Characterizing the Involvement of the Nuclear Factor-kappa B (NFκB) Transcription Factor in Uveal Melanoma

PURPOSE. To examine the involvement of nuclear factor-kappa B (NF kappa B) pathways in uveal melanoma (UM) and to assess their potential as a therapeutic target for metastatic UM. METHODS. Samples from primary (n = 7) and metastatic (n = 7) UM were evaluated for NF kappa B transcription factor family expression by quantitative PCR (QPCR), immunofluorescent staining, and Western blot analysis. The effect of two NF kappa B inhibitors, DHMEQ and BMS-345541, on two cell lines derived from UM liver metastases was assessed. Cell proliferation was examined by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, methylene blue assay, and immunostaining for Ki-67. Apoptosis was assessed by immunostaining for activated caspase 3. RESULTS. NF kappa B1, NF kappa B2, RelA, RelB, and NIK were expressed in primary UM and in its liver metastases. NF kappa B2, RelB, and NIK showed significantly higher mRNA levels in metastases from UM compared with primary tumors (3.4-fold, P = 0.03; 3.6-fold, P = 0.05; 3.5-fold, P = 0.03; respectively). NF kappa B2 protein activation was 3.9-fold higher in metastases (P = 0.03). NF kappa B inhibition reduced metastatic cell proliferation by 9.2-fold and 1.9-fold according to Ki67 staining (P = 0.04) and methylene blue assay (P = 6 x 10(-7)), respectively. Both NF kappa B inhibitors achieved dose-dependent reductions of UM cell proliferation in both cell lines (P < 0.001). NF kappa B inhibition resulted in a 6.3-fold increase of apoptosis (P = 7 x 10(-7)). CONCLUSIONS. These data indicate that the NF kappa B1 and NF kappa B2 pathways are active in both primary and metastatic UM and that these pathways regulate metastatic cell proliferation and apoptosis. The role of NF kappa B as a therapeutic target for UM should be further evaluated. (Invest Ophthalmol Vis Sci. 2010; 51:1811-1816) DOI: 10.1167/iovs.09-3392