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F. U. Ricci, P. Mazzarelli, M. J. Zonetti, F. Missiroli, Jr., M. Cesareo, Sr., S. Pucci; 810 nm Micropulse Laser Irradiation Selectively Regulates VEGF165 Isoforms Expression Acting on RNA Binding Splice Factor Activation in Indocyanine Green Loaded ARPE19 and Caco2 Cultured Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):56.
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© ARVO (1962-2015); The Authors (2016-present)
In order to characterize the biological effects and molecular mechanism underlying indocyanine green (ICG)-mediated photodynamic therapy , ICG loaded cultured retinal pigmented epithelium cells (ARPE19) and colon cancer epithelial cells (Caco2) were exposed to 810-nm laser radiation. Cell viability and death induction were examined, as well as the modulation of proteins involved in cell death and DNA repair and the effect on the expression of VEGF165 antagonistic isoforms .
ICG preloaded ARPE19 cells and Caco2 cells were exposed to micropulse 810 nm laser radiation. VEGF165a and b isoforms, HIF1α and the shift of the antagonistic isoforms of Clusterin (nCLU and sCLU) expression were evaluated. Bax release from Ku70 protein was also investigated. In addition,Caco2 cells were underskin injected in nude mice. ICG-preloaded mice were laser irradiated and molecular mechanisms inducing the specific VEGF165a inhibition and the preferential VEGF165b expression, growth arrest and apoptosis induction were studied.
A selective induction of VEGF165b isoform was found in irradiated ARPE19 and Caco2 cells, as compared to un-irradiated controls. In colon cancer xenografts a strong induction of the anti-proliferative and anti-angiogenic VEGF 165b isoform was observed, as compared to untreated tumors. The VEGF165b expression correlated to an increased RNA binding splice factor activation.
VEGF is a key component involved in physiological and pathological angiogenesis. Inhibition of VEGF has been shown to be effective in cancer and eye diseases. Two different splicing isoforms of VEGFA165 (a and b) have been recently identified, exerting pro- or anti-angiogenic actions and whose formation is strictly controlled by micro-environmental factors. The production of these forms of VEGF depends upon splice site selection of RNA, controlled by binding splice factors previously shown to regulate VEGF splice site choice.Our data show that ICG mediated photodynamic therapy could stimulate the selective and specific expression of antiangiogenic isoform of VEGF, influencing its splice variant formation (VEGF165b) in cultured ARPE19 and Caco2 cells as well as in experimental models of colon cancer.Uncovering the molecular mechanisms involved in the differential expression of the 2 VEGF isoforms may yield novel therapeutic strategy in the therapy of neovascular eye diseases and cancer.
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