Expression of SIRT1 in choroidal neovascular membranes.

PURPOSE: SIRT1 is a deacetylase that has been shown to be instrumental in embryonic and pathologic vascular formation. The purpose of this study was to evaluate the potential role of SIRT1 in the pathogenesis of choroidal neovascularization in age-related macular degeneration. METHODS: The expression of SIRT1 was assessed via immunohistochemistry in nine excised human choroidal neovascularization membranes and seven non-age-related macular degeneration donor eyes. Enzyme-linked immunosorbent assay-based angiogenesis arrays were used to assess the potential of an SIRT1 inhibitor, nicotinamide, to reduce secretion of 10 unique proangiogenic cytokines from retinal pigment epithelial cells. RESULTS: SIRT1 was expressed more frequently in choroidal neovascularization membranes than donor eyes about vascular endothelial cells (78 vs. 29% positive cases) and retinal pigment epithelial cells (57 vs. 14% positive cases). SIRT1 inhibition in retinal pigment epithelial cells correlated with significantly decreased secretion of three potent proangiogenic cytokines: angiogenin, platelet-derived growth factor BB, and vascular endothelial growth factor A. CONCLUSION: SIRT1 levels appear elevated in human choroidal neovascularization membranes compared with control eyes. Moreover, inhibition of SIRT1 activity is correlated with decreased secretion of potent proangiogenic cytokines. Collectively, these data support a potential role for SIRT1 in the pathogenesis of neovascular age-related macular degeneration.

Aberrant nuclear repressor coreceptor 1 localization in human retinoblastoma.

BACKGROUND/AIMS: Nuclear receptor corepressor 1 (NCoR1) is a protein complex with diverse functions in development and tumorigenesis. We investigated the pattern of expression and histopathological correlation of NCoR1 in 41 retinoblastoma tumor samples, 1 retinoblastoma cell line (WERI-Rb-1) and human retinal progenitor cells (hRPCs). METHODS: Tissue sections from 41 retinoblastoma cases, the retinoblastoma cell line WERI-Rb-1 and hRPCs were stained with rabbit polyclonal anti-NCoR1 H76 antibody. Percentage and intensity of staining were classified by an ocular pathologist from 0 to 3. The paired t test was used to test for differences. RESULTS: In the nonneoplastic retina, NCoR1 was expressed mainly in cell nuclei. The retinoblastoma tumor cells similarly had nuclear NCoR1 but also had a higher level of cytoplasmic NCoR1 expression compared to all 3 normal retinal cell layers (p < 0.002). In contrast to the normal retina, NCoR1 was mainly expressed in the cytoplasm of the proliferating WERI-Rb-1 cells. This cytoplasmic expression pattern was also seen in the undifferentiated hRPCs. CONCLUSIONS: The aberrant cytoplasmic expression of NCoR1 in retinoblastoma appears to be associated with the proliferative and/or dedifferentiated properties of retinoblastoma. Further investigation into the role of NCoR1 in retinoblastoma may provide insight into how therapeutically inhibiting its nucleocytoplasmic shuttling may affect retinoblastoma tumor biology.

3,4 dihydroxyphenyl ethanol reduces secretion of angiogenin in human retinal pigment epithelial cells.

BACKGROUND: Age-related macular degeneration (AMD) is currently the leading cause of blindness in developed countries. Bevacizumab is a widely used anti-VEGF agent that is a commonly applied therapy for neovascular AMD; however, a consequence of bevacizumab therapy may be the activation of compensatory angiogenic signalling. Combination of bevacizumab with 3,4 dihydroxyphenyl ethanol (DPE) may attenuate this compensatory signalling. The goal of the study was to investigate this therapeutic option in a human retinal pigment epithelial cell line (ARPE-19). METHODS: ARPE-19 cells were incubated under both normoxic and hypoxic conditions. The cells were treated as follows: control, 100 µM DPE, 0.25 mg/ml bevacizumab, the combination of DPE and bevacizumab. Media was harvested after 24 h for sandwich ELISA-based angiogenesis assays. The secretion of the following 10 pro-angiogenic cytokines was measured: angiogenin, ANG2, EGF, bFGF, HB-EGF, PDGF-BB, Leptin, PIGF, HGF, and VEGF-A. RESULTS: Treatment of ARPE-19 cells with bevacizumab significantly increased the secretion of angiogenin. Secretion of angiogenin and VEGF-A were significantly reduced following treatment with DPE under both normoxia and hypoxia. In addition, angiogenin secretion was significantly reduced following treatment with the combination of DPE and bevacizumab compared to bevacizumab alone. CONCLUSIONS: Compensatory angiogenic signalling may occur in neovascular AMD following treatment with bevacizumab. Here we show that DPE, both alone and in combination with bevacizumab, can reduce the secretion of angiogenin, a cytokine that has been upregulated following treatment with bevacizumab in RPE cells. Therefore, DPE may represent a possible therapeutic agent to be used in combination with bevacizumab for the treatment of neovascular AMD.