Protamine sulfate downregulates vascular endothelial growth factor (VEGF) expression and inhibits VEGF and its receptor binding in vitro.
OBJECTIVE
To investigate protamine sulfate inhibition of expression of the vascular endothelial growth factor (VEGF) and VEGF-VEGFR binding in vitro and to find a new drug that inhibits neovascularization, which can potentially be used to treat angiogenic eye diseases such as diabetic retinopathy and age-related macular degeneration (AMD).


METHODS
Monkey retinal vascular endothelial cells (RF/6A) were cultured in vitro and different concentrations of protamine sulfate were added to the vascular endothelial cells after three passages. VEGF expression level was examined by ELISA and immunohistochemistry after the cells were treated with protamine sulfate.


RESULTS
VEGF expression decreased in a dose-dependent pattern in 10-80 mug/ml of protamine sulfate. We also found that protamine sulfate could inhibit VEGF to bind to its receptor, VEGFR.


CONCLUSIONS
Protamine sulfate could inhibit VEGF expression and VEGF-VEGFR binding in vitro. Protamine sulfate may be used for inhibiting neovascularization in angiogenic eye diseases. Angiogenic eye diseases such as diabetic retinopathy (DR), age-related macular degeneration (AMD) and retinal vein occlusion are the main blindness-causing diseases. Previous studies indicated that VEGF and its receptor were involved in the pathogenesis, development and prognosis of these diseases. VEGF inhibition drugs have been used successfully in clinical treatment, but the cost is prohibitive.Protamine sulfate is a common, inexpensive anti-coagulation drug widely used for anti-coagulation in cases when heparin has been overused in the clinic. Recent studies suggest that protamine sulfate can inhibit tumor growth, probably through inhibiting vascular growth of the tumor. In this study we showed that protamine sulfate could inhibit VEGF and the binding of VEGF and its receptor, implying that protamine sulfate may inhibit blood vessel growth through inhibition of the VEGF pathway. This study further suggested that protamine sulfate may be potentially used to treat angiogenic eye diseases.
Department of Ophthalmology, Sichuan Academy of Medical Sciences, Sichuan, China. jbinhy@hotmail.com
Jianbin
J
Hu
Chao
C
Qu
Yufeng
Y
Yu
Ma
M
Ping
Dong
D
Wei
Dong
D
Dandan
D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line; D015536:Down-Regulation / Q000187:drug effects*; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000882:Haplorhini; D011479:Protamines / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D040262:Receptors, Vascular Endothelial Growth Factor / Q000378:metabolism*; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
D011479:Protamines; D042461:Vascular Endothelial Growth Factor A; D040262:Receptors, Vascular Endothelial Growth Factor