Genistein Inhibits Growth And Induces Apoptosis Of Cultured Human Retinal Pigment Epithelial Cells

Purpose Proliferative vitreoretinopathy (PVR) after rhegmato- genous retinal detachment or surgical intervention is a series of cellular events that mostly include retinal pigment epithelial cell migration, proliferation, morphologic changes, as well as synthesis of some proteins and extracellular matrix (ECM), followed by membrane formation and traction along surfaces of the detached retina, resulting in failure of surgical retinal reattachment. PVR is an excessively wound healing which has imbalance between cellular proliferation and cell death. How to reduce growth and induce apoptosis of hRPE is important to the progession of PVR. Genistein, a natural tyrosine kinase inhibitor, has been reported to inhibit growth and induce apoptosis of various turner cells. This article aims to study effects of genistein on cultured human retinal pigment epithelial cells in vitro. Methods The effect of genistein on the proliferation of cultured hRPE was examined by tetrazolium salt (MIT) assay and AgNORs staining. Cell apoptosis were detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick-end labeling (TUNEL) methods, in the mean time, the morphologic changes of cell apoptosis were observed by light microscopy and transmission electronic microscopy Results (1)Ranging from 25mg/L to lOOmg/L, genistein had a dose-dependent and time-dependent antiproliferative effects on hRPE(the range of inhibitory rate: 12 O%?4.6%) AgNORs staining results showed: the number of AgNORs in the nuclear decreased when treated by genistein. AiIer treated with 5Omg/L genistein for 12h, the mean number of AgNORs was 3.8(P=O.034); and 25 mg/L genistein for 24h it was 3.9(P=O.023) 6 (2)TUNEL positive RPE were detected in the cells coverlips treated with 50 mg/L genistein for 24h. At the time point of 24h, 48h, 72h, the median positive cells of TUNEL staining treated with 50 mg/L genistein were7.6%, 9.8%, 13.7~/o, respectively. And treated with 75 mg/L genistein, the median positivee cells of TUNEL were 10.3%, 16.4%, 23.4%, respectively. And with lOOmgIL genistein, they were 15.4%, 21.2%, 35.8%. (3)Afier SOmg/L genistein treatment, margination of nuclear chromatin and intact plasmalemma was observed, RPE exhibited earlier stage of apoposis presentation. While after 75mg/L genistein treatment, RPE showed condensation of nuclear chromatin and dense apoptosiS bodies, which was identified typical apoptosis characterization. When treated with lOOmg/L genistein~ besides apoptosis manifestation, part of RPE presented progressively lysis of cytoplasm and destruction of cell membrane, thus the rate of necrosis RPE increased. Conclusion Ranging from 25mg/L to lOOmg/L, genistein has a dose-dependent and time-dependent antiproliferative effect on hRPE. Genistein can induce the apoptosis of hRPE, which to the extent, have dose-dependent and time-dependent effect. High concentration of genistein (100 mgIL) can induce RIPE necrosis with its cytotoxicity. It suggests a new approach for the mechanism and prevention and cure of PVR.