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R. Dror, M. Lederman, K. Umezawa, V. Barak, J. Pe’er, I. Chowers; NFkB Transcription Factor as a Therapeutic Target in Uveal Melanoma. Invest. Ophthalmol. Vis. Sci. 2008;49(13):65.
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© ARVO (1962-2015); The Authors (2016-present)
We previously showed that NFkB transcription factor influences the expression of several genes with altered mRNA levels in liver metastases from uveal melanoma (UM). Here we aim to further elucidate NFkB activity in UM and to evaluate its inhibition as a potential therapeutic strategy for metastatic UM.
Samples from primary and metastatic UM were evaluated for NFkB transcription factor family gene expression by quantitative PCR (QPCR), immunoflurecence staining, western blot, and ELISA. The effect of two NFkB inhibitors, DHMEQ and BMS-345541, on two cells lines derived from UM liver metastases (M15 and M85) was assessed. Cell proliferation was examined by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, Methylene blue assay, and staining for Ki-67. Apoptosis was assessed by staining for activated caspase-3.
NFkB1, NFkB2, RelA and RelB were expressed in primary UM and in its liver metastases. NFkB2 and RelB showed significantly higher mRNA levels in UM metastases in comparison to the primary tumor (3.4-fold; p=0.03, and 3.6-fold; p=0.05, respectively). NFkB2 protein activation was 3.9-fold higher in metastases samples (p=0.03). NFkB inhibition reduced metastases cells proliferation by 9.2-fold according to Ki67 staining (p=0.04), and by 1.9-fold according to methylene blue assay (p=6*10-7). Both NFkB inhibitors achieved dose dependent reduction of UM cell proliferation according to MTT analysis, in both cell lines which were evaluated (p<0.001 for both DHMEQ and BMS-345541). NFkB inhibition resulted in 6.3-fold increase of apoptosis (p=7*10-7), and significantly reduced the expression of genes downstream to NFkB including OPN, TNFα, IL6, IL8 and Gadd45β.
These data indicate that NFkB1 and NFkB2 pathways are active in both primary and metastatic UM and that these pathways regulate metastases cells proliferation and apoptosis. Therefore, NFkB may serve as a new therapeutic target for UM metastases.
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