Metastasis is a major obstacle in the therapeutic intervention of
melanoma, and several
GTP-binding proteins were found to play important roles in regulating
cancer metastasis. To assess systematically the regulatory roles of these
proteins in
melanoma metastasis, we employed a targeted chemoproteomic method, which relies on the application of stable
isotope-labeled
desthiobiotin-
GTP acyl
phosphate probes in conjunction with scheduled multiple-reaction monitoring (MRM), for profiling quantitatively the
GTP-binding proteins. Following probe labeling, tryptic digestion, and affinity pull-down of
desthiobiotin-conjugated
peptides, differences in expression levels of
GTP-binding proteins in two matched pairs of primary/metastatic
melanoma cell lines were measured using liquid chromatography-MRM analysis. We also showed that among the top upregulated
proteins in metastatic
melanoma cells, AK4 promotes the migration and invasion of
melanoma cells; overexpression of AK4 in primary
melanoma cells leads to augmented migration and invasion, and reciprocally, knockdown of AK4 in metastatic
melanoma cells results in repressed invasiveness. In summary, we examined the relative expression levels of
GTP-binding proteins in two pairs of primary/metastatic
melanoma cell lines. Our results confirmed some previously reported regulators of
melanoma metastasis and revealed a potential role of AK4 in promoting
melanoma metastasis.