum follow-up of 7 years) comparing nine uveal melanoma tumors from patients who developed metastatic disease and 16 from those who did not. Most of the tumors which metastasized also exhibited chromosome 3 monosomy. Selected differentially expressed proteins were further followed up by immunohistochemistry and functional validation in vitro using siRNA.
Results: Proteomic analysis revealed 14 statistically significant differentially expressed proteins, with nine showing increased expression (PDIA3, VIM/HEXA, SELENBP1, ENO1, CAPZA1, ERP29, TPI1, PARK7, and FABP3) and five showing decreased expression (EIF2S, PSMA3, RPSA, TUBB, and TUBA1B) in uveal melanomas that subsequently metastasized compared with those that did not. Immunohistochemical analysis was performed for six of the differentially expressed proteins and gave similar results to the 2D DIGE study for two of these proteins, fatty acid-binding protein, heart-type (FABP3) and triosephosphate isomerase (TPI1). siRNA knockdown in the 92.1 uveal melanoma cell line confirmed a functional role for FABP3 and TPI1 in invasion in vitro.
Conclusions: Proteomic analysis identified proteins differentially expressed in uveal melanoma that will subsequently metastasize, some of which appear to have a functional role in invasion. These results may contribute to better predictive tests (along with genetic analysis) and to the identification of new therapeutic targets.